perf tests: Add breakpoint accounting/modify test

Adding test that:

  - detects the number of watch/break-points,
    skip test if any is missing
  - detects PERF_EVENT_IOC_MODIFY_ATTRIBUTES ioctl,
    skip test if it's missing
  - detects if watchpoints and breakpoints share
    same slots
  - create all possible watchpoints on cpu 0
  - change one of it to breakpoint
  - in case wp and bp do not share slots,
    we create another watchpoint to ensure
    the slot accounting is correct

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Milind Chabbi <chabbi.milind@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Oleg Nesterov <onestero@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20180312134548.31532-9-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tools/perf/tests/Build

@@ -20,6 +20,7 @@ perf-y += hists_cumulate.o
 perf-y += python-use.o
 perf-y += bp_signal.o
 perf-y += bp_signal_overflow.o
+perf-y += bp_account.o
 perf-y += task-exit.o
 perf-y += sw-clock.o
 perf-y += mmap-thread-lookup.o

tools/perf/tests/bp_account.c

@@ -0,0 +1,195 @@
+/*
+ * Powerpc needs __SANE_USERSPACE_TYPES__ before <linux/types.h> to select
+ * 'int-ll64.h' and avoid compile warnings when printing __u64 with %llu.
+ */
+#define __SANE_USERSPACE_TYPES__
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <time.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/mman.h>
+#include <linux/compiler.h>
+#include <linux/hw_breakpoint.h>
+#include <sys/ioctl.h>
+
+#include "tests.h"
+#include "debug.h"
+#include "perf.h"
+#include "cloexec.h"
+
+volatile long the_var;
+
+static noinline int test_function(void)
+{
+	return 0;
+}
+
+static int __event(bool is_x, void *addr, struct perf_event_attr *attr)
+{
+	int fd;
+
+	memset(attr, 0, sizeof(struct perf_event_attr));
+	attr->type = PERF_TYPE_BREAKPOINT;
+	attr->size = sizeof(struct perf_event_attr);
+
+	attr->config = 0;
+	attr->bp_type = is_x ? HW_BREAKPOINT_X : HW_BREAKPOINT_W;
+	attr->bp_addr = (unsigned long) addr;
+	attr->bp_len = sizeof(long);
+
+	attr->sample_period = 1;
+	attr->sample_type = PERF_SAMPLE_IP;
+
+	attr->exclude_kernel = 1;
+	attr->exclude_hv = 1;
+
+	fd = sys_perf_event_open(attr, -1, 0, -1,
+				 perf_event_open_cloexec_flag());
+	if (fd < 0) {
+		pr_debug("failed opening event %llx\n", attr->config);
+		return TEST_FAIL;
+	}
+
+	return fd;
+}
+
+static int wp_event(void *addr, struct perf_event_attr *attr)
+{
+	return __event(false, addr, attr);
+}
+
+static int bp_event(void *addr, struct perf_event_attr *attr)
+{
+	return __event(true, addr, attr);
+}
+
+static int bp_accounting(int wp_cnt, int share)
+{
+	struct perf_event_attr attr, attr_mod, attr_new;
+	int i, fd[wp_cnt], fd_wp, ret;
+
+	for (i = 0; i < wp_cnt; i++) {
+		fd[i] = wp_event((void *)&the_var, &attr);
+		TEST_ASSERT_VAL("failed to create wp\n", fd[i] != -1);
+		pr_debug("wp %d created\n", i);
+	}
+
+	attr_mod = attr;
+	attr_mod.bp_type = HW_BREAKPOINT_X;
+	attr_mod.bp_addr = (unsigned long) test_function;
+
+	ret = ioctl(fd[0], PERF_EVENT_IOC_MODIFY_ATTRIBUTES, &attr_mod);
+	TEST_ASSERT_VAL("failed to modify wp\n", ret == 0);
+
+	pr_debug("wp 0 modified to bp\n");
+
+	if (!share) {
