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* [glibc] hurd: Only check for TLS initialization inside rtld or in static builds
@ 2023-04-10 21:33 Samuel Thibault
0 siblings, 0 replies; 2+ messages in thread
From: Samuel Thibault @ 2023-04-10 21:33 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b37899d34d2190ef4b454283188f22519f096048
commit b37899d34d2190ef4b454283188f22519f096048
Author: Sergey Bugaev <bugaevc@gmail.com>
Date: Sun Mar 19 18:10:07 2023 +0300
hurd: Only check for TLS initialization inside rtld or in static builds
When glibc is built as a shared library, TLS is always initialized by
the call of TLS_INIT_TP () macro made inside the dynamic loader, prior
to running the main program (see dl-call_tls_init_tp.h). We can take
advantage of this: we know for sure that __LIBC_NO_TLS () will evaluate
to 0 in all other cases, so let the compiler know that explicitly too.
Also, only define _hurd_tls_init () and TLS_INIT_TP () under the same
conditions (either !SHARED or inside rtld), to statically assert that
this is the case.
Other than a microoptimization, this also helps with avoiding awkward
sharing of the __libc_tls_initialized variable between ld.so and libc.so
that we would have to do otherwise -- we know for sure that no sharing
is required, simply because __libc_tls_initialized would always be set
to true inside libc.so.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230319151017.531737-25-bugaevc@gmail.com>
Diff:
---
sysdeps/mach/hurd/Makefile | 4 +++
sysdeps/mach/hurd/i386/dl-tls-initialized.c | 21 +++++++++++++
sysdeps/mach/hurd/i386/tls.h | 43 ++++++++++++++++-----------
sysdeps/mach/hurd/x86/init-first.c | 11 +------
sysdeps/mach/hurd/x86_64/dl-tls-initialized.c | 21 +++++++++++++
sysdeps/mach/hurd/x86_64/tls.h | 19 +++++++-----
6 files changed, 85 insertions(+), 34 deletions(-)
diff --git a/sysdeps/mach/hurd/Makefile b/sysdeps/mach/hurd/Makefile
index d5584930a1..f43e92bab3 100644
--- a/sysdeps/mach/hurd/Makefile
+++ b/sysdeps/mach/hurd/Makefile
@@ -197,6 +197,10 @@ ifeq (hurd, $(subdir))
sysdep_routines += cthreads
endif
+ifeq (elf, $(subdir))
+sysdep-dl-routines += dl-tls-initialized
+endif
+
ifeq (io, $(subdir))
sysdep_routines += f_setlk close_nocancel close_nocancel_nostatus \
fcntl_nocancel open_nocancel openat_nocancel read_nocancel \
diff --git a/sysdeps/mach/hurd/i386/dl-tls-initialized.c b/sysdeps/mach/hurd/i386/dl-tls-initialized.c
new file mode 100644
index 0000000000..493ec2396c
--- /dev/null
+++ b/sysdeps/mach/hurd/i386/dl-tls-initialized.c
@@ -0,0 +1,21 @@
+/* Determine whether TLS is initialized, for i386/Hurd.
