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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
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