* [PATCH v7 0/8] Extend rseq support
@ 2024-02-01 19:36 Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 1/8] nptl: fix potential merge of __rseq_* relro symbols Michael Jeanson
` (8 more replies)
0 siblings, 9 replies; 11+ messages in thread
From: Michael Jeanson @ 2024-02-01 19:36 UTC (permalink / raw)
To: libc-alpha
Cc: Michael Jeanson, Florian Weimer, Carlos O'Donell, Mathieu Desnoyers
This series rebases the standalone "Add rseq extensible ABI" patch on
current master and adds an accelerated getcpu() implementation using the
rseq extensible ABI with initial support for aarch64 and x86_64.
On an aarch64 system (Snapdragon 8cx Gen 3) which lacks a vDSO for
getcpu() we measured an improvement from 130 ns to 1 ns while on x86_64
(i7-8550U) which has a vDSO we measured a more modest improvement from
10 ns to 2 ns.
Tested on i386, aarch64 and x86_64.
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Carlos O'Donell <carlos@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Mathieu Desnoyers (2):
x86-64: Add rseq_load32_load32_relaxed
aarch64: Add rseq_load32_load32_relaxed
Michael Jeanson (6):
nptl: fix potential merge of __rseq_* relro symbols
Add rseq extensible ABI support
nptl: Add public __rseq_feature_size symbol
nptl: Add features to internal 'struct rseq_area'
nptl: Add rseq internal utils
Linux: Use rseq to accelerate getcpu
csu/Makefile | 2 +-
csu/libc-tls.c | 66 ++++++-
csu/rseq-sizes.sym | 11 ++
elf/Makefile | 1 +
elf/dl-rseq-symbols.S | 72 ++++++++
elf/dl-tls.c | 62 +++++++
elf/rtld_static_init.c | 12 ++
manual/threads.texi | 8 +
nptl/descr.h | 20 +-
nptl/pthread_create.c | 2 +-
sysdeps/generic/dl-rseq.h | 26 +++
sysdeps/generic/ldsodefs.h | 12 ++
sysdeps/i386/nptl/tcb-access.h | 56 ++++++
sysdeps/nptl/dl-tls_init_tp.c | 16 +-
sysdeps/nptl/tcb-access.h | 5 +
sysdeps/unix/sysv/linux/Makefile | 10 +
sysdeps/unix/sysv/linux/Versions | 3 +
sysdeps/unix/sysv/linux/aarch64/ld.abilist | 1 +
.../unix/sysv/linux/aarch64/rseq-internal.h | 173 ++++++++++++++++++
sysdeps/unix/sysv/linux/alpha/ld.abilist | 1 +
sysdeps/unix/sysv/linux/arc/ld.abilist | 1 +
sysdeps/unix/sysv/linux/arm/be/ld.abilist | 1 +
sysdeps/unix/sysv/linux/arm/le/ld.abilist | 1 +
sysdeps/unix/sysv/linux/csky/ld.abilist | 1 +
sysdeps/unix/sysv/linux/dl-parse_auxv.h | 6 +
sysdeps/unix/sysv/linux/getcpu.c | 32 +++-
sysdeps/unix/sysv/linux/hppa/ld.abilist | 1 +
sysdeps/unix/sysv/linux/i386/ld.abilist | 1 +
.../unix/sysv/linux/loongarch/lp64/ld.abilist | 1 +
.../unix/sysv/linux/m68k/coldfire/ld.abilist | 1 +
.../unix/sysv/linux/m68k/m680x0/ld.abilist | 1 +
sysdeps/unix/sysv/linux/microblaze/ld.abilist | 1 +
.../unix/sysv/linux/mips/mips32/ld.abilist | 1 +
.../sysv/linux/mips/mips64/n32/ld.abilist | 1 +
.../sysv/linux/mips/mips64/n64/ld.abilist | 1 +
sysdeps/unix/sysv/linux/nios2/ld.abilist | 1 +
sysdeps/unix/sysv/linux/or1k/ld.abilist | 1 +
.../sysv/linux/powerpc/powerpc32/ld.abilist | 1 +
.../linux/powerpc/powerpc64/be/ld.abilist | 1 +
.../linux/powerpc/powerpc64/le/ld.abilist | 1 +
sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist | 1 +
sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist | 1 +
sysdeps/unix/sysv/linux/rseq-internal.h | 89 ++++++++-
.../unix/sysv/linux/s390/s390-32/ld.abilist | 1 +
.../unix/sysv/linux/s390/s390-64/ld.abilist | 1 +
sysdeps/unix/sysv/linux/sched_getcpu.c | 3 +-
sysdeps/unix/sysv/linux/sh/be/ld.abilist | 1 +
sysdeps/unix/sysv/linux/sh/le/ld.abilist | 1 +
.../unix/sysv/linux/sparc/sparc32/ld.abilist | 1 +
.../unix/sysv/linux/sparc/sparc64/ld.abilist | 1 +
sysdeps/unix/sysv/linux/sys/rseq.h | 4 +
.../unix/sysv/linux/tst-rseq-disable-static.c | 1 +
sysdeps/unix/sysv/linux/tst-rseq-disable.c | 20 +-
.../unix/sysv/linux/tst-rseq-nptl-static.c | 1 +
sysdeps/unix/sysv/linux/tst-rseq-static.c | 1 +
sysdeps/unix/sysv/linux/tst-rseq.c | 24 ++-
sysdeps/unix/sysv/linux/tst-rseq.h | 9 +-
sysdeps/unix/sysv/linux/x86_64/64/ld.abilist | 1 +
.../unix/sysv/linux/x86_64/rseq-internal.h | 109 +++++++++++
sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist | 1 +
sysdeps/x86_64/nptl/tcb-access.h | 56 ++++++
61 files changed, 886 insertions(+), 56 deletions(-)
create mode 100644 csu/rseq-sizes.sym
create mode 100644 elf/dl-rseq-symbols.S
create mode 100644 sysdeps/generic/dl-rseq.h
create mode 100644 sysdeps/unix/sysv/linux/aarch64/rseq-internal.h
create mode 100644 sysdeps/unix/sysv/linux/tst-rseq-disable-static.c
create mode 100644 sysdeps/unix/sysv/linux/tst-rseq-nptl-static.c
create mode 100644 sysdeps/unix/sysv/linux/tst-rseq-static.c
create mode 100644 sysdeps/unix/sysv/linux/x86_64/rseq-internal.h
--
2.34.1
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v7 1/8] nptl: fix potential merge of __rseq_* relro symbols
2024-02-01 19:36 [PATCH v7 0/8] Extend rseq support Michael Jeanson
@ 2024-02-01 19:36 ` Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 2/8] Add rseq extensible ABI support Michael Jeanson
` (7 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: Michael Jeanson @ 2024-02-01 19:36 UTC (permalink / raw)
To: libc-alpha
Cc: Michael Jeanson, Florian Weimer, Carlos O'Donell, Mathieu Desnoyers
While working on a patch to add support for the extensible rseq ABI, we
came across an issue where a new 'const' variable would be merged with
the existing '__rseq_size' variable. We tracked this to the use of
'-fmerge-all-constants' which allows the compiler to merge identical
constant variables. This means that all 'const' variables in a compile
unit that are of the same size and are initialized to the same value can
be merged.
In this specific case, on 32 bit systems 'unsigned int' and 'ptrdiff_t'
are both 4 bytes and initialized to 0 which should trigger the merge.
However for reasons we haven't delved into when the attribute 'section
(".data.rel.ro")' is added to the mix, only variables of the same exact
types are merged. As far as we know this behavior is not specified
anywhere and could change with a new compiler version, hence this patch.
Move the definitions of these variables into an assembler file and add
hidden writable aliases for internal use. This has the added bonus of
removing the asm workaround to set the values on rseq registration.
Tested on Debian 12 with GCC 12.2.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
csu/Makefile | 2 +-
csu/rseq-sizes.sym | 8 +++++
elf/Makefile | 1 +
elf/dl-rseq-symbols.S | 55 +++++++++++++++++++++++++++++++++++
sysdeps/nptl/dl-tls_init_tp.c | 14 ++++-----
5 files changed, 71 insertions(+), 9 deletions(-)
create mode 100644 csu/rseq-sizes.sym
create mode 100644 elf/dl-rseq-symbols.S
diff --git a/csu/Makefile b/csu/Makefile
index ac05ab24d5..0bf51a0e48 100644
--- a/csu/Makefile
+++ b/csu/Makefile
@@ -99,7 +99,7 @@ before-compile += $(objpfx)abi-tag.h
generated += abi-tag.h
# Put it here to generate it earlier.
-gen-as-const-headers += rtld-sizes.sym
+gen-as-const-headers += rtld-sizes.sym rseq-sizes.sym
# These are the special initializer/finalizer files. They are always the
# first and last file in the link. crti.o ... crtn.o define the global
diff --git a/csu/rseq-sizes.sym b/csu/rseq-sizes.sym
new file mode 100644
index 0000000000..c959758ff0
--- /dev/null
+++ b/csu/rseq-sizes.sym
@@ -0,0 +1,8 @@
+#include <stddef.h>
+
+--
+RSEQ_SIZE_SIZE sizeof (unsigned int)
+RSEQ_SIZE_ALIGN __alignof (unsigned int)
+
+RSEQ_OFFSET_SIZE sizeof (ptrdiff_t)
+RSEQ_OFFSET_ALIGN __alignof (ptrdiff_t)
diff --git a/elf/Makefile b/elf/Makefile
index 5d78b659ce..7d711aedf0 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -73,6 +73,7 @@ dl-routines = \
dl-origin \
dl-printf \
dl-reloc \
+ dl-rseq-symbols \
dl-runtime \
dl-scope \
dl-setup_hash \
diff --git a/elf/dl-rseq-symbols.S b/elf/dl-rseq-symbols.S
new file mode 100644
index 0000000000..2d8e88367f
--- /dev/null
+++ b/elf/dl-rseq-symbols.S
@@ -0,0 +1,55 @@
+/* Define symbols used by rseq.
+ Copyright (C) 2024 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <rseq-sizes.h>
+#include <sysdep.h>
+
+/* Some targets define a macro to denote the zero register. */
+#undef zero
+
+/* Define 2 symbols, __rseq_size is public const and _rseq_size, which is an
+ alias of __rseq_size, but hidden and writable for internal use. */
+
+ .globl __rseq_size
+ .type __rseq_size, %object
+ .size __rseq_size, RSEQ_SIZE_SIZE
+ .hidden _rseq_size
+ .globl _rseq_size
+ .type _rseq_size, %object
+ .size _rseq_size, RSEQ_SIZE_SIZE
+ .section .data.rel.ro
+ .balign RSEQ_SIZE_ALIGN
+__rseq_size:
+_rseq_size:
+ .zero RSEQ_SIZE_SIZE
+
+/* Define 2 symbols, __rseq_offset is public const and _rseq_offset, which is an
+ alias of __rseq_offset, but hidden and writable for internal use. */
+
+ .globl __rseq_offset
+ .type __rseq_offset, %object
+ .size __rseq_offset, RSEQ_OFFSET_SIZE
+ .hidden _rseq_offset
+ .globl _rseq_offset
+ .type _rseq_offset, %object
+ .size _rseq_offset, RSEQ_OFFSET_SIZE
+ .section .data.rel.ro
+ .balign RSEQ_OFFSET_ALIGN
+__rseq_offset:
+_rseq_offset:
+ .zero RSEQ_OFFSET_SIZE
diff --git a/sysdeps/nptl/dl-tls_init_tp.c b/sysdeps/nptl/dl-tls_init_tp.c
index 092c274f36..80eb0107b5 100644
--- a/sysdeps/nptl/dl-tls_init_tp.c
+++ b/sysdeps/nptl/dl-tls_init_tp.c
@@ -45,8 +45,10 @@ rtld_mutex_dummy (pthread_mutex_t *lock)
#endif
const unsigned int __rseq_flags;
-const unsigned int __rseq_size attribute_relro;
-const ptrdiff_t __rseq_offset attribute_relro;
+
+/* The variables are in .data.relro but are not yet write-protected. */
+extern unsigned int _rseq_size attribute_relro attribute_hidden;
+extern ptrdiff_t _rseq_offset attribute_relro attribute_hidden;
void
__tls_pre_init_tp (void)
@@ -105,10 +107,7 @@ __tls_init_tp (void)
do_rseq = TUNABLE_GET (rseq, int, NULL);
if (rseq_register_current_thread (pd, do_rseq))
{
- /* We need a writable view of the variables. They are in
- .data.relro and are not yet write-protected. */
- extern unsigned int size __asm__ ("__rseq_size");
- size = sizeof (pd->rseq_area);
+ _rseq_size = sizeof (pd->rseq_area);
}
#ifdef RSEQ_SIG
@@ -117,8 +116,7 @@ __tls_init_tp (void)
all targets support __thread_pointer, so set __rseq_offset only
if the rseq registration may have happened because RSEQ_SIG is
defined. */
- extern ptrdiff_t offset __asm__ ("__rseq_offset");
- offset = (char *) &pd->rseq_area - (char *) __thread_pointer ();
+ _rseq_offset = (char *) &pd->rseq_area - (char *) __thread_pointer ();
#endif
}
--
2.34.1
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v7 2/8] Add rseq extensible ABI support
2024-02-01 19:36 [PATCH v7 0/8] Extend rseq support Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 1/8] nptl: fix potential merge of __rseq_* relro symbols Michael Jeanson
@ 2024-02-01 19:36 ` Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 3/8] nptl: Add public __rseq_feature_size symbol Michael Jeanson
` (6 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: Michael Jeanson @ 2024-02-01 19:36 UTC (permalink / raw)
To: libc-alpha
Cc: Michael Jeanson, Florian Weimer, Carlos O'Donell, Mathieu Desnoyers
Introduced in Linux v6.3 the rseq extensible ABI [1] will allow adding
rseq features past the initial 32 bytes of the original ABI.
