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bpftool: Provide a helper method for accessing skeleton's embedded ELF data 

This adds a skeleton method X__elf_bytes() which returns the binary data of
the compiled and embedded BPF object file. It additionally sets the size of
the return data to the provided size_t pointer argument.

The assignment to s->data is cast to void * to ensure no warning is issued if
compiled with a previous version of libbpf where the bpf_object_skeleton field
is void * instead of const void *

Signed-off-by: Matt Smith <alastorze@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210901194439.3853238-3-alastorze@fb.com
This commit is contained in:
Matt Smith 2021-09-01 12:44:38 -07:00 committed by Andrii Nakryiko
parent 08a6f22ef6
commit a6cc6b34b9
1 changed files with 19 additions and 12 deletions
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31
tools/bpf/bpftool/gen.c
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@ -238,8 +238,8 @@ static void codegen(const char *template, ...)
} else if (c == '\n') {
break;
} else {
p_err("unrecognized character at pos %td in template '%s'",
src - template - 1, template);
p_err("unrecognized character at pos %td in template '%s': '%c'",
src - template - 1, template, c);
free(s);
exit(-1);
}
@ -406,7 +406,7 @@ static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
}
bpf_object__for_each_map(map, obj) {
const char * ident;
const char *ident;
ident = get_map_ident(map);
if (!ident)
@ -862,6 +862,8 @@ static int do_skeleton(int argc, char **argv)
codegen("\
\n\
\n\
static inline const void *%1$s__elf_bytes(size_t *sz); \n\
\n\
static inline int \n\
%1$s__create_skeleton(struct %1$s *obj) \n\
{ \n\
@ -943,10 +945,20 @@ static int do_skeleton(int argc, char **argv)
codegen("\
\n\
\n\
s->data_sz = %d; \n\
s->data = (void *)\"\\ \n\
",
file_sz);
s->data = (void *)%2$s__elf_bytes(&s->data_sz); \n\
\n\
return 0; \n\
err: \n\
bpf_object__destroy_skeleton(s); \n\
return -ENOMEM; \n\
} \n\
\n\
static inline const void *%2$s__elf_bytes(size_t *sz) \n\
{ \n\
*sz = %1$d; \n\
return (const void *)\"\\ \n\
"
, file_sz, obj_name);
/* embed contents of BPF object file */
print_hex(obj_data, file_sz);
@ -954,11 +966,6 @@ static int do_skeleton(int argc, char **argv)
codegen("\
\n\
\"; \n\
\n\
return 0; \n\
err: \n\
bpf_object__destroy_skeleton(s); \n\
return -ENOMEM; \n\
} \n\
\n\
#endif /* %s */ \n\