mirror of
https://sourceware.org/git/glibc.git
synced 2025-05-19 05:53:43 +03:00
461cab1de7
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
85 lines
3.3 KiB
C
85 lines
3.3 KiB
C
/* Syscall definitions, Linux s390 version.
|
|
Copyright (C) 2019-2024 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
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#ifndef __ASSEMBLY__
|
|
|
|
#undef SYS_ify
|
|
#define SYS_ify(syscall_name) __NR_##syscall_name
|
|
|
|
#undef INTERNAL_SYSCALL_NCS
|
|
#define INTERNAL_SYSCALL_NCS(no, nr, args...) \
|
|
({ \
|
|
DECLARGS_##nr(args) \
|
|
register unsigned long int _nr __asm__("1") = (unsigned long int)(no); \
|
|
register long int _ret __asm__("2"); \
|
|
__asm__ __volatile__ ( \
|
|
"svc 0\n\t" \
|
|
: "=d" (_ret) \
|
|
: "d" (_nr) ASMFMT_##nr \
|
|
: "memory" ); \
|
|
_ret; })
|
|
|
|
#undef INTERNAL_SYSCALL
|
|
#define INTERNAL_SYSCALL(name, nr, args...) \
|
|
INTERNAL_SYSCALL_NCS(__NR_##name, nr, args)
|
|
|
|
#define DECLARGS_0()
|
|
#define DECLARGS_1(arg1) \
|
|
register unsigned long int gpr2 __asm__ ("2") = (unsigned long int)(arg1);
|
|
#define DECLARGS_2(arg1, arg2) \
|
|
DECLARGS_1(arg1) \
|
|
register unsigned long int gpr3 __asm__ ("3") = (unsigned long int)(arg2);
|
|
#define DECLARGS_3(arg1, arg2, arg3) \
|
|
DECLARGS_2(arg1, arg2) \
|
|
register unsigned long int gpr4 __asm__ ("4") = (unsigned long int)(arg3);
|
|
#define DECLARGS_4(arg1, arg2, arg3, arg4) \
|
|
DECLARGS_3(arg1, arg2, arg3) \
|
|
register unsigned long int gpr5 __asm__ ("5") = (unsigned long int)(arg4);
|
|
#define DECLARGS_5(arg1, arg2, arg3, arg4, arg5) \
|
|
DECLARGS_4(arg1, arg2, arg3, arg4) \
|
|
register unsigned long int gpr6 __asm__ ("6") = (unsigned long int)(arg5);
|
|
#define DECLARGS_6(arg1, arg2, arg3, arg4, arg5, arg6) \
|
|
DECLARGS_5(arg1, arg2, arg3, arg4, arg5) \
|
|
register unsigned long int gpr7 __asm__ ("7") = (unsigned long int)(arg6);
|
|
|
|
#define ASMFMT_0
|
|
#define ASMFMT_1 , "0" (gpr2)
|
|
#define ASMFMT_2 , "0" (gpr2), "d" (gpr3)
|
|
#define ASMFMT_3 , "0" (gpr2), "d" (gpr3), "d" (gpr4)
|
|
#define ASMFMT_4 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5)
|
|
#define ASMFMT_5 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5), "d" (gpr6)
|
|
#define ASMFMT_6 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5), "d" (gpr6), "d" (gpr7)
|
|
|
|
#define VDSO_NAME "LINUX_2.6.29"
|
|
#define VDSO_HASH 123718585
|
|
|
|
/* List of system calls which are supported as vsyscalls. */
|
|
#ifdef __s390x__
|
|
#define HAVE_CLOCK_GETRES64_VSYSCALL "__kernel_clock_getres"
|
|
#define HAVE_CLOCK_GETTIME64_VSYSCALL "__kernel_clock_gettime"
|
|
#define HAVE_GETRANDOM_VSYSCALL "__kernel_getrandom"
|
|
#else
|
|
#define HAVE_CLOCK_GETRES_VSYSCALL "__kernel_clock_getres"
|
|
#define HAVE_CLOCK_GETTIME_VSYSCALL "__kernel_clock_gettime"
|
|
#endif
|
|
#define HAVE_GETTIMEOFDAY_VSYSCALL "__kernel_gettimeofday"
|
|
#define HAVE_GETCPU_VSYSCALL "__kernel_getcpu"
|
|
|
|
#define HAVE_CLONE3_WRAPPER 1
|
|
#endif
|