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Subject[PATCH 3.16] Backport of x86/vdso: Fix vDSO syscall fallback asm constraint regression
Date
On Fri, Jan 18, 2019 at 9:07 PM tedheadster <tedheadster@gmail.com> wrote:
>
> I do not see this problem with the upstream kernel, so 3.16 probably
> needs a missing upstream patch.

This was indeed fixed by Andy Lutomirski's follow-up patch "x86/vdso: Fix vDSO syscall fallback asm constraint regression". I tested part of Andy's patch and it resolved the failure.

The 3.16 LTS kernel does not have the tools/testing/selftests/x86/test_vdso.c code, so a partial patch is indicated, unless Andy wants to provide that.

Kindly backport to 3.16 LTS series.

reported-by: Matthew Whitehead <tedheadster@gmail.com>
tested-by: Matthew Whitehead <tedheadster@gmail.com>
---
arch/x86/vdso/vclock_gettime.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index 00b5ea4..a3d5326 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -147,11 +147,11 @@ notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)

asm (
"mov %%ebx, %%edx \n"
- "mov %2, %%ebx \n"
+ "mov %[clock], %%ebx \n"
"call __kernel_vsyscall \n"
"mov %%edx, %%ebx \n"
: "=a" (ret), "=m" (*ts)
- : "0" (__NR_clock_gettime), "g" (clock), "c" (ts)
+ : "0" (__NR_clock_gettime), [clock] "g" (clock), "c" (ts)
: "memory", "edx");
return ret;
}
@@ -162,11 +162,11 @@ notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz)

asm (
"mov %%ebx, %%edx \n"
- "mov %2, %%ebx \n"
+ "mov %[tv], %%ebx \n"
"call __kernel_vsyscall \n"
"mov %%edx, %%ebx \n"
: "=a" (ret), "=m" (*tv), "=m" (*tz)
- : "0" (__NR_gettimeofday), "g" (tv), "c" (tz)
+ : "0" (__NR_gettimeofday), [tv] "g" (tv), "c" (tz)
: "memory", "edx");
return ret;
}
--
1.8.3.1
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