Commit a0e5bf9f authored by Alexandre Chartre's avatar Alexandre Chartre Committed by Peter Zijlstra
Browse files

objtool: Extract code to validate instruction from the validate branch loop 



The code to validate a branch loops through all instructions of the
branch and validate each instruction. Move the code to validate an
instruction to a separated function.

Signed-off-by: default avatarAlexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Link: https://patch.msgid.link/20251121095340.464045-9-alexandre.chartre@oracle.com
parent 0bb080ba

tools/objtool/check.c

+205 −181
Original line number Diff line number Diff line
@@ -3654,47 +3654,27 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func, 
	checksum_update(func, insn, &offset, sizeof(offset));

}



/*

 * Follow the branch starting at the given instruction, and recursively follow

 * any other branches (jumps).  Meanwhile, track the frame pointer state at

 * each instruction and validate all the rules described in

 * tools/objtool/Documentation/objtool.txt.

 */

static int validate_branch(struct objtool_file *file, struct symbol *func,

			   struct instruction *insn, struct insn_state state)

			   struct instruction *insn, struct insn_state state);



static int validate_insn(struct objtool_file *file, struct symbol *func,

			 struct instruction *insn, struct insn_state *statep,

			 struct instruction *prev_insn, struct instruction *next_insn,

			 bool *dead_end)

{

	struct alternative *alt;

	struct instruction *next_insn, *prev_insn = NULL;

	u8 visited;

	int ret;



	if (func && func->ignore)

		return 0;



	while (1) {

		next_insn = next_insn_to_validate(file, insn);



		if (opts.checksum && func && insn->sec)

			checksum_update_insn(file, func, insn);



		if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {

			/* Ignore KCFI type preambles, which always fall through */

			if (is_prefix_func(func))

				return 0;



			if (file->ignore_unreachables)

				return 0;



			WARN("%s() falls through to next function %s()",

			     func->name, insn_func(insn)->name);

			func->warned = 1;



			return 1;

		}

	/*

	 * Any returns before the end of this function are effectively dead

	 * ends, i.e. validate_branch() has reached the end of the branch.

	 */

	*dead_end = true;



		visited = VISITED_BRANCH << state.uaccess;

	visited = VISITED_BRANCH << statep->uaccess;

	if (insn->visited & VISITED_BRANCH_MASK) {

			if (!insn->hint && !insn_cfi_match(insn, &state.cfi))

		if (!insn->hint && !insn_cfi_match(insn, &statep->cfi))

			return 1;



		if (insn->visited & visited)
@@ -3703,8 +3683,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 
		nr_insns_visited++;

	}



		if (state.noinstr)

			state.instr += insn->instr;

	if (statep->noinstr)

		statep->instr += insn->instr;



	if (insn->hint) {

		if (insn->restore) {
@@ -3746,15 +3726,15 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 
			nr_cfi_reused++;

		}



			state.cfi = *insn->cfi;

		statep->cfi = *insn->cfi;

	} else {

			/* XXX track if we actually changed state.cfi */

		/* XXX track if we actually changed statep->cfi */



			if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) {

		if (prev_insn && !cficmp(prev_insn->cfi, &statep->cfi)) {

			insn->cfi = prev_insn->cfi;

			nr_cfi_reused++;

		} else {

				insn->cfi = cfi_hash_find_or_add(&state.cfi);

			insn->cfi = cfi_hash_find_or_add(&statep->cfi);

		}

	}
@@ -3765,7 +3745,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 


	if (insn->alts) {

		for (alt = insn->alts; alt; alt = alt->next) {

				ret = validate_branch(file, func, alt->insn, state);

			ret = validate_branch(file, func, alt->insn, *statep);

			if (ret) {

				BT_INSN(insn, "(alt)");

				return ret;
@@ -3776,22 +3756,22 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 
	if (skip_alt_group(insn))

		return 0;



		if (handle_insn_ops(insn, next_insn, &state))

	if (handle_insn_ops(insn, next_insn, statep))

		return 1;



	switch (insn->type) {



	case INSN_RETURN:

			return validate_return(func, insn, &state);

		return validate_return(func, insn, statep);



	case INSN_CALL:

	case INSN_CALL_DYNAMIC:

			ret = validate_call(file, insn, &state);

		ret = validate_call(file, insn, statep);

		if (ret)

			return ret;



		if (opts.stackval && func && !is_special_call(insn) &&

			    !has_valid_stack_frame(&state)) {

		    !has_valid_stack_frame(statep)) {

			WARN_INSN(insn, "call without frame pointer save/setup");

			return 1;

