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x86/vdso: Fix vDSO syscall fallback asm constraint regression

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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: 715bd9d12f ("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>
This commit is contained in:
Andy Lutomirski 2018-10-03 16:23:49 -07:00 committed by Ingo Molnar
parent 88296bd42b
commit 02e425668f
2 changed files with 77 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/x86/entry/vdso/vclock_gettime.c
View File

@ -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;
}

73
tools/testing/selftests/x86/test_vdso.c
View File

@ -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,