x86/vdso: Fix vDSO syscall fallback asm constraint regression

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>
Cc: stable@vger.kernel.org
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index 722cbed..049327e 100644 (file)
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/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;
 }