+		fd_wp = wp_event((void *)&the_var, &attr_new);
+		TEST_ASSERT_VAL("failed to create max wp\n", fd_wp != -1);
+		pr_debug("wp max created\n");
+	}
+
+	for (i = 0; i < wp_cnt; i++)
+		close(fd[i]);
+
+	return 0;
+}
+
+static int detect_cnt(bool is_x)
+{
+	struct perf_event_attr attr;
+	void *addr = is_x ? test_function : (void *) &the_var;
+	int fd[100], cnt = 0, i;
+
+	while (1) {
+		fd[cnt] = __event(is_x, addr, &attr);
+
+		if (fd[cnt] < 0)
+			break;
+
+		if (cnt == 100) {
+			pr_debug("way too many debug registers, fix the test\n");
+			return 0;
+		}
+
+		cnt++;
+	}
+
+	for (i = 0; i < cnt; i++)
+		close(fd[i]);
+
+	return cnt;
+}
+
+static int detect_ioctl(void)
+{
+	struct perf_event_attr attr;
+	int fd, ret = 1;
+
+	fd = wp_event((void *) &the_var, &attr);
+	if (fd > 0) {
+		ret = ioctl(fd, PERF_EVENT_IOC_MODIFY_ATTRIBUTES, &attr);
+		close(fd);
+	}
+
+	return ret ? 0 : 1;
+}
+
+static int detect_share(int wp_cnt, int bp_cnt)
+{
+	struct perf_event_attr attr;
+	int i, fd[wp_cnt + bp_cnt], ret;
+
+	for (i = 0; i < wp_cnt; i++) {
+		fd[i] = wp_event((void *)&the_var, &attr);
+		TEST_ASSERT_VAL("failed to create wp\n", fd[i] != -1);
+	}
+
+	for (; i < (bp_cnt + wp_cnt); i++) {
+		fd[i] = bp_event((void *)test_function, &attr);
+		if (fd[i] == -1)
+			break;
+	}
+
+	ret = i != (bp_cnt + wp_cnt);
+
+	while (i--)
+		close(fd[i]);
+
+	return ret;
+}
+
+/*
+ * This test does following:
+ *   - detects the number of watch/break-points,
+ *     skip test if any is missing
+ *   - detects PERF_EVENT_IOC_MODIFY_ATTRIBUTES ioctl,
+ *     skip test if it's missing
+ *   - detects if watchpoints and breakpoints share
+ *     same slots
+ *   - create all possible watchpoints on cpu 0
+ *   - change one of it to breakpoint
+ *   - in case wp and bp do not share slots,
+ *     we create another watchpoint to ensure
+ *     the slot accounting is correct
+ */
+int test__bp_accounting(struct test *test __maybe_unused, int subtest __maybe_unused)
+{
+	int has_ioctl = detect_ioctl();
+	int wp_cnt = detect_cnt(false);
+	int bp_cnt = detect_cnt(true);
+	int share  = detect_share(wp_cnt, bp_cnt);
+
+	pr_debug("watchpoints count %d, breakpoints count %d, has_ioctl %d, share %d\n",
+		 wp_cnt, bp_cnt, has_ioctl, share);
+
+	if (!wp_cnt || !bp_cnt || !has_ioctl)
+		return TEST_SKIP;
+
+	return bp_accounting(wp_cnt, share);
+}

tools/perf/tests/builtin-test.c

@@ -115,6 +115,10 @@ static struct test generic_tests[] = {
 		.func = test__bp_signal_overflow,
 		.is_supported = test__bp_signal_is_supported,
 	},
+	{
+		.desc = "Breakpoint accounting",
+		.func = test__bp_accounting,
+	},
 	{
 		.desc = "Number of exit events of a simple workload",
 		.func = test__task_exit,

tools/perf/tests/tests.h

@@ -58,6 +58,7 @@ int test__hists_link(struct test *test, int subtest);
 int test__python_use(struct test *test, int subtest);
 int test__bp_signal(struct test *test, int subtest);
 int test__bp_signal_overflow(struct test *test, int subtest);
+int test__bp_accounting(struct test *test, int subtest);
 int test__task_exit(struct test *test, int subtest);
 int test__mem(struct test *test, int subtest);
 int test__sw_clock_freq(struct test *test, int subtest);