While the rseq features in the latest kernel still fit within the
original ABI size, there are currently only 4 bytes left. It would thus
be a good time to add support for the extensible ABI so that when new
features are added, they are immediately available to GNU libc users.
We use the ELF auxiliary vectors to query the kernel for the size and
alignment of the rseq area, if this fails we default to the original
fixed size and alignment of '32' which the kernel will accept as a
compatibility mode with the original ABI.
This makes the size of the rseq area variable and thus requires to
relocate it out of 'struct pthread'. We chose to move it after (in block
allocation order) the last TLS block since it required a fairly small
modification to the TLS block allocator and did not interfere with the
main executable TLS block which must always be first.
[1] https://lore.kernel.org/all/20221122203932.231377-4-mathieu.desnoyers@efficios.com/
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Co-Authored-By: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-By: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
Changes since RFC v1:
- Insert the rseq area after the last TLS block
- Add proper support for TLS_TCB_AT_TP variant
Changes since RFC v2:
- Set __rseq_size even when the registration fails
- Adjust rseq tests to the new ABI
- Added support for statically linked executables
Changes since RFC v3:
- Fix RSEQ_SETMEM for rseq disabled
- Replace sys/auxv.h usage with dl-parse_auxv.h
- Fix offset for TLS_TCB_AT_TP with statically linked executables
- Zero the rseq area before registration
Changes since RFC v4:
- Move dynamic linker defines to a header file
- Fix alignment when tls block align is smaller than rseq align with
statically linked executables
- Add statically linked rseq tests
- Revert: Set __rseq_size even when the registration fails
- Use minimum size when rseq is disabled by tunable
Changes since v5:
- Fix TLS_DTV_AT_TP rseq offset with statically linked executables
Changes since v6:
- Fix tst-rseq for feature size over 32 bytes
- Rebased on 'nptl: fix potential merge of __rseq_* relro symbols'
---
csu/libc-tls.c | 66 ++++++++++++++++---
elf/dl-tls.c | 62 +++++++++++++++++
elf/rtld_static_init.c | 12 ++++
nptl/descr.h | 20 +-----
nptl/pthread_create.c | 2 +-
sysdeps/generic/dl-rseq.h | 26 ++++++++
sysdeps/generic/ldsodefs.h | 12 ++++
sysdeps/i386/nptl/tcb-access.h | 56 ++++++++++++++++
sysdeps/nptl/dl-tls_init_tp.c | 4 +-
sysdeps/nptl/tcb-access.h | 5 ++
sysdeps/unix/sysv/linux/Makefile | 10 +++
sysdeps/unix/sysv/linux/dl-parse_auxv.h | 6 ++
sysdeps/unix/sysv/linux/rseq-internal.h | 29 ++++++--
sysdeps/unix/sysv/linux/sched_getcpu.c | 3 +-
.../unix/sysv/linux/tst-rseq-disable-static.c | 1 +
sysdeps/unix/sysv/linux/tst-rseq-disable.c | 19 +++---
.../unix/sysv/linux/tst-rseq-nptl-static.c | 1 +
sysdeps/unix/sysv/linux/tst-rseq-static.c | 1 +
sysdeps/unix/sysv/linux/tst-rseq.c | 22 +++++--
sysdeps/unix/sysv/linux/tst-rseq.h | 9 ++-
sysdeps/x86_64/nptl/tcb-access.h | 56 ++++++++++++++++
21 files changed, 375 insertions(+), 47 deletions(-)
create mode 100644 sysdeps/generic/dl-rseq.h
create mode 100644 sysdeps/unix/sysv/linux/tst-rseq-disable-static.c
create mode 100644 sysdeps/unix/sysv/linux/tst-rseq-nptl-static.c
create mode 100644 sysdeps/unix/sysv/linux/tst-rseq-static.c
diff --git a/csu/libc-tls.c b/csu/libc-tls.c
index b7682bdf43..9c70f53284 100644
--- a/csu/libc-tls.c
+++ b/csu/libc-tls.c
@@ -26,6 +26,8 @@
#include <array_length.h>
#include <pthreadP.h>
#include <dl-call_tls_init_tp.h>
+#include <dl-rseq.h>
+#include <elf/dl-tunables.h>
#ifdef SHARED
#error makefile bug, this file is for static only
@@ -62,6 +64,18 @@ size_t _dl_tls_static_surplus;
dynamic TLS access (e.g. with TLSDESC). */
size_t _dl_tls_static_optional;
+/* Size of the features present in the rseq area. */
+size_t _dl_tls_rseq_feature_size;
+
+/* Alignment requirement of the rseq area. */
+size_t _dl_tls_rseq_align;
+
+/* Size of the rseq area in the static TLS block. */
+size_t _dl_tls_rseq_size;
+
+/* Offset of the rseq area from the thread pointer. */
+ptrdiff_t _dl_tls_rseq_offset;
+
/* Generation counter for the dtv. */
size_t _dl_tls_generation;
@@ -110,6 +124,7 @@ __libc_setup_tls (void)
size_t filesz = 0;
void *initimage = NULL;
size_t align = 0;
+ size_t tls_blocks_size = 0;
size_t max_align = TCB_ALIGNMENT;
size_t tcb_offset;
const ElfW(Phdr) *phdr;
@@ -135,22 +150,61 @@ __libc_setup_tls (void)
/* Calculate the size of the static TLS surplus, with 0 auditors. */
_dl_tls_static_surplus_init (0);
+ /* Default to the rseq ABI minimum sizes, this will reduce TLS usage to 32
+ bytes when rseq is disabled by tunables. */
+ size_t rseq_size = TLS_DL_RSEQ_MIN_SIZE;
+ size_t rseq_align = TLS_DL_RSEQ_MIN_ALIGN;
+ bool do_rseq = true;
+ do_rseq = TUNABLE_GET_FULL (glibc, pthread, rseq, int, NULL);
+ if (do_rseq)
+ {
+ rseq_align = GLRO(dl_tls_rseq_align);
+ /* Make sure the rseq area size is at least the minimum ABI size and a
+ multiple of the requested aligment. */
+ rseq_size = roundup (MAX (GLRO(dl_tls_rseq_feature_size),
+ TLS_DL_RSEQ_MIN_SIZE), rseq_align);
+ }
+
+ /* Increase the max_align if necessary. */
+ max_align = MAX (max_align, rseq_align);
+
+ /* Record the rseq_area block size. */
+ GLRO (dl_tls_rseq_size) = rseq_size;
+
/* We have to set up the TCB block which also (possibly) contains
'errno'. Therefore we avoid 'malloc' which might touch 'errno'.
Instead we use 'sbrk' which would only uses 'errno' if it fails.
In this case we are right away out of memory and the user gets
what she/he deserves. */
#if TLS_TCB_AT_TP
+ /* Before the the thread pointer, add the aligned tls block size and then
+ align the rseq area block on top. */
+ tls_blocks_size = roundup (roundup (memsz, align ?: 1) + rseq_size, rseq_align);
+
+ /* Record the rseq_area offset. The offset is negative with TLS_TCB_AT_TP
+ because the TLS blocks are located before the thread pointer. */
+ GLRO (dl_tls_rseq_offset) = -tls_blocks_size;
+
/* Align the TCB offset to the maximum alignment, as
_dl_allocate_tls_storage (in elf/dl-tls.c) does using __libc_memalign
and dl_tls_static_align. */
- tcb_offset = roundup (memsz + GLRO(dl_tls_static_surplus), max_align);
+ tcb_offset = roundup (tls_blocks_size + GLRO(dl_tls_static_surplus), max_align);
tlsblock = _dl_early_allocate (tcb_offset + TLS_INIT_TCB_SIZE + max_align);
if (tlsblock == NULL)
_startup_fatal_tls_error ();
#elif TLS_DTV_AT_TP
+ /* Align memsz on top of the initial tcb. */
tcb_offset = roundup (TLS_INIT_TCB_SIZE, align ?: 1);
- tlsblock = _dl_early_allocate (tcb_offset + memsz + max_align
+
+ /* After the thread pointer, add the initial tcb plus the tls block size and
+ then align the rseq area block on top. */
+ tls_blocks_size = roundup (tcb_offset + memsz + rseq_size, rseq_align);
+
+ /* Record the rseq_area offset. The offset is positive with TLS_DTV_AT_TP
+ because the TLS blocks are located after the thread pointer. */
+ GLRO (dl_tls_rseq_offset) = tls_blocks_size - rseq_size;
+
+ tlsblock = _dl_early_allocate (tls_blocks_size + max_align
+ TLS_PRE_TCB_SIZE
+ GLRO(dl_tls_static_surplus));
if (tlsblock == NULL)
@@ -209,11 +263,5 @@ __libc_setup_tls (void)
/* static_slotinfo.slotinfo[1].gen = 0; -- Already zero. */
static_slotinfo.slotinfo[1].map = main_map;
- memsz = roundup (memsz, align ?: 1);
-
-#if TLS_DTV_AT_TP
- memsz += tcb_offset;
-#endif
-
- init_static_tls (memsz, MAX (TCB_ALIGNMENT, max_align));
+ init_static_tls (tls_blocks_size, MAX (TCB_ALIGNMENT, max_align));
}
diff --git a/elf/dl-tls.c b/elf/dl-tls.c
index 7b3dd9ab60..70fbe7095f 100644
--- a/elf/dl-tls.c
+++ b/elf/dl-tls.c
@@ -27,6 +27,7 @@
#include <tls.h>
#include <dl-tls.h>
+#include <dl-rseq.h>
#include <ldsodefs.h>
#if PTHREAD_IN_LIBC
@@ -298,6 +299,35 @@ _dl_determine_tlsoffset (void)
slotinfo[cnt].map->l_tls_offset = off;
}
+ /* Insert the rseq area block after the last TLS block. */
+
+ /* Default to the rseq ABI minimum sizes, this will reduce TLS usage to 32
+ bytes when rseq is disabled by tunables. */
+ size_t rseq_size = TLS_DL_RSEQ_MIN_SIZE;
+ size_t rseq_align = TLS_DL_RSEQ_MIN_ALIGN;
+ bool do_rseq = true;
+ do_rseq = TUNABLE_GET_FULL (glibc, pthread, rseq, int, NULL);
+ if (do_rseq)
+ {
+ rseq_align = GLRO(dl_tls_rseq_align);
+ /* Make sure the rseq area size is at least the minimum ABI size and a
+ multiple of the requested aligment. */
+ rseq_size = roundup (MAX (GLRO(dl_tls_rseq_feature_size),
+ TLS_DL_RSEQ_MIN_SIZE), rseq_align);
+ }
+
+ /* Add the rseq area block to the global offset. */
+ offset = roundup (offset, rseq_align) + rseq_size;
+
+ /* Increase the max_align if necessary. */
+ max_align = MAX (max_align, rseq_align);
+
+ /* Record the rseq_area block size and offset. The offset is negative
+ with TLS_TCB_AT_TP because the TLS blocks are located before the
+ thread pointer. */
+ GLRO (dl_tls_rseq_offset) = -offset;
+ GLRO (dl_tls_rseq_size) = rseq_size;
+
GL(dl_tls_static_used) = offset;
GLRO (dl_tls_static_size) = (roundup (offset + GLRO(dl_tls_static_surplus),
max_align)
@@ -343,6 +373,38 @@ _dl_determine_tlsoffset (void)
offset = off + slotinfo[cnt].map->l_tls_blocksize - firstbyte;
}
+ /* Insert the rseq area block after the last TLS block. */
+
+ /* Default to the rseq ABI minimum sizes, this will reduce TLS usage to 32
+ bytes when rseq is disabled by tunables. */
+ size_t rseq_size = TLS_DL_RSEQ_MIN_SIZE;
+ size_t rseq_align = TLS_DL_RSEQ_MIN_ALIGN;
+ bool do_rseq = true;
+ do_rseq = TUNABLE_GET_FULL (glibc, pthread, rseq, int, NULL);
+ if (do_rseq)
+ {
+ rseq_align = GLRO(dl_tls_rseq_align);
+ /* Make sure the rseq area size is at least the minimum ABI size and a
+ multiple of the requested aligment. */
+ rseq_size = roundup (MAX (GLRO(dl_tls_rseq_feature_size),
