mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 19:29:37 +00:00
6939f4ef16
Some subsystems only have bare tracepoints (a tracepoint with no associated trace event) to avoid the problem of trace events being an ABI that can't be changed. >From bpf presepective, bare tracepoints are what it calls RAW_TRACEPOINT(). Since bpf assumed there's 1:1 mapping, it relied on hooking to DEFINE_EVENT() macro to create bpf mapping of the tracepoints. Since bare tracepoints use DECLARE_TRACE() to create the tracepoint, bpf had no knowledge about their existence. By teaching bpf_probe.h to parse DECLARE_TRACE() in a similar fashion to DEFINE_EVENT(), bpf can find and attach to the new raw tracepoints. Enabling that comes with the contract that changes to raw tracepoints don't constitute a regression if they break existing bpf programs. We need the ability to continue to morph and modify these raw tracepoints without worrying about any ABI. Update Documentation/bpf/bpf_design_QA.rst to document this contract. Signed-off-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210119122237.2426878-2-qais.yousef@arm.com
128 lines
4.2 KiB
C
128 lines
4.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
|
|
#undef TRACE_SYSTEM_VAR
|
|
|
|
#ifdef CONFIG_BPF_EVENTS
|
|
|
|
#undef __entry
|
|
#define __entry entry
|
|
|
|
#undef __get_dynamic_array
|
|
#define __get_dynamic_array(field) \
|
|
((void *)__entry + (__entry->__data_loc_##field & 0xffff))
|
|
|
|
#undef __get_dynamic_array_len
|
|
#define __get_dynamic_array_len(field) \
|
|
((__entry->__data_loc_##field >> 16) & 0xffff)
|
|
|
|
#undef __get_str
|
|
#define __get_str(field) ((char *)__get_dynamic_array(field))
|
|
|
|
#undef __get_bitmask
|
|
#define __get_bitmask(field) (char *)__get_dynamic_array(field)
|
|
|
|
#undef __perf_count
|
|
#define __perf_count(c) (c)
|
|
|
|
#undef __perf_task
|
|
#define __perf_task(t) (t)
|
|
|
|
/* cast any integer, pointer, or small struct to u64 */
|
|
#define UINTTYPE(size) \
|
|
__typeof__(__builtin_choose_expr(size == 1, (u8)1, \
|
|
__builtin_choose_expr(size == 2, (u16)2, \
|
|
__builtin_choose_expr(size == 4, (u32)3, \
|
|
__builtin_choose_expr(size == 8, (u64)4, \
|
|
(void)5)))))
|
|
#define __CAST_TO_U64(x) ({ \
|
|
typeof(x) __src = (x); \
|
|
UINTTYPE(sizeof(x)) __dst; \
|
|
memcpy(&__dst, &__src, sizeof(__dst)); \
|
|
(u64)__dst; })
|
|
|
|
#define __CAST1(a,...) __CAST_TO_U64(a)
|
|
#define __CAST2(a,...) __CAST_TO_U64(a), __CAST1(__VA_ARGS__)
|
|
#define __CAST3(a,...) __CAST_TO_U64(a), __CAST2(__VA_ARGS__)
|
|
#define __CAST4(a,...) __CAST_TO_U64(a), __CAST3(__VA_ARGS__)
|
|
#define __CAST5(a,...) __CAST_TO_U64(a), __CAST4(__VA_ARGS__)
|
|
#define __CAST6(a,...) __CAST_TO_U64(a), __CAST5(__VA_ARGS__)
|
|
#define __CAST7(a,...) __CAST_TO_U64(a), __CAST6(__VA_ARGS__)
|
|
#define __CAST8(a,...) __CAST_TO_U64(a), __CAST7(__VA_ARGS__)
|
|
#define __CAST9(a,...) __CAST_TO_U64(a), __CAST8(__VA_ARGS__)
|
|
#define __CAST10(a,...) __CAST_TO_U64(a), __CAST9(__VA_ARGS__)
|
|
#define __CAST11(a,...) __CAST_TO_U64(a), __CAST10(__VA_ARGS__)
|
|
#define __CAST12(a,...) __CAST_TO_U64(a), __CAST11(__VA_ARGS__)
|
|
/* tracepoints with more than 12 arguments will hit build error */
|
|
#define CAST_TO_U64(...) CONCATENATE(__CAST, COUNT_ARGS(__VA_ARGS__))(__VA_ARGS__)
|
|
|
|
#define __BPF_DECLARE_TRACE(call, proto, args) \
|
|
static notrace void \
|
|
__bpf_trace_##call(void *__data, proto) \
|
|
{ \
|
|
struct bpf_prog *prog = __data; \
|
|
CONCATENATE(bpf_trace_run, COUNT_ARGS(args))(prog, CAST_TO_U64(args)); \
|
|
}
|
|
|
|
#undef DECLARE_EVENT_CLASS
|
|
#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
|
|
__BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args))
|
|
|
|
/*
|
|
* This part is compiled out, it is only here as a build time check
|
|
* to make sure that if the tracepoint handling changes, the
|
|
* bpf probe will fail to compile unless it too is updated.
|
|
*/
|
|
#define __DEFINE_EVENT(template, call, proto, args, size) \
|
|
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 union { \
|
|
struct bpf_raw_event_map event; \
|
|
btf_trace_##call handler; \
|
|
} __bpf_trace_tp_map_##call __used \
|
|
__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
|
|
|
|
#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))
|
|
|
|
#undef DECLARE_TRACE
|
|
#define DECLARE_TRACE(call, proto, args) \
|
|
__BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args)) \
|
|
__DEFINE_EVENT(call, call, PARAMS(proto), PARAMS(args), 0)
|
|
|
|
#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
|
|
|
|
#undef DEFINE_EVENT_WRITABLE
|
|
#undef __DEFINE_EVENT
|
|
#undef FIRST
|
|
|
|
#endif /* CONFIG_BPF_EVENTS */
|