This is a note to let you know that I've just added the patch titled
selftests: vDSO: fix the way vDSO functions are called for powerpc
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
selftests-vdso-fix-the-way-vdso-functions-are-called.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 768c397f50d08415807c129965abcf7d920afd1f
Author: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Date: Fri Aug 30 14:28:38 2024 +0200
selftests: vDSO: fix the way vDSO functions are called for powerpc
[ Upstream commit 6eda706a535c3d0119eaefaad5fc119609639ed2 ]
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@xxxxxxxxxx>
Acked-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/Documentation/ABI/stable/vdso b/Documentation/ABI/stable/vdso
index 951838d427811..85dbb6a160df8 100644
--- a/Documentation/ABI/stable/vdso
+++ b/Documentation/ABI/stable/vdso
@@ -9,9 +9,11 @@ maps an ELF DSO into that program's address space. This DSO is called
the vDSO and it often contains useful and highly-optimized alternatives
to real syscalls.
-These functions are called just like ordinary C function according to
-your platform's ABI. Call them from a sensible context. (For example,
-if you set CS on x86 to something strange, the vDSO functions are
+These functions are called according to your platform's ABI. On many
+platforms they are called just like ordinary C function. On other platforms
+(ex: powerpc) they are called with the same convention as system calls which
+is different from ordinary C functions. Call them from a sensible context.
+(For example, if you set CS on x86 to something strange, the vDSO functions are
within their rights to crash.) In addition, if you pass a bad
pointer to a vDSO function, you might get SIGSEGV instead of -EFAULT.
diff --git a/tools/testing/selftests/vDSO/vdso_call.h b/tools/testing/selftests/vDSO/vdso_call.h
new file mode 100644
index 0000000000000..bb237d771051b
--- /dev/null
+++ b/tools/testing/selftests/vDSO/vdso_call.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Macro to call vDSO functions
+ *
+ * Copyright (C) 2024 Christophe Leroy <christophe.leroy@xxxxxxxxxx>, CS GROUP France
+ */
+#ifndef __VDSO_CALL_H__
+#define __VDSO_CALL_H__
+
+#ifdef __powerpc__
+
+#define LOADARGS_1(fn, __arg1) do { \
+ _r0 = fn; \
+ _r3 = (long)__arg1; \
+} while (0)
+
+#define LOADARGS_2(fn, __arg1, __arg2) do { \
+ _r0 = fn; \
+ _r3 = (long)__arg1; \
+ _r4 = (long)__arg2; \
+} while (0)
+
+#define LOADARGS_3(fn, __arg1, __arg2, __arg3) do { \
+ _r0 = fn; \
+ _r3 = (long)__arg1; \
+ _r4 = (long)__arg2; \
+ _r5 = (long)__arg3; \
+} while (0)
+
+#define LOADARGS_5(fn, __arg1, __arg2, __arg3, __arg4, __arg5) do { \
+ _r0 = fn; \
+ _r3 = (long)__arg1; \
+ _r4 = (long)__arg2; \
+ _r5 = (long)__arg3; \
+ _r6 = (long)__arg4; \
+ _r7 = (long)__arg5; \
+} while (0)
+
+#define VDSO_CALL(fn, nr, args...) ({ \
+ register void *_r0 asm ("r0"); \
+ register long _r3 asm ("r3"); \
+ register long _r4 asm ("r4"); \
+ register long _r5 asm ("r5"); \
+ register long _r6 asm ("r6"); \
+ register long _r7 asm ("r7"); \
+ register long _r8 asm ("r8"); \
+ register long _rval asm ("r3"); \
+ \
+ LOADARGS_##nr(fn, args); \
+ \
+ asm volatile( \
+ " mtctr %0\n" \
+ " bctrl\n" \
+ " bns+ 1f\n" \
+ " neg 3, 3\n" \
+ "1:" \
+ : "+r" (_r0), "=r" (_r3), "+r" (_r4), "+r" (_r5), \
+ "+r" (_r6), "+r" (_r7), "+r" (_r8) \
+ : "r" (_rval) \
+ : "r9", "r10", "r11", "r12", "cr0", "cr1", "cr5", \
+ "cr6", "cr7", "xer", "lr", "ctr", "memory" \
+ ); \
+ _rval; \
+})
+
+#else
+#define VDSO_CALL(fn, nr, args...) fn(args)
+#endif
+
+#endif
diff --git a/tools/testing/selftests/vDSO/vdso_test_abi.c b/tools/testing/selftests/vDSO/vdso_test_abi.c
index 96d32fd65b42b..00034208c4c64 100644
--- a/tools/testing/selftests/vDSO/vdso_test_abi.c
+++ b/tools/testing/selftests/vDSO/vdso_test_abi.c