+ TLS_DL_RSEQ_MIN_SIZE), rseq_align);
+ }
+
+ /* Align the global offset to the beginning of the rseq area. */
+ offset = roundup (offset, rseq_align);
+
+ /* Record the rseq_area block size and offset. The offset is positive
+ with TLS_DTV_AT_TP because the TLS blocks are located after the
+ thread pointer. */
+ GLRO (dl_tls_rseq_size) = rseq_size;
+ GLRO (dl_tls_rseq_offset) = offset;
+
+ /* Add the rseq area block to the global offset. */
+ offset += rseq_size;
+
+ /* Increase the max_align if necessary. */
+ max_align = MAX (max_align, rseq_align);
+
GL(dl_tls_static_used) = offset;
GLRO (dl_tls_static_size) = roundup (offset + GLRO(dl_tls_static_surplus),
TCB_ALIGNMENT);
diff --git a/elf/rtld_static_init.c b/elf/rtld_static_init.c
index e918e4ebdf..0606317b8c 100644
--- a/elf/rtld_static_init.c
+++ b/elf/rtld_static_init.c
@@ -78,6 +78,18 @@ __rtld_static_init (struct link_map *map)
extern __typeof (dl->_dl_tls_static_size) _dl_tls_static_size
attribute_hidden;
dl->_dl_tls_static_size = _dl_tls_static_size;
+ extern __typeof (dl->_dl_tls_rseq_feature_size) _dl_tls_rseq_feature_size
+ attribute_hidden;
+ dl->_dl_tls_rseq_feature_size = _dl_tls_rseq_feature_size;
+ extern __typeof (dl->_dl_tls_rseq_align) _dl_tls_rseq_align
+ attribute_hidden;
+ dl->_dl_tls_rseq_align = _dl_tls_rseq_align;
+ extern __typeof (dl->_dl_tls_rseq_size) _dl_tls_rseq_size
+ attribute_hidden;
+ dl->_dl_tls_rseq_size = _dl_tls_rseq_size;
+ extern __typeof (dl->_dl_tls_rseq_offset) _dl_tls_rseq_offset
+ attribute_hidden;
+ dl->_dl_tls_rseq_offset = _dl_tls_rseq_offset;
dl->_dl_find_object = _dl_find_object;
__rtld_static_init_arch (map, dl);
diff --git a/nptl/descr.h b/nptl/descr.h
index 8cef95810c..cdc3c82d9a 100644
--- a/nptl/descr.h
+++ b/nptl/descr.h
@@ -404,25 +404,11 @@ struct pthread
/* Used on strsignal. */
struct tls_internal_t tls_state;
- /* rseq area registered with the kernel. Use a custom definition
- here to isolate from kernel struct rseq changes. The
- implementation of sched_getcpu needs acccess to the cpu_id field;
- the other fields are unused and not included here. */
- union
- {
- struct
- {
- uint32_t cpu_id_start;
- uint32_t cpu_id;
- };
- char pad[32]; /* Original rseq area size. */
- } rseq_area __attribute__ ((aligned (32)));
-
/* Amount of end padding, if any, in this structure.
- This definition relies on rseq_area being last. */
+ This definition relies on tls_state being last. */
#define PTHREAD_STRUCT_END_PADDING \
- (sizeof (struct pthread) - offsetof (struct pthread, rseq_area) \
- + sizeof ((struct pthread) {}.rseq_area))
+ (sizeof (struct pthread) - offsetof (struct pthread, tls_state) \
+ + sizeof ((struct pthread) {}.tls_state))
} __attribute ((aligned (TCB_ALIGNMENT)));
static inline bool
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 1d3665d5ed..9b49ee7121 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -691,7 +691,7 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
/* Inherit rseq registration state. Without seccomp filters, rseq
registration will either always fail or always succeed. */
- if ((int) THREAD_GETMEM_VOLATILE (self, rseq_area.cpu_id) >= 0)
+ if ((int) RSEQ_GETMEM_VOLATILE (rseq_get_area(), cpu_id) >= 0)
pd->flags |= ATTR_FLAG_DO_RSEQ;
/* Initialize the field for the ID of the thread which is waiting
diff --git a/sysdeps/generic/dl-rseq.h b/sysdeps/generic/dl-rseq.h
new file mode 100644
index 0000000000..0855981c89
--- /dev/null
+++ b/sysdeps/generic/dl-rseq.h
@@ -0,0 +1,26 @@
+/* RSEQ defines for the dynamic linker. Generic version.
+ Copyright (C) 2023 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+/* Minimum size of the rseq area. */
+#define TLS_DL_RSEQ_MIN_SIZE 32
+
+/* Minimum feature size of the rseq area. */
+#define TLS_DL_RSEQ_MIN_FEATURE_SIZE 20
+
+/* Minimum size of the rseq area alignment. */
+#define TLS_DL_RSEQ_MIN_ALIGN 32
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 117c901ccc..53a0a208d8 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -610,6 +610,18 @@ struct rtld_global_ro
See comments in elf/dl-tls.c where it is initialized. */
EXTERN size_t _dl_tls_static_surplus;
+ /* Size of the features present in the rseq area. */
+ EXTERN size_t _dl_tls_rseq_feature_size;
+
+ /* Alignment requirement of the rseq area. */
+ EXTERN size_t _dl_tls_rseq_align;
+
+ /* Size of the rseq area in the static TLS block. */
+ EXTERN size_t _dl_tls_rseq_size;
+
+ /* Offset of the rseq area from the thread pointer. */
+ EXTERN ptrdiff_t _dl_tls_rseq_offset;
+
/* Name of the shared object to be profiled (if any). */
EXTERN const char *_dl_profile;
/* Filename of the output file. */
diff --git a/sysdeps/i386/nptl/tcb-access.h b/sysdeps/i386/nptl/tcb-access.h
index 4b6221e103..e6988186d0 100644
--- a/sysdeps/i386/nptl/tcb-access.h
+++ b/sysdeps/i386/nptl/tcb-access.h
@@ -123,3 +123,59 @@
"i" (offsetof (struct pthread, member)), \
"r" (idx)); \
}})
+
+
+/* Read member of the RSEQ area directly. */
+#define RSEQ_GETMEM_VOLATILE(descr, member) \
+ ({ __typeof (descr->member) __value; \
+ ptrdiff_t _rseq_offset = GLRO (dl_tls_rseq_offset); \
+ _Static_assert (sizeof (__value) == 1 \
+ || sizeof (__value) == 4 \
+ || sizeof (__value) == 8, \
+ "size of per-thread data"); \
+ if (sizeof (__value) == 1) \
+ asm volatile ("movb %%gs:%P2(%3),%b0" \
+ : "=q" (__value) \
+ : "0" (0), "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ else if (sizeof (__value) == 4) \
+ asm volatile ("movl %%gs:%P1(%2),%0" \
+ : "=r" (__value) \
+ : "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ else /* 8 */ \
+ { \
+ asm volatile ("movl %%gs:%P1(%2),%%eax\n\t" \
+ "movl %%gs:4+%P1(%2),%%edx" \
+ : "=&A" (__value) \
+ : "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ } \
+ __value; })
+
+/* Set member of the RSEQ area directly. */
+#define RSEQ_SETMEM(descr, member, value) \
+ ({ \
+ ptrdiff_t _rseq_offset = GLRO (dl_tls_rseq_offset); \
+ _Static_assert (sizeof (descr->member) == 1 \
+ || sizeof (descr->member) == 4 \
+ || sizeof (descr->member) == 8, \
+ "size of per-thread data"); \
+ if (sizeof (descr->member) == 1) \
+ asm volatile ("movb %b0,%%gs:%P1(%2)" : \
+ : "iq" (value), \
+ "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ else if (sizeof (descr->member) == 4) \
+ asm volatile ("movl %0,%%gs:%P1(%2)" : \
+ : "ir" (value), \
+ "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ else /* 8 */ \
+ { \
+ asm volatile ("movl %%eax,%%gs:%P1(%2)\n\t" \
+ "movl %%edx,%%gs:4+%P1(%2)" : \
+ : "A" ((uint64_t) cast_to_integer (value)), \
+ "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ }})
diff --git a/sysdeps/nptl/dl-tls_init_tp.c b/sysdeps/nptl/dl-tls_init_tp.c
index 80eb0107b5..7aa15558e6 100644
--- a/sysdeps/nptl/dl-tls_init_tp.c
+++ b/sysdeps/nptl/dl-tls_init_tp.c
@@ -107,7 +107,7 @@ __tls_init_tp (void)
do_rseq = TUNABLE_GET (rseq, int, NULL);
if (rseq_register_current_thread (pd, do_rseq))
{
- _rseq_size = sizeof (pd->rseq_area);
+ _rseq_size = GLRO (dl_tls_rseq_size);
}
#ifdef RSEQ_SIG
@@ -116,7 +116,7 @@ __tls_init_tp (void)
all targets support __thread_pointer, so set __rseq_offset only
if the rseq registration may have happened because RSEQ_SIG is
defined. */
- _rseq_offset = (char *) &pd->rseq_area - (char *) __thread_pointer ();
+ _rseq_offset = GLRO (dl_tls_rseq_offset);
#endif
}
diff --git a/sysdeps/nptl/tcb-access.h b/sysdeps/nptl/tcb-access.h
index 600433766f..9532f30022 100644
--- a/sysdeps/nptl/tcb-access.h
+++ b/sysdeps/nptl/tcb-access.h
@@ -30,3 +30,8 @@
descr->member = (value)
#define THREAD_SETMEM_NC(descr, member, idx, value) \
descr->member[idx] = (value)
+
+#define RSEQ_GETMEM_VOLATILE(descr, member) \
+ THREAD_GETMEM_VOLATILE(descr, member)
+#define RSEQ_SETMEM(descr, member, value) \
+ THREAD_SETMEM(descr, member, value)
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 415aa1f14d..6bcf81461b 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -261,6 +261,11 @@ tests-internal += \
tst-rseq-disable \
# tests-internal
+tests-static += \
+ tst-rseq-disable-static \
+ tst-rseq-static \
+ # tests-static
+
tests-time64 += \
tst-adjtimex-time64 \
tst-clock_adjtime-time64 \
@@ -394,6 +399,7 @@ $(objpfx)tst-mount-compile.out: ../sysdeps/unix/sysv/linux/tst-mount-compile.py
$(objpfx)tst-mount-compile.out: $(sysdeps-linux-python-deps)
tst-rseq-disable-ENV = GLIBC_TUNABLES=glibc.pthread.rseq=0
+tst-rseq-disable-static-ENV = GLIBC_TUNABLES=glibc.pthread.rseq=0
endif # $(subdir) == misc
@@ -655,4 +661,8 @@ tests += \
tests-internal += \
tst-rseq-nptl \
# tests-internal
+
+tests-static += \
+ tst-rseq-nptl-static \
+ # tests-static
endif
diff --git a/sysdeps/unix/sysv/linux/dl-parse_auxv.h b/sysdeps/unix/sysv/linux/dl-parse_auxv.h
index e3d758b163..fbc90fc786 100644
--- a/sysdeps/unix/sysv/linux/dl-parse_auxv.h
+++ b/sysdeps/unix/sysv/linux/dl-parse_auxv.h
@@ -21,6 +21,7 @@
#include <fpu_control.h>
#include <ldsodefs.h>
#include <link.h>
+#include <dl-rseq.h>
typedef ElfW(Addr) dl_parse_auxv_t[AT_MINSIGSTKSZ + 1];
@@ -57,5 +58,10 @@ void _dl_parse_auxv (ElfW(auxv_t) *av, dl_parse_auxv_t auxv_values)
GLRO(dl_sysinfo) = auxv_values[AT_SYSINFO];
#endif
+ GLRO(dl_tls_rseq_feature_size) = MAX (auxv_values[AT_RSEQ_FEATURE_SIZE],
+ TLS_DL_RSEQ_MIN_FEATURE_SIZE);
+ GLRO(dl_tls_rseq_align) = MAX (auxv_values[AT_RSEQ_ALIGN],
+ TLS_DL_RSEQ_MIN_ALIGN);
+
DL_PLATFORM_AUXV
}
diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h
index 48eebc1e16..b6c9deea6b 100644
--- a/sysdeps/unix/sysv/linux/rseq-internal.h
+++ b/sysdeps/unix/sysv/linux/rseq-internal.h
@@ -24,6 +24,24 @@
#include <stdbool.h>
#include <stdio.h>
#include <sys/rseq.h>
+#include <thread_pointer.h>
+#include <ldsodefs.h>
+
+/* rseq area registered with the kernel. Use a custom definition
+ here to isolate from kernel struct rseq changes. The
