* [PATCH v3 1/3] ia64: Always define IA64_USE_NEW_STUB as a flag macro
@ 2022-05-05 12:14 Florian Weimer
2022-05-05 12:14 ` [PATCH v3 2/3] Linux: Implement a useful version of _startup_fatal Florian Weimer
2022-05-05 12:15 ` [PATCH v3 3/3] csu: Implement and use _dl_early_allocate during static startup Florian Weimer
0 siblings, 2 replies; 3+ messages in thread
From: Florian Weimer @ 2022-05-05 12:14 UTC (permalink / raw)
To: libc-alpha
And keep the previous definition if it exists. This allows
disabling IA64_USE_NEW_STUB while keeping USE_DL_SYSINFO defined.
---
v3: Fix “statup” typo. Do not use libpthread and librt in conditional.
sysdeps/unix/sysv/linux/ia64/brk.c | 5 ++---
sysdeps/unix/sysv/linux/ia64/sysdep.h | 23 +++++++++++++----------
2 files changed, 15 insertions(+), 13 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/ia64/brk.c b/sysdeps/unix/sysv/linux/ia64/brk.c
index 65142aeae9..d2135b74fc 100644
--- a/sysdeps/unix/sysv/linux/ia64/brk.c
+++ b/sysdeps/unix/sysv/linux/ia64/brk.c
@@ -16,7 +16,6 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#include <dl-sysdep.h>
-/* brk is used by statup before TCB is properly set. */
-#undef USE_DL_SYSINFO
+/* brk is used by startup before TCB is properly set up. */
+#define IA64_USE_NEW_STUB 0
#include <sysdeps/unix/sysv/linux/brk.c>
diff --git a/sysdeps/unix/sysv/linux/ia64/sysdep.h b/sysdeps/unix/sysv/linux/ia64/sysdep.h
index 193ecee023..14adbdf4ff 100644
--- a/sysdeps/unix/sysv/linux/ia64/sysdep.h
+++ b/sysdeps/unix/sysv/linux/ia64/sysdep.h
@@ -44,12 +44,15 @@
#undef SYS_ify
#define SYS_ify(syscall_name) __NR_##syscall_name
-#if defined USE_DL_SYSINFO \
- && (IS_IN (libc) \
- || IS_IN (libpthread) || IS_IN (librt))
-# define IA64_USE_NEW_STUB
-#else
-# undef IA64_USE_NEW_STUB
+#ifndef IA64_USE_NEW_STUB
+# if defined USE_DL_SYSINFO && IS_IN (libc)
+# define IA64_USE_NEW_STUB 1
+# else
+# define IA64_USE_NEW_STUB 0
+# endif
+#endif
+#if IA64_USE_NEW_STUB && !USE_DL_SYSINFO
+# error IA64_USE_NEW_STUB needs USE_DL_SYSINFO
#endif
#ifdef __ASSEMBLER__
@@ -101,7 +104,7 @@
mov r15=num; \
break __IA64_BREAK_SYSCALL
-#ifdef IA64_USE_NEW_STUB
+#if IA64_USE_NEW_STUB
# ifdef SHARED
# define DO_CALL(num) \
.prologue; \
@@ -185,7 +188,7 @@
(non-negative) errno on error or the return value on success.
*/
-#ifdef IA64_USE_NEW_STUB
+#if IA64_USE_NEW_STUB
# define INTERNAL_SYSCALL_NCS(name, nr, args...) \
({ \
@@ -277,7 +280,7 @@
#define ASM_OUTARGS_5 ASM_OUTARGS_4, "=r" (_out4)
#define ASM_OUTARGS_6 ASM_OUTARGS_5, "=r" (_out5)
-#ifdef IA64_USE_NEW_STUB
+#if IA64_USE_NEW_STUB
#define ASM_ARGS_0
#define ASM_ARGS_1 ASM_ARGS_0, "4" (_out0)
#define ASM_ARGS_2 ASM_ARGS_1, "5" (_out1)
@@ -313,7 +316,7 @@
/* Branch registers. */ \
"b6"
-#ifdef IA64_USE_NEW_STUB
+#if IA64_USE_NEW_STUB
# define ASM_CLOBBERS_6 ASM_CLOBBERS_6_COMMON
#else
# define ASM_CLOBBERS_6 ASM_CLOBBERS_6_COMMON , "b7"
base-commit: c1b68685d438373efe64e5f076f4215723004dfb
--
2.35.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH v3 2/3] Linux: Implement a useful version of _startup_fatal
2022-05-05 12:14 [PATCH v3 1/3] ia64: Always define IA64_USE_NEW_STUB as a flag macro Florian Weimer
@ 2022-05-05 12:14 ` Florian Weimer
2022-05-05 12:15 ` [PATCH v3 3/3] csu: Implement and use _dl_early_allocate during static startup Florian Weimer
1 sibling, 0 replies; 3+ messages in thread
From: Florian Weimer @ 2022-05-05 12:14 UTC (permalink / raw)
To: libc-alpha
On i386 and ia64, the TCB is not available at this point.
