From 7cbeabac0fb28e24c99aaa5085e613ea543a2346 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Thu, 23 Apr 2015 09:17:42 -0300 Subject: 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 --- sysdeps/unix/sysv/linux/i386/gettimeofday.c | 10 ---------- sysdeps/unix/sysv/linux/i386/time.c | 11 ----------- sysdeps/unix/sysv/linux/x86/gettimeofday.c | 11 +++++++++-- sysdeps/unix/sysv/linux/x86/time.c | 12 +++++++++++- sysdeps/unix/sysv/linux/x86_64/gettimeofday.c | 26 -------------------------- sysdeps/unix/sysv/linux/x86_64/time.c | 24 ------------------------ 6 files changed, 20 insertions(+), 74 deletions(-) delete mode 100644 sysdeps/unix/sysv/linux/x86_64/gettimeofday.c delete mode 100644 sysdeps/unix/sysv/linux/x86_64/time.c (limited to 'sysdeps/unix') diff --git a/sysdeps/unix/sysv/linux/i386/gettimeofday.c b/sysdeps/unix/sysv/linux/i386/gettimeofday.c index 3e00eb46aa..fdb0fabedb 100644 --- a/sysdeps/unix/sysv/linux/i386/gettimeofday.c +++ b/sysdeps/unix/sysv/linux/i386/gettimeofday.c @@ -20,16 +20,6 @@ #ifdef SHARED -# include -# include - -/* If the vDSO is not available we fall back on the syscall. */ -static int -__gettimeofday_syscall (struct timeval *tv, struct timezone *tz) -{ - return INLINE_SYSCALL (gettimeofday, 2, tv, tz); -} -# define GETTIMEOFAY_FALLBACK (void*) (&__gettimeofday_syscall) # undef libc_ifunc_hidden_def # define libc_ifunc_hidden_def(name) \ libc_ifunc_hidden_def1 (__GI_##name, __gettimeofday_syscall) diff --git a/sysdeps/unix/sysv/linux/i386/time.c b/sysdeps/unix/sysv/linux/i386/time.c index e8a4e593e1..66b9a6c87a 100644 --- a/sysdeps/unix/sysv/linux/i386/time.c +++ b/sysdeps/unix/sysv/linux/i386/time.c @@ -18,17 +18,6 @@ #ifdef SHARED -# include -# include - -/* If the vDSO is not available we fall back on the old vsyscall. */ -static time_t -__time_syscall (time_t *t) -{ - INTERNAL_SYSCALL_DECL (err); - return INTERNAL_SYSCALL (time, err, 1, t); -} -# define TIME_FALLBACK (void*) &__time_syscall # undef libc_ifunc_hidden_def # define libc_ifunc_hidden_def(name) \ libc_ifunc_hidden_def1 (__GI_##name, __time_syscall) diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c index c820fd767b..440cb0243a 100644 --- a/sysdeps/unix/sysv/linux/x86/gettimeofday.c +++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c @@ -21,6 +21,13 @@ #ifdef SHARED # include +# include + +static int +__gettimeofday_syscall (struct timeval *tv, struct timezone *tz) +{ + return INLINE_SYSCALL (gettimeofday, 2, tv, tz); +} void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday"); @@ -29,9 +36,9 @@ gettimeofday_ifunc (void) { PREPARE_VERSION_KNOWN (linux26, LINUX_2_6); - /* If the vDSO is not available we fall back on the old vsyscall. */ + /* If the vDSO is not available we fall back to syscall. */ return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26) - ?: GETTIMEOFAY_FALLBACK); + ?: (void*) (&__gettimeofday_syscall)); } asm (".type __gettimeofday, %gnu_indirect_function"); diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c index 1ab92489e5..ebf092ae12 100644 --- a/sysdeps/unix/sysv/linux/x86/time.c +++ b/sysdeps/unix/sysv/linux/x86/time.c @@ -21,6 +21,14 @@ #ifdef SHARED #include +#include + +static time_t +__time_syscall (time_t *t) +{ + INTERNAL_SYSCALL_DECL (err); + return INTERNAL_SYSCALL (time, err, 1, t); +} void *time_ifunc (void) __asm__ ("time"); @@ -29,7 +37,9 @@ time_ifunc (void) { PREPARE_VERSION_KNOWN (linux26, LINUX_2_6); - return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK; +/* If the vDSO is not available we fall back on the syscall. */ + return _dl_vdso_vsym ("__vdso_time", &linux26) + ?: (void*) &__time_syscall; } asm (".type time, %gnu_indirect_function"); diff --git a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c b/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c deleted file mode 100644 index daa14defb0..0000000000 --- a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c +++ /dev/null @@ -1,26 +0,0 @@ -/* Copyright (C) 2002-2015 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 - . */ - -#include - -#ifdef SHARED -/* If the vDSO is not available we fall back on the old vsyscall. */ -# define VSYSCALL_ADDR_vgettimeofday 0xffffffffff600000ul -# define GETTIMEOFAY_FALLBACK (void*)VSYSCALL_ADDR_vgettimeofday -#endif - -#include diff --git a/sysdeps/unix/sysv/linux/x86_64/time.c b/sysdeps/unix/sysv/linux/x86_64/time.c deleted file mode 100644 index 6ceb819d82..0000000000 --- a/sysdeps/unix/sysv/linux/x86_64/time.c +++ /dev/null @@ -1,24 +0,0 @@ -/* Copyright (C) 2001-2015 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 - . */ - -#ifdef SHARED -/* If the vDSO is not available we fall back on the old vsyscall. */ -#define VSYSCALL_ADDR_vtime 0xffffffffff600400 -#define TIME_FALLBACK (void*)VSYSCALL_ADDR_vtime -#endif - -#include -- cgit 1.4.1