+ implementation of sched_getcpu needs acccess to the cpu_id field;
+ the other fields are unused and not included here. */
+struct rseq_area
+{
+ uint32_t cpu_id_start;
+ uint32_t cpu_id;
+};
+
+static inline struct rseq_area *
+rseq_get_area(void)
+{
+ return (struct rseq_area *) ((char *) __thread_pointer() + GLRO (dl_tls_rseq_offset));
+}
#ifdef RSEQ_SIG
static inline bool
@@ -31,20 +49,23 @@ rseq_register_current_thread (struct pthread *self, bool do_rseq)
{
if (do_rseq)
{
- int ret = INTERNAL_SYSCALL_CALL (rseq, &self->rseq_area,
- sizeof (self->rseq_area),
+ /* The kernel expects 'rseq_area->rseq_cs == NULL' on registration, zero
+ the whole rseq area. */
+ memset(rseq_get_area(), 0, GLRO (dl_tls_rseq_size));
+ int ret = INTERNAL_SYSCALL_CALL (rseq, rseq_get_area(),
+ GLRO (dl_tls_rseq_size),
0, RSEQ_SIG);
if (!INTERNAL_SYSCALL_ERROR_P (ret))
return true;
}
- THREAD_SETMEM (self, rseq_area.cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
+ RSEQ_SETMEM (rseq_get_area(), cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
return false;
}
#else /* RSEQ_SIG */
static inline bool
rseq_register_current_thread (struct pthread *self, bool do_rseq)
{
- THREAD_SETMEM (self, rseq_area.cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
+ RSEQ_SETMEM (rseq_get_area(), cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
return false;
}
#endif /* RSEQ_SIG */
diff --git a/sysdeps/unix/sysv/linux/sched_getcpu.c b/sysdeps/unix/sysv/linux/sched_getcpu.c
index dfb884568d..4f7cd499d3 100644
--- a/sysdeps/unix/sysv/linux/sched_getcpu.c
+++ b/sysdeps/unix/sysv/linux/sched_getcpu.c
@@ -19,6 +19,7 @@
#include <sched.h>
#include <sysdep.h>
#include <sysdep-vdso.h>
+#include <rseq-internal.h>
static int
vsyscall_sched_getcpu (void)
@@ -37,7 +38,7 @@ vsyscall_sched_getcpu (void)
int
sched_getcpu (void)
{
- int cpu_id = THREAD_GETMEM_VOLATILE (THREAD_SELF, rseq_area.cpu_id);
+ int cpu_id = RSEQ_GETMEM_VOLATILE (rseq_get_area(), cpu_id);
return __glibc_likely (cpu_id >= 0) ? cpu_id : vsyscall_sched_getcpu ();
}
#else /* RSEQ_SIG */
diff --git a/sysdeps/unix/sysv/linux/tst-rseq-disable-static.c b/sysdeps/unix/sysv/linux/tst-rseq-disable-static.c
new file mode 100644
index 0000000000..2687d13d3d
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-rseq-disable-static.c
@@ -0,0 +1 @@
+#include "tst-rseq-disable.c"
diff --git a/sysdeps/unix/sysv/linux/tst-rseq-disable.c b/sysdeps/unix/sysv/linux/tst-rseq-disable.c
index bbc655bec4..ae4143916b 100644
--- a/sysdeps/unix/sysv/linux/tst-rseq-disable.c
+++ b/sysdeps/unix/sysv/linux/tst-rseq-disable.c
@@ -26,27 +26,30 @@
#include <unistd.h>
#ifdef RSEQ_SIG
+# include <sys/auxv.h>
+# include "tst-rseq.h"
+
+static __thread struct rseq local_rseq;
/* Check that rseq can be registered and has not been taken by glibc. */
static void
check_rseq_disabled (void)
{
- struct pthread *pd = THREAD_SELF;
+ struct rseq *rseq_area = (struct rseq *) ((char *) __thread_pointer () + __rseq_offset);
TEST_COMPARE (__rseq_flags, 0);
- TEST_VERIFY ((char *) __thread_pointer () + __rseq_offset
- == (char *) &pd->rseq_area);
TEST_COMPARE (__rseq_size, 0);
- TEST_COMPARE ((int) pd->rseq_area.cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
+ TEST_COMPARE ((int) rseq_area->cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
+
+ TEST_COMPARE (sizeof (local_rseq), RSEQ_TEST_MIN_SIZE);
- int ret = syscall (__NR_rseq, &pd->rseq_area, sizeof (pd->rseq_area),
- 0, RSEQ_SIG);
+ int ret = syscall (__NR_rseq, &local_rseq, RSEQ_TEST_MIN_SIZE, 0, RSEQ_SIG);
if (ret == 0)
{
- ret = syscall (__NR_rseq, &pd->rseq_area, sizeof (pd->rseq_area),
+ ret = syscall (__NR_rseq, &local_rseq, RSEQ_TEST_MIN_SIZE,
RSEQ_FLAG_UNREGISTER, RSEQ_SIG);
TEST_COMPARE (ret, 0);
- pd->rseq_area.cpu_id = RSEQ_CPU_ID_REGISTRATION_FAILED;
+ rseq_area->cpu_id = RSEQ_CPU_ID_REGISTRATION_FAILED;
}
else
{
diff --git a/sysdeps/unix/sysv/linux/tst-rseq-nptl-static.c b/sysdeps/unix/sysv/linux/tst-rseq-nptl-static.c
new file mode 100644
index 0000000000..6e2c923bb9
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-rseq-nptl-static.c
@@ -0,0 +1 @@
+#include "tst-rseq-nptl.c"
diff --git a/sysdeps/unix/sysv/linux/tst-rseq-static.c b/sysdeps/unix/sysv/linux/tst-rseq-static.c
new file mode 100644
index 0000000000..1d97f3bd3d
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-rseq-static.c
@@ -0,0 +1 @@
+#include "tst-rseq.c"
diff --git a/sysdeps/unix/sysv/linux/tst-rseq.c b/sysdeps/unix/sysv/linux/tst-rseq.c
index 2c90409ba0..c8c0518a5d 100644
--- a/sysdeps/unix/sysv/linux/tst-rseq.c
+++ b/sysdeps/unix/sysv/linux/tst-rseq.c
@@ -31,18 +31,32 @@
# include <syscall.h>
# include <thread_pointer.h>
# include <tls.h>
+# include <sys/auxv.h>
# include "tst-rseq.h"
static void
do_rseq_main_test (void)
{
- struct pthread *pd = THREAD_SELF;
+ size_t rseq_align = MAX (getauxval (AT_RSEQ_ALIGN), RSEQ_TEST_MIN_ALIGN);
+ size_t rseq_size = roundup (MAX (getauxval (AT_RSEQ_FEATURE_SIZE), RSEQ_TEST_MIN_SIZE), rseq_align);
+ struct rseq *rseq = __thread_pointer () + __rseq_offset;
TEST_VERIFY_EXIT (rseq_thread_registered ());
TEST_COMPARE (__rseq_flags, 0);
- TEST_VERIFY ((char *) __thread_pointer () + __rseq_offset
- == (char *) &pd->rseq_area);
- TEST_COMPARE (__rseq_size, sizeof (pd->rseq_area));
+ TEST_COMPARE (__rseq_size, rseq_size);
+ /* The size of the rseq area must be a multiple of the alignment. */
+ TEST_VERIFY ((__rseq_size % rseq_align) == 0);
+ /* The rseq area address must be aligned. */
+ TEST_VERIFY (((unsigned long) rseq % rseq_align) == 0);
+#if TLS_TCB_AT_TP
+ /* The rseq area block should come before the thread pointer and be at least 32 bytes. */
+ TEST_VERIFY (__rseq_offset <= RSEQ_TEST_MIN_SIZE);
+#elif TLS_DTV_AT_TP
+ /* The rseq area block should come after the thread pointer. */
+ TEST_VERIFY (__rseq_offset >= 0);
+#else
+# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
+#endif
}
static void
diff --git a/sysdeps/unix/sysv/linux/tst-rseq.h b/sysdeps/unix/sysv/linux/tst-rseq.h
index dc603327d3..4931aa3d14 100644
--- a/sysdeps/unix/sysv/linux/tst-rseq.h
+++ b/sysdeps/unix/sysv/linux/tst-rseq.h
@@ -23,11 +23,18 @@
#include <syscall.h>
#include <sys/rseq.h>
#include <tls.h>
+#include <rseq-internal.h>
+
+#define RSEQ_TEST_MIN_SIZE 32
+#define RSEQ_TEST_MIN_FEATURE_SIZE 20
+#define RSEQ_TEST_MIN_ALIGN 32
static inline bool
rseq_thread_registered (void)
{
- return THREAD_GETMEM_VOLATILE (THREAD_SELF, rseq_area.cpu_id) >= 0;
+ struct rseq_area *rseq = (struct rseq_area *) ((char *) __thread_pointer () + __rseq_offset);
+
+ return __atomic_load_n (&rseq->cpu_id, __ATOMIC_RELAXED) >= 0;
}
static inline int
diff --git a/sysdeps/x86_64/nptl/tcb-access.h b/sysdeps/x86_64/nptl/tcb-access.h
index d35948f111..75ba4b3ce9 100644
--- a/sysdeps/x86_64/nptl/tcb-access.h
+++ b/sysdeps/x86_64/nptl/tcb-access.h
@@ -130,3 +130,59 @@
"i" (offsetof (struct pthread, member[0])), \
"r" (idx)); \
}})
+
+/* Read member of the RSEQ area directly. */
+# define RSEQ_GETMEM_VOLATILE(descr, member) \
+ ({ __typeof (descr->member) __value; \
+ ptrdiff_t _rseq_offset = GLRO (dl_tls_rseq_offset); \
+ _Static_assert (sizeof (__value) == 1 \
+ || sizeof (__value) == 4 \
+ || sizeof (__value) == 8, \
+ "size of per-thread data"); \
+ if (sizeof (__value) == 1) \
+ asm volatile ("movb %%fs:%P2(%q3),%b0" \
+ : "=q" (__value) \
+ : "0" (0), "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ else if (sizeof (__value) == 4) \
+ asm volatile ("movl %%fs:%P1(%q2),%0" \
+ : "=r" (__value) \
+ : "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ else /* 8 */ \
+ { \
+ asm volatile ("movq %%fs:%P1(%q2),%q0" \
+ : "=r" (__value) \
+ : "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ } \
+ __value; })
+
+/* Set member of the RSEQ area directly. */
+# define RSEQ_SETMEM(descr, member, value) \
+ ({ \
+ ptrdiff_t _rseq_offset = GLRO (dl_tls_rseq_offset); \
+ _Static_assert (sizeof (descr->member) == 1 \
+ || sizeof (descr->member) == 4 \
+ || sizeof (descr->member) == 8, \
+ "size of per-thread data"); \
+ if (sizeof (descr->member) == 1) \
+ asm volatile ("movb %b0,%%fs:%P1(%q2)" : \
+ : "iq" (value), \
+ "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ else if (sizeof (descr->member) == 4) \
+ asm volatile ("movl %0,%%fs:%P1(%q2)" : \
+ : IMM_MODE (value), \
+ "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ else /* 8 */ \
+ { \
+ /* Since movq takes a signed 32-bit immediate or a register source \
+ operand, use "er" constraint for 32-bit signed integer constant \
+ or register. */ \
+ asm volatile ("movq %q0,%%fs:%P1(%q2)" : \
+ : "er" ((uint64_t) cast_to_integer (value)), \
+ "i" (offsetof (struct rseq_area, member)), \
+ "r" (_rseq_offset)); \
+ }})
--
2.34.1
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v7 3/8] nptl: Add public __rseq_feature_size symbol
2024-02-01 19:36 [PATCH v7 0/8] Extend rseq support Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 1/8] nptl: fix potential merge of __rseq_* relro symbols Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 2/8] Add rseq extensible ABI support Michael Jeanson
@ 2024-02-01 19:36 ` Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 4/8] nptl: Add features to internal 'struct rseq_area' Michael Jeanson
` (5 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: Michael Jeanson @ 2024-02-01 19:36 UTC (permalink / raw)
To: libc-alpha
Cc: Michael Jeanson, Florian Weimer, Carlos O'Donell, Mathieu Desnoyers
Exposing this symbol allows applications wishing to use rseq features
which are part of the extensible rseq ABI like 'node_id' and 'mm_cid' to
test the two following conditions in a single load / conditional branch:
- rseq is registered
- the specific rseq feature is available
This is useful as rseq is expected to be used in hot paths.