---
v3: Use 2022 copyright year. Fix “statup” typo. Use __message_length
local variable in _startup_fatal.
sysdeps/unix/sysv/linux/i386/startup.h | 23 +++------------
sysdeps/unix/sysv/linux/ia64/startup.h | 22 +++++++++++++++
sysdeps/unix/sysv/linux/startup.h | 39 ++++++++++++++++++++++++++
3 files changed, 65 insertions(+), 19 deletions(-)
create mode 100644 sysdeps/unix/sysv/linux/ia64/startup.h
create mode 100644 sysdeps/unix/sysv/linux/startup.h
diff --git a/sysdeps/unix/sysv/linux/i386/startup.h b/sysdeps/unix/sysv/linux/i386/startup.h
index 67c9310f3a..213805d7d2 100644
--- a/sysdeps/unix/sysv/linux/i386/startup.h
+++ b/sysdeps/unix/sysv/linux/i386/startup.h
@@ -1,5 +1,5 @@
/* Linux/i386 definitions of functions used by static libc main startup.
- Copyright (C) 2017-2022 Free Software Foundation, Inc.
+ Copyright (C) 2022 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
@@ -16,22 +16,7 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#if BUILD_PIE_DEFAULT
-/* Can't use "call *%gs:SYSINFO_OFFSET" during statup in static PIE. */
-# define I386_USE_SYSENTER 0
+/* Can't use "call *%gs:SYSINFO_OFFSET" during startup. */
+#define I386_USE_SYSENTER 0
-# include <sysdep.h>
-# include <abort-instr.h>
-
-__attribute__ ((__noreturn__))
-static inline void
-_startup_fatal (const char *message __attribute__ ((unused)))
-{
- /* This is only called very early during startup in static PIE.
- FIXME: How can it be improved? */
- ABORT_INSTRUCTION;
- __builtin_unreachable ();
-}
-#else
-# include_next <startup.h>
-#endif
+#include_next <startup.h>
diff --git a/sysdeps/unix/sysv/linux/ia64/startup.h b/sysdeps/unix/sysv/linux/ia64/startup.h
new file mode 100644
index 0000000000..77f29f15a2
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/ia64/startup.h
@@ -0,0 +1,22 @@
+/* Linux/ia64 definitions of functions used by static libc main startup.
+ Copyright (C) 2022 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/>. */
+
+/* This code is used before the TCB is set up. */
+#define IA64_USE_NEW_STUB 0
+
+#include_next <startup.h>
diff --git a/sysdeps/unix/sysv/linux/startup.h b/sysdeps/unix/sysv/linux/startup.h
new file mode 100644
index 0000000000..39859b404a
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/startup.h
@@ -0,0 +1,39 @@
+/* Linux definitions of functions used by static libc main startup.
+ Copyright (C) 2017-2022 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/>. */
+
+#ifdef SHARED
+# include_next <startup.h>
+#else
+# include <sysdep.h>
+
+/* Avoid a run-time invocation of strlen. */
+#define _startup_fatal(message) \
+ do \
+ { \
+ size_t __message_length = __builtin_strlen (message); \
+ if (! __builtin_constant_p (__message_length)) \
+ { \
+ extern void _startup_fatal_not_constant (void); \
+ _startup_fatal_not_constant (); \
+ } \
+ INTERNAL_SYSCALL_CALL (write, STDERR_FILENO, (message), \
+ __message_length); \
+ INTERNAL_SYSCALL_CALL (exit_group, 127); \
+ } \
+ while (0)
+#endif /* !SHARED */
--
2.35.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH v3 3/3] csu: Implement and use _dl_early_allocate during static startup
2022-05-05 12:14 [PATCH v3 1/3] ia64: Always define IA64_USE_NEW_STUB as a flag macro Florian Weimer
2022-05-05 12:14 ` [PATCH v3 2/3] Linux: Implement a useful version of _startup_fatal Florian Weimer
@ 2022-05-05 12:15 ` Florian Weimer
1 sibling, 0 replies; 3+ messages in thread
From: Florian Weimer @ 2022-05-05 12:15 UTC (permalink / raw)
To: libc-alpha
This implements mmap fallback for a brk failure during TLS
allocation.
scripts/tls-elf-edit.py is updated to support the new patching method.
