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-rw-r--r--samples/bpf/offwaketime_kern.c131
1 files changed, 131 insertions, 0 deletions
diff --git a/samples/bpf/offwaketime_kern.c b/samples/bpf/offwaketime_kern.c
new file mode 100644
index 000000000..c0aa5a9b9
--- /dev/null
+++ b/samples/bpf/offwaketime_kern.c
@@ -0,0 +1,131 @@
+/* Copyright (c) 2016 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <uapi/linux/bpf.h>
+#include "bpf_helpers.h"
+#include <uapi/linux/ptrace.h>
+#include <uapi/linux/perf_event.h>
+#include <linux/version.h>
+#include <linux/sched.h>
+
+#define _(P) ({typeof(P) val = 0; bpf_probe_read(&val, sizeof(val), &P); val;})
+
+#define MINBLOCK_US 1
+
+struct key_t {
+ char waker[TASK_COMM_LEN];
+ char target[TASK_COMM_LEN];
+ u32 wret;
+ u32 tret;
+};
+
+struct bpf_map_def SEC("maps") counts = {
+ .type = BPF_MAP_TYPE_HASH,
+ .key_size = sizeof(struct key_t),
+ .value_size = sizeof(u64),
+ .max_entries = 10000,
+};
+
+struct bpf_map_def SEC("maps") start = {
+ .type = BPF_MAP_TYPE_HASH,
+ .key_size = sizeof(u32),
+ .value_size = sizeof(u64),
+ .max_entries = 10000,
+};
+
+struct wokeby_t {
+ char name[TASK_COMM_LEN];
+ u32 ret;
+};
+
+struct bpf_map_def SEC("maps") wokeby = {
+ .type = BPF_MAP_TYPE_HASH,
+ .key_size = sizeof(u32),
+ .value_size = sizeof(struct wokeby_t),
+ .max_entries = 10000,
+};
+
+struct bpf_map_def SEC("maps") stackmap = {
+ .type = BPF_MAP_TYPE_STACK_TRACE,
+ .key_size = sizeof(u32),
+ .value_size = PERF_MAX_STACK_DEPTH * sizeof(u64),
+ .max_entries = 10000,
+};
+
+#define STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)
+
+SEC("kprobe/try_to_wake_up")
+int waker(struct pt_regs *ctx)
+{
+ struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
+ struct wokeby_t woke = {};
+ u32 pid;
+
+ pid = _(p->pid);
+
+ bpf_get_current_comm(&woke.name, sizeof(woke.name));
+ woke.ret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
+
+ bpf_map_update_elem(&wokeby, &pid, &woke, BPF_ANY);
+ return 0;
+}
+
+static inline int update_counts(struct pt_regs *ctx, u32 pid, u64 delta)
+{
+ struct key_t key = {};
+ struct wokeby_t *woke;
+ u64 zero = 0, *val;
+
+ bpf_get_current_comm(&key.target, sizeof(key.target));
+ key.tret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
+
+ woke = bpf_map_lookup_elem(&wokeby, &pid);
+ if (woke) {
+ key.wret = woke->ret;
+ __builtin_memcpy(&key.waker, woke->name, TASK_COMM_LEN);
+ bpf_map_delete_elem(&wokeby, &pid);
+ }
+
+ val = bpf_map_lookup_elem(&counts, &key);
+ if (!val) {
+ bpf_map_update_elem(&counts, &key, &zero, BPF_NOEXIST);
+ val = bpf_map_lookup_elem(&counts, &key);
+ if (!val)
+ return 0;
+ }
+ (*val) += delta;
+ return 0;
+}
+
+SEC("kprobe/finish_task_switch")
+int oncpu(struct pt_regs *ctx)
+{
+ struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
+ u64 delta, ts, *tsp;
+ u32 pid;
+
+ /* record previous thread sleep time */
+ pid = _(p->pid);
+ ts = bpf_ktime_get_ns();
+ bpf_map_update_elem(&start, &pid, &ts, BPF_ANY);
+
+ /* calculate current thread's delta time */
+ pid = bpf_get_current_pid_tgid();
+ tsp = bpf_map_lookup_elem(&start, &pid);
+ if (!tsp)
+ /* missed start or filtered */
+ return 0;
+
+ delta = bpf_ktime_get_ns() - *tsp;
+ bpf_map_delete_elem(&start, &pid);
+ delta = delta / 1000;
+ if (delta < MINBLOCK_US)
+ return 0;
+
+ return update_counts(ctx, pid, delta);
+}
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;