This variable is either zero (if restartable sequence registration
failed or has been disabled) or the size of the available restartable
sequence features.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
---
csu/rseq-sizes.sym | 3 +++
elf/dl-rseq-symbols.S | 17 +++++++++++++++++
manual/threads.texi | 8 ++++++++
sysdeps/nptl/dl-tls_init_tp.c | 2 ++
sysdeps/unix/sysv/linux/Versions | 3 +++
sysdeps/unix/sysv/linux/aarch64/ld.abilist | 1 +
sysdeps/unix/sysv/linux/alpha/ld.abilist | 1 +
sysdeps/unix/sysv/linux/arc/ld.abilist | 1 +
sysdeps/unix/sysv/linux/arm/be/ld.abilist | 1 +
sysdeps/unix/sysv/linux/arm/le/ld.abilist | 1 +
sysdeps/unix/sysv/linux/csky/ld.abilist | 1 +
sysdeps/unix/sysv/linux/hppa/ld.abilist | 1 +
sysdeps/unix/sysv/linux/i386/ld.abilist | 1 +
.../unix/sysv/linux/loongarch/lp64/ld.abilist | 1 +
.../unix/sysv/linux/m68k/coldfire/ld.abilist | 1 +
sysdeps/unix/sysv/linux/m68k/m680x0/ld.abilist | 1 +
sysdeps/unix/sysv/linux/microblaze/ld.abilist | 1 +
sysdeps/unix/sysv/linux/mips/mips32/ld.abilist | 1 +
.../unix/sysv/linux/mips/mips64/n32/ld.abilist | 1 +
.../unix/sysv/linux/mips/mips64/n64/ld.abilist | 1 +
sysdeps/unix/sysv/linux/nios2/ld.abilist | 1 +
sysdeps/unix/sysv/linux/or1k/ld.abilist | 1 +
.../sysv/linux/powerpc/powerpc32/ld.abilist | 1 +
.../sysv/linux/powerpc/powerpc64/be/ld.abilist | 1 +
.../sysv/linux/powerpc/powerpc64/le/ld.abilist | 1 +
sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist | 1 +
sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist | 1 +
sysdeps/unix/sysv/linux/s390/s390-32/ld.abilist | 1 +
sysdeps/unix/sysv/linux/s390/s390-64/ld.abilist | 1 +
sysdeps/unix/sysv/linux/sh/be/ld.abilist | 1 +
sysdeps/unix/sysv/linux/sh/le/ld.abilist | 1 +
.../unix/sysv/linux/sparc/sparc32/ld.abilist | 1 +
.../unix/sysv/linux/sparc/sparc64/ld.abilist | 1 +
sysdeps/unix/sysv/linux/sys/rseq.h | 4 ++++
sysdeps/unix/sysv/linux/tst-rseq-disable.c | 1 +
sysdeps/unix/sysv/linux/tst-rseq.c | 4 +++-
sysdeps/unix/sysv/linux/x86_64/64/ld.abilist | 1 +
sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist | 1 +
38 files changed, 71 insertions(+), 1 deletion(-)
diff --git a/csu/rseq-sizes.sym b/csu/rseq-sizes.sym
index c959758ff0..dde53bfa60 100644
--- a/csu/rseq-sizes.sym
+++ b/csu/rseq-sizes.sym
@@ -4,5 +4,8 @@
RSEQ_SIZE_SIZE sizeof (unsigned int)
RSEQ_SIZE_ALIGN __alignof (unsigned int)
+RSEQ_FEATURE_SIZE_SIZE sizeof (unsigned int)
+RSEQ_FEATURE_SIZE_ALIGN __alignof (unsigned int)
+
RSEQ_OFFSET_SIZE sizeof (ptrdiff_t)
RSEQ_OFFSET_ALIGN __alignof (ptrdiff_t)
diff --git a/elf/dl-rseq-symbols.S b/elf/dl-rseq-symbols.S
index 2d8e88367f..709188ae22 100644
--- a/elf/dl-rseq-symbols.S
+++ b/elf/dl-rseq-symbols.S
@@ -38,6 +38,23 @@ __rseq_size:
_rseq_size:
.zero RSEQ_SIZE_SIZE
+/* Define 2 symbols, __rseq_feature_size is public const and
+ _rseq_feature_size, which is an alias of __rseq_feature_size, but hidden and
+ writable for internal use. */
+
+ .globl __rseq_feature_size
+ .type __rseq_feature_size, %object
+ .size __rseq_feature_size, RSEQ_FEATURE_SIZE_SIZE
+ .hidden _rseq_feature_size
+ .globl _rseq_feature_size
+ .type _rseq_feature_size, %object
+ .size _rseq_feature_size, RSEQ_FEATURE_SIZE_SIZE
+ .section .data.rel.ro
+ .balign RSEQ_FEATURE_SIZE_ALIGN
+__rseq_feature_size:
+_rseq_feature_size:
+ .zero RSEQ_FEATURE_SIZE_SIZE
+
/* Define 2 symbols, __rseq_offset is public const and _rseq_offset, which is an
alias of __rseq_offset, but hidden and writable for internal use. */
diff --git a/manual/threads.texi b/manual/threads.texi
index e5544ff3da..2c9aaa9fb5 100644
--- a/manual/threads.texi
+++ b/manual/threads.texi
@@ -1011,6 +1011,14 @@ registration is successful, @code{__rseq_size} is at least 32 (the
initial size of @code{struct rseq}).
@end deftypevar
+@deftypevar {unsigned int} __rseq_feature_size
+@standards{Linux, sys/rseq.h}
+This variable is either zero (if restartable sequence registration
+failed or has been disabled) or the size of the restartable sequence
+features. If registration is successful, @code{__rseq_feature_size}
+is at least 20 (the initial feature size of @code{struct rseq}).
+@end deftypevar
+
@deftypevar {unsigned int} __rseq_flags
@standards{Linux, sys/rseq.h}
The flags used during restartable sequence registration with the kernel.
diff --git a/sysdeps/nptl/dl-tls_init_tp.c b/sysdeps/nptl/dl-tls_init_tp.c
index 7aa15558e6..8f19c22a74 100644
--- a/sysdeps/nptl/dl-tls_init_tp.c
+++ b/sysdeps/nptl/dl-tls_init_tp.c
@@ -48,6 +48,7 @@ const unsigned int __rseq_flags;
/* The variables are in .data.relro but are not yet write-protected. */
extern unsigned int _rseq_size attribute_relro attribute_hidden;
+extern unsigned int _rseq_feature_size attribute_relro attribute_hidden;
extern ptrdiff_t _rseq_offset attribute_relro attribute_hidden;
void
@@ -108,6 +109,7 @@ __tls_init_tp (void)
if (rseq_register_current_thread (pd, do_rseq))
{
_rseq_size = GLRO (dl_tls_rseq_size);
+ _rseq_feature_size = GLRO (dl_tls_rseq_feature_size);
}
#ifdef RSEQ_SIG
diff --git a/sysdeps/unix/sysv/linux/Versions b/sysdeps/unix/sysv/linux/Versions
index 268ba1b6ac..055be26dde 100644
--- a/sysdeps/unix/sysv/linux/Versions
+++ b/sysdeps/unix/sysv/linux/Versions
@@ -356,6 +356,9 @@ ld {
__rseq_offset;
__rseq_size;
}
+ GLIBC_2.40 {
+ __rseq_feature_size;
+ }
GLIBC_PRIVATE {
__nptl_change_stack_perm;
}
diff --git a/sysdeps/unix/sysv/linux/aarch64/ld.abilist b/sysdeps/unix/sysv/linux/aarch64/ld.abilist
index 5151c0781d..93039b756d 100644
--- a/sysdeps/unix/sysv/linux/aarch64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/ld.abilist
@@ -7,3 +7,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x8
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/alpha/ld.abilist b/sysdeps/unix/sysv/linux/alpha/ld.abilist
index 3e296c5473..a18f952057 100644
--- a/sysdeps/unix/sysv/linux/alpha/ld.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/ld.abilist
@@ -6,4 +6,5 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x8
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __stack_chk_guard D 0x8
diff --git a/sysdeps/unix/sysv/linux/arc/ld.abilist b/sysdeps/unix/sysv/linux/arc/ld.abilist
index 55f0c2ab9c..31156b6ee1 100644
--- a/sysdeps/unix/sysv/linux/arc/ld.abilist
+++ b/sysdeps/unix/sysv/linux/arc/ld.abilist
@@ -7,3 +7,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/arm/be/ld.abilist b/sysdeps/unix/sysv/linux/arm/be/ld.abilist
index f1da2c636d..dac120b385 100644
--- a/sysdeps/unix/sysv/linux/arm/be/ld.abilist
+++ b/sysdeps/unix/sysv/linux/arm/be/ld.abilist
@@ -2,6 +2,7 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __libc_stack_end D 0x4
GLIBC_2.4 __stack_chk_guard D 0x4
GLIBC_2.4 __tls_get_addr F
diff --git a/sysdeps/unix/sysv/linux/arm/le/ld.abilist b/sysdeps/unix/sysv/linux/arm/le/ld.abilist
index f1da2c636d..dac120b385 100644
--- a/sysdeps/unix/sysv/linux/arm/le/ld.abilist
+++ b/sysdeps/unix/sysv/linux/arm/le/ld.abilist
@@ -2,6 +2,7 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __libc_stack_end D 0x4
GLIBC_2.4 __stack_chk_guard D 0x4
GLIBC_2.4 __tls_get_addr F
diff --git a/sysdeps/unix/sysv/linux/csky/ld.abilist b/sysdeps/unix/sysv/linux/csky/ld.abilist
index 7f482276ed..088f000c4e 100644
--- a/sysdeps/unix/sysv/linux/csky/ld.abilist
+++ b/sysdeps/unix/sysv/linux/csky/ld.abilist
@@ -7,3 +7,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/hppa/ld.abilist b/sysdeps/unix/sysv/linux/hppa/ld.abilist
index 7f5527fb30..1fb6c33c7b 100644
--- a/sysdeps/unix/sysv/linux/hppa/ld.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/ld.abilist
@@ -6,4 +6,5 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/i386/ld.abilist b/sysdeps/unix/sysv/linux/i386/ld.abilist
index 9c4a45d8dc..d9761c34e3 100644
--- a/sysdeps/unix/sysv/linux/i386/ld.abilist
+++ b/sysdeps/unix/sysv/linux/i386/ld.abilist
@@ -7,3 +7,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/loongarch/lp64/ld.abilist b/sysdeps/unix/sysv/linux/loongarch/lp64/ld.abilist
index 93fcd64eee..f5dbb17ec9 100644
--- a/sysdeps/unix/sysv/linux/loongarch/lp64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/loongarch/lp64/ld.abilist
@@ -6,3 +6,4 @@ GLIBC_2.36 __stack_chk_guard D 0x8
GLIBC_2.36 __tls_get_addr F
GLIBC_2.36 _dl_mcount F
GLIBC_2.36 _r_debug D 0x28
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/ld.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/ld.abilist
index f1da2c636d..dac120b385 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/ld.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/ld.abilist
@@ -2,6 +2,7 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __libc_stack_end D 0x4
GLIBC_2.4 __stack_chk_guard D 0x4
GLIBC_2.4 __tls_get_addr F
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/ld.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/ld.abilist
index dadbf852d0..d78f7ea1e3 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/ld.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/ld.abilist
@@ -6,4 +6,5 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/microblaze/ld.abilist b/sysdeps/unix/sysv/linux/microblaze/ld.abilist
index 89a0b7e4fd..c83b62dce7 100644
--- a/sysdeps/unix/sysv/linux/microblaze/ld.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/ld.abilist
@@ -7,3 +7,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/ld.abilist b/sysdeps/unix/sysv/linux/mips/mips32/ld.abilist
index e304d1bb46..25dc3d1fd2 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/ld.abilist
@@ -6,4 +6,5 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/ld.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/ld.abilist
index e304d1bb46..25dc3d1fd2 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/ld.abilist
@@ -6,4 +6,5 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/ld.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/ld.abilist
index f26e594a13..4bdab645cf 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/ld.abilist
@@ -6,4 +6,5 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x8