+ Copyright (C) 1995-2023 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/>. */
+
+#ifndef SHARED
+unsigned short __init1_desc;
+#endif
diff --git a/sysdeps/mach/hurd/i386/tls.h b/sysdeps/mach/hurd/i386/tls.h
index 0f8dd24145..ee7b8004bc 100644
--- a/sysdeps/mach/hurd/i386/tls.h
+++ b/sysdeps/mach/hurd/i386/tls.h
@@ -69,18 +69,6 @@ _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x30,
| (desc->high_word & 0xff000000)); \
})
-/* Return 1 if TLS is not initialized yet. */
-#ifndef SHARED
-extern unsigned short __init1_desc;
-#define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds) || (gs) == __init1_desc)
-#else
-#define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds))
-#endif
-
-#define __LIBC_NO_TLS() \
- ({ unsigned short ds, gs; \
- asm ("movw %%ds,%w0; movw %%gs,%w1" : "=q" (ds), "=q" (gs)); \
- __builtin_expect(__HURD_DESC_INITIAL(gs, ds), 0); })
#endif
/* The TCB can have any size and the memory following the address the
@@ -125,6 +113,28 @@ extern unsigned short __init1_desc;
# define HURD_SEL_LDT(sel) (__builtin_expect ((sel) & 4, 0))
+#ifndef SHARED
+extern unsigned short __init1_desc;
+# define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds) || (gs) == __init1_desc)
+#else
+# define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds))
+#endif
+
+#if !defined (SHARED) || IS_IN (rtld)
+/* Return 1 if TLS is not initialized yet. */
+extern inline bool __attribute__ ((unused))
+__LIBC_NO_TLS (void)
+{
+ unsigned short ds, gs;
+ asm ("movw %%ds, %w0\n"
+ "movw %%gs, %w1"
+ : "=q" (ds), "=q" (gs));
+ return __glibc_unlikely (__HURD_DESC_INITIAL (gs, ds));
+}
+
+/* Code to initially initialize the thread pointer. This might need
+ special attention since 'errno' is not yet available and if the
+ operation can cause a failure 'errno' must not be touched. */
static inline bool __attribute__ ((unused))
_hurd_tls_init (tcbhead_t *tcb)
{
@@ -168,11 +178,10 @@ out:
return success;
}
-/* Code to initially initialize the thread pointer. This might need
- special attention since 'errno' is not yet available and if the
- operation can cause a failure 'errno' must not be touched. */
-# define TLS_INIT_TP(descr) \
- _hurd_tls_init ((tcbhead_t *) (descr))
+# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr))
+#else /* defined (SHARED) && !IS_IN (rtld) */
+# define __LIBC_NO_TLS() 0
+#endif
# if __GNUC_PREREQ (6, 0)
diff --git a/sysdeps/mach/hurd/x86/init-first.c b/sysdeps/mach/hurd/x86/init-first.c
index 48c330ec06..89a5f44cdd 100644
--- a/sysdeps/mach/hurd/x86/init-first.c
+++ b/sysdeps/mach/hurd/x86/init-first.c
@@ -40,13 +40,6 @@ extern char **_dl_argv;
#ifndef SHARED
static tcbhead_t __init1_tcbhead;
-# ifndef __x86_64__
-unsigned short __init1_desc;
-# endif
-#endif
-
-#ifdef __x86_64__
-unsigned char __libc_tls_initialized;
#endif
/* Things that want to be run before _hurd_init or much anything else.
@@ -166,9 +159,7 @@ first_init (void)
_hurd_tls_init (&__init1_tcbhead);
/* Make sure __LIBC_NO_TLS () keeps evaluating to 1. */
-# ifdef __x86_64__
- __libc_tls_initialized = 0;
-# else
+# ifndef __x86_64__
asm ("movw %%gs,%w0" : "=m" (__init1_desc));
# endif
#endif
diff --git a/sysdeps/mach/hurd/x86_64/dl-tls-initialized.c b/sysdeps/mach/hurd/x86_64/dl-tls-initialized.c
new file mode 100644
index 0000000000..d0766f955d
--- /dev/null
+++ b/sysdeps/mach/hurd/x86_64/dl-tls-initialized.c
@@ -0,0 +1,21 @@
+/* Determine whether TLS is initialized, for x86_64/Hurd.
