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| author |   Andrii Nakryiko <andriin@fb.com> | 2020-03-01 00:10:43 -0800 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2020-03-02 16:49:55 -0800 |
| commit | 441420a1f0b3031f228453697406c86f110e59d4 (patch) | |
| tree | d223a75dcdd795660206c0be228148de5c1aa944 /include/trace | |
| parent | Merge branch 'move_BPF_PROG_to_libbpf' (diff) | |
| download | wireguard-linux-441420a1f0b3031f228453697406c86f110e59d4.tar.xz wireguard-linux-441420a1f0b3031f228453697406c86f110e59d4.zip | |
bpf: Reliably preserve btf_trace_xxx types
btf_trace_xxx types, crucial for tp_btf BPF programs (raw tracepoint with
verifier-checked direct memory access), have to be preserved in kernel BTF to
allow verifier do its job and enforce type/memory safety. It was reported
([0]) that for kernels built with Clang current type-casting approach doesn't
preserve these types.
This patch fixes it by declaring an anonymous union for each registered
tracepoint, capturing both struct bpf_raw_event_map information, as well as
recording btf_trace_##call type reliably. Structurally, it's still the same
content as for a plain struct bpf_raw_event_map, so no other changes are
necessary.
[0] https://github.com/iovisor/bcc/issues/2770#issuecomment-591007692
Fixes: e8c423fb31fa ("bpf: Add typecast to raw_tracepoints to help BTF generation")
Reported-by: Wenbo Zhang <ethercflow@gmail.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200301081045.3491005-2-andriin@fb.com
Diffstat (limited to 'include/trace')
| -rw-r--r-- | include/trace/bpf_probe.h | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h index b04c29270973..1ce3be63add1 100644 --- a/include/trace/bpf_probe.h +++ b/include/trace/bpf_probe.h @@ -75,13 +75,17 @@ static inline void bpf_test_probe_##call(void) \ check_trace_callback_type_##call(__bpf_trace_##template); \ } \ typedef void (*btf_trace_##call)(void *__data, proto); \ -static struct bpf_raw_event_map __used \ - __attribute__((section("__bpf_raw_tp_map"))) \ -__bpf_trace_tp_map_##call = { \ - .tp = &__tracepoint_##call, \ - .bpf_func = (void *)(btf_trace_##call)__bpf_trace_##template, \ - .num_args = COUNT_ARGS(args), \ - .writable_size = size, \ +static union { \ + struct bpf_raw_event_map event; \ + btf_trace_##call handler; \ +} __bpf_trace_tp_map_##call __used \ +__attribute__((section("__bpf_raw_tp_map"))) = { \ + .event = { \ + .tp = &__tracepoint_##call, \ + .bpf_func = __bpf_trace_##template, \ + .num_args = COUNT_ARGS(args), \ + .writable_size = size, \ + }, \ }; #define FIRST(x, ...) x |