1 files changed, 334 insertions, 548 deletions

diff --git a/tools/testing/selftests/powerpc/ptrace/ptrace-perf-hwbreak.c b/tools/testing/selftests/powerpc/ptrace/ptrace-perf-hwbreak.c
index 3344e74a97b4..a0a0b9bb5854 100644
--- a/tools/testing/selftests/powerpc/ptrace/ptrace-perf-hwbreak.c
+++ b/tools/testing/selftests/powerpc/ptrace/ptrace-perf-hwbreak.c
@@ -1,659 +1,445 @@
 // SPDX-License-Identifier: GPL-2.0+
-#include <stdio.h>
-#include <string.h>
-#include <signal.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <errno.h>
-#include <linux/hw_breakpoint.h>
-#include <linux/perf_event.h>
+
 #include <asm/unistd.h>
-#include <sys/ptrace.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/ptrace.h>
+#include <memory.h>
+#include <stdlib.h>
 #include <sys/wait.h>
-#include "ptrace.h"
 
-char data[16];
+#include "utils.h"
 
-/* Overlapping address range */
-volatile __u64 *ptrace_data1 = (__u64 *)&data[0];
-volatile __u64 *perf_data1 = (__u64 *)&data[4];
+/*
+ * Child subroutine that performs a load on the address, then traps
+ */
+void same_watch_addr_child(unsigned long *addr);
 
-/* Non-overlapping address range */
-volatile __u64 *ptrace_data2 = (__u64 *)&data[0];
-volatile __u64 *perf_data2 = (__u64 *)&data[8];
+/* Address of the ld instruction in same_watch_addr_child() */
+extern char same_watch_addr_load[];
 
-static unsigned long pid_max_addr(void)
-{
-	FILE *fp;
-	char *line, *c;
-	char addr[100];
-	size_t len = 0;
-
-	fp = fopen("/proc/kallsyms", "r");
-	if (!fp) {
-		printf("Failed to read /proc/kallsyms. Exiting..\n");
-		exit(EXIT_FAILURE);
-	}
+/* Address of the end trap instruction in same_watch_addr_child() */
+extern char same_watch_addr_trap[];
 
-	while (getline(&line, &len, fp) != -1) {
-		if (!strstr(line, "pid_max") || strstr(line, "pid_max_max") ||
-		    strstr(line, "pid_max_min"))
-			continue;
+/*
+ * Child subroutine that performs a load on the first address, then a load on
+ * the second address (with no instructions separating this from the first
+ * load), then traps.
+ */
+void perf_then_ptrace_child(unsigned long *first_addr, unsigned long *second_addr);
 
-		strncpy(addr, line, len < 100 ? len : 100);
-		c = strchr(addr, ' ');
-		*c = '\0';
-		return strtoul(addr, &c, 16);
-	}
-	fclose(fp);
-	printf("Could not find pix_max. Exiting..\n");
-	exit(EXIT_FAILURE);
-	return -1;
-}
+/* Address of the first ld instruction in perf_then_ptrace_child() */
+extern char perf_then_ptrace_load1[];
 
-static void perf_user_event_attr_set(struct perf_event_attr *attr, __u64 addr, __u64 len)
-{
-	memset(attr, 0, sizeof(struct perf_event_attr));
-	attr->type           = PERF_TYPE_BREAKPOINT;
-	attr->size           = sizeof(struct perf_event_attr);
-	attr->bp_type        = HW_BREAKPOINT_R;
-	attr->bp_addr        = addr;
-	attr->bp_len         = len;
-	attr->exclude_kernel = 1;
-	attr->exclude_hv     = 1;
-}
+/* Address of the second ld instruction in perf_then_ptrace_child() */
+extern char perf_then_ptrace_load2[];
 
-static void perf_kernel_event_attr_set(struct perf_event_attr *attr)
+/* Address of the end trap instruction in perf_then_ptrace_child() */
+extern char perf_then_ptrace_trap[];
+
+static inline long sys_ptrace(long request, pid_t pid, unsigned long addr, unsigned long data)
 {
-	memset(attr, 0, sizeof(struct perf_event_attr));
-	attr->type           = PERF_TYPE_BREAKPOINT;
-	attr->size           = sizeof(struct perf_event_attr);
-	attr->bp_type        = HW_BREAKPOINT_R;
-	attr->bp_addr        = pid_max_addr();
-	attr->bp_len         = sizeof(unsigned long);
-	attr->exclude_user   = 1;
-	attr->exclude_hv     = 1;
+	return syscall(__NR_ptrace, request, pid, addr, data);
 }
 
