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Diffstat (limited to 'tools/bpf/bpftool/Documentation/bpftool-gen.rst')
| -rw-r--r-- | tools/bpf/bpftool/Documentation/bpftool-gen.rst | 78 |
1 files changed, 59 insertions, 19 deletions
diff --git a/tools/bpf/bpftool/Documentation/bpftool-gen.rst b/tools/bpf/bpftool/Documentation/bpftool-gen.rst index 84cf0639696f..7cd6681137f3 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-gen.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-gen.rst @@ -14,16 +14,37 @@ SYNOPSIS *OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] } - *COMMAND* := { **skeleton** | **help** } + *COMMAND* := { **object** | **skeleton** | **help** } GEN COMMANDS ============= -| **bpftool** **gen skeleton** *FILE* +| **bpftool** **gen object** *OUTPUT_FILE* *INPUT_FILE* [*INPUT_FILE*...] +| **bpftool** **gen skeleton** *FILE* [**name** *OBJECT_NAME*] | **bpftool** **gen help** DESCRIPTION =========== + **bpftool gen object** *OUTPUT_FILE* *INPUT_FILE* [*INPUT_FILE*...] + Statically link (combine) together one or more *INPUT_FILE*'s + into a single resulting *OUTPUT_FILE*. All the files involved + are BPF ELF object files. + + The rules of BPF static linking are mostly the same as for + user-space object files, but in addition to combining data + and instruction sections, .BTF and .BTF.ext (if present in + any of the input files) data are combined together. .BTF + data is deduplicated, so all the common types across + *INPUT_FILE*'s will only be represented once in the resulting + BTF information. + + BPF static linking allows to partition BPF source code into + individually compiled files that are then linked into + a single resulting BPF object file, which can be used to + generated BPF skeleton (with **gen skeleton** command) or + passed directly into **libbpf** (using **bpf_object__open()** + family of APIs). + **bpftool gen skeleton** *FILE* Generate BPF skeleton C header file for a given *FILE*. @@ -75,10 +96,13 @@ DESCRIPTION specific maps, programs, etc. As part of skeleton, few custom functions are generated. - Each of them is prefixed with object name, derived from - object file name. I.e., if BPF object file name is - **example.o**, BPF object name will be **example**. The - following custom functions are provided in such case: + Each of them is prefixed with object name. Object name can + either be derived from object file name, i.e., if BPF object + file name is **example.o**, BPF object name will be + **example**. Object name can be also specified explicitly + through **name** *OBJECT_NAME* parameter. The following + custom functions are provided (assuming **example** as + the object name): - **example__open** and **example__open_opts**. These functions are used to instantiate skeleton. It @@ -130,26 +154,19 @@ OPTIONS EXAMPLES ======== -**$ cat example.c** +**$ cat example1.bpf.c** :: #include <stdbool.h> #include <linux/ptrace.h> #include <linux/bpf.h> - #include "bpf_helpers.h" + #include <bpf/bpf_helpers.h> const volatile int param1 = 42; bool global_flag = true; struct { int x; } data = {}; - struct { - __uint(type, BPF_MAP_TYPE_HASH); - __uint(max_entries, 128); - __type(key, int); - __type(value, long); - } my_map SEC(".maps"); - SEC("raw_tp/sys_enter") int handle_sys_enter(struct pt_regs *ctx) { @@ -161,6 +178,21 @@ EXAMPLES return 0; } +**$ cat example2.bpf.c** + +:: + + #include <linux/ptrace.h> + #include <linux/bpf.h> + #include <bpf/bpf_helpers.h> + + struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 128); + __type(key, int); + __type(value, long); + } my_map SEC(".maps"); + SEC("raw_tp/sys_exit") int handle_sys_exit(struct pt_regs *ctx) { @@ -170,9 +202,17 @@ EXAMPLES } This is example BPF application with two BPF programs and a mix of BPF maps -and global variables. +and global variables. Source code is split across two source code files. -**$ bpftool gen skeleton example.o** +**$ clang -target bpf -g example1.bpf.c -o example1.bpf.o** +**$ clang -target bpf -g example2.bpf.c -o example2.bpf.o** +**$ bpftool gen object example.bpf.o example1.bpf.o example2.bpf.o** + +This set of commands compiles *example1.bpf.c* and *example2.bpf.c* +individually and then statically links respective object files into the final +BPF ELF object file *example.bpf.o*. + +**$ bpftool gen skeleton example.bpf.o name example | tee example.skel.h** :: @@ -227,7 +267,7 @@ and global variables. #endif /* __EXAMPLE_SKEL_H__ */ -**$ cat example_user.c** +**$ cat example.c** :: @@ -270,7 +310,7 @@ and global variables. return err; } -**# ./example_user** +**# ./example** :: |