Commit a3493b33 authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

objtool/klp: Add --debug-checksum=<funcs> to show per-instruction checksums 



Add a --debug-checksum=<funcs> option to the check subcommand to print
the calculated checksum of each instruction in the given functions.

This is useful for determining where two versions of a function begin to
diverge.

Acked-by: default avatarPetr Mladek <pmladek@suse.com>
Tested-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent 0d83da43

tools/objtool/builtin-check.c

+6 −0
Original line number Diff line number Diff line
@@ -94,6 +94,7 @@ static const struct option check_options[] = { 
	OPT_GROUP("Options:"),

	OPT_BOOLEAN(0,		 "backtrace", &opts.backtrace, "unwind on error"),

	OPT_BOOLEAN(0,		 "backup", &opts.backup, "create backup (.orig) file on warning/error"),

	OPT_STRING(0,		 "debug-checksum", &opts.debug_checksum,  "funcs", "enable checksum debug output"),

	OPT_BOOLEAN(0,		 "dry-run", &opts.dryrun, "don't write modifications"),

	OPT_BOOLEAN(0,		 "link", &opts.link, "object is a linked object"),

	OPT_BOOLEAN(0,		 "module", &opts.module, "object is part of a kernel module"),
@@ -168,6 +169,11 @@ static bool opts_valid(void) 
	}

#endif



	if (opts.debug_checksum && !opts.checksum) {

		ERROR("--debug-checksum requires --checksum");

		return false;

	}



	if (opts.checksum		||

	    opts.hack_jump_label	||

	    opts.hack_noinstr		||

tools/objtool/check.c

+42 −0
Original line number Diff line number Diff line
@@ -3580,6 +3580,44 @@ static bool skip_alt_group(struct instruction *insn) 
	return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;

}



static int checksum_debug_init(struct objtool_file *file)

{

	char *dup, *s;



	if (!opts.debug_checksum)

		return 0;



	dup = strdup(opts.debug_checksum);

	if (!dup) {

		ERROR_GLIBC("strdup");

		return -1;

	}



	s = dup;

	while (*s) {

		struct symbol *func;

		char *comma;



		comma = strchr(s, ',');

		if (comma)

			*comma = '\0';



		func = find_symbol_by_name(file->elf, s);

		if (!func || !is_func_sym(func))

			WARN("--debug-checksum: can't find '%s'", s);

		else

			func->debug_checksum = 1;



		if (!comma)

			break;



		s = comma + 1;

	}



	free(dup);

	return 0;

}



static void checksum_update_insn(struct objtool_file *file, struct symbol *func,

				 struct instruction *insn)

{
@@ -4818,6 +4856,10 @@ int check(struct objtool_file *file) 
	cfi_hash_add(&init_cfi);

	cfi_hash_add(&func_cfi);



	ret = checksum_debug_init(file);

	if (ret)

		goto out;



	ret = decode_sections(file);

	if (ret)

		goto out;

tools/objtool/include/objtool/builtin.h

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ struct opts { 
	/* options: */

	bool backtrace;

	bool backup;

	const char *debug_checksum;

	bool dryrun;

	bool link;

	bool mnop;

tools/objtool/include/objtool/checksum.h

+1 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ static inline void checksum_update(struct symbol *func, 
				   const void *data, size_t size)

{

	XXH3_64bits_update(func->csum.state, data, size);

	dbg_checksum(func, insn, XXH3_64bits_digest(func->csum.state));

}



static inline void checksum_finish(struct symbol *func)

tools/objtool/include/objtool/elf.h

+1 −0
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ struct symbol { 
	u8 nocfi             : 1;

	u8 cold		     : 1;

	u8 prefix	     : 1;

	u8 debug_checksum    : 1;

	struct list_head pv_target;

	struct reloc *relocs;

	struct section *group_sec;