[PATCH 3/3] selftest/arm64/ptrace: add a test for NT_ARM_PRSTATUS

[Andrei Vagin]

Test output:
 TAP version 13
 1..1
 # selftests: arm64/ptrace: ptrace_syscall_regs_test
 # 1..3
 # ok 1 NT_PRSTATUS: x7 0
 # ok 2 NT_ARM_PRSTATUS: x7 686920776f726c64
 # ok 3 The child exited with code 0.
 # # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0
 ok 1 selftests: arm64/ptrace: ptrace_syscall_regs_test

Signed-off-by: Andrei Vagin <avagin@xxxxxxxxx>
---
 tools/testing/selftests/arm64/Makefile        |   2 +-
 tools/testing/selftests/arm64/ptrace/Makefile |   6 +
 .../arm64/ptrace/ptrace_syscall_regs_test.c   | 147 ++++++++++++++++++
 3 files changed, 154 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/arm64/ptrace/Makefile
 create mode 100644 tools/testing/selftests/arm64/ptrace/ptrace_syscall_regs_test.c

diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile
index 2c9d012797a7..704770a60ece 100644
--- a/tools/testing/selftests/arm64/Makefile
+++ b/tools/testing/selftests/arm64/Makefile
@@ -4,7 +4,7 @@
 ARCH ?= $(shell uname -m 2>/dev/null || echo not)
 
 ifneq (,$(filter $(ARCH),aarch64 arm64))
-ARM64_SUBTARGETS ?= tags signal pauth fp mte
+ARM64_SUBTARGETS ?= tags signal pauth fp mte ptrace
 else
 ARM64_SUBTARGETS :=
 endif
diff --git a/tools/testing/selftests/arm64/ptrace/Makefile b/tools/testing/selftests/arm64/ptrace/Makefile
new file mode 100644
index 000000000000..ca906ce3a581
--- /dev/null
+++ b/tools/testing/selftests/arm64/ptrace/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+
+CFLAGS += -g -I../../../../../usr/include/
+TEST_GEN_PROGS := ptrace_syscall_regs_test
+
+include ../../lib.mk
diff --git a/tools/testing/selftests/arm64/ptrace/ptrace_syscall_regs_test.c b/tools/testing/selftests/arm64/ptrace/ptrace_syscall_regs_test.c
new file mode 100644
index 000000000000..601378b7591d
--- /dev/null
+++ b/tools/testing/selftests/arm64/ptrace/ptrace_syscall_regs_test.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/ptrace.h>
+#include <sys/user.h>
+#include <sys/wait.h>
+#include <sys/uio.h>
+#include <linux/elf.h>
+#include <linux/unistd.h>
+
+#include "../../kselftest.h"
+
+#define TEST_VAL 0x686920776f726c64UL
+
+#define pr_p(func, fmt, ...)	func(fmt ": %m", ##__VA_ARGS__)
+
+#define pr_err(fmt, ...)						\
+	({								\
+		ksft_test_result_error(fmt "\n", ##__VA_ARGS__);		\
+		-1;							\
+	})
+
+#define pr_fail(fmt, ...)					\
+	({							\
+		ksft_test_result_fail(fmt "\n", ##__VA_ARGS__);	\
+		-1;						\
+	})
+
+#define pr_perror(fmt, ...)	pr_p(pr_err, fmt, ##__VA_ARGS__)
+
+static long loop(void *val)
+{
+	register long x0 __asm__("x0");
+	register void *x1 __asm__("x1") = val;
+	register long x8 __asm__("x8") = 555;
+
+	__asm__ (
+		"again:\n"
+		"ldr x7, [x1, 0]\n"
+		"svc 0\n"
+		"str x7, [x1, 0]\n"
+			   : "=r"(x0)
+			   : "r"(x1), "r"(x8)
+			   :
+	);
+	return 0;
+}
+
+static int child(void)
+{
+	long  val = TEST_VAL;
+
+	loop(&val);
+	if (val != ~TEST_VAL) {
+		ksft_print_msg("Unexpected x7: %lx\n", val);
+		return 1;
+	}
+
+	return 0;
+}
+
+#ifndef PTRACE_SYSEMU
+#define PTRACE_SYSEMU 31
+#endif
+
+#ifndef NT_ARM_PRSTATUS
+#define NT_ARM_PRSTATUS 0x410
+#endif
+
+int main(int argc, void **argv)
+{
+	struct user_regs_struct regs = {};
+	struct iovec iov = {
+		.iov_base = &regs,
+		.iov_len = sizeof(struct user_regs_struct),
+	};
+	int status;
+	pid_t pid;
+
+	ksft_set_plan(3);
+
+	pid = fork();
+	if (pid == 0) {
+		kill(getpid(), SIGSTOP);
+		child();
+		_exit(0);
+	}
+	if (pid < 0)
+		return 1;
+
+	if (ptrace(PTRACE_ATTACH, pid, 0, 0))
+		return pr_perror("Can't attach to the child %d", pid);
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("Can't wait for the child %d", pid);
+	/* skip SIGSTOP */
+	if (ptrace(PTRACE_CONT, pid, 0, 0))
+		return pr_perror("Can't resume the child %d", pid);
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("Can't wait for the child %d", pid);
+
+	/* Resume the child to the next system call. */
+	if (ptrace(PTRACE_SYSEMU, pid, 0, 0))
+		return pr_perror("Can't resume the child %d", pid);
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("Can't wait for the child %d", pid);
+	if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGTRAP)
+		return pr_err("Unexpected status: %d", status);
+
+	/* Check that x7 is zero in the case of NT_PRSTATUS. */
+	if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &iov))
+		return pr_perror("Can't get child registers");
+	if (regs.regs[7] != 0)
+		return pr_fail("NT_PRSTATUS: unexpected x7: %lx", regs.regs[7]);
+	ksft_test_result_pass("NT_PRSTATUS: x7 %llx\n", regs.regs[7]);
+
+	/* Check that x7 isnt't clobbered in the case of NT_ARM_PRSTATUS. */
+	if (ptrace(PTRACE_GETREGSET, pid, NT_ARM_PRSTATUS, &iov))
+		return pr_perror("Can't get child registers");
+	if (regs.regs[7] != TEST_VAL)
+		return pr_fail("NT_ARM_PRSTATUS: unexpected x7: %lx", regs.regs[7]);
+	ksft_test_result_pass("NT_ARM_PRSTATUS: x7 %llx\n", regs.regs[7]);
+
+	/* Check that the child will see a new value of x7. */
+	regs.regs[0] = 0;
+	regs.regs[7] = ~TEST_VAL;
+	if (ptrace(PTRACE_SETREGSET, pid, NT_PRSTATUS, &iov))
+		return pr_perror("Can't set child registers");
+
+	if (ptrace(PTRACE_CONT, pid, 0, 0))
+		return pr_perror("Can't resume the child %d", pid);
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("Can't wait for the child %d", pid);
+
+	if (status != 0)
+		return pr_fail("Child exited with code %d.", status);
+
+	ksft_test_result_pass("The child exited with code 0.\n");
+	ksft_exit_pass();
+	return 0;
+}
+
-- 
2.29.2