Message-ID: <20250805193955.798277-9-jesse@rivosinc.com>
Date: Tue,  5 Aug 2025 12:39:55 -0700
From: Jesse Taube <jesse@...osinc.com>
To: linux-riscv@...ts.infradead.org
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
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	linux-kselftest@...r.kernel.org
Subject: [PATCH 8/8] selftests: riscv: Add test for hardware breakpoints

Add riscv specific selftest for hardhardware breakpoints.
These tests are based on:
tools/testing/selftests/breakpoints/breakpoint_test_arm64.c

Signed-off-by: Jesse Taube <jesse@...osinc.com>
---
The selftest fails as register_user_hw_breakpoint seemingly does not
call arch_install_hw_breakpoint. The test also seems to fail on arm64
in the same way when I tested it.

RFC -> V1:
 - New commit
---
 tools/perf/tests/tests.h                      |   3 +-
 tools/testing/selftests/riscv/Makefile        |   2 +-
 .../selftests/riscv/breakpoints/.gitignore    |   1 +
 .../selftests/riscv/breakpoints/Makefile      |  12 +
 .../riscv/breakpoints/breakpoint_test.c       | 246 ++++++++++++++++++
 5 files changed, 262 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/selftests/riscv/breakpoints/.gitignore
 create mode 100644 tools/testing/selftests/riscv/breakpoints/Makefile
 create mode 100644 tools/testing/selftests/riscv/breakpoints/breakpoint_test.c

diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index 8aea344536b8..5ff35304c11a 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -183,7 +183,8 @@ DECLARE_SUITE(util);
  * Just disable the test for these architectures until these issues are
  * resolved.
  */
-#if defined(__powerpc__) || defined(__s390x__) || defined(__arm__) || defined(__aarch64__)
+#if defined(__powerpc__) || defined(__s390x__) || defined(__arm__) || defined(__aarch64__) || \
+    defined(__riscv)
 #define BP_SIGNAL_IS_SUPPORTED 0
 #else
 #define BP_SIGNAL_IS_SUPPORTED 1
diff --git a/tools/testing/selftests/riscv/Makefile b/tools/testing/selftests/riscv/Makefile
index 099b8c1f46f8..96aba246cb3e 100644
--- a/tools/testing/selftests/riscv/Makefile
+++ b/tools/testing/selftests/riscv/Makefile
@@ -5,7 +5,7 @@
 ARCH ?= $(shell uname -m 2>/dev/null || echo not)
 
