diff options
| author | Matt Mullins | 2019-04-26 11:49:47 -0700 |
|---|---|---|
| committer | Alexei Starovoitov | 2019-04-26 19:04:19 -0700 |
| commit | 9df1c28bb75217b244257152ab7d788bb2a386d0 (patch) | |
| tree | 7fe10ffd9b59716b52b992f5663ec8b5102406b6 /include/trace | |
| parent | 34b8ab091f9ef57a2bb3c8c8359a0a03a8abf2f9 (diff) | |
bpf: add writable context for raw tracepoints
This is an opt-in interface that allows a tracepoint to provide a safe
buffer that can be written from a BPF_PROG_TYPE_RAW_TRACEPOINT program.
The size of the buffer must be a compile-time constant, and is checked
before allowing a BPF program to attach to a tracepoint that uses this
feature.
The pointer to this buffer will be the first argument of tracepoints
that opt in; the pointer is valid and can be bpf_probe_read() by both
BPF_PROG_TYPE_RAW_TRACEPOINT and BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE
programs that attach to such a tracepoint, but the buffer to which it
points may only be written by the latter.
Signed-off-by: Matt Mullins <mmullins@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/trace')
| -rw-r--r-- | include/trace/bpf_probe.h | 27 |
1 files changed, 25 insertions, 2 deletions
diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h index 505dae0bed80..d6e556c0a085 100644 --- a/include/trace/bpf_probe.h +++ b/include/trace/bpf_probe.h @@ -69,8 +69,7 @@ __bpf_trace_##call(void *__data, proto) \ * to make sure that if the tracepoint handling changes, the * bpf probe will fail to compile unless it too is updated. */ -#undef DEFINE_EVENT -#define DEFINE_EVENT(template, call, proto, args) \ +#define __DEFINE_EVENT(template, call, proto, args, size) \ static inline void bpf_test_probe_##call(void) \ { \ check_trace_callback_type_##call(__bpf_trace_##template); \ @@ -81,12 +80,36 @@ __bpf_trace_tp_map_##call = { \ .tp = &__tracepoint_##call, \ .bpf_func = (void *)__bpf_trace_##template, \ .num_args = COUNT_ARGS(args), \ + .writable_size = size, \ }; +#define FIRST(x, ...) x + +#undef DEFINE_EVENT_WRITABLE +#define DEFINE_EVENT_WRITABLE(template, call, proto, args, size) \ +static inline void bpf_test_buffer_##call(void) \ +{ \ + /* BUILD_BUG_ON() is ignored if the code is completely eliminated, but \ + * BUILD_BUG_ON_ZERO() uses a different mechanism that is not \ + * dead-code-eliminated. \ + */ \ + FIRST(proto); \ + (void)BUILD_BUG_ON_ZERO(size != sizeof(*FIRST(args))); \ +} \ +__DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args), size) + +#undef DEFINE_EVENT +#define DEFINE_EVENT(template, call, proto, args) \ + __DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args), 0) #undef DEFINE_EVENT_PRINT #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \ DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args)) #include TRACE_INCLUDE(TRACE_INCLUDE_FILE) + +#undef DEFINE_EVENT_WRITABLE +#undef __DEFINE_EVENT +#undef FIRST + #endif /* CONFIG_BPF_EVENTS */ |