diff options
| -rw-r--r-- | elf/Makefile | 1 | ||||
| -rw-r--r-- | elf/dl-rseq-symbols.S | 64 | ||||
| -rw-r--r-- | sysdeps/nptl/dl-tls_init_tp.c | 14 |
3 files changed, 71 insertions, 8 deletions
diff --git a/elf/Makefile b/elf/Makefile index a3475f3fb5..147f1d3437 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..b4bba06a99 --- /dev/null +++ b/elf/dl-rseq-symbols.S @@ -0,0 +1,64 @@ +/* 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 <sysdep.h> + +#if __WORDSIZE == 64 +#define RSEQ_OFFSET_SIZE 8 +#else +#define RSEQ_OFFSET_SIZE 4 +#endif + +/* Some targets define a macro to denote the zero register. */ +#undef zero + +/* Define 2 symbols: '__rseq_size' is public const and '_rseq_size' (an + alias of '__rseq_size') is hidden and writable for internal use by the + dynamic linker which will initialize the value both symbols point to + before copy relocations take place. */ + + .globl __rseq_size + .type __rseq_size, %object + .size __rseq_size, 4 + .hidden _rseq_size + .globl _rseq_size + .type _rseq_size, %object + .size _rseq_size, 4 + .section .data.rel.ro + .balign 4 +__rseq_size: +_rseq_size: + .zero 4 + +/* Define 2 symbols: '__rseq_offset' is public const and '_rseq_offset' (an + alias of '__rseq_offset') is hidden and writable for internal use by the + dynamic linker which will initialize the value both symbols point to + before copy relocations take place. */ + + .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_SIZE +__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..7eb35fb133 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_hidden; +extern ptrdiff_t _rseq_offset 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 } |