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Subject[PATCH 32/47] perf tests: Add kcore to the object code reading test
Date
From: Adrian Hunter <adrian.hunter@intel.com>

Make the "object code reading" test attempt to read from kcore.

The test uses objdump which struggles with kcore. i.e. doesn't always
work, sometimes takes a long time. The test has been made to work
around those issues.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1375875537-4509-10-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/tests/code-reading.c | 100 ++++++++++++++++++++++++++++++++--------
1 file changed, 82 insertions(+), 18 deletions(-)

diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
index 0c7b052..8e0943b 100644
--- a/tools/perf/tests/code-reading.c
+++ b/tools/perf/tests/code-reading.c
@@ -20,6 +20,11 @@
#define BUFSZ 1024
#define READLEN 128

+struct state {
+ u64 done[1024];
+ size_t done_cnt;
+};
+
static unsigned int hex(char c)
{
if (c >= '0' && c <= '9')
@@ -107,6 +112,9 @@ static int read_via_objdump(const char *filename, u64 addr, void *buf,

pr_debug("Objdump command is: %s\n", cmd);

+ /* Ignore objdump errors */
+ strcat(cmd, " 2>/dev/null");
+
f = popen(cmd, "r");
if (!f) {
pr_debug("popen failed\n");
@@ -126,7 +134,8 @@ static int read_via_objdump(const char *filename, u64 addr, void *buf,
}

static int read_object_code(u64 addr, size_t len, u8 cpumode,
- struct thread *thread, struct machine *machine)
+ struct thread *thread, struct machine *machine,
+ struct state *state)
{
struct addr_location al;
unsigned char buf1[BUFSZ];
@@ -146,7 +155,8 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,

pr_debug("File is: %s\n", al.map->dso->long_name);

- if (al.map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS) {
+ if (al.map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
+ !dso__is_kcore(al.map->dso)) {
pr_debug("Unexpected kernel address - skipping\n");
return 0;
}
@@ -175,6 +185,24 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
if (map__load(al.map, NULL))
return -1;

+ /* objdump struggles with kcore - try each map only once */
+ if (dso__is_kcore(al.map->dso)) {
+ size_t d;
+
+ for (d = 0; d < state->done_cnt; d++) {
+ if (state->done[d] == al.map->start) {
+ pr_debug("kcore map tested already");
+ pr_debug(" - skipping\n");
+ return 0;
+ }
+ }
+ if (state->done_cnt >= ARRAY_SIZE(state->done)) {
+ pr_debug("Too many kcore maps - skipping\n");
+ return 0;
+ }
+ state->done[state->done_cnt++] = al.map->start;
+ }
+
/* Read the object code using objdump */
objdump_addr = map__rip_2objdump(al.map, al.addr);
ret = read_via_objdump(al.map->dso->long_name, objdump_addr, buf2, len);
@@ -186,10 +214,19 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
if (cpumode == PERF_RECORD_MISC_KERNEL ||
cpumode == PERF_RECORD_MISC_GUEST_KERNEL) {
len -= ret;
- if (len)
+ if (len) {
pr_debug("Reducing len to %zu\n", len);
- else
+ } else if (dso__is_kcore(al.map->dso)) {
+ /*
+ * objdump cannot handle very large segments
+ * that may be found in kcore.
+ */
+ pr_debug("objdump failed for kcore");
+ pr_debug(" - skipping\n");
+ return 0;
+ } else {
return -1;
+ }
}
}
if (ret < 0) {
@@ -209,7 +246,7 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,

static int process_sample_event(struct machine *machine,
struct perf_evlist *evlist,
- union perf_event *event)
+ union perf_event *event, struct state *state)
{
struct perf_sample sample;
struct thread *thread;
@@ -228,14 +265,15 @@ static int process_sample_event(struct machine *machine,

cpumode = event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;

- return read_object_code(sample.ip, READLEN, cpumode, thread, machine);
+ return read_object_code(sample.ip, READLEN, cpumode, thread, machine,
+ state);
}

static int process_event(struct machine *machine, struct perf_evlist *evlist,
- union perf_event *event)
+ union perf_event *event, struct state *state)
{
if (event->header.type == PERF_RECORD_SAMPLE)
- return process_sample_event(machine, evlist, event);
+ return process_sample_event(machine, evlist, event, state);

if (event->header.type < PERF_RECORD_MAX)
return machine__process_event(machine, event);
@@ -243,14 +281,15 @@ static int process_event(struct machine *machine, struct perf_evlist *evlist,
return 0;
}

