A subsequent patch alters perf to perf_event_open with the
PERF_SAMPLE_ARCH_1 bit on.
This patch deals with the case where the kernel does not know about the
PERF_SAMPLE_ARCH_1 bit, and does not know to send the pointer
authentication masks. In this case the perf_event_open system call
returns -EINVAL (-22) and perf exits with an error.
This patch causes userspace process to re-attempt the perf_event_open
system call but without asking for the PERF_SAMPLE_ARCH_1 sample
field, allowing the perf_event_open system call to succeed.
The check is placed to disable PERF_SAMPLE_ARCH_1 as the first thing
to do in the try_fallback section of evsel__open_cpu() because it's the
most recent sample field added, so should probably be the first thing to
attempt to turn off.
Signed-off-by: Andrew Kilroy <andrew.kilroy@xxxxxxx>
---
tools/include/uapi/linux/perf_event.h | 5 ++++-
tools/perf/util/evsel.c | 19 +++++++++++++++++++
tools/perf/util/evsel.h | 1 +
tools/perf/util/perf_event_attr_fprintf.c | 2 +-
4 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index d37629dbad72..821bf5ff6a19 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h
@@ -162,12 +162,15 @@ enum perf_event_sample_format {
PERF_SAMPLE_DATA_PAGE_SIZE = 1U << 22,
PERF_SAMPLE_CODE_PAGE_SIZE = 1U << 23,
PERF_SAMPLE_WEIGHT_STRUCT = 1U << 24,
+ PERF_SAMPLE_ARCH_1 = 1U << 25,
- PERF_SAMPLE_MAX = 1U << 25, /* non-ABI */
+ PERF_SAMPLE_MAX = 1U << 26, /* non-ABI */
__PERF_SAMPLE_CALLCHAIN_EARLY = 1ULL << 63, /* non-ABI; internal use */
};
+#define PERF_SAMPLE_ARM64_PTRAUTH PERF_SAMPLE_ARCH_1
+
#define PERF_SAMPLE_WEIGHT_TYPE (PERF_SAMPLE_WEIGHT | PERF_SAMPLE_WEIGHT_STRUCT)
/*
* values to program into branch_sample_type when PERF_SAMPLE_BRANCH is set
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index ce499c5da8d7..25d8f804f49a 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1830,6 +1830,8 @@ static int __evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
static void evsel__disable_missing_features(struct evsel *evsel)
{
+ if (perf_missing_features.ptrauth)
+ evsel__reset_sample_bit(evsel, ARM64_PTRAUTH);
if (perf_missing_features.weight_struct) {
evsel__set_sample_bit(evsel, WEIGHT);
evsel__reset_sample_bit(evsel, WEIGHT_STRUCT);
@@ -1875,6 +1877,20 @@ int evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
return err;
}
+static bool evsel__detect_ptrauth_masks_missing(struct evsel *evsel __maybe_unused)
+{
+#if defined(__aarch64__)
+ if (!perf_missing_features.ptrauth &&
+ (evsel->core.attr.sample_type & PERF_SAMPLE_ARM64_PTRAUTH)) {
+ perf_missing_features.ptrauth = true;
+ pr_debug2_peo("switching off request for pointer authentication masks\n");
+ return true;
+ }
+#endif
+
+ return false;
+}
+
bool evsel__detect_missing_features(struct evsel *evsel)
{
/*
@@ -2114,6 +2130,9 @@ static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus,
return 0;
try_fallback:
+ if (evsel__detect_ptrauth_masks_missing(evsel))
+ goto fallback_missing_features;
+
if (evsel__precise_ip_fallback(evsel))
goto retry_open;
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 73ea48e94079..9690c35088bf 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -188,6 +188,7 @@ struct perf_missing_features {
bool data_page_size;
bool code_page_size;
bool weight_struct;
+ bool ptrauth;
};
extern struct perf_missing_features perf_missing_features;
diff --git a/tools/perf/util/perf_event_attr_fprintf.c b/tools/perf/util/perf_event_attr_fprintf.c
index 98af3fa4ea35..d18d5f2c6891 100644
--- a/tools/perf/util/perf_event_attr_fprintf.c
+++ b/tools/perf/util/perf_event_attr_fprintf.c
@@ -36,7 +36,7 @@ static void __p_sample_type(char *buf, size_t size, u64 value)
bit_name(IDENTIFIER), bit_name(REGS_INTR), bit_name(DATA_SRC),
bit_name(WEIGHT), bit_name(PHYS_ADDR), bit_name(AUX),
bit_name(CGROUP), bit_name(DATA_PAGE_SIZE), bit_name(CODE_PAGE_SIZE),
- bit_name(WEIGHT_STRUCT),
+ bit_name(WEIGHT_STRUCT), bit_name(ARCH_1),
{ .name = NULL, }
};
#undef bit_name
--
2.17.1
