From patchwork series 421697

https://patchwork.ozlabs.org//project/linuxppc-dev/list/?series=421697

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.
 

tools/testing/selftests/vDSO/parse_vdso.c

@@ -216,7 +216,8 @@ void *vdso_sym(const char *version, const char *name)
 		ELF(Sym) *sym = &vdso_info.symtab[chain];
 
 		/* Check for a defined global or weak function w/ right name. */
-		if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
+		if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC &&
+		    ELF64_ST_TYPE(sym->st_info) != STT_NOTYPE)
 			continue;
 		if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
 		    ELF64_ST_BIND(sym->st_info) != STB_WEAK)

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 <[email protected]>, 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

tools/testing/selftests/vDSO/vdso_config.h

@@ -18,13 +18,13 @@
 #elif defined(__aarch64__)
 #define VDSO_VERSION		3
 #define VDSO_NAMES		0
-#elif defined(__powerpc__)
+#elif defined(__powerpc64__)
 #define VDSO_VERSION		1
 #define VDSO_NAMES		0
-#define VDSO_32BIT		1
-#elif defined(__powerpc64__)
+#elif defined(__powerpc__)
 #define VDSO_VERSION		1
 #define VDSO_NAMES		0
+#define VDSO_32BIT		1
 #elif defined (__s390__)
 #define VDSO_VERSION		2
 #define VDSO_NAMES		0

tools/testing/selftests/vDSO/vdso_test_abi.c

@@ -20,10 +20,8 @@
 
 #include "../kselftest.h"
 #include "vdso_config.h"
-
-extern void *vdso_sym(const char *version, const char *name);
-extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
-extern void vdso_init_from_auxv(void *auxv);
+#include "vdso_call.h"
+#include "parse_vdso.h"
 
 static const char *version;
 static const char **name;
@@ -61,7 +59,7 @@ 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 +84,7 @@ 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 +109,7 @@ 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 +136,7 @@ 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",

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;
@@ -114,6 +115,12 @@ static void fill_function_pointers()
 	if (!vdso)
 		vdso = dlopen("linux-gate.so.1",
 			      RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+	if (!vdso)
+		vdso = dlopen("linux-vdso32.so.1",
+			      RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+	if (!vdso)
+		vdso = dlopen("linux-vdso64.so.1",
+			      RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
 	if (!vdso) {
 		printf("[WARN]\tfailed to find vDSO\n");
 		return;
@@ -180,7 +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);
 
@@ -263,7 +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 {
@@ -276,7 +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) {
@@ -325,7 +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 {
@@ -338,7 +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) {
@@ -395,7 +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) {
@@ -425,7 +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)

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 {

tools/testing/selftests/vDSO/vdso_test_getrandom.c

@@ -21,6 +21,7 @@
 
 #include "../kselftest.h"
 #include "parse_vdso.h"
+#include "vdso_call.h"
 
 #ifndef timespecsub
 #define	timespecsub(tsp, usp, vsp)					\
@@ -120,7 +121,7 @@ static void vgetrandom_init(void)
 		printf("__vdso_getrandom is missing!\n");
 		exit(KSFT_FAIL);
 	}
-	if (grnd_ctx.fn(NULL, 0, 0, &grnd_ctx.params, ~0UL) != 0) {
+	if (VDSO_CALL(grnd_ctx.fn, 5, NULL, 0, 0, &grnd_ctx.params, ~0UL) != 0) {
 		printf("failed to fetch vgetrandom params!\n");
 		exit(KSFT_FAIL);
 	}
@@ -143,7 +144,7 @@ static ssize_t vgetrandom(void *buf, size_t len, unsigned long flags)
 			exit(KSFT_FAIL);
 		}
 	}
-	return grnd_ctx.fn(buf, len, flags, state, grnd_ctx.params.size_of_opaque_state);
+	return VDSO_CALL(grnd_ctx.fn, 5, buf, len, flags, state, grnd_ctx.params.size_of_opaque_state);
 }
 
 enum { TRIALS = 25000000, THREADS = 256 };

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",