-static int perf_cpu_event_open(int cpu, __u64 addr, __u64 len)
+static long ptrace_traceme(void)
 {
-	struct perf_event_attr attr;
-
-	perf_user_event_attr_set(&attr, addr, len);
-	return syscall(__NR_perf_event_open, &attr, -1, cpu, -1, 0);
+	return sys_ptrace(PTRACE_TRACEME, 0, 0, 0);
 }
 
-static int perf_thread_event_open(pid_t child_pid, __u64 addr, __u64 len)
+static long ptrace_getregs(pid_t pid, struct pt_regs *result)
 {
-	struct perf_event_attr attr;
-
-	perf_user_event_attr_set(&attr, addr, len);
-	return syscall(__NR_perf_event_open, &attr, child_pid, -1, -1, 0);
+	return sys_ptrace(PTRACE_GETREGS, pid, 0, (unsigned long)result);
 }
 
-static int perf_thread_cpu_event_open(pid_t child_pid, int cpu, __u64 addr, __u64 len)
+static long ptrace_setregs(pid_t pid, struct pt_regs *result)
 {
-	struct perf_event_attr attr;
-
-	perf_user_event_attr_set(&attr, addr, len);
-	return syscall(__NR_perf_event_open, &attr, child_pid, cpu, -1, 0);
+	return sys_ptrace(PTRACE_SETREGS, pid, 0, (unsigned long)result);
 }
 
-static int perf_thread_kernel_event_open(pid_t child_pid)
+static long ptrace_cont(pid_t pid, long signal)
 {
-	struct perf_event_attr attr;
-
-	perf_kernel_event_attr_set(&attr);
-	return syscall(__NR_perf_event_open, &attr, child_pid, -1, -1, 0);
+	return sys_ptrace(PTRACE_CONT, pid, 0, signal);
 }
 
-static int perf_cpu_kernel_event_open(int cpu)
+static long ptrace_singlestep(pid_t pid, long signal)
 {
-	struct perf_event_attr attr;
-
-	perf_kernel_event_attr_set(&attr);
-	return syscall(__NR_perf_event_open, &attr, -1, cpu, -1, 0);
+	return sys_ptrace(PTRACE_SINGLESTEP, pid, 0, signal);
 }
 
-static int child(void)
+static long ppc_ptrace_gethwdbginfo(pid_t pid, struct ppc_debug_info *dbginfo)
 {
-	int ret;
-
-	ret = ptrace(PTRACE_TRACEME, 0, NULL, 0);
-	if (ret) {
-		printf("Error: PTRACE_TRACEME failed\n");
-		return 0;
-	}
-	kill(getpid(), SIGUSR1); /* --> parent (SIGUSR1) */
-
-	return 0;
+	return sys_ptrace(PPC_PTRACE_GETHWDBGINFO, pid, 0, (unsigned long)dbginfo);
 }
 
-static void ptrace_ppc_hw_breakpoint(struct ppc_hw_breakpoint *info, int type,
-				     __u64 addr, int len)
+static long ppc_ptrace_sethwdbg(pid_t pid, struct ppc_hw_breakpoint *bp_info)
 {
-	info->version = 1;
-	info->trigger_type = type;
-	info->condition_mode = PPC_BREAKPOINT_CONDITION_NONE;
-	info->addr = addr;
-	info->addr2 = addr + len;
-	info->condition_value = 0;
-	if (!len)
-		info->addr_mode = PPC_BREAKPOINT_MODE_EXACT;
-	else
-		info->addr_mode = PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE;
+	return sys_ptrace(PPC_PTRACE_SETHWDEBUG, pid, 0, (unsigned long)bp_info);
 }
 
-static int ptrace_open(pid_t child_pid, __u64 wp_addr, int len)
+static long ppc_ptrace_delhwdbg(pid_t pid, int bp_id)
 {
-	struct ppc_hw_breakpoint info;
-
-	ptrace_ppc_hw_breakpoint(&info, PPC_BREAKPOINT_TRIGGER_RW, wp_addr, len);
-	return ptrace(PPC_PTRACE_SETHWDEBUG, child_pid, 0, &info);
+	return sys_ptrace(PPC_PTRACE_DELHWDEBUG, pid, 0L, bp_id);
 }
 
