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glibc/sysdeps/unix/sysv/linux/dl-vdso-setup.c

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elf: Move vDSO setup to rtld (BZ#24967) This patch moves the vDSO setup from libc to loader code, just after the vDSO link_map setup. For static case the initialization is moved to _dl_non_dynamic_init instead. Instead of using the mangled pointer, the vDSO data is set as attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for static). It is read-only even with partial relro. It fixes BZ#24967 now that the vDSO pointer is setup earlier than malloc interposition is called. Also, vDSO calls should not be a problem for static dlopen as indicated by BZ#20802. The vDSO pointer would be zero-initialized and the syscall will be issued instead. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. I also run some tests on mips. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2019-11-29 13:44:59 +00:00
/* Data for vDSO support. Linux version.
Update copyright dates with scripts/update-copyrights
2025-01-01 18:14:45 +00:00
Copyright (C) 2020-2025 Free Software Foundation, Inc.
elf: Move vDSO setup to rtld (BZ#24967) This patch moves the vDSO setup from libc to loader code, just after the vDSO link_map setup. For static case the initialization is moved to _dl_non_dynamic_init instead. Instead of using the mangled pointer, the vDSO data is set as attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for static). It is read-only even with partial relro. It fixes BZ#24967 now that the vDSO pointer is setup earlier than malloc interposition is called. Also, vDSO calls should not be a problem for static dlopen as indicated by BZ#20802. The vDSO pointer would be zero-initialized and the syscall will be issued instead. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. I also run some tests on mips. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2019-11-29 13:44:59 +00:00
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 file is included in three different modes for both static (libc.a)
and shared (rtld) modes:
1. PROCINFO_DECL is defined, meaning we are only interested in
Fix misspellings in sysdeps/unix -- BZ 25337 Applying this commit results in bit-identical rebuild of libc.so.6 math/libm.so.6 elf/ld-linux-x86-64.so.2 mathvec/libmvec.so.1 Reviewed-by: Florian Weimer <fweimer@redhat.com>
2023-05-23 10:50:31 +00:00
declarations. For static it requires use the extern keyword along with
elf: Move vDSO setup to rtld (BZ#24967) This patch moves the vDSO setup from libc to loader code, just after the vDSO link_map setup. For static case the initialization is moved to _dl_non_dynamic_init instead. Instead of using the mangled pointer, the vDSO data is set as attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for static). It is read-only even with partial relro. It fixes BZ#24967 now that the vDSO pointer is setup earlier than malloc interposition is called. Also, vDSO calls should not be a problem for static dlopen as indicated by BZ#20802. The vDSO pointer would be zero-initialized and the syscall will be issued instead. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. I also run some tests on mips. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2019-11-29 13:44:59 +00:00
the attribute_relro while for shared it will be embedded in the
rtld_global_ro.
2. PROCINFO_DECL and SHARED are not defined. Nothing to do, the default
zero initializion is suffice.
3. PROCINFO_DECL is not defined while SHARED is. Similar to 2., the zero
initialization of rtld_global_ro is suffice. */
#ifndef PROCINFO_CLASS
# define PROCINFO_CLASS
#endif
#ifndef SHARED
# define RELRO attribute_relro
#else
# define RELRO
#endif
#if defined PROCINFO_DECL || !defined SHARED
# ifdef HAVE_CLOCK_GETTIME_VSYSCALL
PROCINFO_CLASS int (*_dl_vdso_clock_gettime) (clockid_t,
struct timespec *) RELRO;
#endif
linux: Add support for clock_gettime64 vDSO No architecture currently defines the vDSO symbol. On architectures with 64-bit time_t the HAVE_CLOCK_GETTIME_VSYSCALL is renamed to HAVE_CLOCK_GETTIME64_VSYSCALL, it simplifies clock_gettime code. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2019-12-11 14:13:50 +00:00
# ifdef HAVE_CLOCK_GETTIME64_VSYSCALL
PROCINFO_CLASS int (*_dl_vdso_clock_gettime64) (clockid_t,
struct __timespec64 *) RELRO;
#endif
elf: Move vDSO setup to rtld (BZ#24967) This patch moves the vDSO setup from libc to loader code, just after the vDSO link_map setup. For static case the initialization is moved to _dl_non_dynamic_init instead. Instead of using the mangled pointer, the vDSO data is set as attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for static). It is read-only even with partial relro. It fixes BZ#24967 now that the vDSO pointer is setup earlier than malloc interposition is called. Also, vDSO calls should not be a problem for static dlopen as indicated by BZ#20802. The vDSO pointer would be zero-initialized and the syscall will be issued instead. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. I also run some tests on mips. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2019-11-29 13:44:59 +00:00
# ifdef HAVE_GETTIMEOFDAY_VSYSCALL
PROCINFO_CLASS int (*_dl_vdso_gettimeofday) (struct timeval *, void *) RELRO;
#endif