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __stack_chk_guard D 0x8
diff --git a/sysdeps/unix/sysv/linux/nios2/ld.abilist b/sysdeps/unix/sysv/linux/nios2/ld.abilist
index 811ae9da2f..d2b742ec25 100644
--- a/sysdeps/unix/sysv/linux/nios2/ld.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/ld.abilist
@@ -7,3 +7,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/or1k/ld.abilist b/sysdeps/unix/sysv/linux/or1k/ld.abilist
index cff2ffd23b..eb225ca4c5 100644
--- a/sysdeps/unix/sysv/linux/or1k/ld.abilist
+++ b/sysdeps/unix/sysv/linux/or1k/ld.abilist
@@ -6,3 +6,4 @@ GLIBC_2.35 __stack_chk_guard D 0x4
GLIBC_2.35 __tls_get_addr F
GLIBC_2.35 _dl_mcount F
GLIBC_2.35 _r_debug D 0x14
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist
index b1073f0942..7a94751723 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist
@@ -9,3 +9,4 @@ GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
GLIBC_2.39 __parse_hwcap_3_4_and_convert_at_platform F
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist
index 40942a2cc6..f6bdd89083 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist
@@ -9,3 +9,4 @@ GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x8
GLIBC_2.35 __rseq_size D 0x4
GLIBC_2.39 __parse_hwcap_3_4_and_convert_at_platform F
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist
index 01f2694a4d..672bade9ba 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist
@@ -9,3 +9,4 @@ GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x8
GLIBC_2.35 __rseq_size D 0x4
GLIBC_2.39 __parse_hwcap_3_4_and_convert_at_platform F
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist b/sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist
index 068368878e..d3be9236c2 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist
@@ -7,3 +7,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist b/sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist
index a7758a0e52..46b22238ce 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist
@@ -7,3 +7,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x8
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/ld.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/ld.abilist
index c15288394a..f438808c08 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/ld.abilist
@@ -6,3 +6,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/ld.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/ld.abilist
index 78d071600b..f5fbc6de43 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/ld.abilist
@@ -6,3 +6,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x8
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/sh/be/ld.abilist b/sysdeps/unix/sysv/linux/sh/be/ld.abilist
index 7f5527fb30..1fb6c33c7b 100644
--- a/sysdeps/unix/sysv/linux/sh/be/ld.abilist
+++ b/sysdeps/unix/sysv/linux/sh/be/ld.abilist
@@ -6,4 +6,5 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/sh/le/ld.abilist b/sysdeps/unix/sysv/linux/sh/le/ld.abilist
index 7f5527fb30..1fb6c33c7b 100644
--- a/sysdeps/unix/sysv/linux/sh/le/ld.abilist
+++ b/sysdeps/unix/sysv/linux/sh/le/ld.abilist
@@ -6,4 +6,5 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/ld.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/ld.abilist
index 3aac73f3df..df3f7fefb3 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/ld.abilist
@@ -6,3 +6,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/ld.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/ld.abilist
index 5471b24d59..3bf61e1210 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/ld.abilist
@@ -6,3 +6,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x8
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/sys/rseq.h b/sysdeps/unix/sysv/linux/sys/rseq.h
index b8afab8945..a048ba8958 100644
--- a/sysdeps/unix/sysv/linux/sys/rseq.h
+++ b/sysdeps/unix/sysv/linux/sys/rseq.h
@@ -163,6 +163,10 @@ extern const ptrdiff_t __rseq_offset;
unsuccessful. */
extern const unsigned int __rseq_size;
+/* Size of the registered rseq features. 0 if the registration was
+ unsuccessful. */
+extern const unsigned int __rseq_feature_size;
+
/* Flags used during rseq registration. */
extern const unsigned int __rseq_flags;
diff --git a/sysdeps/unix/sysv/linux/tst-rseq-disable.c b/sysdeps/unix/sysv/linux/tst-rseq-disable.c
index ae4143916b..eb4b6278dc 100644
--- a/sysdeps/unix/sysv/linux/tst-rseq-disable.c
+++ b/sysdeps/unix/sysv/linux/tst-rseq-disable.c
@@ -39,6 +39,7 @@ check_rseq_disabled (void)
TEST_COMPARE (__rseq_flags, 0);
TEST_COMPARE (__rseq_size, 0);
+ TEST_COMPARE (__rseq_feature_size, 0);
TEST_COMPARE ((int) rseq_area->cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
TEST_COMPARE (sizeof (local_rseq), RSEQ_TEST_MIN_SIZE);
diff --git a/sysdeps/unix/sysv/linux/tst-rseq.c b/sysdeps/unix/sysv/linux/tst-rseq.c
index c8c0518a5d..c5d9afbb0a 100644
--- a/sysdeps/unix/sysv/linux/tst-rseq.c
+++ b/sysdeps/unix/sysv/linux/tst-rseq.c
@@ -38,12 +38,14 @@ static void
do_rseq_main_test (void)
{
size_t rseq_align = MAX (getauxval (AT_RSEQ_ALIGN), RSEQ_TEST_MIN_ALIGN);
- size_t rseq_size = roundup (MAX (getauxval (AT_RSEQ_FEATURE_SIZE), RSEQ_TEST_MIN_SIZE), rseq_align);
+ size_t rseq_feature_size = MAX (getauxval (AT_RSEQ_FEATURE_SIZE), RSEQ_TEST_MIN_FEATURE_SIZE);
+ size_t rseq_size = roundup (MAX (rseq_feature_size, RSEQ_TEST_MIN_SIZE), rseq_align);
struct rseq *rseq = __thread_pointer () + __rseq_offset;
TEST_VERIFY_EXIT (rseq_thread_registered ());
TEST_COMPARE (__rseq_flags, 0);
TEST_COMPARE (__rseq_size, rseq_size);
+ TEST_COMPARE (__rseq_feature_size, rseq_feature_size);
/* The size of the rseq area must be a multiple of the alignment. */
TEST_VERIFY ((__rseq_size % rseq_align) == 0);
/* The rseq area address must be aligned. */
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist b/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist
index 5a8bd322cd..25c2153c21 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist
@@ -6,3 +6,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x8
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist
index e17496d124..05327004e2 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist
@@ -6,3 +6,4 @@ GLIBC_2.34 __rtld_version_placeholder F
GLIBC_2.35 __rseq_flags D 0x4
GLIBC_2.35 __rseq_offset D 0x4
GLIBC_2.35 __rseq_size D 0x4
+GLIBC_2.40 __rseq_feature_size D 0x4
--
2.34.1
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v7 4/8] nptl: Add features to internal 'struct rseq_area'
2024-02-01 19:36 [PATCH v7 0/8] Extend rseq support Michael Jeanson
` (2 preceding siblings ...)
2024-02-01 19:36 ` [PATCH v7 3/8] nptl: Add public __rseq_feature_size symbol Michael Jeanson
@ 2024-02-01 19:36 ` Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 5/8] nptl: Add rseq internal utils Michael Jeanson
` (4 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: Michael Jeanson @ 2024-02-01 19:36 UTC (permalink / raw)
To: libc-alpha
Cc: Michael Jeanson, Florian Weimer, Carlos O'Donell, Mathieu Desnoyers
The 'struct rseq_area' is used to define the offset of the various
features available in the rseq ABI. Add fields that follow cpu_id
(rseq_cs, flags, node_id, mm_cid) in preparation for their use.
Access to features following the original rseq ABI 20 bytes (after
'flags') starting with 'node_id' must be gated by an rseq feature size
test.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
---
sysdeps/unix/sysv/linux/rseq-internal.h | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h
index b6c9deea6b..a63e4afbdb 100644
--- a/sysdeps/unix/sysv/linux/rseq-internal.h
+++ b/sysdeps/unix/sysv/linux/rseq-internal.h
@@ -28,13 +28,17 @@
#include <ldsodefs.h>
/* rseq area registered with the kernel. Use a custom definition
- here to isolate from kernel struct rseq changes. The
- implementation of sched_getcpu needs acccess to the cpu_id field;
- the other fields are unused and not included here. */
+ here to isolate from kernel struct rseq changes. Access to fields
+ beyond the 20 bytes of the original ABI (after 'flags') must be gated
+ by a check of the feature size. */
struct rseq_area
{
uint32_t cpu_id_start;
uint32_t cpu_id;
+ uint64_t rseq_cs;
+ uint32_t flags;
+ uint32_t node_id;
+ uint32_t mm_cid;
};
static inline struct rseq_area *
--
2.34.1
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v7 5/8] nptl: Add rseq internal utils
2024-02-01 19:36 [PATCH v7 0/8] Extend rseq support Michael Jeanson
` (3 preceding siblings ...)
2024-02-01 19:36 ` [PATCH v7 4/8] nptl: Add features to internal 'struct rseq_area' Michael Jeanson
@ 2024-02-01 19:36 ` Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 6/8] x86-64: Add rseq_load32_load32_relaxed Michael Jeanson
` (3 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: Michael Jeanson @ 2024-02-01 19:36 UTC (permalink / raw)
To: libc-alpha
Cc: Michael Jeanson, Florian Weimer, Carlos O'Donell, Mathieu Desnoyers
Implement internal rseq utils in preparation for their use in
rseq_load32_load32_relaxed().
This implementation is imported from the librseq project.
Co-authored-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
---
sysdeps/unix/sysv/linux/rseq-internal.h | 56 +++++++++++++++++++++++++
1 file changed, 56 insertions(+)
diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h
index a63e4afbdb..b6c29c14cc 100644
--- a/sysdeps/unix/sysv/linux/rseq-internal.h
+++ b/sysdeps/unix/sysv/linux/rseq-internal.h
@@ -41,12 +41,68 @@ struct rseq_area
uint32_t mm_cid;
};
+/*
+ * gcc prior to 4.8.2 miscompiles asm goto.
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
+ *
+ * gcc prior to 8.1.0 miscompiles asm goto at O1.
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103908
+ *
+ * clang prior to version 13.0.1 miscompiles asm goto at O2.
+ * https://github.com/llvm/llvm-project/issues/52735
+ *
+ * Work around these issues by adding a volatile inline asm with
+ * memory clobber in the fallthrough after the asm goto and at each
+ * label target. Emit this for all compilers in case other similar
+ * issues are found in the future.