 ifneq (,$(filter $(ARCH),riscv))
-RISCV_SUBTARGETS ?= abi hwprobe mm sigreturn vector
+RISCV_SUBTARGETS ?= abi hwprobe mm sigreturn vector breakpoints
 else
 RISCV_SUBTARGETS :=
 endif
diff --git a/tools/testing/selftests/riscv/breakpoints/.gitignore b/tools/testing/selftests/riscv/breakpoints/.gitignore
new file mode 100644
index 000000000000..9b3193d06608
--- /dev/null
+++ b/tools/testing/selftests/riscv/breakpoints/.gitignore
@@ -0,0 +1 @@
+breakpoint_test
diff --git a/tools/testing/selftests/riscv/breakpoints/Makefile b/tools/testing/selftests/riscv/breakpoints/Makefile
new file mode 100644
index 000000000000..91e1c02c0073
--- /dev/null
+++ b/tools/testing/selftests/riscv/breakpoints/Makefile
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2021 ARM Limited
+# Originally tools/testing/arm64/abi/Makefile
+
+CFLAGS += -I$(top_srcdir)/tools/include
+
+TEST_GEN_PROGS := breakpoint_test
+
+include ../../lib.mk
+
+$(OUTPUT)/breakpoint_test: breakpoint_test.c
+	$(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^
diff --git a/tools/testing/selftests/riscv/breakpoints/breakpoint_test.c b/tools/testing/selftests/riscv/breakpoints/breakpoint_test.c
new file mode 100644
index 000000000000..faeecc72da12
--- /dev/null
+++ b/tools/testing/selftests/riscv/breakpoints/breakpoint_test.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016 Google, Inc.
+ *
+ * Original Code by Pavel Labath <labath@...gle.com>
+ *
+ * Code modified by Pratyush Anand <panand@...hat.com>
+ * for testing different byte select for each access size.
+ * Originally tools/testing/selftests/breakpoints/breakpoint_test_arm64.c
+ */
+
+#define _GNU_SOURCE
+
+#include <asm/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/ptrace.h>
+#include <sys/param.h>
+#include <sys/uio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <elf.h>
+#include <errno.h>
+#include <signal.h>
+
+#include "../../kselftest.h"
+
+#define MAX_BP_SIZE 8
+
+static volatile uint8_t var[3*MAX_BP_SIZE] __attribute__((__aligned__(MAX_BP_SIZE)));
+
+static void child(int size, int wr)
+{
+	volatile uint8_t *addr = &var[MAX_BP_SIZE + wr];
+
+	if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) != 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_TRACEME) failed: %s\n",
+			strerror(errno));
+		_exit(1);
+	}
+
+	if (raise(SIGSTOP) != 0) {
+		ksft_print_msg(
+			"raise(SIGSTOP) failed: %s\n", strerror(errno));
+		_exit(1);
+	}
+
+	if ((uintptr_t) addr % size) {
+		ksft_print_msg(
+			 "Wrong address write for the given size: %s\n",
+			 strerror(errno));
+		_exit(1);
+	}
+
+	switch (size) {
+	case 1:
+		*addr = 47;
+		break;
+	case 2:
+		*(uint16_t *)addr = 47;
+		break;
+	case 4:
+		*(uint32_t *)addr = 47;
+		break;
+	case 8:
+		*(uint64_t *)addr = 47;
+		break;
+	}
+
+	_exit(0);
+}
+
+static bool set_watchpoint(pid_t pid, int size, int wp)
+{
+	const volatile uint8_t *addr = &var[MAX_BP_SIZE + wp];
+	const int offset = (uintptr_t)addr % 8;
+	const unsigned int type = 2; /* Write */
+	const unsigned int enable = 1;
+	struct __riscv_hwdebug_state debug_state;
+	struct iovec iov;
+
+	memset(&debug_state, 0, sizeof(debug_state));
+	debug_state.addr = (uintptr_t)(addr - offset);
+	debug_state.len = size;
+	debug_state.ctrl = enable;
+	debug_state.type = type;
+	iov.iov_base = &debug_state;
+	iov.iov_len = sizeof(debug_state);
+	if (ptrace(PTRACE_SETREGSET, pid, NT_RISCV_HW_BREAK, &iov) == 0)
+		return true;
+
+	if (errno == EIO)
+		ksft_print_msg(
+			"ptrace(PTRACE_SETREGSET, NT_RISCV_HW_BREAK) not supported on this hardware: %s\n",
+			strerror(errno));
+
+	ksft_print_msg(
+		"ptrace(PTRACE_SETREGSET, NT_RISCV_HW_BREAK) failed: %s\n",
+		strerror(errno));
+	return false;
+}
+
+static bool run_test(int wr_size, int wp_size, int wr, int wp)
+{
+	int status;
+	siginfo_t siginfo;
+	pid_t pid = fork();
+	pid_t wpid;
+
+	if (pid < 0) {
+		ksft_test_result_fail(
+			"fork() failed: %s\n", strerror(errno));
+		return false;
+	}
+	if (pid == 0)
+		child(wr_size, wr);
+
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg(
+			"child did not stop: %s\n", strerror(errno));
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGSTOP) {
+		ksft_print_msg("child did not stop with SIGSTOP\n");
+		return false;
+	}
+
+	if (!set_watchpoint(pid, wp_size, wp))
+		return false;
+
+	if (ptrace(PTRACE_CONT, pid, NULL, NULL) < 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_CONT) failed: %s\n",
+			strerror(errno));
+		return false;
+	}
+
+	alarm(3);
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	alarm(0);
+	if (WIFEXITED(status)) {
+		ksft_print_msg("child exited prematurely\n");
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg("child did not stop\n");
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGTRAP) {
+		ksft_print_msg("child did not stop with SIGTRAP\n");
+		return false;
+	}
+	if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo) != 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_GETSIGINFO): %s\n",
+			strerror(errno));
+		return false;
+	}
+	if (siginfo.si_code != TRAP_HWBKPT) {
+		ksft_print_msg(
+			"Unexpected si_code %d\n", siginfo.si_code);
+		return false;
+	}
+
+	kill(pid, SIGKILL);
+	wpid = waitpid(pid, &status, 0);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	return true;
+}
+
+static void sigalrm(int sig)
+{
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+	bool succeeded = true;
+	struct sigaction act;
+	int wr, wp, size;
+	bool result;
+
+	ksft_print_header();
+	ksft_set_plan(213);
+
+	act.sa_handler = sigalrm;
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = 0;
+	sigaction(SIGALRM, &act, NULL);
+	for (size = 1; size <= MAX_BP_SIZE; size = size*2) {
+		for (wr = 0; wr <= MAX_BP_SIZE; wr = wr + size) {
+			for (wp = wr - size; wp <= wr + size; wp = wp + size) {
+				result = run_test(size, MIN(size, 8), wr, wp);
+				if ((result && wr == wp) ||
+				    (!result && wr != wp))
+					ksft_test_result_pass(
+						"Test size = %d write offset = %d watchpoint offset = %d\n",
+						size, wr, wp);
+				else {
+					ksft_test_result_fail(
+						"Test size = %d write offset = %d watchpoint offset = %d\n",
+						size, wr, wp);
+					succeeded = false;
+				}
+			}
+		}
+	}
+
+	for (size = 1; size <= MAX_BP_SIZE; size = size*2) {
+		if (run_test(size, 8, -size, -8))
+			ksft_test_result_pass(
+				"Test size = %d write offset = %d watchpoint offset = -8\n",
+				size, -size);
+		else {
+			ksft_test_result_fail(
+				"Test size = %d write offset = %d watchpoint offset = -8\n",
+				size, -size);
+			succeeded = false;
+		}
+	}
+
+	if (succeeded)
+		ksft_exit_pass();
+	else
+		ksft_exit_fail();
+}
-- 
2.43.0

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