@@ -20,6 +20,7 @@
#include "../kselftest.h"
#include "vdso_config.h"
+#include "vdso_call.h"
extern void *vdso_sym(const char *version, const char *name);
extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
@@ -61,7 +62,7 @@ static void vdso_test_gettimeofday(void)
}
struct timeval tv;
- long ret = vdso_gettimeofday(&tv, 0);
+ long ret = VDSO_CALL(vdso_gettimeofday, 2, &tv, 0);
if (ret == 0) {
ksft_print_msg("The time is %lld.%06lld\n",
@@ -86,7 +87,7 @@ static void vdso_test_clock_gettime(clockid_t clk_id)
}
struct timespec ts;
- long ret = vdso_clock_gettime(clk_id, &ts);
+ long ret = VDSO_CALL(vdso_clock_gettime, 2, clk_id, &ts);
if (ret == 0) {
ksft_print_msg("The time is %lld.%06lld\n",
@@ -111,7 +112,7 @@ static void vdso_test_time(void)
return;
}
- long ret = vdso_time(NULL);
+ long ret = VDSO_CALL(vdso_time, 1, NULL);
if (ret > 0) {
ksft_print_msg("The time in hours since January 1, 1970 is %lld\n",
@@ -138,7 +139,7 @@ static void vdso_test_clock_getres(clockid_t clk_id)
}
struct timespec ts, sys_ts;
- long ret = vdso_clock_getres(clk_id, &ts);
+ long ret = VDSO_CALL(vdso_clock_getres, 2, clk_id, &ts);
if (ret == 0) {
ksft_print_msg("The vdso resolution is %lld %lld\n",
diff --git a/tools/testing/selftests/vDSO/vdso_test_correctness.c b/tools/testing/selftests/vDSO/vdso_test_correctness.c
index cdb697ae8343c..5fb97ad67eeaf 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)
diff --git a/tools/testing/selftests/vDSO/vdso_test_getcpu.c b/tools/testing/selftests/vDSO/vdso_test_getcpu.c
index b758f68c6c9c2..cdeaed45fb26c 100644
--- a/tools/testing/selftests/vDSO/vdso_test_getcpu.c
+++ b/tools/testing/selftests/vDSO/vdso_test_getcpu.c
@@ -14,6 +14,7 @@
#include "../kselftest.h"
#include "parse_vdso.h"
#include "vdso_config.h"
+#include "vdso_call.h"
struct getcpu_cache;
typedef long (*getcpu_t)(unsigned int *, unsigned int *,
@@ -42,7 +43,7 @@ int main(int argc, char **argv)
return KSFT_SKIP;
}
- ret = get_cpu(&cpu, &node, 0);
+ ret = VDSO_CALL(get_cpu, 3, &cpu, &node, 0);
if (ret == 0) {
printf("Running on CPU %u node %u\n", cpu, node);
} else {
diff --git a/tools/testing/selftests/vDSO/vdso_test_getrandom.c b/tools/testing/selftests/vDSO/vdso_test_getrandom.c
index 5db8ac8999cd0..351daeb649c84 100644
--- a/tools/testing/selftests/vDSO/vdso_test_getrandom.c
+++ b/tools/testing/selftests/vDSO/vdso_test_getrandom.c
@@ -22,6 +22,7 @@
#include "../kselftest.h"
#include "parse_vdso.h"
#include "vdso_config.h"
+#include "vdso_call.h"
#ifndef timespecsub
#define timespecsub(tsp, usp, vsp) \
@@ -116,7 +117,7 @@ static void vgetrandom_init(void)
printf("%s is missing!\n", name);
exit(KSFT_FAIL);
}
- ret = vgrnd.fn(NULL, 0, 0, &vgrnd.params, ~0UL);
+ ret = VDSO_CALL(vgrnd.fn, 5, NULL, 0, 0, &vgrnd.params, ~0UL);
if (ret == -ENOSYS) {
printf("unsupported architecture\n");
exit(KSFT_SKIP);
@@ -137,7 +138,7 @@ static ssize_t vgetrandom(void *buf, size_t len, unsigned long flags)
exit(KSFT_FAIL);
}
}
- return vgrnd.fn(buf, len, flags, state, vgrnd.params.size_of_opaque_state);
+ return VDSO_CALL(vgrnd.fn, 5, buf, len, flags, state, vgrnd.params.size_of_opaque_state);
}
enum { TRIALS = 25000000, THREADS = 256 };
diff --git a/tools/testing/selftests/vDSO/vdso_test_gettimeofday.c b/tools/testing/selftests/vDSO/vdso_test_gettimeofday.c
index ee4f1ca56a71a..e31b18ffae338 100644
--- a/tools/testing/selftests/vDSO/vdso_test_gettimeofday.c
+++ b/tools/testing/selftests/vDSO/vdso_test_gettimeofday.c
@@ -19,6 +19,7 @@
#include "../kselftest.h"
#include "parse_vdso.h"
#include "vdso_config.h"
+#include "vdso_call.h"
int main(int argc, char **argv)
{
@@ -43,7 +44,7 @@ int main(int argc, char **argv)
}
struct timeval tv;
- long ret = gtod(&tv, 0);
+ long ret = VDSO_CALL(gtod, 2, &tv, 0);
if (ret == 0) {
printf("The time is %lld.%06lld\n",