The script no longer requires that in the input object is of ET_DYN
type.
---
v3: Remove spurious empty line change.
csu/libc-tls.c | 11 ++-
elf/Makefile | 19 +++++
elf/dl-early_allocate.c | 30 ++++++++
elf/tst-tls-allocation-failure-static.c | 31 ++++++++
scripts/tst-elf-edit.py | 34 +++++++--
sysdeps/generic/ldsodefs.h | 5 ++
sysdeps/unix/sysv/linux/dl-early_allocate.c | 81 +++++++++++++++++++++
7 files changed, 201 insertions(+), 10 deletions(-)
create mode 100644 elf/dl-early_allocate.c
create mode 100644 elf/tst-tls-allocation-failure-static.c
create mode 100644 sysdeps/unix/sysv/linux/dl-early_allocate.c
diff --git a/csu/libc-tls.c b/csu/libc-tls.c
index bef92a7568..0a216c5502 100644
--- a/csu/libc-tls.c
+++ b/csu/libc-tls.c
@@ -145,11 +145,16 @@ __libc_setup_tls (void)
_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);
- tlsblock = __sbrk (tcb_offset + TLS_INIT_TCB_SIZE + max_align);
+ tlsblock = _dl_early_allocate (tcb_offset + TLS_INIT_TCB_SIZE + max_align);
+ if (tlsblock == NULL)
+ _startup_fatal ("Fatal glibc error: Cannot allocate TLS block\n");
#elif TLS_DTV_AT_TP
tcb_offset = roundup (TLS_INIT_TCB_SIZE, align ?: 1);
- tlsblock = __sbrk (tcb_offset + memsz + max_align
- + TLS_PRE_TCB_SIZE + GLRO(dl_tls_static_surplus));
+ tlsblock = _dl_early_allocate (tcb_offset + memsz + max_align
+ + TLS_PRE_TCB_SIZE
+ + GLRO(dl_tls_static_surplus));
+ if (tlsblock == NULL)
+ _startup_fatal ("Fatal glibc error: Cannot allocate TLS block\n");
tlsblock += TLS_PRE_TCB_SIZE;
#else
/* In case a model with a different layout for the TCB and DTV
diff --git a/elf/Makefile b/elf/Makefile
index fc9860edee..ce3345ed92 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -33,6 +33,7 @@ routines = \
$(all-dl-routines) \
dl-addr \
dl-addr-obj \
+ dl-early_allocate \
dl-error \
dl-iteratephdr \
dl-libc \
@@ -108,6 +109,7 @@ all-dl-routines = $(dl-routines) $(sysdep-dl-routines)
# But they are absent from the shared libc, because that code is in ld.so.
elide-routines.os = \
$(all-dl-routines) \
+ dl-early_allocate \
dl-exception \
dl-origin \
dl-reloc-static-pie \
@@ -276,6 +278,7 @@ tests-static-normal := \
tst-linkall-static \
tst-single_threaded-pthread-static \
tst-single_threaded-static \
+ tst-tls-allocation-failure-static \
tst-tlsalign-extern-static \
tst-tlsalign-static \
# tests-static-normal
@@ -1213,6 +1216,10 @@ $(objpfx)tst-glibcelf.out: tst-glibcelf.py elf.h $(..)/scripts/glibcelf.py \
--cc="$(CC) $(patsubst -DMODULE_NAME=%,-DMODULE_NAME=testsuite,$(CPPFLAGS))" \
< /dev/null > $@ 2>&1; $(evaluate-test)
+ifeq ($(run-built-tests),yes)
