x86/vdso: Fix vDSO syscall fallback asm constraint regression

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>

diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index 134e2d2e8addc1ca40da4eb2f9ea50e07561fef1..e48ca3afa0912cc8bb03bd6dba84b0999abe1982 100644 (file)
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -68,11 +68,11 @@ 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;
 }
@@ -83,11 +83,11 @@ 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;
 }

diff --git a/tools/testing/selftests/x86/test_vdso.c b/tools/testing/selftests/x86/test_vdso.c
index 49f7294fb382c002c163ce3867ce3fe107a8ea96..35edd61d1663eb6fc0378f606638b7b2cc0e26cb 100644 (file)
--- a/tools/testing/selftests/x86/test_vdso.c
+++ b/tools/testing/selftests/x86/test_vdso.c
@@ -36,6 +36,10 @@ typedef int (*vgettime_t)(clockid_t, struct timespec *);
 
 vgettime_t vdso_clock_gettime;
 
+typedef long (*vgtod_t)(struct timeval *tv, struct timezone *tz);
+
+vgtod_t vdso_gettimeofday;
+
 typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
 
 getcpu_t vgetcpu;
@@ -104,6 +108,11 @@ static void fill_function_pointers()
        vdso_clock_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
        if (!vdso_clock_gettime)
                printf("Warning: failed to find clock_gettime in vDSO\n");
+
+       vdso_gettimeofday = (vgtod_t)dlsym(vdso, "__vdso_gettimeofday");
+       if (!vdso_gettimeofday)
+               printf("Warning: failed to find gettimeofday in vDSO\n");
+
 }
 
 static long sys_getcpu(unsigned * cpu, unsigned * node,
@@ -117,6 +126,11 @@ static inline int sys_clock_gettime(clockid_t id, struct timespec *ts)
        return syscall(__NR_clock_gettime, id, ts);
 }
 
+static inline int sys_gettimeofday(struct timeval *tv, struct timezone *tz)
+{
+       return syscall(__NR_gettimeofday, tv, tz);
+}
+
 static void test_getcpu(void)
 {
        printf("[RUN]\tTesting getcpu...\n");
@@ -177,6 +191,14 @@ static bool ts_leq(const struct timespec *a, const struct timespec *b)
                return a->tv_nsec <= b->tv_nsec;
 }
 
+static bool tv_leq(const struct timeval *a, const struct timeval *b)
+{
+       if (a->tv_sec != b->tv_sec)
+               return a->tv_sec < b->tv_sec;
+       else
+               return a->tv_usec <= b->tv_usec;
+}
+
 static char const * const clocknames[] = {
        [0] = "CLOCK_REALTIME",
        [1] = "CLOCK_MONOTONIC",
@@ -248,11 +270,62 @@ static void test_clock_gettime(void)
        test_one_clock_gettime(INT_MAX, "invalid");
 }
 
+static void test_gettimeofday(void)
+{
+       struct timeval start, vdso, end;
+       struct timezone sys_tz, vdso_tz;
+       int vdso_ret, end_ret;
+
+       if (!vdso_gettimeofday)
+               return;
+
+       printf("[RUN]\tTesting gettimeofday...\n");
+
+       if (sys_gettimeofday(&start, &sys_tz) < 0) {
+               printf("[FAIL]\tsys_gettimeofday failed (%d)\n", errno);
+               nerrs++;
+               return;
+       }
+
+       vdso_ret = vdso_gettimeofday(&vdso, &vdso_tz);
+       end_ret = sys_gettimeofday(&end, NULL);
+
+       if (vdso_ret != 0 || end_ret != 0) {
+               printf("[FAIL]\tvDSO returned %d, syscall errno=%d\n",
+                      vdso_ret, errno);
+               nerrs++;
+               return;
+       }
+
+       printf("\t%llu.%06ld %llu.%06ld %llu.%06ld\n",
+              (unsigned long long)start.tv_sec, start.tv_usec,
+              (unsigned long long)vdso.tv_sec, vdso.tv_usec,
+              (unsigned long long)end.tv_sec, end.tv_usec);
+
+       if (!tv_leq(&start, &vdso) || !tv_leq(&vdso, &end)) {
+               printf("[FAIL]\tTimes are out of sequence\n");
+               nerrs++;
+       }
+
+       if (sys_tz.tz_minuteswest == vdso_tz.tz_minuteswest &&
+           sys_tz.tz_dsttime == vdso_tz.tz_dsttime) {
+               printf("[OK]\ttimezones match: minuteswest=%d, dsttime=%d\n",
+                      sys_tz.tz_minuteswest, sys_tz.tz_dsttime);
+       } else {
+               printf("[FAIL]\ttimezones do not match\n");
+               nerrs++;
+       }
+
+       /* And make sure that passing NULL for tz doesn't crash. */
+       vdso_gettimeofday(&vdso, NULL);
+}
+
 int main(int argc, char **argv)
 {
        fill_function_pointers();
 
        test_clock_gettime();
+       test_gettimeofday();
 
        /*
         * Test getcpu() last so that, if something goes wrong setting affinity,