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7cbeabac0f
This patch removes the vsyscall usage for x86_64 port. As indicated by kernel code comments [1], vsyscalls are a legacy ABI and its concept is problematic: - It interferes with ASLR. - It's awkward to write code that lives in kernel addresses but is callable by userspace at fixed addresses. - The whole concept is impossible for 32-bit compat userspace. - UML cannot easily virtualize a vsyscall. The VDSO is a better approach for such functionality. Tested on i686, x86_64, and x32. * sysdeps/unix/sysv/linux/i386/gettimeofday.c (__gettimeofday_syscall): Remove vsyscall fallback. * sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Likewise. * sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall): Add syscall fallback function. (gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism if vDSO is not present. * sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add syscall fallback function. (time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not present. * sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file. * sysdeps/unix/sysv/linux/x86_64/time.c: Likewise. [1] arch/x86/kernel/vsyscall_64.c
60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
/* time -- Get number of seconds since Epoch. Linux/x86 version.
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Copyright (C) 2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <time.h>
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#ifdef SHARED
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#include <dl-vdso.h>
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#include <errno.h>
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static time_t
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__time_syscall (time_t *t)
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{
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INTERNAL_SYSCALL_DECL (err);
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return INTERNAL_SYSCALL (time, err, 1, t);
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}
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void *time_ifunc (void) __asm__ ("time");
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void *
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time_ifunc (void)
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{
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PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
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/* If the vDSO is not available we fall back on the syscall. */
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return _dl_vdso_vsym ("__vdso_time", &linux26)
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?: (void*) &__time_syscall;
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}
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asm (".type time, %gnu_indirect_function");
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libc_ifunc_hidden_def(time)
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#else
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# include <sysdep.h>
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time_t
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time (time_t *t)
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{
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INTERNAL_SYSCALL_DECL (err);
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return INTERNAL_SYSCALL (time, err, 1, t);
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}
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#endif
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