+tests-special += $(objpfx)tst-tls-allocation-failure-static-patched.out
+endif
+
# The test requires shared _and_ PIE because the executable
# unit test driver must be able to link with the shared object
# that is going to eventually go into an installed DSO.
@@ -2937,3 +2944,15 @@ $(eval $(call tst-trace-skeleton,4,\
$(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4))
$(eval $(call tst-trace-skeleton,5,\
$(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4:$(objpfx)libtracemod5))
+
+$(objpfx)tst-tls-allocation-failure-static-patched: \
+ $(objpfx)tst-tls-allocation-failure-static $(..)scripts/tst-elf-edit.py
+ cp $< $@
+ $(PYTHON) $(..)scripts/tst-elf-edit.py --maximize-tls-size $@
+
+$(objpfx)tst-tls-allocation-failure-static-patched.out: \
+ $(objpfx)tst-tls-allocation-failure-static-patched
+ $< > $@ 2>&1; echo "status: $$?" >> $@
+ grep -q '^Fatal glibc error: Cannot allocate TLS block$$' $@ \
+ && grep -q '^status: 127$$' $@; \
+ $(evaluate-test)
diff --git a/elf/dl-early_allocate.c b/elf/dl-early_allocate.c
new file mode 100644
index 0000000000..d7f59d41e5
--- /dev/null
+++ b/elf/dl-early_allocate.c
@@ -0,0 +1,30 @@
+/* Early memory allocation for the dynamic loader. Generic version.
+ Copyright (C) 2022 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 <ldsodefs.h>
+#include <stddef.h>
+#include <unistd.h>
+
+void *
+_dl_early_allocate (size_t size)
+{
+ void *result = __sbrk (size);
+ if (result == (void *) -1)
+ _dl_fatal_printf ("Fatal glibc error: Early memory allocation failed\n");
+ return result;
+}
diff --git a/elf/tst-tls-allocation-failure-static.c b/elf/tst-tls-allocation-failure-static.c
new file mode 100644
index 0000000000..8de831b246
--- /dev/null
+++ b/elf/tst-tls-allocation-failure-static.c
@@ -0,0 +1,31 @@
+/* Base for test program with impossiblyh large PT_TLS segment.
+ Copyright (C) 2022 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/>. */
+
+/* The test actual binary is patched using scripts/tst-elf-edit.py
+ --maximize-tls-size, and this introduces the expected test
+ allocation failure due to an excessive PT_LS p_memsz value.
+
+ Patching the binary is required because on some 64-bit targets, TLS
+ relocations can only cover a 32-bit range, and glibc-internal TLS
+ variables such as errno end up outside that range. */
+
+int
+main (void)
+{
+ return 0;
+}
diff --git a/scripts/tst-elf-edit.py b/scripts/tst-elf-edit.py
index a514179bbf..0e19ce1e73 100644
--- a/scripts/tst-elf-edit.py
+++ b/scripts/tst-elf-edit.py
@@ -43,9 +43,11 @@ EI_DATA=5
ELFDATA2LSB=b'\x01'
ELFDATA2MSB=b'\x02'
+ET_EXEC=2
ET_DYN=3
PT_LOAD=1
+PT_TLS=7
def elf_types_fmts(e_ident):
endian = '<' if e_ident[EI_DATA] == ELFDATA2LSB else '>'
@@ -146,8 +148,15 @@ def elf_edit_align(phdr, align):
else:
phdr.p_align = int(align)
+def elf_edit_maximize_tls_size(phdr, elfclass):
+ if elfclass == ELFCLASS32:
+ # It is possible that the kernel can allocate half of the
+ # address space, so use something larger.
