Commit a6cc6b34 authored by Matt Smith's avatar Matt Smith Committed by Andrii Nakryiko
Browse files

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: default avatarMatt Smith <alastorze@fb.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210901194439.3853238-3-alastorze@fb.com
parent 08a6f22e

tools/bpf/bpftool/gen.c

+19 −12
Original line number Diff line number Diff line
@@ -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);

		}
@@ -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\