+ */
+#define rseq_after_asm_goto() __asm__ __volatile__ ("" : : : "memory")
+
+#define __rseq_str_1(x) #x
+#define __rseq_str(x) __rseq_str_1(x)
+
+/* Offset of rseq_cs field in struct rseq. */
+#define RSEQ_CS_OFFSET 8
+
+#define rseq_sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
+#define rseq_offsetofend(TYPE, MEMBER) \
+ (offsetof(TYPE, MEMBER) + rseq_sizeof_field(TYPE, MEMBER))
+
+/* Returns a pointer to the current thread rseq area. */
static inline struct rseq_area *
rseq_get_area(void)
{
return (struct rseq_area *) ((char *) __thread_pointer() + GLRO (dl_tls_rseq_offset));
}
+/* Returns the int value of 'rseq_area->cpu_id'. */
+static inline int
+rseq_get_cpu_id(void)
+{
+ return (int) RSEQ_GETMEM_VOLATILE (rseq_get_area(), cpu_id);
+}
+
+/* Returns true if the rseq registration is active. */
+static inline bool
+rseq_is_registered(void)
+{
+ return rseq_get_cpu_id() >= 0;
+}
+
+/* Returns true if the current rseq registration has the 'node_id' field. */
+static inline bool
+rseq_node_id_available(void)
+{
+ return __rseq_feature_size >= rseq_offsetofend(struct rseq_area, node_id);
+}
+
+/* Returns true if the current rseq registration has the 'mm_cid' field. */
+static inline bool
+rseq_mm_cid_available(void)
+{
+ return __rseq_feature_size >= rseq_offsetofend(struct rseq_area, mm_cid);
+}
+
#ifdef RSEQ_SIG
static inline bool
rseq_register_current_thread (struct pthread *self, bool do_rseq)
--
2.34.1
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v7 6/8] x86-64: Add rseq_load32_load32_relaxed
2024-02-01 19:36 [PATCH v7 0/8] Extend rseq support Michael Jeanson
` (4 preceding siblings ...)
2024-02-01 19:36 ` [PATCH v7 5/8] nptl: Add rseq internal utils Michael Jeanson
@ 2024-02-01 19:36 ` Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 7/8] aarch64: " Michael Jeanson
` (2 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: Michael Jeanson @ 2024-02-01 19:36 UTC (permalink / raw)
To: libc-alpha
Cc: Michael Jeanson, Florian Weimer, Carlos O'Donell, Mathieu Desnoyers
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Implement rseq_load32_load32_relaxed() for the x86-64 architecture. This
static inline function implements a rseq critical section to load two
32-bit integer values atomically with respect to preemption and signal
delivery.
This implementation is imported from the librseq project.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
---
.../unix/sysv/linux/x86_64/rseq-internal.h | 109 ++++++++++++++++++
1 file changed, 109 insertions(+)
create mode 100644 sysdeps/unix/sysv/linux/x86_64/rseq-internal.h
diff --git a/sysdeps/unix/sysv/linux/x86_64/rseq-internal.h b/sysdeps/unix/sysv/linux/x86_64/rseq-internal.h
new file mode 100644
index 0000000000..fdca1b6439
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/rseq-internal.h
@@ -0,0 +1,109 @@
+/* Restartable Sequences internal API. x86_64 macros.
+ Copyright (C) 2023 Free Software Foundation, Inc.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <sysdeps/unix/sysv/linux/rseq-internal.h>
+
+#define __RSEQ_ASM_DEFINE_TABLE(label, version, flags, \
+ start_ip, post_commit_offset, abort_ip) \
+ ".pushsection __rseq_cs, \"aw\"\n\t" \
+ ".balign 32\n\t" \
+ __rseq_str(label) ":\n\t" \
+ ".long " __rseq_str(version) ", " __rseq_str(flags) "\n\t" \
+ ".quad " __rseq_str(start_ip) ", " __rseq_str(post_commit_offset) ", " __rseq_str(abort_ip) "\n\t" \
+ ".popsection\n\t" \
+ ".pushsection __rseq_cs_ptr_array, \"aw\"\n\t" \
+ ".quad " __rseq_str(label) "b\n\t" \
+ ".popsection\n\t"
+
+#define RSEQ_ASM_DEFINE_TABLE(label, start_ip, post_commit_ip, abort_ip) \
+ __RSEQ_ASM_DEFINE_TABLE(label, 0x0, 0x0, start_ip, \
+ (post_commit_ip - start_ip), abort_ip)
+
+/*
+ * Exit points of a rseq critical section consist of all instructions outside
+ * of the critical section where a critical section can either branch to or
+ * reach through the normal course of its execution. The abort IP and the
+ * post-commit IP are already part of the __rseq_cs section and should not be
+ * explicitly defined as additional exit points. Knowing all exit points is
+ * useful to assist debuggers stepping over the critical section.
+ */
+#define RSEQ_ASM_DEFINE_EXIT_POINT(start_ip, exit_ip) \
+ ".pushsection __rseq_exit_point_array, \"aw\"\n\t" \
+ ".quad " __rseq_str(start_ip) ", " __rseq_str(exit_ip) "\n\t" \
+ ".popsection\n\t"
+
+#define RSEQ_ASM_STORE_RSEQ_CS(label, cs_label, rseq_cs) \
+ "leaq " __rseq_str(cs_label) "(%%rip), %%rax\n\t" \
+ "movq %%rax, " __rseq_str(rseq_cs) "\n\t" \
+ __rseq_str(label) ":\n\t"
+
+#define RSEQ_ASM_CMP_CPU_ID(cpu_id, current_cpu_id, label) \
+ "cmpl %[" __rseq_str(cpu_id) "], " __rseq_str(current_cpu_id) "\n\t" \
+ "jnz " __rseq_str(label) "\n\t"
+
+#define RSEQ_ASM_DEFINE_ABORT(label, teardown, abort_label) \
+ ".pushsection __rseq_failure, \"ax\"\n\t" \
+ /* Disassembler-friendly signature: ud1 <sig>(%rip),%edi. */ \
+ ".byte 0x0f, 0xb9, 0x3d\n\t" \
+ ".long " __rseq_str(RSEQ_SIG) "\n\t" \
+ __rseq_str(label) ":\n\t" \
+ teardown \
+ "jmp %l[" __rseq_str(abort_label) "]\n\t" \
+ ".popsection\n\t"
+
+#define RSEQ_ASM_DEFINE_CMPFAIL(label, teardown, cmpfail_label) \
+ ".pushsection __rseq_failure, \"ax\"\n\t" \
+ __rseq_str(label) ":\n\t" \
+ teardown \
+ "jmp %l[" __rseq_str(cmpfail_label) "]\n\t" \
+ ".popsection\n\t"
+
+/*
+ * Load @src1 (32-bit) into @dst1 and load @src2 (32-bit) into @dst2.
+ */
+#define RSEQ_HAS_LOAD32_LOAD32_RELAXED 1
+static __always_inline int
+rseq_load32_load32_relaxed(uint32_t *dst1, uint32_t *src1,
+ uint32_t *dst2, uint32_t *src2)
+{
+ __asm__ __volatile__ goto (
+ RSEQ_ASM_DEFINE_TABLE(3, 1f, 2f, 4f) /* start, commit, abort */
+ /* Start rseq by storing table entry pointer into rseq_cs. */
+ RSEQ_ASM_STORE_RSEQ_CS(1, 3b, %%fs:RSEQ_CS_OFFSET(%[rseq_offset]))
+ "movl %[src1], %%ebx\n\t"
+ "movl %[src2], %%ecx\n\t"
+ "movl %%ebx, %[dst1]\n\t"
+ /* final store */
+ "movl %%ecx, %[dst2]\n\t"
+ "2:\n\t"
+ RSEQ_ASM_DEFINE_ABORT(4, "", abort)
+ : /* gcc asm goto does not allow outputs */
+ : [rseq_offset] "r" (__rseq_offset),
+ /* final store input */
+ [dst1] "m" (*dst1),
+ [dst2] "m" (*dst2),
+ [src1] "m" (*src1),
+ [src2] "m" (*src2)
+ : "memory", "cc", "ebx", "ecx", "rax"
+ : abort
+ );
+ rseq_after_asm_goto();
+ return 0;
+abort:
+ rseq_after_asm_goto();
+ return -1;
+}
--
2.34.1
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v7 7/8] aarch64: Add rseq_load32_load32_relaxed
2024-02-01 19:36 [PATCH v7 0/8] Extend rseq support Michael Jeanson
` (5 preceding siblings ...)
2024-02-01 19:36 ` [PATCH v7 6/8] x86-64: Add rseq_load32_load32_relaxed Michael Jeanson
@ 2024-02-01 19:36 ` Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 8/8] Linux: Use rseq to accelerate getcpu Michael Jeanson
2024-02-02 15:40 ` [PATCH v7 0/8] Extend rseq support Michael Jeanson
8 siblings, 0 replies; 11+ messages in thread
From: Michael Jeanson @ 2024-02-01 19:36 UTC (permalink / raw)
To: libc-alpha
Cc: Michael Jeanson, Florian Weimer, Carlos O'Donell, Mathieu Desnoyers
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Implement rseq_load32_load32_relaxed() for the aarch64 architecture.
This static inline function implements a rseq critical section to load
two 32-bit integer values atomically with respect to preemption and
signal delivery.
This implementation is imported from the librseq project.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
---
.../unix/sysv/linux/aarch64/rseq-internal.h | 173 ++++++++++++++++++
1 file changed, 173 insertions(+)
create mode 100644 sysdeps/unix/sysv/linux/aarch64/rseq-internal.h
diff --git a/sysdeps/unix/sysv/linux/aarch64/rseq-internal.h b/sysdeps/unix/sysv/linux/aarch64/rseq-internal.h
new file mode 100644
index 0000000000..3c03f67dbe
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/rseq-internal.h
@@ -0,0 +1,173 @@
+/* Restartable Sequences internal API. aarch64 macros.
+ Copyright (C) 2023 Free Software Foundation, Inc.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <sysdeps/unix/sysv/linux/rseq-internal.h>
+
+#define RSEQ_ASM_TMP_REG32 "w15"
+#define RSEQ_ASM_TMP_REG "x15"
+#define RSEQ_ASM_TMP_REG_2 "x14"
+
+#define __RSEQ_ASM_DEFINE_TABLE(label, version, flags, start_ip, \
+ post_commit_offset, abort_ip) \
+ " .pushsection __rseq_cs, \"aw\"\n" \
+ " .balign 32\n" \
+ __rseq_str(label) ":\n" \
+ " .long " __rseq_str(version) ", " __rseq_str(flags) "\n" \
+ " .quad " __rseq_str(start_ip) ", " \
+ __rseq_str(post_commit_offset) ", " \
+ __rseq_str(abort_ip) "\n" \
+ " .popsection\n\t" \
+ " .pushsection __rseq_cs_ptr_array, \"aw\"\n" \
+ " .quad " __rseq_str(label) "b\n" \
+ " .popsection\n"
+
+#define RSEQ_ASM_DEFINE_TABLE(label, start_ip, post_commit_ip, abort_ip) \
+ __RSEQ_ASM_DEFINE_TABLE(label, 0x0, 0x0, start_ip, \
+ (post_commit_ip - start_ip), abort_ip)
+
+/*
+ * Exit points of a rseq critical section consist of all instructions outside
+ * of the critical section where a critical section can either branch to or
+ * reach through the normal course of its execution. The abort IP and the
+ * post-commit IP are already part of the __rseq_cs section and should not be
+ * explicitly defined as additional exit points. Knowing all exit points is
+ * useful to assist debuggers stepping over the critical section.
