selftests/mm: use sys_pkey helpers consistently

sys_pkey_alloc, sys_pkey_free and sys_mprotect_pkey are currently used in
protections_keys.c, while pkey_sighandler_tests.c calls the libc wrappers
directly (e.g. pkey_mprotect()). This is probably ok when using glibc
(those symbols appeared a while ago), but Musl does not currently provide
them. The logging in the helpers from pkey-helpers.h can also come in
handy.

Make things more consistent by using the sys_pkey helpers in
pkey_sighandler_tests.c too. To that end their implementation is moved to
a common .c file (pkey_util.c). This also enables calling
is_pkeys_supported() outside of protections_keys.c, since it relies on
sys_pkey_{alloc,free}.

[[e-mail]: fix dependency on pkey_util.c]
Link: https://lkml.kernel.org/r/[e-mail]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Kevin Brodsky <[e-mail]>
Cc: Aruna Ramakrishna <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: Joey Gouly <[e-mail]>
Cc: Keith Lucas <[e-mail]>
Cc: Ryan Roberts <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/testing/selftests/mm/Makefile

···
 
 $(OUTPUT)/uffd-stress: uffd-common.c
 $(OUTPUT)/uffd-unit-tests: uffd-common.c
+$(OUTPUT)/protection_keys: pkey_util.c
+$(OUTPUT)/pkey_sighandler_tests: pkey_util.c
 
 ifeq ($(ARCH),x86_64)
 BINARIES_32 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_32))
 BINARIES_64 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_64))
+
+$(BINARIES_32) $(BINARIES_64): pkey_util.c
 
 define gen-target-rule-32
 $(1) $(1)_32: $(OUTPUT)/$(1)_32

tools/testing/selftests/mm/pkey-helpers.h

···
 
 int sys_pkey_alloc(unsigned long flags, unsigned long init_val);
 int sys_pkey_free(unsigned long pkey);
+int sys_mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
+		unsigned long pkey);
 
 /* For functions called from protection_keys.c only */
 noinline int read_ptr(int *ptr);

tools/testing/selftests/mm/pkey_sighandler_tests.c

···
 	__write_pkey_reg(pkey_reg);
 
 	/* Protect the new stack with MPK 1 */
-	pkey = pkey_alloc(0, 0);
-	pkey_mprotect(stack, STACK_SIZE, PROT_READ | PROT_WRITE, pkey);
+	pkey = sys_pkey_alloc(0, 0);
+	sys_mprotect_pkey(stack, STACK_SIZE, PROT_READ | PROT_WRITE, pkey);
 
 	/* Set up alternate signal stack that will use the default MPK */
 	sigstack.ss_sp = mmap(0, STACK_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
···
 	__write_pkey_reg(pkey_reg);
 
 	/* Protect the stack with MPK 2 */
-	pkey = pkey_alloc(0, 0);
-	pkey_mprotect(stack, STACK_SIZE, PROT_READ | PROT_WRITE, pkey);
+	pkey = sys_pkey_alloc(0, 0);
+	sys_mprotect_pkey(stack, STACK_SIZE, PROT_READ | PROT_WRITE, pkey);
 
 	/* Set up alternate signal stack that will use the default MPK */
 	sigstack.ss_sp = mmap(0, STACK_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,

tools/testing/selftests/mm/pkey_util.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "pkey-helpers.h"
+
+int sys_pkey_alloc(unsigned long flags, unsigned long init_val)
+{
+	int ret = syscall(SYS_pkey_alloc, flags, init_val);
+	dprintf1("%s(flags=%lx, init_val=%lx) syscall ret: %d errno: %d\n",
+			__func__, flags, init_val, ret, errno);
+	return ret;
+}
+
+int sys_pkey_free(unsigned long pkey)
+{
+	int ret = syscall(SYS_pkey_free, pkey);
+	dprintf1("%s(pkey=%ld) syscall ret: %d\n", __func__, pkey, ret);
+	return ret;
+}
+
+int sys_mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
+		unsigned long pkey)
+{
+	int sret;
+
+	dprintf2("%s(0x%p, %zx, prot=%lx, pkey=%lx)\n", __func__,
+			ptr, size, orig_prot, pkey);
+
+	errno = 0;
+	sret = syscall(__NR_pkey_mprotect, ptr, size, orig_prot, pkey);
+	if (errno) {
+		dprintf2("SYS_mprotect_key sret: %d\n", sret);
+		dprintf2("SYS_mprotect_key prot: 0x%lx\n", orig_prot);
+		dprintf2("SYS_mprotect_key failed, errno: %d\n", errno);
+		if (DEBUG_LEVEL >= 2)
+			perror("SYS_mprotect_pkey");
+	}
+	return sret;
+}

tools/testing/selftests/mm/protection_keys.c

···
 	return forkret;
 }
 
-int sys_mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
-		unsigned long pkey)
-{
-	int sret;
-
-	dprintf2("%s(0x%p, %zx, prot=%lx, pkey=%lx)\n", __func__,
-			ptr, size, orig_prot, pkey);
-
-	errno = 0;
-	sret = syscall(__NR_pkey_mprotect, ptr, size, orig_prot, pkey);
-	if (errno) {
-		dprintf2("SYS_mprotect_key sret: %d\n", sret);
-		dprintf2("SYS_mprotect_key prot: 0x%lx\n", orig_prot);
-		dprintf2("SYS_mprotect_key failed, errno: %d\n", errno);
-		if (DEBUG_LEVEL >= 2)
-			perror("SYS_mprotect_pkey");
-	}
-	return sret;
-}
-
-int sys_pkey_alloc(unsigned long flags, unsigned long init_val)
-{
-	int ret = syscall(SYS_pkey_alloc, flags, init_val);
-	dprintf1("%s(flags=%lx, init_val=%lx) syscall ret: %d errno: %d\n",
-			__func__, flags, init_val, ret, errno);
-	return ret;
-}
-
 static int alloc_pkey(void)
 {
 	int ret;
···
 		 " shadow: 0x%016llx\n",
 		__func__, __LINE__, ret, __read_pkey_reg(),
 		shadow_pkey_reg);
-	return ret;
-}
-
-int sys_pkey_free(unsigned long pkey)
-{
-	int ret = syscall(SYS_pkey_free, pkey);
-	dprintf1("%s(pkey=%ld) syscall ret: %d\n", __func__, pkey, ret);
 	return ret;
 }