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Both livepatch and BPF trampoline use ftrace. Special attention is needed
when livepatch and fexit program touch the same function at the same
time, because livepatch updates a kernel function and the BPF trampoline
need to call into the right version of the kernel function.
Use samples/livepatch/livepatch-sample.ko for the test.
The test covers two cases:
1) When a fentry program is loaded first. This exercises the
modify_ftrace_direct code path.
2) When a fentry program is loaded first. This exercises the
register_ftrace_direct code path.
Signed-off-by: Song Liu <song@kernel.org>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20251027175023.1521602-4-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
31 lines
537 B
C
31 lines
537 B
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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int fentry_hit;
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int fexit_hit;
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int my_pid;
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SEC("fentry/cmdline_proc_show")
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int BPF_PROG(fentry_cmdline)
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{
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if (my_pid != (bpf_get_current_pid_tgid() >> 32))
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return 0;
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fentry_hit = 1;
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return 0;
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}
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SEC("fexit/cmdline_proc_show")
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int BPF_PROG(fexit_cmdline)
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{
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if (my_pid != (bpf_get_current_pid_tgid() >> 32))
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return 0;
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fexit_hit = 1;
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return 0;
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}
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