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Commit 25bc6e80 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Greg Kroah-Hartman
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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: default avatarAndy 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: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1194e838

arch/x86/entry/vdso/vclock_gettime.c

+4 −4
Original line number Diff line number Diff line
@@ -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;

}

tools/testing/selftests/x86/test_vdso.c

+73 −0
Original line number Diff line number Diff line
@@ -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,