+ */
+#define RSEQ_ASM_DEFINE_EXIT_POINT(start_ip, exit_ip) \
+ " .pushsection __rseq_exit_point_array, \"aw\"\n" \
+ " .quad " __rseq_str(start_ip) ", " __rseq_str(exit_ip) "\n" \
+ " .popsection\n"
+
+#define RSEQ_ASM_STORE_RSEQ_CS(label, cs_label, rseq_cs) \
+ " adrp " RSEQ_ASM_TMP_REG ", " __rseq_str(cs_label) "\n" \
+ " add " RSEQ_ASM_TMP_REG ", " RSEQ_ASM_TMP_REG \
+ ", :lo12:" __rseq_str(cs_label) "\n" \
+ " str " RSEQ_ASM_TMP_REG ", %[" __rseq_str(rseq_cs) "]\n" \
+ __rseq_str(label) ":\n"
+
+#define RSEQ_ASM_DEFINE_ABORT(label, abort_label) \
+ " b 222f\n" \
+ " .inst " __rseq_str(RSEQ_SIG_CODE) "\n" \
+ __rseq_str(label) ":\n" \
+ " b %l[" __rseq_str(abort_label) "]\n" \
+ "222:\n"
+
+#define RSEQ_ASM_OP_STORE(value, var) \
+ " str %[" __rseq_str(value) "], %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_STORE_RELEASE(value, var) \
+ " stlr %[" __rseq_str(value) "], %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_FINAL_STORE(value, var, post_commit_label) \
+ RSEQ_ASM_OP_STORE(value, var) \
+ __rseq_str(post_commit_label) ":\n"
+
+#define RSEQ_ASM_OP_FINAL_STORE_RELEASE(value, var, post_commit_label) \
+ RSEQ_ASM_OP_STORE_RELEASE(value, var) \
+ __rseq_str(post_commit_label) ":\n"
+
+#define RSEQ_ASM_OP_CMPEQ(var, expect, label) \
+ " ldr " RSEQ_ASM_TMP_REG ", %[" __rseq_str(var) "]\n" \
+ " sub " RSEQ_ASM_TMP_REG ", " RSEQ_ASM_TMP_REG \
+ ", %[" __rseq_str(expect) "]\n" \
+ " cbnz " RSEQ_ASM_TMP_REG ", " __rseq_str(label) "\n"
+
+#define RSEQ_ASM_OP_CMPEQ32(var, expect, label) \
+ " ldr " RSEQ_ASM_TMP_REG32 ", %[" __rseq_str(var) "]\n" \
+ " sub " RSEQ_ASM_TMP_REG32 ", " RSEQ_ASM_TMP_REG32 \
+ ", %w[" __rseq_str(expect) "]\n" \
+ " cbnz " RSEQ_ASM_TMP_REG32 ", " __rseq_str(label) "\n"
+
+#define RSEQ_ASM_OP_CMPNE(var, expect, label) \
+ " ldr " RSEQ_ASM_TMP_REG ", %[" __rseq_str(var) "]\n" \
+ " sub " RSEQ_ASM_TMP_REG ", " RSEQ_ASM_TMP_REG \
+ ", %[" __rseq_str(expect) "]\n" \
+ " cbz " RSEQ_ASM_TMP_REG ", " __rseq_str(label) "\n"
+
+#define RSEQ_ASM_CMP_CPU_ID(cpu_id, current_cpu_id, label) \
+ RSEQ_ASM_OP_CMPEQ32(current_cpu_id, cpu_id, label)
+
+#define RSEQ_ASM_OP_R_LOAD(var) \
+ " ldr " RSEQ_ASM_TMP_REG ", %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_R_STORE(var) \
+ " str " RSEQ_ASM_TMP_REG ", %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_R_LOAD32(var) \
+ " ldr " RSEQ_ASM_TMP_REG32 ", %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_R_STORE32(var) \
+ " str " RSEQ_ASM_TMP_REG32 ", %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_R_LOAD_OFF(offset) \
+ " ldr " RSEQ_ASM_TMP_REG ", [" RSEQ_ASM_TMP_REG \
+ ", %[" __rseq_str(offset) "]]\n"
+
+#define RSEQ_ASM_OP_R_ADD(count) \
+ " add " RSEQ_ASM_TMP_REG ", " RSEQ_ASM_TMP_REG \
+ ", %[" __rseq_str(count) "]\n"
+
+#define RSEQ_ASM_OP_R_FINAL_STORE(var, post_commit_label) \
+ " str " RSEQ_ASM_TMP_REG ", %[" __rseq_str(var) "]\n" \
+ __rseq_str(post_commit_label) ":\n"
+
+#define RSEQ_ASM_OP_R_FINAL_STORE32(var, post_commit_label) \
+ " str " RSEQ_ASM_TMP_REG32 ", %[" __rseq_str(var) "]\n" \
+ __rseq_str(post_commit_label) ":\n"
+
+#define RSEQ_ASM_OP_R_BAD_MEMCPY(dst, src, len) \
+ " cbz %[" __rseq_str(len) "], 333f\n" \
+ " mov " RSEQ_ASM_TMP_REG_2 ", %[" __rseq_str(len) "]\n" \
+ "222: sub " RSEQ_ASM_TMP_REG_2 ", " RSEQ_ASM_TMP_REG_2 ", #1\n" \
+ " ldrb " RSEQ_ASM_TMP_REG32 ", [%[" __rseq_str(src) "]" \
+ ", " RSEQ_ASM_TMP_REG_2 "]\n" \
+ " strb " RSEQ_ASM_TMP_REG32 ", [%[" __rseq_str(dst) "]" \
+ ", " RSEQ_ASM_TMP_REG_2 "]\n" \
+ " cbnz " RSEQ_ASM_TMP_REG_2 ", 222b\n" \
+ "333:\n"
+
+/*
+ * Load @src1 (32-bit) into @dst1 and load @src2 (32-bit) into @dst2.
+ */
+#define RSEQ_HAS_LOAD32_LOAD32_RELAXED 1
+static __always_inline int
+rseq_load32_load32_relaxed(uint32_t *dst1, uint32_t *src1,
+ uint32_t *dst2, uint32_t *src2)
+{
+ __asm__ __volatile__ goto (
+ RSEQ_ASM_DEFINE_TABLE(1, 2f, 3f, 4f)
+ RSEQ_ASM_STORE_RSEQ_CS(2, 1b, rseq_cs)
+ RSEQ_ASM_OP_R_LOAD32(src1)
+ RSEQ_ASM_OP_R_STORE32(dst1)
+ RSEQ_ASM_OP_R_LOAD32(src2)
+ RSEQ_ASM_OP_R_FINAL_STORE32(dst2, 3)
+ RSEQ_ASM_DEFINE_ABORT(4, abort)
+ : /* gcc asm goto does not allow outputs */
+ : [rseq_cs] "m" (rseq_get_area()->rseq_cs),
+ [dst1] "Qo" (*dst1),
+ [dst2] "Qo" (*dst2),
+ [src1] "Qo" (*src1),
+ [src2] "Qo" (*src2)
+ : "memory", RSEQ_ASM_TMP_REG
+ : abort
+ );
+ rseq_after_asm_goto();
+ return 0;
+abort:
+ rseq_after_asm_goto();
+ return -1;
+}
--
2.34.1
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v7 8/8] Linux: Use rseq to accelerate getcpu
2024-02-01 19:36 [PATCH v7 0/8] Extend rseq support Michael Jeanson
` (6 preceding siblings ...)
2024-02-01 19:36 ` [PATCH v7 7/8] aarch64: " Michael Jeanson
@ 2024-02-01 19:36 ` Michael Jeanson
2024-02-02 15:40 ` [PATCH v7 0/8] Extend rseq support Michael Jeanson
8 siblings, 0 replies; 11+ messages in thread
From: Michael Jeanson @ 2024-02-01 19:36 UTC (permalink / raw)
To: libc-alpha
Cc: Michael Jeanson, Florian Weimer, Carlos O'Donell, Mathieu Desnoyers
On architectures that implement rseq_load32_load32_relaxed() (and thus
define RSEQ_HAS_LOAD32_LOAD32_RELAXED), when the node_id feature is
available, use rseq to fetch the cpu_id and node_id atomically with
respect to preemption and signal delivery to speed up getcpu() compared
to a vsyscall or system call implementation.
Loading both cpu_id and node_id atomically with respect to preemption
is required to ensure consistency of the topology mapping between cpu_id
and node_id due to migration between both loads.
On an aarch64 system (Snapdragon 8cx Gen 3) which lacks a vDSO for
getcpu() we measured an improvement from 130 ns to 1 ns while on x86_64
(i7-8550U) which has a vDSO we measured a more modest improvement from
10 ns to 2 ns.
Co-authored-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
---
sysdeps/unix/sysv/linux/getcpu.c | 32 ++++++++++++++++++++++++++++++--
1 file changed, 30 insertions(+), 2 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/getcpu.c b/sysdeps/unix/sysv/linux/getcpu.c
index 0e7c3238c9..7e34d6d1eb 100644
--- a/sysdeps/unix/sysv/linux/getcpu.c
+++ b/sysdeps/unix/sysv/linux/getcpu.c
@@ -19,9 +19,10 @@
#include <sched.h>
#include <sysdep.h>
#include <sysdep-vdso.h>
+#include <rseq-internal.h>
-int
-__getcpu (unsigned int *cpu, unsigned int *node)
+static int
+vsyscall_getcpu (unsigned int *cpu, unsigned int *node)
{
#ifdef HAVE_GETCPU_VSYSCALL
return INLINE_VSYSCALL (getcpu, 3, cpu, node, NULL);
@@ -29,5 +30,32 @@ __getcpu (unsigned int *cpu, unsigned int *node)
return INLINE_SYSCALL_CALL (getcpu, cpu, node, NULL);
#endif
}
+
+#if defined (RSEQ_SIG) && defined (RSEQ_HAS_LOAD32_LOAD32_RELAXED)
+int
+__getcpu (unsigned int *cpu, unsigned int *node)
+{
+ /* Check if rseq is registered and the node_id feature is available. */
+ if (__glibc_likely (rseq_node_id_available()))
+ {
+ struct rseq_area *rseq_area = rseq_get_area();
+
+ if (rseq_load32_load32_relaxed(cpu, &rseq_area->cpu_id,
+ node, &rseq_area->node_id) == 0)
+ {
+ /* The critical section was not aborted, return 0. */
+ return 0;
+ }
+ }
+
+ return vsyscall_getcpu (cpu, node);
+}
+#else
+int
+__getcpu (unsigned int *cpu, unsigned int *node)
+{
+ return vsyscall_getcpu (cpu, node);
+}
+#endif
weak_alias (__getcpu, getcpu)
libc_hidden_def (__getcpu)
--
2.34.1
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v7 0/8] Extend rseq support
2024-02-01 19:36 [PATCH v7 0/8] Extend rseq support Michael Jeanson
` (7 preceding siblings ...)
2024-02-01 19:36 ` [PATCH v7 8/8] Linux: Use rseq to accelerate getcpu Michael Jeanson
@ 2024-02-02 15:40 ` Michael Jeanson
2024-02-02 16:18 ` Adhemerval Zanella Netto
8 siblings, 1 reply; 11+ messages in thread
From: Michael Jeanson @ 2024-02-02 15:40 UTC (permalink / raw)
To: libc-alpha
On 2024-02-01 14:36, Michael Jeanson wrote:
> This series rebases the standalone "Add rseq extensible ABI" patch on
> current master and adds an accelerated getcpu() implementation using the
> rseq extensible ABI with initial support for aarch64 and x86_64.
>
> On an aarch64 system (Snapdragon 8cx Gen 3) which lacks a vDSO for
> getcpu() we measured an improvement from 130 ns to 1 ns while on x86_64
> (i7-8550U) which has a vDSO we measured a more modest improvement from
> 10 ns to 2 ns.
>
> Tested on i386, aarch64 and x86_64.
The failures reported by the Linaro-TCWG-CI on arm seem to be only an issue of
symbol sorting in the abilist files. Is there tooling to regenerate those for
all architectures?
Thanks,
Michael
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v7 0/8] Extend rseq support
2024-02-02 15:40 ` [PATCH v7 0/8] Extend rseq support Michael Jeanson
@ 2024-02-02 16:18 ` Adhemerval Zanella Netto
0 siblings, 0 replies; 11+ messages in thread
From: Adhemerval Zanella Netto @ 2024-02-02 16:18 UTC (permalink / raw)
To: Michael Jeanson, libc-alpha
On 02/02/24 12:40, Michael Jeanson wrote:
> On 2024-02-01 14:36, Michael Jeanson wrote:
>> This series rebases the standalone "Add rseq extensible ABI" patch on
>> current master and adds an accelerated getcpu() implementation using the
>> rseq extensible ABI with initial support for aarch64 and x86_64.
>>
>> On an aarch64 system (Snapdragon 8cx Gen 3) which lacks a vDSO for
>> getcpu() we measured an improvement from 130 ns to 1 ns while on x86_64
>> (i7-8550U) which has a vDSO we measured a more modest improvement from
>> 10 ns to 2 ns.
>>
>> Tested on i386, aarch64 and x86_64.
>
> The failures reported by the Linaro-TCWG-CI on arm seem to be only an issue of symbol sorting in the abilist files. Is there tooling to regenerate those for all architectures?
The 'make update-abi' on the build folder will sort this out.
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2024-02-02 16:18 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-02-01 19:36 [PATCH v7 0/8] Extend rseq support Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 1/8] nptl: fix potential merge of __rseq_* relro symbols Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 2/8] Add rseq extensible ABI support Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 3/8] nptl: Add public __rseq_feature_size symbol Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 4/8] nptl: Add features to internal 'struct rseq_area' Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 5/8] nptl: Add rseq internal utils Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 6/8] x86-64: Add rseq_load32_load32_relaxed Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 7/8] aarch64: " Michael Jeanson
2024-02-01 19:36 ` [PATCH v7 8/8] Linux: Use rseq to accelerate getcpu Michael Jeanson
2024-02-02 15:40 ` [PATCH v7 0/8] Extend rseq support Michael Jeanson
2024-02-02 16:18 ` Adhemerval Zanella Netto
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).