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    Subject[PATCH 3.16 305/305] x86/vdso: Fix vDSO syscall fallback asm constraint regression
    3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Andy Lutomirski <luto@kernel.org>

    commit 02e425668f5c9deb42787d10001a3b605993ad15 upstream.

    When I added the missing memory outputs, I failed to update the
    index of the first argument (ebx) on 32-bit builds, which broke the
    fallbacks. Somehow I must have screwed up my testing or gotten
    lucky.

    Add another test to cover gettimeofday() as well.

    Signed-off-by: Andy Lutomirski <luto@kernel.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Fixes: 715bd9d12f84 ("x86/vdso: Fix asm constraints on vDSO syscall fallbacks")
    Link: http://lkml.kernel.org/r/21bd45ab04b6d838278fa5bebfa9163eceffa13c.1538608971.git.luto@kernel.org
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    [bwh: Backported to 3.16:
    - Drop selftest changes
    - Adjust filename]
    Tested-by: Matthew Whitehead <tedheadster@gmail.com>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    arch/x86/vdso/vclock_gettime.c | 8 ++++----
    1 file changed, 4 insertions(+), 4 deletions(-)

    --- a/arch/x86/vdso/vclock_gettime.c
    +++ b/arch/x86/vdso/vclock_gettime.c
    @@ -147,11 +147,11 @@ notrace static long vdso_fallback_gettim

    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(s

    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;
    }
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