blob: 5bcef8c4828ff9a24f57fa190f12497c0509705f [file] [log] [blame]
#!/usr/bin/env bcc-lua
--[[
Copyright 2016 GitHub, Inc
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
--]]
local program = [[
#include <uapi/linux/ptrace.h>
#include <linux/sched.h>
struct data_t {
u64 stack_id;
u32 pid;
char comm[TASK_COMM_LEN];
};
BPF_STACK_TRACE(stack_traces, 128);
BPF_PERF_OUTPUT(events);
void trace_stack(struct pt_regs *ctx) {
u32 pid = bpf_get_current_pid_tgid();
FILTER
struct data_t data = {};
data.stack_id = stack_traces.get_stackid(ctx, BPF_F_REUSE_STACKID),
data.pid = pid;
bpf_get_current_comm(&data.comm, sizeof(data.comm));
events.perf_submit(ctx, &data, sizeof(data));
}
]]
local ffi = require("ffi")
return function(BPF, utils)
local parser = utils.argparse("stacksnoop",
"Trace and print kernel stack traces for a kernel function")
parser:flag("-s --offset")
parser:flag("-v --verbose")
parser:option("-p --pid"):convert(tonumber)
parser:argument("function", "kernel function name"):target("fn")
local args = parser:parse()
local ksym = BPF.SymbolCache()
local filter = ""
if args.pid then
filter = "if (pid != %d) { return; }" % args.pid
end
local text = program:gsub("FILTER", filter)
local bpf = BPF:new{text=text}
bpf:attach_kprobe{event=args.fn, fn_name="trace_stack"}
if BPF.num_open_kprobes() == 0 then
print("Function \"%s\" not found. Exiting." % {args.fn})
return
end
if args.verbose then
print("%-18s %-12s %-6s %-3s %s" %
{"TIME(s)", "COMM", "PID", "CPU", "FUNCTION"})
else
print("%-18s %s" % {"TIME(s)", "FUNCTION"})
end
local stack_traces = bpf:get_table("stack_traces")
local start_ts = utils.posix.time_ns()
local function print_event(cpu, event)
local ts = (utils.posix.time_ns() - start_ts) / 1e9
if args.verbose then
print("%-18.9f %-12.12s %-6d %-3d %s" %
{ts, ffi.string(event.comm), event.pid, cpu, args.fn})
else
print("%-18.9f %s" % {ts, args.fn})
end
for addr in stack_traces:walk(tonumber(event.stack_id)) do
local sym, offset = ksym:resolve(addr)
if args.offset then
print("\t%-16p %s+0x%x" % {addr, sym, tonumber(offset)})
else
print("\t%-16p %s" % {addr, sym})
end
end
print()
end
local TASK_COMM_LEN = 16 -- linux/sched.h
bpf:get_table("events"):open_perf_buffer(print_event,
"struct { uint64_t stack_id; uint32_t pid; char comm[$]; }",
{TASK_COMM_LEN})
bpf:perf_buffer_poll_loop()
end