diff options
| author | Andrii Nakryiko <andriin@fb.com> | 2019-10-08 10:59:41 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-10-08 23:16:03 +0200 |
| commit | 7db3822ab99157e16c41caa5e7d788834d5a3c7c (patch) | |
| tree | efa28d61256bd444894a495495ca22c0787dff0f /tools/lib/bpf/bpf_helpers.h | |
| parent | e01a75c159691714607b8a22daa2ba7be275dd01 (diff) | |
libbpf: Add BPF_CORE_READ/BPF_CORE_READ_INTO helpers
Add few macros simplifying BCC-like multi-level probe reads, while also
emitting CO-RE relocations for each read.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20191008175942.1769476-7-andriin@fb.com
Diffstat (limited to 'tools/lib/bpf/bpf_helpers.h')
| -rw-r--r-- | tools/lib/bpf/bpf_helpers.h | 32 |
1 files changed, 9 insertions, 23 deletions
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h index 6d059c0a7845..2203595f38c3 100644 --- a/tools/lib/bpf/bpf_helpers.h +++ b/tools/lib/bpf/bpf_helpers.h @@ -7,7 +7,7 @@ #define __uint(name, val) int (*name)[val] #define __type(name, val) typeof(val) *name -/* helper macro to print out debug messages */ +/* Helper macro to print out debug messages */ #define bpf_printk(fmt, ...) \ ({ \ char ____fmt[] = fmt; \ @@ -15,13 +15,19 @@ ##__VA_ARGS__); \ }) -/* helper macro to place programs, maps, license in +/* + * Helper macro to place programs, maps, license in * different sections in elf_bpf file. Section names * are interpreted by elf_bpf loader */ #define SEC(NAME) __attribute__((section(NAME), used)) -/* a helper structure used by eBPF C program +#ifndef __always_inline +#define __always_inline __attribute__((always_inline)) +#endif + +/* + * Helper structure used by eBPF C program * to describe BPF map attributes to libbpf loader */ struct bpf_map_def { @@ -32,24 +38,4 @@ struct bpf_map_def { unsigned int map_flags; }; -/* - * bpf_core_read() abstracts away bpf_probe_read() call and captures offset - * relocation for source address using __builtin_preserve_access_index() - * built-in, provided by Clang. - * - * __builtin_preserve_access_index() takes as an argument an expression of - * taking an address of a field within struct/union. It makes compiler emit - * a relocation, which records BTF type ID describing root struct/union and an - * accessor string which describes exact embedded field that was used to take - * an address. See detailed description of this relocation format and - * semantics in comments to struct bpf_offset_reloc in libbpf_internal.h. - * - * This relocation allows libbpf to adjust BPF instruction to use correct - * actual field offset, based on target kernel BTF type that matches original - * (local) BTF, used to record relocation. - */ -#define bpf_core_read(dst, sz, src) \ - bpf_probe_read(dst, sz, \ - (const void *)__builtin_preserve_access_index(src)) - #endif |