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authorAndrii Nakryiko <andriin@fb.com>2020-03-01 11:10:43 +0300
committerAlexei Starovoitov <ast@kernel.org>2020-03-03 03:49:55 +0300
commit441420a1f0b3031f228453697406c86f110e59d4 (patch)
treed223a75dcdd795660206c0be228148de5c1aa944 /include/trace/bpf_probe.h
parent82dbbfc822cd7230c657b49da6557c8bf2f6621d (diff)
downloadlinux-441420a1f0b3031f228453697406c86f110e59d4.tar.xz
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/bpf_probe.h')
-rw-r--r--include/trace/bpf_probe.h18
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