-static int test1(pid_t child_pid)
+static long ptrace_getreg_pc(pid_t pid, void **pc)
 {
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread event by ptrace)
-	 *	if (existing cpu event by perf)
-	 *		if (addr range overlaps)
-	 *			fail;
-	 */
+	struct pt_regs regs;
+	long err;
 
-	perf_fd = perf_cpu_event_open(0, (__u64)perf_data1, sizeof(*perf_data1));
-	if (perf_fd < 0)
-		return -1;
+	err = ptrace_getregs(pid, &regs);
+	if (err)
+		return err;
 
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
-	if (ptrace_fd > 0 || errno != ENOSPC)
-		ret = -1;
+	*pc = (void *)regs.nip;
 
-	close(perf_fd);
-	return ret;
+	return 0;
 }
 
-static int test2(pid_t child_pid)
+static long ptrace_setreg_pc(pid_t pid, void *pc)
 {
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread event by ptrace)
-	 *	if (existing cpu event by perf)
-	 *		if (addr range does not overlaps)
-	 *			allow;
-	 */
+	struct pt_regs regs;
+	long err;
 
-	perf_fd = perf_cpu_event_open(0, (__u64)perf_data2, sizeof(*perf_data2));
-	if (perf_fd < 0)
-		return -1;
-
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data2, sizeof(*ptrace_data2));
-	if (ptrace_fd < 0) {
-		ret = -1;
-		goto perf_close;
-	}
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-
-perf_close:
-	close(perf_fd);
-	return ret;
-}
+	err = ptrace_getregs(pid, &regs);
+	if (err)
+		return err;
 
-static int test3(pid_t child_pid)
-{
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread event by ptrace)
-	 *	if (existing thread event by perf on the same thread)
-	 *		if (addr range overlaps)
-	 *			fail;
-	 */
-	perf_fd = perf_thread_event_open(child_pid, (__u64)perf_data1,
-					 sizeof(*perf_data1));
-	if (perf_fd < 0)
-		return -1;
+	regs.nip = (unsigned long)pc;
 
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
-	if (ptrace_fd > 0 || errno != ENOSPC)
-		ret = -1;
+	err = ptrace_setregs(pid, &regs);
+	if (err)
+		return err;
 
-	close(perf_fd);
-	return ret;
+	return 0;
 }
 
-static int test4(pid_t child_pid)
+static int perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu,
+			   int group_fd, unsigned long flags)
 {
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread event by ptrace)
-	 *	if (existing thread event by perf on the same thread)
-	 *		if (addr range does not overlaps)
-	 *			fail;
-	 */
-	perf_fd = perf_thread_event_open(child_pid, (__u64)perf_data2,
-					 sizeof(*perf_data2));
-	if (perf_fd < 0)
-		return -1;
-
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data2, sizeof(*ptrace_data2));
-	if (ptrace_fd < 0) {
-		ret = -1;
-		goto perf_close;
-	}
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-
-perf_close:
-	close(perf_fd);
-	return ret;
+	return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags);
 }
 
-static int test5(pid_t child_pid)
+static void perf_user_event_attr_set(struct perf_event_attr *attr, void *addr, u64 len)
 {
-	int perf_fd;
-	int ptrace_fd;
-	int cpid;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread event by ptrace)
-	 *	if (existing thread event by perf on the different thread)
-	 *		allow;
-	 */
-	cpid = fork();
-	if (!cpid) {
-		/* Temporary Child */
-		pause();
-		exit(EXIT_SUCCESS);
-	}
-
-	perf_fd = perf_thread_event_open(cpid, (__u64)perf_data1, sizeof(*perf_data1));
-	if (perf_fd < 0) {
-		ret = -1;
-		goto kill_child;
-	}
-
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
-	if (ptrace_fd < 0) {
-		ret = -1;
-		goto perf_close;
-	}
+	memset(attr, 0, sizeof(struct perf_event_attr));
 
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-perf_close:
-	close(perf_fd);
-kill_child:
-	kill(cpid, SIGINT);
-	return ret;
+	attr->type		= PERF_TYPE_BREAKPOINT;
+	attr->size		= sizeof(struct perf_event_attr);
+	attr->bp_type		= HW_BREAKPOINT_R;
+	attr->bp_addr		= (u64)addr;
+	attr->bp_len		= len;
+	attr->exclude_kernel	= 1;
+	attr->exclude_hv	= 1;
 }
 
