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x86: Remove vsyscall usage
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
This commit is contained in:
Adhemerval Zanella
Adhemerval Zanella
parent
2f44ee08db
commit
7cbeabac0f
16
ChangeLog
16
ChangeLog
@ -1,3 +1,19 @@
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2015-06-09 Adhemerval Zanella <adhemerval.zanella@linaro.org>
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* sysdeps/unix/sysv/linux/i386/gettimeofday.c
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(__gettimeofday_syscall): Remove vsyscall fallback.
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* sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Likewise.
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* sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall):
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Add syscall fallback function.
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(gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism
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if vDSO is not present.
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* sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add syscall
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fallback function.
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(time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not
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present.
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* sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file.
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* sysdeps/unix/sysv/linux/x86_64/time.c: Likewise.
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2015-06-09 Joseph Myers <joseph@codesourcery.com>
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[BZ #18497]
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@ -20,16 +20,6 @@
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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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/* If the vDSO is not available we fall back on the syscall. */
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static int
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__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
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{
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return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
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}
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# define GETTIMEOFAY_FALLBACK (void*) (&__gettimeofday_syscall)
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# undef libc_ifunc_hidden_def
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# define libc_ifunc_hidden_def(name) \
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libc_ifunc_hidden_def1 (__GI_##name, __gettimeofday_syscall)
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@ -18,17 +18,6 @@
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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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/* If the vDSO is not available we fall back on the old vsyscall. */
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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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# define TIME_FALLBACK (void*) &__time_syscall
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# undef libc_ifunc_hidden_def
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# define libc_ifunc_hidden_def(name) \
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libc_ifunc_hidden_def1 (__GI_##name, __time_syscall)
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@ -21,6 +21,13 @@
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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 int
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__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
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{
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return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
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}
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void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
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@ -29,9 +36,9 @@ gettimeofday_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 old vsyscall. */
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/* If the vDSO is not available we fall back to syscall. */
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return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
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?: GETTIMEOFAY_FALLBACK);
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?: (void*) (&__gettimeofday_syscall));
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}
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asm (".type __gettimeofday, %gnu_indirect_function");
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@ -21,6 +21,14 @@
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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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@ -29,7 +37,9 @@ time_ifunc (void)
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{
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PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
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return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK;
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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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@ -1,26 +0,0 @@
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/* Copyright (C) 2002-2015 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 <sys/time.h>
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#ifdef SHARED
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/* If the vDSO is not available we fall back on the old vsyscall. */
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# define VSYSCALL_ADDR_vgettimeofday 0xffffffffff600000ul
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# define GETTIMEOFAY_FALLBACK (void*)VSYSCALL_ADDR_vgettimeofday
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#endif
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#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
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@ -1,24 +0,0 @@
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/* Copyright (C) 2001-2015 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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#ifdef SHARED
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/* If the vDSO is not available we fall back on the old vsyscall. */
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#define VSYSCALL_ADDR_vtime 0xffffffffff600400
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#define TIME_FALLBACK (void*)VSYSCALL_ADDR_vtime
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#endif
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#include <sysdeps/unix/sysv/linux/x86/time.c>
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