+ phdr.p_memsz = 0xfff00000
+ else:
+ phdr.p_memsz = 1 << 63
-def elf_edit(f, align):
+def elf_edit(f, opts):
ei_nident_fmt = 'c' * EI_NIDENT
ei_nident_len = struct.calcsize(ei_nident_fmt)
@@ -172,24 +181,35 @@ def elf_edit(f, align):
ehdr = Elf_Ehdr(e_ident)
ehdr.read(f)
- if ehdr.e_type != ET_DYN:
- error('{}: not a shared library'.format(f.name))
+ if ehdr.e_type not in (ET_EXEC, ET_DYN):
+ error('{}: not an executable or shared library'.format(f.name))
phdr = Elf_Phdr(e_ident)
+ maximize_tls_size_done = False
for i in range(0, ehdr.e_phnum):
f.seek(ehdr.e_phoff + i * phdr.len)
phdr.read(f)
- if phdr.p_type == PT_LOAD:
- elf_edit_align(phdr, align)
+ if phdr.p_type == PT_LOAD and opts.align is not None:
+ elf_edit_align(phdr, opts.align)
+ f.seek(ehdr.e_phoff + i * phdr.len)
+ phdr.write(f)
+ break
+ if phdr.p_type == PT_TLS and opts.maximize_tls_size:
+ elf_edit_maximize_tls_size(phdr, e_ident[EI_CLASS])
f.seek(ehdr.e_phoff + i * phdr.len)
phdr.write(f)
+ maximize_tls_size_done = True
break
+ if opts.maximize_tls_size and not maximize_tls_size_done:
+ error('{}: TLS maximum size was not updated'.format(f.name))
def get_parser():
parser = argparse.ArgumentParser(description=__doc__)
- parser.add_argument('-a', dest='align', required=True,
+ parser.add_argument('-a', dest='align',
help='How to set the LOAD alignment')
+ parser.add_argument('--maximize-tls-size', action='store_true',
+ help='Set maximum PT_TLS size')
parser.add_argument('output',
help='ELF file to edit')
return parser
@@ -199,7 +219,7 @@ def main(argv):
parser = get_parser()
opts = parser.parse_args(argv)
with open(opts.output, 'r+b') as fout:
- elf_edit(fout, opts.align)
+ elf_edit(fout, opts)
if __name__ == '__main__':
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 4a5e698db2..5d0369358d 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -1211,6 +1211,11 @@ extern struct link_map * _dl_get_dl_main_map (void)
# endif
#endif
+/* Perform early memory allocation, avoding a TCB dependency.
+ Terminate the process if allocation fails. May attempt to use
+ brk. */
+void *_dl_early_allocate (size_t size) attribute_hidden;
+
/* Initialize the DSO sort algorithm to use. */
#if !HAVE_TUNABLES
static inline void
diff --git a/sysdeps/unix/sysv/linux/dl-early_allocate.c b/sysdeps/unix/sysv/linux/dl-early_allocate.c
new file mode 100644
index 0000000000..2c77b6e3ff
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/dl-early_allocate.c
@@ -0,0 +1,81 @@
+/* Early memory allocation for the dynamic loader. Generic version.
+ Copyright (C) 2022 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/>. */
+
+/* Mark symbols hidden in static PIE for early self relocation to work. */
+#if BUILD_PIE_DEFAULT
+# pragma GCC visibility push(hidden)
+#endif
+#include <startup.h>
+
+#include <ldsodefs.h>
+#include <stddef.h>
+#include <string.h>
+#include <sysdep.h>
+#include <unistd.h>
+
+#include <mmap_call.h>
+
+/* Defined in brk.c. */
+extern void *__curbrk;
+
+void *
+_dl_early_allocate (size_t size)
+{
+ void *result;
+
+ if (__curbrk != NULL)
+ /* If the break has been initialized, brk must have run before,
+ so just call it once more. */
+ {
+ result = __sbrk (size);
+ if (result == (void *) -1)
+ result = NULL;
+ }
+ else
+ {
+ /* If brk has not been invoked, there is no need to update
+ __curbrk. The first call to brk will take care of that. */
+ void *previous = (void *) INTERNAL_SYSCALL_CALL (brk, 0);
+ result = (void *) INTERNAL_SYSCALL_CALL (brk, previous + size);
+ if (result == previous)
+ result = NULL;
+ else
+ result = previous;
+ }
+
+ /* If brk fails, fall back to mmap. This can happen due to
+ unfortunate ASLR layout decisions and kernel bugs, particularly
+ for static PIE. */
+ if (result == NULL)
+ {
+ long int ret;
+ int prot = PROT_READ | PROT_WRITE;
+ int flags = MAP_PRIVATE | MAP_ANONYMOUS;
+#ifdef __NR_mmap2
+ ret = MMAP_CALL_INTERNAL (mmap2, 0, size, prot, flags, -1, 0);
+#else
+ ret = MMAP_CALL_INTERNAL (mmap, 0, size, prot, flags, -1, 0);
+#endif
+ if (INTERNAL_SYSCALL_ERROR_P (ret))
+ result = NULL;
+ else
+ result = (void *) ret;
+ }
+
+ return result;
+}
--
2.35.1
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2022-05-05 12:14 [PATCH v3 1/3] ia64: Always define IA64_USE_NEW_STUB as a flag macro Florian Weimer
2022-05-05 12:14 ` [PATCH v3 2/3] Linux: Implement a useful version of _startup_fatal Florian Weimer
2022-05-05 12:15 ` [PATCH v3 3/3] csu: Implement and use _dl_early_allocate during static startup Florian Weimer
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