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Subject[PATCH 4/8] perf tools: arm64: Read ptrauth data from kernel
Date
This patch alters the userspace perf program to request the
pointer authentication code masks using the PERF_SAMPLE_ARCH_1 sample
field and write the data to perf.data file.

A subsequent commit will make use of the masks in the data file to do
the unwinding.

Signed-off-by: Andrew Kilroy <andrew.kilroy@arm.com>
---
tools/perf/tests/sample-parsing.c | 2 +-
tools/perf/util/event.h | 8 ++++++
tools/perf/util/evsel.c | 45 +++++++++++++++++++++++++++++++
3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
index 07f2411b0ad4..dd78ca279c01 100644
--- a/tools/perf/tests/sample-parsing.c
+++ b/tools/perf/tests/sample-parsing.c
@@ -381,7 +381,7 @@ static int test__sample_parsing(struct test_suite *test __maybe_unused, int subt
* were added. Please actually update the test rather than just change
* the condition below.
*/
- if (PERF_SAMPLE_MAX > PERF_SAMPLE_WEIGHT_STRUCT << 1) {
+ if (PERF_SAMPLE_MAX > PERF_SAMPLE_ARCH_1 << 1) {
pr_debug("sample format has changed, some new PERF_SAMPLE_ bit was introduced - test needs updating\n");
return -1;
}
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index cdd72e05fd28..b99fc81dd37e 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -128,6 +128,13 @@ struct aux_sample {
void *data;
};

+
+struct ptrauth_info {
+ u64 enabled_keys; // arm64 ptrauth is in use if this is non-zero.
+ u64 insn_mask;
+ u64 data_mask;
+};
+
struct perf_sample {
u64 ip;
u32 pid, tid;
@@ -163,6 +170,7 @@ struct perf_sample {
struct stack_dump user_stack;
struct sample_read read;
struct aux_sample aux_sample;
+ struct ptrauth_info ptrauth;
};

#define PERF_MEM_DATA_SRC_NONE \
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 25d8f804f49a..4627a68a7797 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -887,8 +887,22 @@ static void __evsel__config_callchain(struct evsel *evsel, struct record_opts *o
"Falling back to framepointers.\n");
}

+#if defined(__aarch64__)
+ /*
+ * We need to set ARM64_PTRAUTH in FP mode so that b9f6fbb3b2c2 ("perf arm64: Inject missing
+ * frames when using 'perf record --call-graph=fp'") continues to work in the presence of
+ * PACs.
+ */
+ if (param->record_mode == CALLCHAIN_FP)
+ evsel__set_sample_bit(evsel, ARM64_PTRAUTH);
+
+#endif
+
if (param->record_mode == CALLCHAIN_DWARF) {
if (!function) {
+#if defined(__aarch64__)
+ evsel__set_sample_bit(evsel, ARM64_PTRAUTH);
+#endif
evsel__set_sample_bit(evsel, REGS_USER);
evsel__set_sample_bit(evsel, STACK_USER);
if (opts->sample_user_regs && DWARF_MINIMAL_REGS != PERF_REGS_MASK) {
@@ -2344,6 +2358,17 @@ u64 evsel__bitfield_swap_branch_flags(u64 value)
return new_val;
}

+/*
+ * To return the normalised arch that is recorded in a perf.data file
+ */
+static const char *recorded_normalized_arch(struct evsel *evsel)
+{
+ if (evsel && evsel->evlist && evsel->evlist->env)
+ return perf_env__arch(evsel->evlist->env);
+ else
+ return NULL;
+}
+
int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
struct perf_sample *data)
{
@@ -2681,6 +2706,26 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
array = (void *)array + sz;
}

+ if (type & PERF_SAMPLE_ARCH_1) {
+ const char *normlzd_arch = recorded_normalized_arch(evsel);
+
+ if (normlzd_arch)
+ pr_debug4("PERF_SAMPLE_ARCH_1 is on, detected recorded arch as %s\n", normlzd_arch);
+ else
+ pr_debug4("PERF_SAMPLE_ARCH_1 is on, but arch not detected\n");
+
+ if (normlzd_arch && strcmp(normlzd_arch, "arm64") == 0) {
+ OVERFLOW_CHECK(array, 3 * sizeof(u64), max_size);
+
+ data->ptrauth.enabled_keys = *array;
+ array++;
+ data->ptrauth.insn_mask = *array;
+ array++;
+ data->ptrauth.data_mask = *array;
+ array++;
+ }
+ }
+
return 0;
}

--
2.17.1
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