openkylin
/
platform_kernel-5.15
mirror of https://gitee.com/openkylin/platform_kernel-5.15.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

[PATCH] x86-64: fix vtime() vsyscall 

There is a tiny probability that the return value from vtime(time_t *t) is
Signed-off-by: Andi Kleen <ak@suse.de>

different than the value stored in *t

Using a temporary variable solves the problem and gives a faster code.

   17:   48 85 ff                test   %rdi,%rdi
   1a:   48 8b 05 00 00 00 00    mov    0(%rip),%rax        #
__vsyscall_gtod_data.wall_time_tv.tv_sec
   21:   74 03                   je     26
   23:   48 89 07                mov    %rax,(%rdi)
   26:   c9                      leaveq
   27:   c3                      retq

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
This commit is contained in:
Eric Dumazet 2007-05-02 19:27:11 +02:00 committed by Andi Kleen
parent bd8559c38e
commit 272a3713bb
1 changed files with 5 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/x86_64/kernel/vsyscall.c
View File

@ -156,11 +156,13 @@ int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
* unlikely */ * unlikely */
time_t __vsyscall(1) vtime(time_t *t) time_t __vsyscall(1) vtime(time_t *t)
{ {
time_t result;
if (unlikely(!__vsyscall_gtod_data.sysctl_enabled)) if (unlikely(!__vsyscall_gtod_data.sysctl_enabled))
return time_syscall(t); return time_syscall(t);
else if (t) result = __vsyscall_gtod_data.wall_time_tv.tv_sec;
*t = __vsyscall_gtod_data.wall_time_tv.tv_sec; if (t)
return __vsyscall_gtod_data.wall_time_tv.tv_sec; *t = result;
return result;
} }
/* Fast way to get current CPU and node. /* Fast way to get current CPU and node.