-static int test6(pid_t child_pid)
+static int perf_watchpoint_open(pid_t child_pid, void *addr, u64 len)
 {
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread kernel event by perf)
-	 *	if (existing thread event by ptrace on the same thread)
-	 *		allow;
-	 * -- OR --
-	 * if (new per cpu kernel event by perf)
-	 *	if (existing thread event by ptrace)
-	 *		allow;
-	 */
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
-	if (ptrace_fd < 0)
-		return -1;
-
-	perf_fd = perf_thread_kernel_event_open(child_pid);
-	if (perf_fd < 0) {
-		ret = -1;
-		goto ptrace_close;
-	}
-	close(perf_fd);
-
-	perf_fd = perf_cpu_kernel_event_open(0);
-	if (perf_fd < 0) {
-		ret = -1;
-		goto ptrace_close;
-	}
-	close(perf_fd);
+	struct perf_event_attr attr;
 
-ptrace_close:
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-	return ret;
+	perf_user_event_attr_set(&attr, addr, len);
+	return perf_event_open(&attr, child_pid, -1, -1, 0);
 }
 
-static int test7(pid_t child_pid)
+static int perf_read_counter(int perf_fd, u64 *count)
 {
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread event by perf)
-	 *	if (existing thread event by ptrace on the same thread)
-	 *		if (addr range overlaps)
-	 *			fail;
+	/*
+	 * A perf counter is retrieved by the read() syscall. It contains
+	 * the current count as 8 bytes that are interpreted as a u64
 	 */
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
-	if (ptrace_fd < 0)
-		return -1;
+	ssize_t len = read(perf_fd, count, sizeof(*count));
 
-	perf_fd = perf_thread_event_open(child_pid, (__u64)perf_data1,
-					 sizeof(*perf_data1));
-	if (perf_fd > 0 || errno != ENOSPC)
-		ret = -1;
+	if (len != sizeof(*count))
+		return -1;
 
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-	return ret;
+	return 0;
 }
 
-static int test8(pid_t child_pid)
+static void ppc_ptrace_init_breakpoint(struct ppc_hw_breakpoint *info,
+				       int type, void *addr, int len)
 {
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread event by perf)
-	 *	if (existing thread event by ptrace on the same thread)
-	 *		if (addr range does not overlaps)
-	 *			allow;
-	 */
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data2, sizeof(*ptrace_data2));
-	if (ptrace_fd < 0)
-		return -1;
-
-	perf_fd = perf_thread_event_open(child_pid, (__u64)perf_data2,
-					 sizeof(*perf_data2));
-	if (perf_fd < 0) {
-		ret = -1;
-		goto ptrace_close;
-	}
-	close(perf_fd);
-
-ptrace_close:
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-	return ret;
+	info->version = 1;
+	info->trigger_type = type;
+	info->condition_mode = PPC_BREAKPOINT_CONDITION_NONE;
+	info->addr = (u64)addr;
+	info->addr2 = (u64)addr + len;
+	info->condition_value = 0;
+	if (!len)
+		info->addr_mode = PPC_BREAKPOINT_MODE_EXACT;
+	else
+		info->addr_mode = PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE;
 }
 
-static int test9(pid_t child_pid)
+/*
+ * Checks if we can place at least 2 watchpoints on the child process
+ */
+static int check_watchpoints(pid_t pid)
 {
-	int perf_fd;
-	int ptrace_fd;
-	int cpid;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread event by perf)
-	 *	if (existing thread event by ptrace on the other thread)
-	 *		allow;
-	 */
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
-	if (ptrace_fd < 0)
-		return -1;
-
-	cpid = fork();
-	if (!cpid) {
-		/* Temporary Child */
-		pause();
-		exit(EXIT_SUCCESS);
-	}
+	struct ppc_debug_info dbginfo;
 
-	perf_fd = perf_thread_event_open(cpid, (__u64)perf_data1, sizeof(*perf_data1));
-	if (perf_fd < 0) {
-		ret = -1;
-		goto kill_child;
-	}
-	close(perf_fd);
+	FAIL_IF_MSG(ppc_ptrace_gethwdbginfo(pid, &dbginfo), "PPC_PTRACE_GETHWDBGINFO failed");
+	SKIP_IF_MSG(dbginfo.num_data_bps <= 1, "Not enough data watchpoints (need at least 2)");
 