-static int process_events(struct machine *machine, struct perf_evlist *evlist)
+static int process_events(struct machine *machine, struct perf_evlist *evlist,
+ struct state *state)
{
union perf_event *event;
int i, ret;

for (i = 0; i < evlist->nr_mmaps; i++) {
while ((event = perf_evlist__mmap_read(evlist, i)) != NULL) {
- ret = process_event(machine, evlist, event);
+ ret = process_event(machine, evlist, event, state);
if (ret < 0)
return ret;
}
@@ -331,10 +370,12 @@ static void do_something(void)
enum {
TEST_CODE_READING_OK,
TEST_CODE_READING_NO_VMLINUX,
+ TEST_CODE_READING_NO_KCORE,
TEST_CODE_READING_NO_ACCESS,
+ TEST_CODE_READING_NO_KERNEL_OBJ,
};

-static int do_test_code_reading(void)
+static int do_test_code_reading(bool try_kcore)
{
struct machines machines;
struct machine *machine;
@@ -348,6 +389,9 @@ static int do_test_code_reading(void)
.uses_mmap = true,
},
};
+ struct state state = {
+ .done_cnt = 0,
+ };
struct thread_map *threads = NULL;
struct cpu_map *cpus = NULL;
struct perf_evlist *evlist = NULL;
@@ -355,7 +399,7 @@ static int do_test_code_reading(void)
int err = -1, ret;
pid_t pid;
struct map *map;
- bool have_vmlinux, excl_kernel = false;
+ bool have_vmlinux, have_kcore, excl_kernel = false;

pid = getpid();

@@ -368,6 +412,10 @@ static int do_test_code_reading(void)
goto out_err;
}

+ /* Force the use of kallsyms instead of vmlinux to try kcore */
+ if (try_kcore)
+ symbol_conf.kallsyms_name = "/proc/kallsyms";
+
/* Load kernel map */
map = machine->vmlinux_maps[MAP__FUNCTION];
ret = map__load(map, NULL);
@@ -375,9 +423,15 @@ static int do_test_code_reading(void)
pr_debug("map__load failed\n");
goto out_err;
}
- have_vmlinux = map->dso->symtab_type == DSO_BINARY_TYPE__VMLINUX;
- /* No point getting kernel events if there is no vmlinux */
- if (!have_vmlinux)
+ have_vmlinux = dso__is_vmlinux(map->dso);
+ have_kcore = dso__is_kcore(map->dso);
+
+ /* 2nd time through we just try kcore */
+ if (try_kcore && !have_kcore)
+ return TEST_CODE_READING_NO_KCORE;
+
+ /* No point getting kernel events if there is no kernel object */
+ if (!have_vmlinux && !have_kcore)
excl_kernel = true;

threads = thread_map__new_by_tid(pid);
@@ -461,11 +515,13 @@ static int do_test_code_reading(void)

perf_evlist__disable(evlist);

- ret = process_events(machine, evlist);
+ ret = process_events(machine, evlist, &state);
if (ret < 0)
goto out_err;

- if (!have_vmlinux)
+ if (!have_vmlinux && !have_kcore && !try_kcore)
+ err = TEST_CODE_READING_NO_KERNEL_OBJ;
+ else if (!have_vmlinux && !try_kcore)
err = TEST_CODE_READING_NO_VMLINUX;
else if (excl_kernel)
err = TEST_CODE_READING_NO_ACCESS;
@@ -492,7 +548,9 @@ int test__code_reading(void)
{
int ret;

- ret = do_test_code_reading();
+ ret = do_test_code_reading(false);
+ if (!ret)
+ ret = do_test_code_reading(true);

switch (ret) {
case TEST_CODE_READING_OK:
@@ -500,9 +558,15 @@ int test__code_reading(void)
case TEST_CODE_READING_NO_VMLINUX:
fprintf(stderr, " (no vmlinux)");
return 0;
+ case TEST_CODE_READING_NO_KCORE:
+ fprintf(stderr, " (no kcore)");
+ return 0;
case TEST_CODE_READING_NO_ACCESS:
fprintf(stderr, " (no access)");
return 0;
+ case TEST_CODE_READING_NO_KERNEL_OBJ:
+ fprintf(stderr, " (no kernel obj)");
+ return 0;
default:
return -1;
};
--
1.8.1.4


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