powerpc/selftests: Add selftest to test concurrent perf/ptrace events

ptrace and perf watchpoints can't co-exists if their address range
overlaps. See commit 29da4f91 ("powerpc/watchpoint: Don't allow
concurrent perf and ptrace events") for more detail. Add selftest
for the same.

Sample o/p:
  # ./ptrace-perf-hwbreak
  test: ptrace-perf-hwbreak
  tags: git_version:powerpc-5.8-7-118-g937fa174a15d-dirty
  perf cpu event -> ptrace thread event (Overlapping): Ok
  perf cpu event -> ptrace thread event (Non-overlapping): Ok
  perf thread event -> ptrace same thread event (Overlapping): Ok
  perf thread event -> ptrace same thread event (Non-overlapping): Ok
  perf thread event -> ptrace other thread event: Ok
  ptrace thread event -> perf kernel event: Ok
  ptrace thread event -> perf same thread event (Overlapping): Ok
  ptrace thread event -> perf same thread event (Non-overlapping): Ok
  ptrace thread event -> perf other thread event: Ok
  ptrace thread event -> perf cpu event (Overlapping): Ok
  ptrace thread event -> perf cpu event (Non-overlapping): Ok
  ptrace thread event -> perf same thread & cpu event (Overlapping): Ok
  ptrace thread event -> perf same thread & cpu event (Non-overlapping): Ok
  ptrace thread event -> perf other thread & cpu event: Ok
  success: ptrace-perf-hwbreak
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210412112218.128183-5-ravi.bangoria@linux.ibm.com

tools/testing/selftests/powerpc/ptrace/.gitignore

@@ -14,3 +14,4 @@ perf-hwbreak
 core-pkey
 ptrace-pkey
 ptrace-syscall
+ptrace-perf-hwbreak

tools/testing/selftests/powerpc/ptrace/Makefile

@@ -2,7 +2,7 @@
 TEST_GEN_PROGS := ptrace-gpr ptrace-tm-gpr ptrace-tm-spd-gpr \
               ptrace-tar ptrace-tm-tar ptrace-tm-spd-tar ptrace-vsx ptrace-tm-vsx \
               ptrace-tm-spd-vsx ptrace-tm-spr ptrace-hwbreak ptrace-pkey core-pkey \
-              perf-hwbreak ptrace-syscall
+              perf-hwbreak ptrace-syscall ptrace-perf-hwbreak
 
