[PATCH v6 04/11] perf lock contention: Extend get_lock_owner() for rt_mutex and mutex handoff

[Ian Rogers]

Extend get_lock_owner() in tools/perf/util/bpf_skel/lock_data.h to:
- Support rt_mutex locks (LCB_F_RT) and CONFIG_PREEMPT_RT mutexes via
  struct rt_mutex_base and struct rt_mutex___old, masking out the low
  waiter bit (0x1UL).
- Return NULL when a mutex has MUTEX_FLAG_HANDOFF (0x4UL) set on
  owner.counter and is in the middle of being handed off rather than
  actively held.

Also add rw_semaphore.count and struct rt_mutex_base to the fallback
tools/perf/util/bpf_skel/vmlinux/vmlinux.h.

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/perf/util/bpf_skel/lock_data.h       | 62 ++++++++++++++++++----
 tools/perf/util/bpf_skel/vmlinux/vmlinux.h |  5 ++
 2 files changed, 58 insertions(+), 9 deletions(-)

diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
index 91d464ac18bd..43d8f5030bc1 100644
--- a/tools/perf/util/bpf_skel/lock_data.h
+++ b/tools/perf/util/bpf_skel/lock_data.h
@@ -104,11 +104,24 @@ extern struct rq runqueues __ksym __weak;
 # define __has_builtin(x) 0
 #endif
 
+struct mutex___non_rt {
+	atomic_long_t owner;
+} __attribute__((preserve_access_index));
+
+struct rt_mutex_base___new {
+	struct task_struct *owner;
+} __attribute__((preserve_access_index));
+
+struct rt_mutex___old {
+	struct task_struct *owner;
+} __attribute__((preserve_access_index));
+
 struct rw_semaphore___old {
 	struct task_struct *owner;
 } __attribute__((preserve_access_index));
 
 struct rw_semaphore___new {
+	atomic_long_t count;
 	atomic_long_t owner;
 } __attribute__((preserve_access_index));
 
@@ -146,9 +159,25 @@ static __always_inline struct task_struct *get_lock_owner(__u64 lock, __u32 flag
 	__u64 owner = 0;
 
 	if (flags & LCB_F_MUTEX) {
-		struct mutex *mutex = (void *)lock;
-
-		owner = BPF_CORE_READ(mutex, owner.counter);
+		struct mutex___non_rt *mutex = (void *)lock;
+
+		if (bpf_core_field_exists(mutex->owner.counter)) {
+			owner = BPF_CORE_READ(mutex, owner.counter);
+			if (owner & 0x4UL)
+				return NULL;
+		} else if (bpf_core_type_exists(struct rt_mutex_base___new)) {
+			struct rt_mutex_base___new *rtm = (void *)lock;
+
+			owner = (__u64)BPF_CORE_READ(rtm, owner);
+			return (void *)(owner & ~1UL);
+		} else {
+			struct rt_mutex___old *rtm = (void *)lock;
+
+			if (bpf_core_field_exists(rtm->owner)) {
+				owner = (__u64)BPF_CORE_READ(rtm, owner);
+				return (void *)(owner & ~1UL);
+			}
+		}
 	} else if (flags == LCB_F_READ || flags == LCB_F_WRITE) {
 	/*
 	 * Support for the BPF_TYPE_MATCHES argument to the
@@ -158,20 +187,35 @@ static __always_inline struct task_struct *get_lock_owner(__u64 lock, __u32 flag
 	 */
 #if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
 		if (bpf_core_type_matches(struct rw_semaphore___old)) {
-			struct rw_semaphore___old *rwsem = (void *)lock;
+			struct rw_semaphore___old *old = (void *)lock;
 
-			owner = (unsigned long)BPF_CORE_READ(rwsem, owner);
+			owner = (unsigned long)BPF_CORE_READ(old, owner);
 		} else if (bpf_core_type_matches(struct rw_semaphore___new)) {
-			struct rw_semaphore___new *rwsem = (void *)lock;
+			struct rw_semaphore___new *new = (void *)lock;
 
-			owner = BPF_CORE_READ(rwsem, owner.counter);
+			owner = BPF_CORE_READ(new, owner.counter);
 		}
 #else
 		/* assume new struct */
-		struct rw_semaphore *rwsem = (void *)lock;
+		struct rw_semaphore___new *new = (void *)lock;
 
-		owner = BPF_CORE_READ(rwsem, owner.counter);
+		if (bpf_core_field_exists(new->owner.counter))
+			owner = BPF_CORE_READ(new, owner.counter);
 #endif
+	} else if (flags == LCB_F_RT) {
+		if (bpf_core_type_exists(struct rt_mutex_base___new)) {
+			struct rt_mutex_base___new *rtm = (void *)lock;
+
+			owner = (__u64)BPF_CORE_READ(rtm, owner);
+			return (void *)(owner & ~1UL);
+		} else {
+			struct rt_mutex___old *rtm = (void *)lock;
+
+			if (bpf_core_field_exists(rtm->owner)) {
+				owner = (__u64)BPF_CORE_READ(rtm, owner);
+				return (void *)(owner & ~1UL);
+			}
+		}
 	}
 
 	if (!owner)
diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
index 94e42b022ab1..b75ddc6846bb 100644
--- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
+++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
@@ -76,6 +76,7 @@ struct signal_struct {
 } __attribute__((preserve_access_index));
 
 struct rw_semaphore {
+	atomic_long_t count;
 	atomic_long_t owner;
 } __attribute__((preserve_access_index));
 
@@ -83,6 +84,10 @@ struct mutex {
 	atomic_long_t owner;
 } __attribute__((preserve_access_index));
 
+struct rt_mutex_base {
+	struct task_struct *owner;
+} __attribute__((preserve_access_index));
+
 struct kernfs_node {
 	u64 id;
 } __attribute__((preserve_access_index));
-- 
2.56.0.307.g5fe7bd680c-goog