-kill_child:
-	kill(cpid, SIGINT);
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-	return ret;
+	return 0;
 }
 
-static int test10(pid_t child_pid)
+/*
+ * Wrapper around a plain fork() call that sets up the child for
+ * ptrace-ing. Both the parent and child return from this, though
+ * the child is stopped until ptrace_cont(pid) is run by the parent.
+ */
+static int ptrace_fork_child(pid_t *pid)
 {
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per cpu event by perf)
-	 *	if (existing thread event by ptrace on the same thread)
-	 *		if (addr range overlaps)
-	 *			fail;
-	 */
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
-	if (ptrace_fd < 0)
-		return -1;
+	int status;
 
-	perf_fd = perf_cpu_event_open(0, (__u64)perf_data1, sizeof(*perf_data1));
-	if (perf_fd > 0 || errno != ENOSPC)
-		ret = -1;
-
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-	return ret;
-}
+	*pid = fork();
 
-static int test11(pid_t child_pid)
-{
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per cpu event by perf)
-	 *	if (existing thread event by ptrace on the same thread)
-	 *		if (addr range does not overlap)
-	 *			allow;
-	 */
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data2, sizeof(*ptrace_data2));
-	if (ptrace_fd < 0)
-		return -1;
+	if (*pid < 0)
+		FAIL_IF_MSG(1, "Failed to fork child");
 
-	perf_fd = perf_cpu_event_open(0, (__u64)perf_data2, sizeof(*perf_data2));
-	if (perf_fd < 0) {
-		ret = -1;
-		goto ptrace_close;
+	if (!*pid) {
+		FAIL_IF_EXIT_MSG(ptrace_traceme(), "PTRACE_TRACEME failed");
+		FAIL_IF_EXIT_MSG(raise(SIGSTOP), "Child failed to raise SIGSTOP");
+	} else {
+		/* Synchronise on child SIGSTOP */
+		FAIL_IF_MSG(waitpid(*pid, &status, 0) == -1, "Failed to wait for child");
+		FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped");
 	}
-	close(perf_fd);
 
-ptrace_close:
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-	return ret;
+	return 0;
 }
 
-static int test12(pid_t child_pid)
+/*
+ * Tests the interaction between ptrace and perf watching the same data.
+ *
+ * We expect ptrace to take 'priority', as it is has before-execute
+ * semantics.
+ *
+ * The perf counter should not be incremented yet because perf has after-execute
+ * semantics. E.g., if ptrace changes the child PC, we don't even execute the
+ * instruction at all.
+ *
+ * When the child is stopped for ptrace, we test both continue and single step.
+ * Both should increment the perf counter. We also test changing the PC somewhere
+ * different and stepping, which should not increment the perf counter.
+ */
+int same_watch_addr_test(void)
 {
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread and per cpu event by perf)
-	 *	if (existing thread event by ptrace on the same thread)
-	 *		if (addr range overlaps)
-	 *			fail;
-	 */
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
-	if (ptrace_fd < 0)
-		return -1;
+	struct ppc_hw_breakpoint bp_info;	/* ptrace breakpoint info */
+	int bp_id;	/* Breakpoint handle of ptrace watchpoint */
+	int perf_fd;	/* File descriptor of perf performance counter */
+	u64 perf_count;	/* Most recently fetched perf performance counter value */
+	pid_t pid;	/* PID of child process */
+	void *pc;	/* Most recently fetched child PC value */
+	int status;	/* Stop status of child after waitpid */
+	unsigned long value;	/* Dummy value to be read/written to by child */
+	int err;
+
+	err = ptrace_fork_child(&pid);
+	if (err)
+		return err;
+
+	if (!pid) {
+		same_watch_addr_child(&value);
+		exit(1);
+	}
 
-	perf_fd = perf_thread_cpu_event_open(child_pid, 0, (__u64)perf_data1, sizeof(*perf_data1));
-	if (perf_fd > 0 || errno != ENOSPC)
-		ret = -1;
+	err = check_watchpoints(pid);
+	if (err)
+		return err;
 
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-	return ret;
-}
+	/* Place a perf watchpoint counter on value */
+	perf_fd = perf_watchpoint_open(pid, &value, sizeof(value));
+	FAIL_IF_MSG(perf_fd < 0, "Failed to open perf performance counter");
 
