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Subject[RFC PATCH] arm64: perf test: Improbe bp_signal
Date
Will Deacon [1] has some question on patch [2]. This patch improves
test__bp_signal so we can test:

1. A watchpoint and a breakpoint that fire on the same instruction
2. Nested signals

For detail of this patch see the comment in patch body.

Test result:

On both x86_64:

# ./perf test -v signal
17: Test breakpoint overflow signal handler :
--- start ---
test child forked, pid 10213
count1 1, count2 3, count3 2, overflow 3, overflows_2 3
test child finished with 0
---- end ----
Test breakpoint overflow signal handler: Ok

So at least 2 cases Will doubted are handled correctly.

[1] http://lkml.kernel.org/g/20160104165535.GI1616@arm.com
[2] http://lkml.kernel.org/g/1450921362-198371-1-git-send-email-wangnan0@huawei.com

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/tests/bp_signal.c | 114 ++++++++++++++++++++++++++++++++++++++-----
1 file changed, 101 insertions(+), 13 deletions(-)

diff --git a/tools/perf/tests/bp_signal.c b/tools/perf/tests/bp_signal.c
index fb80c9e..0bc4f76 100644
--- a/tools/perf/tests/bp_signal.c
+++ b/tools/perf/tests/bp_signal.c
@@ -29,14 +29,55 @@

static int fd1;
static int fd2;
+static int fd3;
static int overflows;
+static int overflows_2;
+
+volatile long the_var;
+
+
+#if defined (__x86_64__)
+extern void __test_function(volatile long *ptr);
+asm (
+ ".globl __test_function\n"
+ "__test_function:\n"
+ "incq (%rdi)\n"
+ "ret\n");
+#elif defined (__aarch64__)
+extern void __test_function(volatile long *ptr);
+asm (
+ ".globl __test_function\n"
+ "__test_function:\n"
+ "str x30, [x0]\n"
+ "ret\n");
+
+#else
+static void __test_function(volatile long *ptr)
+{
+ *ptr++;
+}
+#endif

__attribute__ ((noinline))
static int test_function(void)
{
+ __test_function(&the_var);
+ the_var++;
return time(NULL);
}

+static void sig_handler_2(int signum __maybe_unused,
+ siginfo_t *oh __maybe_unused,
+ void *uc __maybe_unused)
+{
+ overflows_2++;
+ if (overflows_2 > 10) {
+ ioctl(fd1, PERF_EVENT_IOC_DISABLE, 0);
+ ioctl(fd2, PERF_EVENT_IOC_DISABLE, 0);
+ ioctl(fd3, PERF_EVENT_IOC_DISABLE, 0);
+ }
+}
+
static void sig_handler(int signum __maybe_unused,
siginfo_t *oh __maybe_unused,
void *uc __maybe_unused)
@@ -54,10 +95,11 @@ static void sig_handler(int signum __maybe_unused,
*/
ioctl(fd1, PERF_EVENT_IOC_DISABLE, 0);
ioctl(fd2, PERF_EVENT_IOC_DISABLE, 0);
+ ioctl(fd3, PERF_EVENT_IOC_DISABLE, 0);
}
}

-static int bp_event(void *fn, int setup_signal)
+static int __xp_event(bool is_bp, void *addr, int setup_signal, int signal)
{
struct perf_event_attr pe;
int fd;
@@ -67,8 +109,8 @@ static int bp_event(void *fn, int setup_signal)
pe.size = sizeof(struct perf_event_attr);

pe.config = 0;
- pe.bp_type = HW_BREAKPOINT_X;
- pe.bp_addr = (unsigned long) fn;
+ pe.bp_type = is_bp ? HW_BREAKPOINT_X : HW_BREAKPOINT_W;
+ pe.bp_addr = (unsigned long) addr;
pe.bp_len = sizeof(long);

pe.sample_period = 1;
@@ -88,7 +130,7 @@ static int bp_event(void *fn, int setup_signal)

if (setup_signal) {
fcntl(fd, F_SETFL, O_RDWR|O_NONBLOCK|O_ASYNC);
- fcntl(fd, F_SETSIG, SIGIO);
+ fcntl(fd, F_SETSIG, signal);
fcntl(fd, F_SETOWN, getpid());
}

@@ -97,6 +139,16 @@ static int bp_event(void *fn, int setup_signal)
return fd;
}

+static int bp_event(void *addr, int setup_signal)
+{
+ return __xp_event(true, addr, setup_signal, SIGIO);
+}
+
+static int wp_event(void *addr, int setup_signal)
+{
+ return __xp_event(false, addr, setup_signal, SIGIO);
+}
+
static long long bp_count(int fd)
{
long long count;
@@ -114,7 +166,7 @@ static long long bp_count(int fd)
int test__bp_signal(int subtest __maybe_unused)
{
struct sigaction sa;
- long long count1, count2;
+ long long count1, count2, count3;

