diff options
Diffstat (limited to 'sysdeps/unix')
| -rw-r--r-- | sysdeps/unix/sysv/linux/Makefile | 4 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/dl-rseq-symbols.S | 64 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/rseq-internal.h | 23 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/tst-rseq.c | 10 |
4 files changed, 98 insertions, 3 deletions
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile index ae66590e91..097b5a26fc 100644 --- a/sysdeps/unix/sysv/linux/Makefile +++ b/sysdeps/unix/sysv/linux/Makefile @@ -616,6 +616,10 @@ tests += \ endif ifeq ($(subdir),elf) +dl-routines += \ + dl-rseq-symbols \ + # dl-routines + sysdep-rtld-routines += \ dl-brk \ dl-getcwd \ diff --git a/sysdeps/unix/sysv/linux/dl-rseq-symbols.S b/sysdeps/unix/sysv/linux/dl-rseq-symbols.S new file mode 100644 index 0000000000..b4bba06a99 --- /dev/null +++ b/sysdeps/unix/sysv/linux/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/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h index 48eebc1e16..7ea935b4ad 100644 --- a/sysdeps/unix/sysv/linux/rseq-internal.h +++ b/sysdeps/unix/sysv/linux/rseq-internal.h @@ -25,15 +25,34 @@ #include <stdio.h> #include <sys/rseq.h> +/* 32 is the initially required value for the area size. The + actually used rseq size may be less (20 bytes initially). */ +#define RSEQ_AREA_SIZE_INITIAL 32 +#define RSEQ_AREA_SIZE_INITIAL_USED 20 + +/* 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; + #ifdef RSEQ_SIG static inline bool rseq_register_current_thread (struct pthread *self, bool do_rseq) { if (do_rseq) { + unsigned int size; +#if IS_IN (rtld) + /* Use the hidden symbol in ld.so. */ + size = _rseq_size; +#else + size = __rseq_size; +#endif + if (size < RSEQ_AREA_SIZE_INITIAL) + /* The initial implementation used only 20 bytes out of 32, + but still expected size 32. */ + size = RSEQ_AREA_SIZE_INITIAL; int ret = INTERNAL_SYSCALL_CALL (rseq, &self->rseq_area, - sizeof (self->rseq_area), - 0, RSEQ_SIG); + size, 0, RSEQ_SIG); if (!INTERNAL_SYSCALL_ERROR_P (ret)) return true; } diff --git a/sysdeps/unix/sysv/linux/tst-rseq.c b/sysdeps/unix/sysv/linux/tst-rseq.c index 2c90409ba0..08a9533130 100644 --- a/sysdeps/unix/sysv/linux/tst-rseq.c +++ b/sysdeps/unix/sysv/linux/tst-rseq.c @@ -29,6 +29,7 @@ # include <stdlib.h> # include <string.h> # include <syscall.h> +# include <sys/auxv.h> # include <thread_pointer.h> # include <tls.h> # include "tst-rseq.h" @@ -42,7 +43,8 @@ do_rseq_main_test (void) TEST_COMPARE (__rseq_flags, 0); TEST_VERIFY ((char *) __thread_pointer () + __rseq_offset == (char *) &pd->rseq_area); - TEST_COMPARE (__rseq_size, sizeof (pd->rseq_area)); + /* The current implementation only supports the initial size. */ + TEST_COMPARE (__rseq_size, 20); } static void @@ -52,6 +54,12 @@ do_rseq_test (void) { FAIL_UNSUPPORTED ("kernel does not support rseq, skipping test"); } + printf ("info: __rseq_size: %u\n", __rseq_size); + printf ("info: __rseq_offset: %td\n", __rseq_offset); + printf ("info: __rseq_flags: %u\n", __rseq_flags); + printf ("info: getauxval (AT_RSEQ_FEATURE_SIZE): %ld\n", + getauxval (AT_RSEQ_FEATURE_SIZE)); + printf ("info: getauxval (AT_RSEQ_ALIGN): %ld\n", getauxval (AT_RSEQ_ALIGN)); do_rseq_main_test (); } #else /* RSEQ_SIG */ |