The old kernel has a different type of the owner field in rwsem.
We can check it using bpf_core_type_matches() builtin in clang but
it also needs its own version check since it's available on recent
versions.
Cc: Hao Luo <haoluo@xxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
.../perf/util/bpf_skel/lock_contention.bpf.c | 57 ++++++++++++++-----
1 file changed, 44 insertions(+), 13 deletions(-)
diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index c5556606134e..e6007eaeda1a 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -84,6 +84,14 @@ struct {
__uint(max_entries, 1);
} addr_filter SEC(".maps");
+struct rw_semaphore___old {
+ struct task_struct *owner;
+} __attribute__((preserve_access_index));
+
+struct rw_semaphore___new {
+ atomic_long_t owner;
+} __attribute__((preserve_access_index));
+
/* control flags */
int enabled;
int has_cpu;
@@ -161,6 +169,41 @@ static inline int update_task_data(struct task_struct *task)
return 0;
}
+#ifndef __has_builtin
+# define __has_builtin(x) 0
+#endif
+
+static inline struct task_struct *get_lock_owner(__u64 lock, __u32 flags)
+{
+ struct task_struct *task;
+ __u64 owner = 0;
+
+ if (flags & LCB_F_MUTEX) {
+ struct mutex *mutex = (void *)lock;
+ owner = BPF_CORE_READ(mutex, owner.counter);
+ } else if (flags == LCB_F_READ || flags == LCB_F_WRITE) {
+#if __has_builtin(bpf_core_type_matches)
+ if (bpf_core_type_matches(struct rw_semaphore___old)) {
+ struct rw_semaphore___old *rwsem = (void *)lock;
+ owner = (unsigned long)BPF_CORE_READ(rwsem, owner);
+ } else if (bpf_core_type_matches(struct rw_semaphore___new)) {
+ struct rw_semaphore___new *rwsem = (void *)lock;
+ owner = BPF_CORE_READ(rwsem, owner.counter);
+ }
+#else
+ /* assume new struct */
+ struct rw_semaphore *rwsem = (void *)lock;
+ owner = BPF_CORE_READ(rwsem, owner.counter);
+#endif
+ }
+
+ if (!owner)
+ return NULL;
+
+ task = (void *)(owner & ~7UL);
+ return task;
+}
+
SEC("tp_btf/contention_begin")
int contention_begin(u64 *ctx)
{
@@ -199,19 +242,7 @@ int contention_begin(u64 *ctx)
struct task_struct *task;
if (lock_owner) {
- if (pelem->flags & LCB_F_MUTEX) {
- struct mutex *lock = (void *)pelem->lock;
- unsigned long owner = BPF_CORE_READ(lock, owner.counter);
-
- task = (void *)(owner & ~7UL);
- } else if (pelem->flags == LCB_F_READ || pelem->flags == LCB_F_WRITE) {
- struct rw_semaphore *lock = (void *)pelem->lock;
- unsigned long owner = BPF_CORE_READ(lock, owner.counter);
-
- task = (void *)(owner & ~7UL);
- } else {
- task = NULL;
- }
+ task = get_lock_owner(pelem->lock, pelem->flags);
/* The flags is not used anymore. Pass the owner pid. */
if (task)
--
2.39.1.519.gcb327c4b5f-goog
