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libbpf-tools/klockstat: Fallback to kprobe if fentry is not available
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If fentry is not available, let's fallback to kprobe instead. This would
allows the tool to run on old kernels or architectures without BPF trampoline.

Signed-off-by: Hengqi Chen <[email protected]>
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@chenhengqi @yonghong-song
chenhengqi authored and yonghong-song committed Sep 11, 2022
1 parent bfc8252 commit dfb0d98
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Showing 4 changed files with 442 additions and 44 deletions.
338 changes: 336 additions & 2 deletions libbpf-tools/klockstat.bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,13 @@ struct {
__type(value, struct lock_stat);
} stat_map SEC(".maps");

struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, MAX_ENTRIES);
__type(key, u32);
__type(value, void *);
} locks SEC(".maps");

static bool tracing_task(u64 task_id)
{
u32 tgid = task_id >> 32;
Expand Down Expand Up @@ -98,8 +105,8 @@ static void lock_contended(void *ctx, void *lock)
* Note: if you make major changes to this bpf program, double check
* that you aren't skipping too many frames.
*/
li->stack_id = bpf_get_stackid(ctx, &stack_map,
4 | BPF_F_FAST_STACK_CMP);
li->stack_id = bpf_get_stackid(ctx, &stack_map, 4 | BPF_F_FAST_STACK_CMP);

/* Legit failures include EEXIST */
if (li->stack_id < 0)
return;
Expand Down Expand Up @@ -405,4 +412,331 @@ int BPF_PROG(up_write, struct rw_semaphore *lock)
return 0;
}

SEC("kprobe/mutex_lock")
int BPF_KPROBE(kprobe_mutex_lock, struct mutex *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
lock_contended(ctx, lock);
return 0;
}

SEC("kretprobe/mutex_lock")
int BPF_KRETPROBE(kprobe_mutex_lock_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);
lock_acquired(*lock);
return 0;
}

SEC("kprobe/mutex_trylock")
int BPF_KPROBE(kprobe_mutex_trylock, struct mutex *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
return 0;
}

SEC("kretprobe/mutex_trylock")
int BPF_KRETPROBE(kprobe_mutex_trylock_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);

if (ret) {
lock_contended(ctx, *lock);
lock_acquired(*lock);
}
return 0;
}

SEC("kprobe/mutex_lock_interruptible")
int BPF_KPROBE(kprobe_mutex_lock_interruptible, struct mutex *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
lock_contended(ctx, lock);
return 0;
}

SEC("kretprobe/mutex_lock_interruptible")
int BPF_KRETPROBE(kprobe_mutex_lock_interruptible_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);

if (ret)
lock_aborted(*lock);
else
lock_acquired(*lock);
return 0;
}

SEC("kprobe/mutex_lock_killable")
int BPF_KPROBE(kprobe_mutex_lock_killable, struct mutex *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
lock_contended(ctx, lock);
return 0;
}

SEC("kretprobe/mutex_lock_killable")
int BPF_KRETPROBE(kprobe_mutex_lock_killable_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);

if (ret)
lock_aborted(*lock);
else
lock_acquired(*lock);
return 0;
}

SEC("kprobe/mutex_unlock")
int BPF_KPROBE(kprobe_mutex_unlock, struct mutex *lock)
{
lock_released(lock);
return 0;
}

SEC("kprobe/down_read")
int BPF_KPROBE(kprobe_down_read, struct rw_semaphore *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
lock_contended(ctx, lock);
return 0;
}

SEC("kretprobe/down_read")
int BPF_KRETPROBE(kprobe_down_read_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);

lock_acquired(*lock);
return 0;
}

SEC("kprobe/down_read_trylock")
int BPF_KPROBE(kprobe_down_read_trylock, struct rw_semaphore *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
return 0;
}

SEC("kretprobe/down_read_trylock")
int BPF_KRETPROBE(kprobe_down_read_trylock_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);

if (ret == 1) {
lock_contended(ctx, *lock);
lock_acquired(*lock);
}
return 0;
}

SEC("kprobe/down_read_interruptible")
int BPF_KPROBE(kprobe_down_read_interruptible, struct rw_semaphore *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
lock_contended(ctx, lock);
return 0;
}

SEC("kretprobe/down_read_interruptible")
int BPF_KRETPROBE(kprobe_down_read_interruptible_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);

if (ret)
lock_aborted(*lock);
else
lock_acquired(*lock);
return 0;
}

SEC("kprobe/down_read_killable")
int BPF_KPROBE(kprobe_down_read_killable, struct rw_semaphore *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
lock_contended(ctx, lock);
return 0;
}

SEC("kretprobe/down_read_killable")
int BPF_KRETPROBE(kprobe_down_read_killable_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);

if (ret)
lock_aborted(*lock);
else
lock_acquired(*lock);
return 0;
}

SEC("kprobe/up_read")
int BPF_KPROBE(kprobe_up_read, struct rw_semaphore *lock)
{
lock_released(lock);
return 0;
}

SEC("kprobe/down_write")
int BPF_KPROBE(kprobe_down_write, struct rw_semaphore *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
lock_contended(ctx, lock);
return 0;
}

SEC("kretprobe/down_write")
int BPF_KRETPROBE(kprobe_down_write_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);

lock_acquired(*lock);
return 0;
}

SEC("kprobe/down_write_trylock")
int BPF_KPROBE(kprobe_down_write_trylock, struct rw_semaphore *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
return 0;
}

SEC("kretprobe/down_write_trylock")
int BPF_KRETPROBE(kprobe_down_write_trylock_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);

if (ret == 1) {
lock_contended(ctx, *lock);
lock_acquired(*lock);
}
return 0;
}

SEC("kprobe/down_write_killable")
int BPF_KPROBE(kprobe_down_write_killable, struct rw_semaphore *lock)
{
u32 tid = (u32)bpf_get_current_pid_tgid();

bpf_map_update_elem(&locks, &tid, &lock, BPF_ANY);
lock_contended(ctx, lock);
return 0;
}

SEC("kretprobe/down_write_killable")
int BPF_KRETPROBE(kprobe_down_write_killable_exit, long ret)
{
u32 tid = (u32)bpf_get_current_pid_tgid();
void **lock;

lock = bpf_map_lookup_elem(&locks, &tid);
if (!lock)
return 0;

bpf_map_delete_elem(&locks, &tid);

if (ret)
lock_aborted(*lock);
else
lock_acquired(*lock);
return 0;
}

SEC("kprobe/up_write")
int BPF_KPROBE(kprobe_up_write, struct rw_semaphore *lock)
{
lock_released(lock);
return 0;
}

char LICENSE[] SEC("license") = "GPL";
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