		}
@@ -3801,13 +3781,13 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 
	case INSN_JUMP_CONDITIONAL:

	case INSN_JUMP_UNCONDITIONAL:

		if (is_sibling_call(insn)) {

				ret = validate_sibling_call(file, insn, &state);

			ret = validate_sibling_call(file, insn, statep);

			if (ret)

				return ret;



		} else if (insn->jump_dest) {

			ret = validate_branch(file, func,

						      insn->jump_dest, state);

					      insn->jump_dest, *statep);

			if (ret) {

				BT_INSN(insn, "(branch)");

				return ret;
@@ -3822,7 +3802,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 
	case INSN_JUMP_DYNAMIC:

	case INSN_JUMP_DYNAMIC_CONDITIONAL:

		if (is_sibling_call(insn)) {

				ret = validate_sibling_call(file, insn, &state);

			ret = validate_sibling_call(file, insn, statep);

			if (ret)

				return ret;

		}
@@ -3852,55 +3832,99 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 
		if (!opts.uaccess)

			break;



			if (state.uaccess) {

		if (statep->uaccess) {

			WARN_INSN(insn, "recursive UACCESS enable");

			return 1;

		}



			state.uaccess = true;

		statep->uaccess = true;

		break;



	case INSN_CLAC:

		if (!opts.uaccess)

			break;



			if (!state.uaccess && func) {

		if (!statep->uaccess && func) {

			WARN_INSN(insn, "redundant UACCESS disable");

			return 1;

		}



			if (func_uaccess_safe(func) && !state.uaccess_stack) {

		if (func_uaccess_safe(func) && !statep->uaccess_stack) {

			WARN_INSN(insn, "UACCESS-safe disables UACCESS");

			return 1;

		}



			state.uaccess = false;

		statep->uaccess = false;

		break;



	case INSN_STD:

			if (state.df) {

		if (statep->df) {

			WARN_INSN(insn, "recursive STD");

			return 1;

		}



			state.df = true;

		statep->df = true;

		break;



	case INSN_CLD:

			if (!state.df && func) {

		if (!statep->df && func) {

			WARN_INSN(insn, "redundant CLD");

			return 1;

		}



			state.df = false;

		statep->df = false;

		break;



	default:

		break;

	}



		if (insn->dead_end)

	*dead_end = insn->dead_end;



	return 0;

}



/*

 * Follow the branch starting at the given instruction, and recursively follow

 * any other branches (jumps).  Meanwhile, track the frame pointer state at

 * each instruction and validate all the rules described in

 * tools/objtool/Documentation/objtool.txt.

 */

static int validate_branch(struct objtool_file *file, struct symbol *func,

			   struct instruction *insn, struct insn_state state)

{

	struct instruction *next_insn, *prev_insn = NULL;

	bool dead_end;

	int ret;



	if (func && func->ignore)

		return 0;



	while (1) {

		next_insn = next_insn_to_validate(file, insn);



		if (opts.checksum && func && insn->sec)

			checksum_update_insn(file, func, insn);



		if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {

			/* Ignore KCFI type preambles, which always fall through */

			if (is_prefix_func(func))

				return 0;



			if (file->ignore_unreachables)

				return 0;



			WARN("%s() falls through to next function %s()",

			     func->name, insn_func(insn)->name);

			func->warned = 1;



			return 1;

		}



		ret = validate_insn(file, func, insn, &state, prev_insn, next_insn,

				    &dead_end);

		if (dead_end)

			break;



		if (!next_insn) {

			if (state.cfi.cfa.base == CFI_UNDEFINED)
@@ -3918,7 +3942,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 
		insn = next_insn;

	}



	return 0;

	return ret;

}



static int validate_unwind_hint(struct objtool_file *file,