+ Copyright (C) 1995-2023 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/>. */
+
+#if !defined (SHARED) || IS_IN (rtld)
+unsigned short __libc_tls_initialized;
+#endif
diff --git a/sysdeps/mach/hurd/x86_64/tls.h b/sysdeps/mach/hurd/x86_64/tls.h
index cf74e1f441..da504d9c81 100644
--- a/sysdeps/mach/hurd/x86_64/tls.h
+++ b/sysdeps/mach/hurd/x86_64/tls.h
@@ -68,10 +68,6 @@ _Static_assert (offsetof (tcbhead_t, stack_guard) == 0x28,
_Static_assert (offsetof (tcbhead_t, __private_ss) == 0x70,
"split stack pointer offset");
-extern unsigned char __libc_tls_initialized;
-
-# define __LIBC_NO_TLS() __builtin_expect (!__libc_tls_initialized, 0)
-
/* The TCB can have any size and the memory following the address the
thread pointer points to is unspecified. Allocate the TCB there. */
# define TLS_TCB_AT_TP 1
@@ -87,8 +83,6 @@ extern unsigned char __libc_tls_initialized;
# define TCB_ALIGNMENT 64
-# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr))
-
# define THREAD_SELF \
(*(tcbhead_t * __seg_fs *) offsetof (tcbhead_t, tcb))
/* Read member of the thread descriptor directly. */
@@ -174,6 +168,10 @@ _hurd_tls_new (thread_t child, tcbhead_t *tcb)
i386_FSGS_BASE_STATE_COUNT);
}
+# if !defined (SHARED) || IS_IN (rtld)
+extern unsigned char __libc_tls_initialized;
+# define __LIBC_NO_TLS() __builtin_expect (!__libc_tls_initialized, 0)
+
static inline bool __attribute__ ((unused))
_hurd_tls_init (tcbhead_t *tcb)
{
@@ -184,11 +182,18 @@ _hurd_tls_init (tcbhead_t *tcb)
tcb->multiple_threads = 1;
err = _hurd_tls_new (self, tcb);
+ if (err == 0)
+ __libc_tls_initialized = 1;
__mach_port_deallocate (__mach_task_self (), self);
- __libc_tls_initialized = 1;
return err == 0;
}
+# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr))
+# else /* defined (SHARED) && !IS_IN (rtld) */
+# define __LIBC_NO_TLS() 0
+# endif
+
+
/* Global scope switch support. */
# define THREAD_GSCOPE_FLAG_UNUSED 0
^ permalink raw reply [flat|nested] 2+ messages in thread
* [glibc] hurd: Only check for TLS initialization inside rtld or in static builds
@ 2023-04-14 17:33 Samuel Thibault
0 siblings, 0 replies; 2+ messages in thread
From: Samuel Thibault @ 2023-04-14 17:33 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=e2756903329365134089d23548e9083d23bc3dd9
commit e2756903329365134089d23548e9083d23bc3dd9
Author: Sergey Bugaev <bugaevc@gmail.com>
Date: Sun Mar 19 18:10:07 2023 +0300
hurd: Only check for TLS initialization inside rtld or in static builds
When glibc is built as a shared library, TLS is always initialized by
the call of TLS_INIT_TP () macro made inside the dynamic loader, prior
to running the main program (see dl-call_tls_init_tp.h). We can take
advantage of this: we know for sure that __LIBC_NO_TLS () will evaluate
to 0 in all other cases, so let the compiler know that explicitly too.
Also, only define _hurd_tls_init () and TLS_INIT_TP () under the same
conditions (either !SHARED or inside rtld), to statically assert that
this is the case.
