Now that the vDSO implementation of clock_gettime() is getting reworked, add a selftest for it. This tests that its output is consistent with the syscall version.

This is marked for stable to serve as a test for commit "x86/vdso: Fix asm constraints on vDSO syscall fallbacks".

Cc: stable@vger.kernel.org Signed-off-by: Andy Lutomirski luto@kernel.org --- tools/testing/selftests/x86/test_vdso.c | 99 +++++++++++++++++++++++++ 1 file changed, 99 insertions(+)

diff --git a/tools/testing/selftests/x86/test_vdso.c b/tools/testing/selftests/x86/test_vdso.c index 235259011704..49f7294fb382 100644 --- a/tools/testing/selftests/x86/test_vdso.c +++ b/tools/testing/selftests/x86/test_vdso.c @@ -17,6 +17,7 @@ #include <errno.h> #include <sched.h> #include <stdbool.h> +#include <limits.h>

#ifndef SYS_getcpu # ifdef __x86_64__ @@ -31,6 +32,10 @@

int nerrs = 0;

+typedef int (*vgettime_t)(clockid_t, struct timespec *); + +vgettime_t vdso_clock_gettime; + typedef long (*getcpu_t)(unsigned *, unsigned *, void *);

getcpu_t vgetcpu; @@ -95,6 +100,10 @@ static void fill_function_pointers() printf("Warning: failed to find getcpu in vDSO\n");

vgetcpu = (getcpu_t) vsyscall_getcpu(); + + vdso_clock_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime"); + if (!vdso_clock_gettime) + printf("Warning: failed to find clock_gettime in vDSO\n"); }

static long sys_getcpu(unsigned * cpu, unsigned * node, @@ -103,6 +112,11 @@ static long sys_getcpu(unsigned * cpu, unsigned * node, return syscall(__NR_getcpu, cpu, node, cache); }

+static inline int sys_clock_gettime(clockid_t id, struct timespec *ts) +{ + return syscall(__NR_clock_gettime, id, ts); +} + static void test_getcpu(void) { printf("[RUN]\tTesting getcpu...\n"); @@ -155,10 +169,95 @@ static void test_getcpu(void) } }

+static bool ts_leq(const struct timespec *a, const struct timespec *b) +{ + if (a->tv_sec != b->tv_sec) + return a->tv_sec < b->tv_sec; + else + return a->tv_nsec <= b->tv_nsec; +} + +static char const * const clocknames[] = { + [0] = "CLOCK_REALTIME", + [1] = "CLOCK_MONOTONIC", + [2] = "CLOCK_PROCESS_CPUTIME_ID", + [3] = "CLOCK_THREAD_CPUTIME_ID", + [4] = "CLOCK_MONOTONIC_RAW", + [5] = "CLOCK_REALTIME_COARSE", + [6] = "CLOCK_MONOTONIC_COARSE", + [7] = "CLOCK_BOOTTIME", + [8] = "CLOCK_REALTIME_ALARM", + [9] = "CLOCK_BOOTTIME_ALARM", + [10] = "CLOCK_SGI_CYCLE", + [11] = "CLOCK_TAI", +}; + +static void test_one_clock_gettime(int clock, const char *name) +{ + struct timespec start, vdso, end; + int vdso_ret, end_ret; + + printf("[RUN]\tTesting clock_gettime for clock %s (%d)...\n", name, clock); + + if (sys_clock_gettime(clock, &start) < 0) { + if (errno == EINVAL) { + vdso_ret = vdso_clock_gettime(clock, &vdso); + if (vdso_ret == -EINVAL) { + printf("[OK]\tNo such clock.\n"); + } else { + printf("[FAIL]\tNo such clock, but __vdso_clock_gettime returned %d\n", vdso_ret); + nerrs++; + } + } else { + printf("[WARN]\t clock_gettime(%d) syscall returned error %d\n", clock, errno); + } + return; + } + + vdso_ret = vdso_clock_gettime(clock, &vdso); + end_ret = sys_clock_gettime(clock, &end); + + if (vdso_ret != 0 || end_ret != 0) { + printf("[FAIL]\tvDSO returned %d, syscall errno=%d\n", + vdso_ret, errno); + nerrs++; + return; + } + + printf("\t%llu.%09ld %llu.%09ld %llu.%09ld\n", + (unsigned long long)start.tv_sec, start.tv_nsec, + (unsigned long long)vdso.tv_sec, vdso.tv_nsec, + (unsigned long long)end.tv_sec, end.tv_nsec); + + if (!ts_leq(&start, &vdso) || !ts_leq(&vdso, &end)) { + printf("[FAIL]\tTimes are out of sequence\n"); + nerrs++; + } +} + +static void test_clock_gettime(void) +{ + for (int clock = 0; clock < sizeof(clocknames) / sizeof(clocknames[0]); + clock++) { + test_one_clock_gettime(clock, clocknames[clock]); + } + + /* Also test some invalid clock ids */ + test_one_clock_gettime(-1, "invalid"); + test_one_clock_gettime(INT_MIN, "invalid"); + test_one_clock_gettime(INT_MAX, "invalid"); +} + int main(int argc, char **argv) { fill_function_pointers();

+ test_clock_gettime(); + + /* + * Test getcpu() last so that, if something goes wrong setting affinity, + * we still run the other tests. + */ test_getcpu();

return nerrs ? 1 : 0;