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This simple example script traces all calls to `malloc` in a process and prints the callsite using the new `BPF_STACK_TRACE` table API.
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#!/usr/bin/python | ||
# | ||
# mallocstacks Trace malloc() calls in a process and print the full | ||
# stack trace for all callsites. | ||
# For Linux, uses BCC, eBPF. Embedded C. | ||
# | ||
# This script is a basic example of the new Linux 4.6+ BPF_STACK_TRACE | ||
# table API. | ||
# | ||
# Copyright 2016 GitHub, Inc. | ||
# Licensed under the Apache License, Version 2.0 (the "License") | ||
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from __future__ import print_function | ||
from bcc import BPF, ProcessSymbols | ||
from time import sleep | ||
import sys | ||
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if len(sys.argv) < 2: | ||
print("USAGE: mallocstacks PID") | ||
exit() | ||
pid = int(sys.argv[1]) | ||
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# load BPF program | ||
b = BPF(text=""" | ||
#include <uapi/linux/ptrace.h> | ||
BPF_HASH(calls, int); | ||
BPF_STACK_TRACE(stack_traces, 1024) | ||
int alloc_enter(struct pt_regs *ctx, size_t size) { | ||
int key = stack_traces.get_stackid(ctx, | ||
BPF_F_USER_STACK|BPF_F_REUSE_STACKID); | ||
if (key < 0) | ||
return 0; | ||
u64 zero = 0, *val; | ||
val = calls.lookup_or_init(&key, &zero); | ||
(*val) += size; | ||
return 0; | ||
}; | ||
""") | ||
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b.attach_uprobe(name="c", sym="malloc", fn_name="alloc_enter", pid=pid) | ||
print("Attaching to malloc in pid %d, Ctrl+C to quit." % pid) | ||
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decoder = ProcessSymbols(pid) | ||
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# sleep until Ctrl-C | ||
try: | ||
sleep(99999999) | ||
except KeyboardInterrupt: | ||
pass | ||
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calls = b.get_table("calls") | ||
stack_traces = b.get_table("stack_traces") | ||
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for k, v in reversed(sorted(calls.items(), key=lambda c: c[1].value)): | ||
print("%d bytes allocated at:" % v.value) | ||
for addr in stack_traces.walk(k.value): | ||
print("\t%s (%x)" % (decoder.decode_addr(addr), addr)) |