2019-01-19 12:41:54

by tedheadster

[permalink] [raw]
Subject: [PATCH 3.16] Backport of x86/vdso: Fix vDSO syscall fallback asm constraint regression

On Fri, Jan 18, 2019 at 9:07 PM tedheadster <[email protected]> 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 <[email protected]>
tested-by: Matthew Whitehead <[email protected]>
---
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



2019-01-29 18:07:58

by Ben Hutchings

[permalink] [raw]
Subject: Re: [PATCH 3.16] Backport of x86/vdso: Fix vDSO syscall fallback asm constraint regression

On Tue, 2019-01-22 at 14:51 +0000, Matthew Whitehead wrote:
> On Fri, Jan 18, 2019 at 9:07 PM tedheadster <[email protected]>
> 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.
[...]

I've queued this up now, thanks.

Ben.

--
Ben Hutchings
The obvious mathematical breakthrough [to break modern encryption]
would be development of an easy way to factor large prime numbers.
- Bill Gates



Attachments:
signature.asc (849.00 B)
This is a digitally signed message part