Other than a microoptimization, this also helps with avoiding awkward
sharing of the __libc_tls_initialized variable between ld.so and libc.so
that we would have to do otherwise -- we know for sure that no sharing
is required, simply because __libc_tls_initialized would always be set
to true inside libc.so.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230319151017.531737-25-bugaevc@gmail.com>
Diff:
---
sysdeps/mach/hurd/Makefile | 4 +++
sysdeps/mach/hurd/i386/dl-tls-initialized.c | 21 +++++++++++++
sysdeps/mach/hurd/i386/tls.h | 43 ++++++++++++++++-----------
sysdeps/mach/hurd/x86/init-first.c | 11 +------
sysdeps/mach/hurd/x86_64/dl-tls-initialized.c | 21 +++++++++++++
sysdeps/mach/hurd/x86_64/tls.h | 16 ++++++----
6 files changed, 83 insertions(+), 33 deletions(-)
diff --git a/sysdeps/mach/hurd/Makefile b/sysdeps/mach/hurd/Makefile
index 0e880755ca..8fb6baf09e 100644
--- a/sysdeps/mach/hurd/Makefile
+++ b/sysdeps/mach/hurd/Makefile
@@ -197,6 +197,10 @@ ifeq (hurd, $(subdir))
sysdep_routines += cthreads
endif
+ifeq (elf, $(subdir))
+sysdep-dl-routines += dl-tls-initialized
+endif
+
ifeq (io, $(subdir))
sysdep_routines += f_setlk close_nocancel close_nocancel_nostatus \
fcntl_nocancel open_nocancel openat_nocancel read_nocancel \
diff --git a/sysdeps/mach/hurd/i386/dl-tls-initialized.c b/sysdeps/mach/hurd/i386/dl-tls-initialized.c
new file mode 100644
index 0000000000..493ec2396c
--- /dev/null
+++ b/sysdeps/mach/hurd/i386/dl-tls-initialized.c
@@ -0,0 +1,21 @@
+/* Determine whether TLS is initialized, for i386/Hurd.
+ Copyright (C) 1995-2023 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/>. */
+
+#ifndef SHARED
+unsigned short __init1_desc;
+#endif
diff --git a/sysdeps/mach/hurd/i386/tls.h b/sysdeps/mach/hurd/i386/tls.h
index 694be9fd64..0ac8917a95 100644
--- a/sysdeps/mach/hurd/i386/tls.h
+++ b/sysdeps/mach/hurd/i386/tls.h
@@ -69,18 +69,6 @@ _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x30,
| (desc->high_word & 0xff000000)); \
})
-/* Return 1 if TLS is not initialized yet. */
-#ifndef SHARED
-extern unsigned short __init1_desc;
-#define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds) || (gs) == __init1_desc)
-#else
-#define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds))
-#endif
-
-#define __LIBC_NO_TLS() \
- ({ unsigned short ds, gs; \
- asm ("movw %%ds,%w0; movw %%gs,%w1" : "=q" (ds), "=q" (gs)); \
- __builtin_expect(__HURD_DESC_INITIAL(gs, ds), 0); })
#endif
/* The TCB can have any size and the memory following the address the
@@ -125,6 +113,28 @@ extern unsigned short __init1_desc;
# define HURD_SEL_LDT(sel) (__builtin_expect ((sel) & 4, 0))
+#ifndef SHARED
+extern unsigned short __init1_desc;
+# define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds) || (gs) == __init1_desc)
+#else
+# define __HURD_DESC_INITIAL(gs, ds) ((gs) == (ds))
+#endif
+
+#if !defined (SHARED) || IS_IN (rtld)
+/* Return 1 if TLS is not initialized yet. */
+extern inline bool __attribute__ ((unused))
+__LIBC_NO_TLS (void)
+{
+ unsigned short ds, gs;
+ asm ("movw %%ds, %w0\n"
+ "movw %%gs, %w1"
+ : "=q" (ds), "=q" (gs));
+ return __glibc_unlikely (__HURD_DESC_INITIAL (gs, ds));
+}
+
+/* Code to initially initialize the thread pointer. This might need
+ special attention since 'errno' is not yet available and if the
+ operation can cause a failure 'errno' must not be touched. */
static inline bool __attribute__ ((unused))
_hurd_tls_init (tcbhead_t *tcb)
{
@@ -173,11 +183,10 @@ out:
return success;
}
-/* Code to initially initialize the thread pointer. This might need
- special attention since 'errno' is not yet available and if the
- operation can cause a failure 'errno' must not be touched. */
-# define TLS_INIT_TP(descr) \
- _hurd_tls_init ((tcbhead_t *) (descr))
+# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr))
+#else /* defined (SHARED) && !IS_IN (rtld) */
+# define __LIBC_NO_TLS() 0
+#endif
# if __GNUC_PREREQ (6, 0)
diff --git a/sysdeps/mach/hurd/x86/init-first.c b/sysdeps/mach/hurd/x86/init-first.c
index 48c330ec06..89a5f44cdd 100644
--- a/sysdeps/mach/hurd/x86/init-first.c
+++ b/sysdeps/mach/hurd/x86/init-first.c
@@ -40,13 +40,6 @@ extern char **_dl_argv;
#ifndef SHARED
static tcbhead_t __init1_tcbhead;
-# ifndef __x86_64__
-unsigned short __init1_desc;
-# endif
-#endif
-
-#ifdef __x86_64__
-unsigned char __libc_tls_initialized;
#endif
/* Things that want to be run before _hurd_init or much anything else.
