diff options
author | Daniel Xu <dxu@dxuuu.xyz> | 2024-06-12 18:58:36 +0300 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2024-06-12 21:01:32 +0300 |
commit | 770abbb5a25a5b767f1c60ba366aea503728e957 (patch) | |
tree | 93fefc8047f6a553b4e4ce76b3a5e5dab71b444d | |
parent | c567cba34585514f82600a10587c8813c50e3a7c (diff) | |
download | linux-770abbb5a25a5b767f1c60ba366aea503728e957.tar.xz |
bpftool: Support dumping kfunc prototypes from BTF
This patch enables dumping kfunc prototypes from bpftool. This is useful
b/c with this patch, end users will no longer have to manually define
kfunc prototypes. For the kernel tree, this also means we can optionally
drop kfunc prototypes from:
tools/testing/selftests/bpf/bpf_kfuncs.h
tools/testing/selftests/bpf/bpf_experimental.h
Example usage:
$ make PAHOLE=/home/dxu/dev/pahole/build/pahole -j30 vmlinux
$ ./tools/bpf/bpftool/bpftool btf dump file ./vmlinux format c | rg "__ksym;" | head -3
extern void cgroup_rstat_updated(struct cgroup *cgrp, int cpu) __weak __ksym;
extern void cgroup_rstat_flush(struct cgroup *cgrp) __weak __ksym;
extern struct bpf_key *bpf_lookup_user_key(u32 serial, u64 flags) __weak __ksym;
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/bf6c08f9263c4bd9d10a717de95199d766a13f61.1718207789.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
-rw-r--r-- | tools/bpf/bpftool/btf.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index af047dedde38..6789c7a4d5ca 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c @@ -20,6 +20,8 @@ #include "json_writer.h" #include "main.h" +#define KFUNC_DECL_TAG "bpf_kfunc" + static const char * const btf_kind_str[NR_BTF_KINDS] = { [BTF_KIND_UNKN] = "UNKNOWN", [BTF_KIND_INT] = "INT", @@ -461,6 +463,49 @@ static int dump_btf_raw(const struct btf *btf, return 0; } +static int dump_btf_kfuncs(struct btf_dump *d, const struct btf *btf) +{ + LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts); + int cnt = btf__type_cnt(btf); + int i; + + printf("\n/* BPF kfuncs */\n"); + printf("#ifndef BPF_NO_KFUNC_PROTOTYPES\n"); + + for (i = 1; i < cnt; i++) { + const struct btf_type *t = btf__type_by_id(btf, i); + const char *name; + int err; + + if (!btf_is_decl_tag(t)) + continue; + + if (btf_decl_tag(t)->component_idx != -1) + continue; + + name = btf__name_by_offset(btf, t->name_off); + if (strncmp(name, KFUNC_DECL_TAG, sizeof(KFUNC_DECL_TAG))) + continue; + + t = btf__type_by_id(btf, t->type); + if (!btf_is_func(t)) + continue; + + printf("extern "); + + opts.field_name = btf__name_by_offset(btf, t->name_off); + err = btf_dump__emit_type_decl(d, t->type, &opts); + if (err) + return err; + + printf(" __weak __ksym;\n"); + } + + printf("#endif\n\n"); + + return 0; +} + static void __printf(2, 0) btf_dump_printf(void *ctx, const char *fmt, va_list args) { @@ -596,6 +641,12 @@ static int dump_btf_c(const struct btf *btf, printf("#ifndef BPF_NO_PRESERVE_ACCESS_INDEX\n"); printf("#pragma clang attribute push (__attribute__((preserve_access_index)), apply_to = record)\n"); printf("#endif\n\n"); + printf("#ifndef __ksym\n"); + printf("#define __ksym __attribute__((section(\".ksyms\")))\n"); + printf("#endif\n\n"); + printf("#ifndef __weak\n"); + printf("#define __weak __attribute__((weak))\n"); + printf("#endif\n\n"); if (root_type_cnt) { for (i = 0; i < root_type_cnt; i++) { @@ -615,6 +666,10 @@ static int dump_btf_c(const struct btf *btf, if (err) goto done; } + + err = dump_btf_kfuncs(d, btf); + if (err) + goto done; } printf("#ifndef BPF_NO_PRESERVE_ACCESS_INDEX\n"); |