-static int test13(pid_t child_pid)
-{
-	int perf_fd;
-	int ptrace_fd;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread and per cpu event by perf)
-	 *	if (existing thread event by ptrace on the same thread)
-	 *		if (addr range does not overlap)
-	 *			allow;
-	 */
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data2, sizeof(*ptrace_data2));
-	if (ptrace_fd < 0)
-		return -1;
+	/* Place a ptrace watchpoint on value */
+	ppc_ptrace_init_breakpoint(&bp_info, PPC_BREAKPOINT_TRIGGER_READ, &value, sizeof(value));
+	bp_id = ppc_ptrace_sethwdbg(pid, &bp_info);
+	FAIL_IF_MSG(bp_id < 0, "Failed to set ptrace watchpoint");
 
-	perf_fd = perf_thread_cpu_event_open(child_pid, 0, (__u64)perf_data2, sizeof(*perf_data2));
-	if (perf_fd < 0) {
-		ret = -1;
-		goto ptrace_close;
-	}
-	close(perf_fd);
+	/* Let the child run. It should stop on the ptrace watchpoint */
+	FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child");
 
-ptrace_close:
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-	return ret;
-}
+	FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child");
+	FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped");
+	FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC");
+	FAIL_IF_MSG(pc != same_watch_addr_load, "Child did not stop on load instruction");
 
-static int test14(pid_t child_pid)
-{
-	int perf_fd;
-	int ptrace_fd;
-	int cpid;
-	int ret = 0;
-
-	/* Test:
-	 * if (new per thread and per cpu event by perf)
-	 *	if (existing thread event by ptrace on the other thread)
-	 *		allow;
+	/*
+	 * We stopped before executing the load, so perf should not have
+	 * recorded any events yet
 	 */
-	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
-	if (ptrace_fd < 0)
-		return -1;
-
-	cpid = fork();
-	if (!cpid) {
-		/* Temporary Child */
-		pause();
-		exit(EXIT_SUCCESS);
-	}
-
-	perf_fd = perf_thread_cpu_event_open(cpid, 0, (__u64)perf_data1,
-					     sizeof(*perf_data1));
-	if (perf_fd < 0) {
-		ret = -1;
-		goto kill_child;
-	}
-	close(perf_fd);
-
-kill_child:
-	kill(cpid, SIGINT);
-	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
-	return ret;
-}
+	FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter");
+	FAIL_IF_MSG(perf_count != 0, "perf recorded unexpected event");
+
+	/* Single stepping over the load should increment the perf counter */
+	FAIL_IF_MSG(ptrace_singlestep(pid, 0), "Failed to single step child");
+
+	FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child");
+	FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped");
+	FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC");
+	FAIL_IF_MSG(pc != same_watch_addr_load + 4, "Failed to single step load instruction");
+	FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter");
+	FAIL_IF_MSG(perf_count != 1, "perf counter did not increment");
+
+	/*
+	 * Set up a ptrace watchpoint on the value again and trigger it.
+	 * The perf counter should not have incremented because we do not
+	 * execute the load yet.
+	 */
+	FAIL_IF_MSG(ppc_ptrace_delhwdbg(pid, bp_id), "Failed to remove old ptrace watchpoint");
+	bp_id = ppc_ptrace_sethwdbg(pid, &bp_info);
+	FAIL_IF_MSG(bp_id < 0, "Failed to set ptrace watchpoint");
+	FAIL_IF_MSG(ptrace_setreg_pc(pid, same_watch_addr_load), "Failed to set child PC");
+	FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child");
+
+	FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child");
+	FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped");
+	FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC");
+	FAIL_IF_MSG(pc != same_watch_addr_load, "Child did not stop on load trap");
+	FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter");
+	FAIL_IF_MSG(perf_count != 1, "perf counter should not have changed");
+
+	/* Continuing over the load should increment the perf counter */
+	FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child");
+
+	FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child");
+	FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped");
+	FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC");
+	FAIL_IF_MSG(pc != same_watch_addr_trap, "Child did not stop on end trap");
+	FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter");
+	FAIL_IF_MSG(perf_count != 2, "perf counter did not increment");
+
+	/*
+	 * If we set the child PC back to the load instruction, then continue,
+	 * we should reach the end trap (because ptrace is one-shot) and have
+	 * another perf event.
+	 */
+	FAIL_IF_MSG(ptrace_setreg_pc(pid, same_watch_addr_load), "Failed to set child PC");
+	FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child");
+
+	FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child");
+	FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped");
+	FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC");
+	FAIL_IF_MSG(pc != same_watch_addr_trap, "Child did not stop on end trap");
+	FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter");
+	FAIL_IF_MSG(perf_count != 3, "perf counter did not increment");
+
+	/*
+	 * If we set the child PC back to the load instruction, set a ptrace
+	 * watchpoint on the load, then continue, we should immediately get
+	 * the ptrace trap without incrementing the perf counter
+	 */
+	FAIL_IF_MSG(ppc_ptrace_delhwdbg(pid, bp_id), "Failed to remove old ptrace watchpoint");
+	bp_id = ppc_ptrace_sethwdbg(pid, &bp_info);
+	FAIL_IF_MSG(bp_id < 0, "Failed to set ptrace watchpoint");
+	FAIL_IF_MSG(ptrace_setreg_pc(pid, same_watch_addr_load), "Failed to set child PC");
+	FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child");
+
+	FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child");
+	FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped");
+	FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC");
+	FAIL_IF_MSG(pc != same_watch_addr_load, "Child did not stop on load instruction");
+	FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter");
+	FAIL_IF_MSG(perf_count != 3, "perf counter should not have changed");
+
+	/*
+	 * If we change the PC while stopped on the load instruction, we should
+	 * not increment the perf counter (because ptrace is before-execute,
+	 * perf is after-execute).
+	 */
+	FAIL_IF_MSG(ptrace_setreg_pc(pid, same_watch_addr_load + 4), "Failed to set child PC");
+	FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child");
 