 top_srcdir = ../../../../..
 include ../../lib.mk

tools/testing/selftests/powerpc/ptrace/ptrace-perf-hwbreak.c

+// 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 <sys/wait.h>
+#include "ptrace.h"
+
+char data[16];
+
+/* Overlapping address range */
+volatile __u64 *ptrace_data1 = (__u64 *)&data[0];
+volatile __u64 *perf_data1 = (__u64 *)&data[4];
+
+/* Non-overlapping address range */
+volatile __u64 *ptrace_data2 = (__u64 *)&data[0];
+volatile __u64 *perf_data2 = (__u64 *)&data[8];
+
+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);
+	}
+
+	while (getline(&line, &len, fp) != -1) {
+		if (!strstr(line, "pid_max") || strstr(line, "pid_max_max") ||
+		    strstr(line, "pid_max_min"))
+			continue;
+
+		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;
+}
+
+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;
+}
+
+static void perf_kernel_event_attr_set(struct perf_event_attr *attr)
+{
+	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;
+}
+
+static int perf_cpu_event_open(int cpu, __u64 addr, __u64 len)
+{
+	struct perf_event_attr attr;
+
+	perf_user_event_attr_set(&attr, addr, len);
+	return syscall(__NR_perf_event_open, &attr, -1, cpu, -1, 0);
+}
+
+static int perf_thread_event_open(pid_t child_pid, __u64 addr, __u64 len)
+{
+	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);
+}
+
+static int perf_thread_cpu_event_open(pid_t child_pid, int cpu, __u64 addr, __u64 len)
+{
+	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);
+}
+
+static int perf_thread_kernel_event_open(pid_t child_pid)
+{
+	struct perf_event_attr attr;
+
+	perf_kernel_event_attr_set(&attr);
+	return syscall(__NR_perf_event_open, &attr, child_pid, -1, -1, 0);
+}
+
+static int perf_cpu_kernel_event_open(int cpu)
+{
+	struct perf_event_attr attr;
+
+	perf_kernel_event_attr_set(&attr);
+	return syscall(__NR_perf_event_open, &attr, -1, cpu, -1, 0);
+}
+
+static int child(void)
+{
+	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;
+}
+
+static void ptrace_ppc_hw_breakpoint(struct ppc_hw_breakpoint *info, int type,
+				     __u64 addr, int len)
+{
+	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;
+}
+
+static int ptrace_open(pid_t child_pid, __u64 wp_addr, int len)
+{
+	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);
+}
+
+static int test1(pid_t child_pid)
+{
+	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;
+	 */
+
+	perf_fd = perf_cpu_event_open(0, (__u64)perf_data1, sizeof(*perf_data1));
+	if (perf_fd < 0)
+		return -1;
+
+	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
+	if (ptrace_fd > 0 || errno != ENOSPC)
+		ret = -1;
+
+	close(perf_fd);
+	return ret;
+}
+
+static int test2(pid_t child_pid)
+{
+	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;
+	 */
+
+	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;
+}
+
+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;
+
+	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
+	if (ptrace_fd > 0 || errno != ENOSPC)
+		ret = -1;
+
+	close(perf_fd);
+	return ret;
+}
+
+static int test4(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 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;
+}
+
+static int test5(pid_t child_pid)
+{
+	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;
+	}
+
+	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
+perf_close:
+	close(perf_fd);
+kill_child:
+	kill(cpid, SIGINT);
+	return ret;
+}
+
+static int test6(pid_t child_pid)
+{
+	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);
+
+ptrace_close:
+	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
+	return ret;
+}
+
+static int test7(pid_t child_pid)
+{
+	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;
+	 */
+	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
+	if (ptrace_fd < 0)
+		return -1;
+
+	perf_fd = perf_thread_event_open(child_pid, (__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;
+}
+
+static int test8(pid_t child_pid)
+{
+	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;
+}
+
+static int test9(pid_t child_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);
+	}
+
+	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);
+
+kill_child:
+	kill(cpid, SIGINT);
+	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
+	return ret;
+}
+
+static int test10(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 overlaps)
+	 *			fail;
+	 */
+	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
+	if (ptrace_fd < 0)
+		return -1;
+
+	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;
+}
+
+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;
+
+	perf_fd = perf_cpu_event_open(0, (__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;
+}
+
+static int test12(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 overlaps)
+	 *			fail;
+	 */
+	ptrace_fd = ptrace_open(child_pid, (__u64)ptrace_data1, sizeof(*ptrace_data1));
+	if (ptrace_fd < 0)
+		return -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;
+
+	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
+	return ret;
+}
+
+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;
+
+	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);
+
+ptrace_close:
+	ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, ptrace_fd);
+	return ret;
+}
+
+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;
+	 */
+	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;
+}
+
+static int do_test(const char *msg, int (*fun)(pid_t arg), pid_t arg)
+{
+	int ret;
+
+	ret = fun(arg);
+	if (ret)
+		printf("%s: Error\n", msg);
+	else
+		printf("%s: Ok\n", msg);
+	return ret;
+}
+
+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;
+}
+
+static void get_dbginfo(pid_t child_pid, struct ppc_debug_info *dbginfo)
+{
+	if (ptrace(PPC_PTRACE_GETHWDBGINFO, child_pid, NULL, dbginfo)) {
+		perror("Can't get breakpoint info");
+		exit(-1);
+	}
+}
+
+static int ptrace_perf_hwbreak(void)
+{
+	int ret;
+	pid_t child_pid;
+	struct ppc_debug_info dbginfo;
+
+	child_pid = fork();
+	if (!child_pid)
+		return child();
+
+	/* parent */
+	wait(NULL); /* <-- child (SIGUSR1) */
+
+	get_dbginfo(child_pid, &dbginfo);
+	SKIP_IF(dbginfo.num_data_bps <= 1);
+
+	ret = perf_cpu_event_open(0, (__u64)perf_data1, sizeof(*perf_data1));
+	SKIP_IF(ret < 0);
+	close(ret);
+
+	ret = test(child_pid);
+
+	ptrace(PTRACE_CONT, child_pid, NULL, 0);
+	return ret;
+}
+
+int main(int argc, char *argv[])
+{
+	return test_harness(ptrace_perf_hwbreak, "ptrace-perf-hwbreak");
+}