/* setup SIGIO signal handler */
memset(&sa, 0, sizeof(struct sigaction));
@@ -126,6 +178,12 @@ int test__bp_signal(int subtest __maybe_unused)
return TEST_FAIL;
}

+ sa.sa_sigaction = (void *) sig_handler_2;
+ if (sigaction(SIGUSR1, &sa, NULL) < 0) {
+ pr_debug("failed setting up signal handler 2\n");
+ return TEST_FAIL;
+ }
+
/*
* We create following events:
*
@@ -133,7 +191,11 @@ int test__bp_signal(int subtest __maybe_unused)
* signal configured. We should get signal
* notification each time the breakpoint is hit
*
- * fd2 - breakpoint event on sig_handler without SIGIO
+ * fd2 - breakpoint event on sig_handler with SIGUSR1
+ * configured. We should get SIGUSR1 each time when
+ * breakpoint is hit
+ *
+ * fd3 - watchpoint event on test_function with SIGIO
* configured.
*
* Following processing should happen:
@@ -141,6 +203,21 @@ int test__bp_signal(int subtest __maybe_unused)
* - fd1 event breakpoint hit -> count1 == 1
* - SIGIO is delivered -> overflows == 1
* - fd2 event breakpoint hit -> count2 == 1
+ * - SIGUSR1 is delivered -> overflows_2 == 1 (nested signal)
+ * - sig_handler_2 return
+ * - sig_handler return
+ * - fd3 event watchpoint hit -> count3 == 1 (wp and bp in one insn)
+ * - SIGIO is delivered -> overflows == 2
+ * - fd2 event breakpoint hit -> count2 == 2
+ * - SIGUSR1 is delivered -> overflows_2 == 2
+ * - sig_handler_2 return
+ * - sig_handler return
+ * - fd3 event watchpoint hit -> count3 == 2 (standalone wp)
+ * - SIGIO is delivered -> overflows = 3
+ * - fd2 event breakpoint hit -> count2 == 3
+ * - SIGUSR1 is delivered -> overflows_2 == 3
+ * - sig_handler_2 return
+ * - sig_handler return
*
* The test case check following error conditions:
* - we get stuck in signal handler because of debug
@@ -152,11 +229,13 @@ int test__bp_signal(int subtest __maybe_unused)
*
*/

- fd1 = bp_event(test_function, 1);
- fd2 = bp_event(sig_handler, 0);
+ fd1 = bp_event(__test_function, 1);
+ fd2 = __xp_event(true, sig_handler, 1, SIGUSR1);
+ fd3 = wp_event((void *)&the_var, 1);

ioctl(fd1, PERF_EVENT_IOC_ENABLE, 0);
ioctl(fd2, PERF_EVENT_IOC_ENABLE, 0);
+ ioctl(fd3, PERF_EVENT_IOC_ENABLE, 0);

/*
* Kick off the test by trigering 'fd1'
@@ -166,15 +245,18 @@ int test__bp_signal(int subtest __maybe_unused)

ioctl(fd1, PERF_EVENT_IOC_DISABLE, 0);
ioctl(fd2, PERF_EVENT_IOC_DISABLE, 0);
+ ioctl(fd3, PERF_EVENT_IOC_DISABLE, 0);

count1 = bp_count(fd1);
count2 = bp_count(fd2);
+ count3 = bp_count(fd3);

close(fd1);
close(fd2);
+ close(fd3);

- pr_debug("count1 %lld, count2 %lld, overflow %d\n",
- count1, count2, overflows);
+ pr_debug("count1 %lld, count2 %lld, count3 %lld, overflow %d, overflows_2 %d\n",
+ count1, count2, count3, overflows, overflows_2);

if (count1 != 1) {
if (count1 == 11)
@@ -183,12 +265,18 @@ int test__bp_signal(int subtest __maybe_unused)
pr_debug("failed: wrong count for bp1%lld\n", count1);
}

- if (overflows != 1)
+ if (overflows != 3)
pr_debug("failed: wrong overflow hit\n");

- if (count2 != 1)
+ if (overflows_2 != 3)
+ pr_debug("failed: wrong overflow_2 hit\n");
+
+ if (count2 != 3)
pr_debug("failed: wrong count for bp2\n");

- return count1 == 1 && overflows == 1 && count2 == 1 ?
+ if (count3 != 2)
+ pr_debug("failed: wrong count for bp3\n");
+
+ return count1 == 1 && overflows == 3 && count2 == 3 && overflows_2 == 3 && count3 == 2 ?
TEST_OK : TEST_FAIL;
}
--
1.8.3.4


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