@@ -166,9 +159,7 @@ first_init (void)
_hurd_tls_init (&__init1_tcbhead);
/* Make sure __LIBC_NO_TLS () keeps evaluating to 1. */
-# ifdef __x86_64__
- __libc_tls_initialized = 0;
-# else
+# ifndef __x86_64__
asm ("movw %%gs,%w0" : "=m" (__init1_desc));
# endif
#endif
diff --git a/sysdeps/mach/hurd/x86_64/dl-tls-initialized.c b/sysdeps/mach/hurd/x86_64/dl-tls-initialized.c
new file mode 100644
index 0000000000..d0766f955d
--- /dev/null
+++ b/sysdeps/mach/hurd/x86_64/dl-tls-initialized.c
@@ -0,0 +1,21 @@
+/* Determine whether TLS is initialized, for x86_64/Hurd.
+ Copyright (C) 1995-2023 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/>. */
+
+#if !defined (SHARED) || IS_IN (rtld)
+unsigned short __libc_tls_initialized;
+#endif
diff --git a/sysdeps/mach/hurd/x86_64/tls.h b/sysdeps/mach/hurd/x86_64/tls.h
index e5c6f82acd..2b7135f635 100644
--- a/sysdeps/mach/hurd/x86_64/tls.h
+++ b/sysdeps/mach/hurd/x86_64/tls.h
@@ -68,10 +68,6 @@ _Static_assert (offsetof (tcbhead_t, stack_guard) == 0x28,
_Static_assert (offsetof (tcbhead_t, __private_ss) == 0x70,
"split stack pointer offset");
-extern unsigned char __libc_tls_initialized;
-
-# define __LIBC_NO_TLS() __builtin_expect (!__libc_tls_initialized, 0)
-
/* The TCB can have any size and the memory following the address the
thread pointer points to is unspecified. Allocate the TCB there. */
# define TLS_TCB_AT_TP 1
@@ -87,8 +83,6 @@ extern unsigned char __libc_tls_initialized;
# define TCB_ALIGNMENT 64
-# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr))
-
# define THREAD_SELF \
(*(tcbhead_t * __seg_fs *) offsetof (tcbhead_t, tcb))
/* Read member of the thread descriptor directly. */
@@ -174,6 +168,10 @@ _hurd_tls_new (thread_t child, tcbhead_t *tcb)
i386_FSGS_BASE_STATE_COUNT);
}
+# if !defined (SHARED) || IS_IN (rtld)
+extern unsigned char __libc_tls_initialized;
+# define __LIBC_NO_TLS() __builtin_expect (!__libc_tls_initialized, 0)
+
static inline bool __attribute__ ((unused))
_hurd_tls_init (tcbhead_t *tcb)
{
@@ -197,6 +195,12 @@ _hurd_tls_init (tcbhead_t *tcb)
return err == 0;
}
+# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr))
+# else /* defined (SHARED) && !IS_IN (rtld) */
+# define __LIBC_NO_TLS() 0
+# endif
+
+
/* Global scope switch support. */
# define THREAD_GSCOPE_FLAG_UNUSED 0
^ permalink raw reply [flat|nested] 2+ messages in thread
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