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

2 files changed, 0 insertions, 21 deletions

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 <dl-vdso.h>
-# include <errno.h>
-
-/* 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 <dl-vdso.h>
-# include <errno.h>
-
-/* 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)