-static int do_test(const char *msg, int (*fun)(pid_t arg), pid_t arg)
-{
-	int ret;
+	FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child");
+	FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped");
+	FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC");
+	FAIL_IF_MSG(pc != same_watch_addr_trap, "Child did not stop on end trap");
+	FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter");
+	FAIL_IF_MSG(perf_count != 3, "perf counter should not have changed");
 
-	ret = fun(arg);
-	if (ret)
-		printf("%s: Error\n", msg);
-	else
-		printf("%s: Ok\n", msg);
-	return ret;
-}
+	/* Clean up child */
+	FAIL_IF_MSG(kill(pid, SIGKILL) != 0, "Failed to kill child");
 
-char *desc[14] = {
-	"perf cpu event -> ptrace thread event (Overlapping)",
-	"perf cpu event -> ptrace thread event (Non-overlapping)",
-	"perf thread event -> ptrace same thread event (Overlapping)",
-	"perf thread event -> ptrace same thread event (Non-overlapping)",
-	"perf thread event -> ptrace other thread event",
-	"ptrace thread event -> perf kernel event",
-	"ptrace thread event -> perf same thread event (Overlapping)",
-	"ptrace thread event -> perf same thread event (Non-overlapping)",
-	"ptrace thread event -> perf other thread event",
-	"ptrace thread event -> perf cpu event (Overlapping)",
-	"ptrace thread event -> perf cpu event (Non-overlapping)",
-	"ptrace thread event -> perf same thread & cpu event (Overlapping)",
-	"ptrace thread event -> perf same thread & cpu event (Non-overlapping)",
-	"ptrace thread event -> perf other thread & cpu event",
-};
-
-static int test(pid_t child_pid)
-{
-	int ret = TEST_PASS;
-
-	ret |= do_test(desc[0], test1, child_pid);
-	ret |= do_test(desc[1], test2, child_pid);
-	ret |= do_test(desc[2], test3, child_pid);
-	ret |= do_test(desc[3], test4, child_pid);
-	ret |= do_test(desc[4], test5, child_pid);
-	ret |= do_test(desc[5], test6, child_pid);
-	ret |= do_test(desc[6], test7, child_pid);
-	ret |= do_test(desc[7], test8, child_pid);
-	ret |= do_test(desc[8], test9, child_pid);
-	ret |= do_test(desc[9], test10, child_pid);
-	ret |= do_test(desc[10], test11, child_pid);
-	ret |= do_test(desc[11], test12, child_pid);
-	ret |= do_test(desc[12], test13, child_pid);
-	ret |= do_test(desc[13], test14, child_pid);
-
-	return ret;
+	return 0;
 }
 
