selftests: vDSO: fix the way vDSO functions are called for powerpc

vdso_test_correctness test fails on powerpc:

~ # ./vdso_test_correctness
...
[RUN]	Testing clock_gettime for clock CLOCK_REALTIME_ALARM (8)...
[FAIL]	No such clock, but __vdso_clock_gettime returned 22
[RUN]	Testing clock_gettime for clock CLOCK_BOOTTIME_ALARM (9)...
[FAIL]	No such clock, but __vdso_clock_gettime returned 22
[RUN]	Testing clock_gettime for clock CLOCK_SGI_CYCLE (10)...
[FAIL]	No such clock, but __vdso_clock_gettime returned 22
...
[RUN]	Testing clock_gettime for clock invalid (-1)...
[FAIL]	No such clock, but __vdso_clock_gettime returned 22
[RUN]	Testing clock_gettime for clock invalid (-2147483648)...
[FAIL]	No such clock, but __vdso_clock_gettime returned 22
[RUN]	Testing clock_gettime for clock invalid (2147483647)...
[FAIL]	No such clock, but __vdso_clock_gettime returned 22

On powerpc, a call to a VDSO function is not an ordinary C function
call. Unlike several architectures which returns a negative error code
in case of an error, powerpc sets CR[SO] and returns the error code
as a positive value.

Define and use a macro called VDSO_CALL() which takes a pointer
to the function to call, the number of arguments and the arguments.

Also update ABI vdso documentation to reflect this subtlety.

Provide a specific version of VDSO_CALL() for powerpc that negates
the error code on return when CR[SO] is set.

Fixes: c7e5789b24d3 ("kselftest: Move test_vdso to the vDSO test suite")
Fixes: 2e9a97256616 ("selftests: vdso: Add a selftest for vDSO getcpu()")
Fixes: 693f5ca08ca0 ("kselftest: Extend vDSO selftest")
Fixes: b2f1c3db2887 ("kselftest: Extend vdso correctness test to clock_gettime64")
Fixes: 4920a2590e91 ("selftests/vDSO: add tests for vgetrandom")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 8 insertions, 7 deletions

diff --git a/tools/testing/selftests/vDSO/vdso_test_correctness.c b/tools/testing/selftests/vDSO/vdso_test_correctness.c
index cdb697ae8343..5fb97ad67eea 100644
--- a/tools/testing/selftests/vDSO/vdso_test_correctness.c
+++ b/tools/testing/selftests/vDSO/vdso_test_correctness.c
@@ -20,6 +20,7 @@
 #include <limits.h>
 
 #include "vdso_config.h"
+#include "vdso_call.h"
 #include "../kselftest.h"
 
 static const char **name;
@@ -186,7 +187,7 @@ static void test_getcpu(void)
 
 		ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);
 		if (vdso_getcpu)
-			ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);
+			ret_vdso = VDSO_CALL(vdso_getcpu, 3, &cpu_vdso, &node_vdso, 0);
 		if (vgetcpu)
 			ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);
 
@@ -269,7 +270,7 @@ static void test_one_clock_gettime(int clock, const char *name)
 
 	if (sys_clock_gettime(clock, &start) < 0) {
 		if (errno == EINVAL) {
-			vdso_ret = vdso_clock_gettime(clock, &vdso);
+			vdso_ret = VDSO_CALL(vdso_clock_gettime, 2, clock, &vdso);
 			if (vdso_ret == -EINVAL) {
 				printf("[OK]\tNo such clock.\n");
 			} else {
@@ -282,7 +283,7 @@ static void test_one_clock_gettime(int clock, const char *name)
 		return;
 	}
 
-	vdso_ret = vdso_clock_gettime(clock, &vdso);
+	vdso_ret = VDSO_CALL(vdso_clock_gettime, 2, clock, &vdso);
 	end_ret = sys_clock_gettime(clock, &end);
 
 	if (vdso_ret != 0 || end_ret != 0) {
@@ -331,7 +332,7 @@ static void test_one_clock_gettime64(int clock, const char *name)
 
 	if (sys_clock_gettime64(clock, &start) < 0) {
 		if (errno == EINVAL) {
-			vdso_ret = vdso_clock_gettime64(clock, &vdso);
+			vdso_ret = VDSO_CALL(vdso_clock_gettime64, 2, clock, &vdso);
 			if (vdso_ret == -EINVAL) {
 				printf("[OK]\tNo such clock.\n");
 			} else {
@@ -344,7 +345,7 @@ static void test_one_clock_gettime64(int clock, const char *name)
 		return;
 	}
 
-	vdso_ret = vdso_clock_gettime64(clock, &vdso);
+	vdso_ret = VDSO_CALL(vdso_clock_gettime64, 2, clock, &vdso);
 	end_ret = sys_clock_gettime64(clock, &end);
 
 	if (vdso_ret != 0 || end_ret != 0) {
@@ -401,7 +402,7 @@ static void test_gettimeofday(void)
 		return;
 	}
 
-	vdso_ret = vdso_gettimeofday(&vdso, &vdso_tz);
+	vdso_ret = VDSO_CALL(vdso_gettimeofday, 2, &vdso, &vdso_tz);
 	end_ret = sys_gettimeofday(&end, NULL);
 
 	if (vdso_ret != 0 || end_ret != 0) {
@@ -431,7 +432,7 @@ static void test_gettimeofday(void)
 	}
 
 	/* And make sure that passing NULL for tz doesn't crash. */
-	vdso_gettimeofday(&vdso, NULL);
+	VDSO_CALL(vdso_gettimeofday, 2, &vdso, NULL);
 }
 
 int main(int argc, char **argv)