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.

Cc: stable@vger.kernel.org Fixes: 715bd9d12f84 ("x86/vdso: Fix asm constraints on vDSO syscall fallbacks") Cc: Thomas Gleixner tglx@linutronix.de Signed-off-by: Andy Lutomirski luto@kernel.org --- arch/x86/entry/vdso/vclock_gettime.c | 8 +-- tools/testing/selftests/x86/test_vdso.c | 73 +++++++++++++++++++++++++ 2 files changed, 77 insertions(+), 4 deletions(-)

diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c index 134e2d2e8add..e48ca3afa091 100644 --- 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 49f7294fb382..35edd61d1663 100644 --- 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,