-static void get_dbginfo(pid_t child_pid, struct ppc_debug_info *dbginfo)
+/*
+ * Tests the interaction between ptrace and perf when:
+ * 1. perf watches a value
+ * 2. ptrace watches a different value
+ * 3. The perf value is read, then the ptrace value is read immediately after
+ *
+ * A breakpoint implementation may accidentally misattribute/skip one of
+ * the ptrace or perf handlers, as interrupt based work is done after perf
+ * and before ptrace.
+ *
+ * We expect the perf counter to increment before the ptrace watchpoint
+ * triggers.
+ */
+int perf_then_ptrace_test(void)
 {
-	if (ptrace(PPC_PTRACE_GETHWDBGINFO, child_pid, NULL, dbginfo)) {
-		perror("Can't get breakpoint info");
-		exit(-1);
+	struct ppc_hw_breakpoint bp_info;	/* ptrace breakpoint info */
+	int bp_id;	/* Breakpoint handle of ptrace watchpoint */
+	int perf_fd;	/* File descriptor of perf performance counter */
+	u64 perf_count;	/* Most recently fetched perf performance counter value */
+	pid_t pid;	/* PID of child process */
+	void *pc;	/* Most recently fetched child PC value */
+	int status;	/* Stop status of child after waitpid */
+	unsigned long perf_value;	/* Dummy value to be watched by perf */
+	unsigned long ptrace_value;	/* Dummy value to be watched by ptrace */
+	int err;
+
+	err = ptrace_fork_child(&pid);
+	if (err)
+		return err;
+
+	/*
+	 * If we are the child, run a subroutine that reads the perf value,
+	 * then reads the ptrace value with consecutive load instructions
+	 */
+	if (!pid) {
+		perf_then_ptrace_child(&perf_value, &ptrace_value);
+		exit(0);
 	}
-}
 
-static int ptrace_perf_hwbreak(void)
-{
-	int ret;
-	pid_t child_pid;
-	struct ppc_debug_info dbginfo;
+	err = check_watchpoints(pid);
+	if (err)
+		return err;
 
-	child_pid = fork();
-	if (!child_pid)
-		return child();
+	/* Place a perf watchpoint counter */
+	perf_fd = perf_watchpoint_open(pid, &perf_value, sizeof(perf_value));
+	FAIL_IF_MSG(perf_fd < 0, "Failed to open perf performance counter");
 
-	/* parent */
-	wait(NULL); /* <-- child (SIGUSR1) */
+	/* Place a ptrace watchpoint */
+	ppc_ptrace_init_breakpoint(&bp_info, PPC_BREAKPOINT_TRIGGER_READ,
+				   &ptrace_value, sizeof(ptrace_value));
+	bp_id = ppc_ptrace_sethwdbg(pid, &bp_info);
+	FAIL_IF_MSG(bp_id < 0, "Failed to set ptrace watchpoint");
 
-	get_dbginfo(child_pid, &dbginfo);
-	SKIP_IF(dbginfo.num_data_bps <= 1);
+	/* Let the child run. It should stop on the ptrace watchpoint */
+	FAIL_IF_MSG(ptrace_cont(pid, 0), "Failed to continue child");
 
-	ret = perf_cpu_event_open(0, (__u64)perf_data1, sizeof(*perf_data1));
-	SKIP_IF(ret < 0);
-	close(ret);
+	FAIL_IF_MSG(waitpid(pid, &status, 0) == -1, "Failed to wait for child");
+	FAIL_IF_MSG(!WIFSTOPPED(status), "Child is not stopped");
+	FAIL_IF_MSG(ptrace_getreg_pc(pid, &pc), "Failed to get child PC");
+	FAIL_IF_MSG(pc != perf_then_ptrace_load2, "Child did not stop on ptrace load");
 
-	ret = test(child_pid);
+	/* perf should have recorded the first load */
+	FAIL_IF_MSG(perf_read_counter(perf_fd, &perf_count), "Failed to read perf counter");
+	FAIL_IF_MSG(perf_count != 1, "perf counter did not increment");
 
-	ptrace(PTRACE_CONT, child_pid, NULL, 0);
-	return ret;
+	/* Clean up child */
+	FAIL_IF_MSG(kill(pid, SIGKILL) != 0, "Failed to kill child");
+
+	return 0;
 }
 
 int main(int argc, char *argv[])
 {
-	return test_harness(ptrace_perf_hwbreak, "ptrace-perf-hwbreak");
+	int err = 0;
+
+	err |= test_harness(same_watch_addr_test, "same_watch_addr");
+	err |= test_harness(perf_then_ptrace_test, "perf_then_ptrace");
+
+	return err;
 }