# ifdef HAVE_TIME_VSYSCALL
PROCINFO_CLASS time_t (*_dl_vdso_time) (time_t *) RELRO;
# endif
# ifdef HAVE_GETCPU_VSYSCALL
PROCINFO_CLASS int (*_dl_vdso_getcpu) (unsigned *, unsigned *, void *) RELRO;
# endif
# ifdef HAVE_CLOCK_GETRES_VSYSCALL
PROCINFO_CLASS int (*_dl_vdso_clock_getres) (clockid_t,
struct timespec *) RELRO;
# endif
linux: Add support for clock_getres64 vDSO No architecture currently defines the vDSO symbol. On archictures with 64-bit time_t the HAVE_CLOCK_GETRES_VSYSCALL is renamed to HAVE_CLOCK_GETRES64_VSYSCALL, it simplifies clock_gettime code. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2019-12-11 19:39:01 +00:00
# ifdef HAVE_CLOCK_GETRES64_VSYSCALL
PROCINFO_CLASS int (*_dl_vdso_clock_getres_time64) (clockid_t,
struct __timespec64 *) RELRO;
# endif
linux: Add support for getrandom vDSO Linux 6.11 has getrandom() in vDSO. It operates on a thread-local opaque state allocated with mmap using flags specified by the vDSO. Multiple states are allocated at once, as many as fit into a page, and these are held in an array of available states to be doled out to each thread upon first use, and recycled when a thread terminates. As these states run low, more are allocated. To make this procedure async-signal-safe, a simple guard is used in the LSB of the opaque state address, falling back to the syscall if there's reentrancy contention. Also, _Fork() is handled by blocking signals on opaque state allocation (so _Fork() always sees a consistent state even if it interrupts a getrandom() call) and by iterating over the thread stack cache on reclaim_stack. Each opaque state will be in the free states list (grnd_alloc.states) or allocated to a running thread. The cancellation is handled by always using GRND_NONBLOCK flags while calling the vDSO, and falling back to the cancellable syscall if the kernel returns EAGAIN (would block). Since getrandom is not defined by POSIX and cancellation is supported as an extension, the cancellation is handled as 'may occur' instead of 'shall occur' [1], meaning that if vDSO does not block (the expected behavior) getrandom will not act as a cancellation entrypoint. It avoids a pthread_testcancel call on the fast path (different than 'shall occur' functions, like sem_wait()). It is currently enabled for x86_64, which is available in Linux 6.11, and aarch64, powerpc32, powerpc64, loongarch64, and s390x, which are available in Linux 6.12. Link: https://pubs.opengroup.org/onlinepubs/9799919799/nframe.html [1] Co-developed-by: Jason A. Donenfeld <Jason@zx2c4.com> Tested-by: Jason A. Donenfeld <Jason@zx2c4.com> # x86_64 Tested-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> # x86_64, aarch64 Tested-by: Xi Ruoyao <xry111@xry111.site> # x86_64, aarch64, loongarch64 Tested-by: Stefan Liebler <stli@linux.ibm.com> # s390x
2024-09-18 14:01:22 +00:00
# ifdef HAVE_GETRANDOM_VSYSCALL
PROCINFO_CLASS ssize_t (*_dl_vdso_getrandom) (void *buffer, size_t len,
unsigned int flags, void *state,
size_t state_len) RELRO;
# endif
elf: Move vDSO setup to rtld (BZ#24967) This patch moves the vDSO setup from libc to loader code, just after the vDSO link_map setup. For static case the initialization is moved to _dl_non_dynamic_init instead. Instead of using the mangled pointer, the vDSO data is set as attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for static). It is read-only even with partial relro. It fixes BZ#24967 now that the vDSO pointer is setup earlier than malloc interposition is called. Also, vDSO calls should not be a problem for static dlopen as indicated by BZ#20802. The vDSO pointer would be zero-initialized and the syscall will be issued instead. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. I also run some tests on mips. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2019-11-29 13:44:59 +00:00
/* PowerPC specific ones. */
# ifdef HAVE_GET_TBFREQ
PROCINFO_CLASS uint64_t (*_dl_vdso_get_tbfreq)(void) RELRO;
# endif
riscv: Add hwprobe vdso call support The new riscv_hwprobe syscall also comes with a vDSO for faster answers to your most common questions. Call in today to speak with a kernel representative near you! Signed-off-by: Evan Green <evan@rivosinc.com> Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-02-27 22:56:39 +00:00
/* RISC-V specific ones. */
# ifdef HAVE_RISCV_HWPROBE
PROCINFO_CLASS int (*_dl_vdso_riscv_hwprobe)(void *,
size_t,
size_t,
unsigned long *,
unsigned int) RELRO;
# endif
elf: Move vDSO setup to rtld (BZ#24967) This patch moves the vDSO setup from libc to loader code, just after the vDSO link_map setup. For static case the initialization is moved to _dl_non_dynamic_init instead. Instead of using the mangled pointer, the vDSO data is set as attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for static). It is read-only even with partial relro. It fixes BZ#24967 now that the vDSO pointer is setup earlier than malloc interposition is called. Also, vDSO calls should not be a problem for static dlopen as indicated by BZ#20802. The vDSO pointer would be zero-initialized and the syscall will be issued instead. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. I also run some tests on mips. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2019-11-29 13:44:59 +00:00
#endif
#undef RELRO
#undef PROCINFO_DECL
#undef PROCINFO_CLASS