| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Thu, 30 Sep 2021 12:34:09 +0530
From: Madhavan Srinivasan <maddy@...ux.ibm.com>
To: acme@...nel.org
Cc: michael@...erman.id.au, eranian@...gle.com, mark.rutland@....com,
namhyung@...nel.org, kjain@...ux.ibm.com,
atrajeev@...ux.vnet.ibm.com, jolsa@...hat.com,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
Madhavan Srinivasan <maddy@...ux.ibm.com>
Subject: [PATCH 1/2] tools/perf: Add reverse_fn to handle branch_stack endian issue
branch_stack struct has bit field definition which
produces different bit ordering for big/little endian.
Because of this, when branch_stack sample is collected
in a BE system and viewed/reported in a LE system, bit
fields of the branch stack are not presented properly.
To address this issue, a evsel__reverse64_branch_stack_flags()
is defined and introduced in evsel__parse_sample.
Signed-off-by: Madhavan Srinivasan <maddy@...ux.ibm.com>
---
tools/perf/util/evsel.c | 64 +++++++++++++++++++++++++++++++++++++++--
tools/perf/util/evsel.h | 5 ++++
2 files changed, 67 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index dbfeceb2546c..007be66b69a2 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2221,6 +2221,46 @@ void __weak arch_perf_parse_sample_weight(struct perf_sample *data,
data->weight = *array;
}
+u64 evsel__reverse64_branch_stack_flags(u64 value)
+{
+ u64 new_val = 0;
+
+ /*
+ * branch_stack flag (u64)
+ * union {
+ * u64 values;
+ * struct {
+ * mispred:1 //target mispredicted
+ * predicted:1 //target predicted
+ * in_tx:1 //in transaction
+ * abort:1 //transaction abort
+ * cycles:16 //cycle count to last branch
+ * type:4 //branch type
+ * reserved:40
+ * }
+ * }
+ */
+ if (bigendian()) {
+ new_val = reverse_64(value, 0, 1);
+ new_val |= reverse_64(value, 1, 1);
+ new_val |= reverse_64(value, 2, 1);
+ new_val |= reverse_64(value, 3, 1);
+ new_val |= reverse_64(value, 4, 16);
+ new_val |= reverse_64(value, 20, 4);
+ new_val |= reverse_64(value, 24, 40);
+ } else {
+ new_val = reverse_64(value, 63, 1);
+ new_val |= reverse_64(value, 62, 1);
+ new_val |= reverse_64(value, 61, 1);
+ new_val |= reverse_64(value, 60, 1);
+ new_val |= reverse_64(value, 44, 16);
+ new_val |= reverse_64(value, 40, 4);
+ new_val |= reverse_64(value, 0, 40);
+ }
+
+ return new_val;
+}
+
int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
struct perf_sample *data)
{
@@ -2408,6 +2448,8 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
if (type & PERF_SAMPLE_BRANCH_STACK) {
const u64 max_branch_nr = UINT64_MAX /
sizeof(struct branch_entry);
+ struct branch_entry *e;
+ unsigned int i;
OVERFLOW_CHECK_u64(array);
data->branch_stack = (struct branch_stack *)array++;
@@ -2416,10 +2458,28 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
return -EFAULT;
sz = data->branch_stack->nr * sizeof(struct branch_entry);
- if (evsel__has_branch_hw_idx(evsel))
+ if (evsel__has_branch_hw_idx(evsel)) {
sz += sizeof(u64);
- else
+ e = &data->branch_stack->entries[0];
+ } else {
data->no_hw_idx = true;
+ e = (struct branch_entry *)&data->branch_stack->hw_idx;
+ }
+
+ if (swapped) {
+ /*
+ * struct branch_flag does not have endian specific
+ * bit field definition. And bswap will not resolve the
+ * issue, since these are bit fields.
+ *
+ * evsel__reverse64_branch_stack_flags() uses a reverse64
+ * macro to reverse the bit position based on the host
+ * endians.
+ */
+ for (i = 0; i < data->branch_stack->nr; i++, e++)
+ e->flags.value = evsel__reverse64_branch_stack_flags(e->flags.value);
+ }
+
OVERFLOW_CHECK(array, sz, max_size);
array = (void *)array + sz;
}
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 1f7edfa8568a..1127c23710cf 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -482,4 +482,9 @@ struct evsel *evsel__leader(struct evsel *evsel);
bool evsel__has_leader(struct evsel *evsel, struct evsel *leader);
bool evsel__is_leader(struct evsel *evsel);
void evsel__set_leader(struct evsel *evsel, struct evsel *leader);
+
+#define reverse_64(src, pos, size) \
+ ((((src) >> (pos)) & ((1ull << (size)) - 1)) << (63 - ((pos) + (size) - 1)))
+
+u64 evsel__reverse64_branch_stack_flags(u64 value);
#endif /* __PERF_EVSEL_H */
--
2.31.1
Powered by blists - more mailing lists