Commit 70589843 authored by Alexandre Chartre's avatar Alexandre Chartre Committed by Peter Zijlstra
Browse files

objtool: Add option to trace function validation 



Add an option to trace and have information during the validation
of specified functions. Functions are specified with the --trace
option which can be a single function name (e.g. --trace foo to
trace the function with the name "foo"), or a shell wildcard
pattern (e.g. --trace foo* to trace all functions with a name
starting with "foo").

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/20251121095340.464045-11-alexandre.chartre@oracle.com
parent de0248fb

tools/objtool/Build

+1 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ objtool-y += elf.o 
objtool-y += objtool.o



objtool-$(BUILD_DISAS) += disas.o

objtool-$(BUILD_DISAS) += trace.o



objtool-$(BUILD_ORC) += orc_gen.o orc_dump.o

objtool-$(BUILD_KLP) += builtin-klp.o klp-diff.o klp-post-link.o

tools/objtool/builtin-check.c

+1 −0
Original line number Diff line number Diff line
@@ -103,6 +103,7 @@ static const struct option check_options[] = { 
	OPT_STRING('o',		 "output", &opts.output, "file", "output file name"),

	OPT_BOOLEAN(0,		 "sec-address", &opts.sec_address, "print section addresses in warnings"),

	OPT_BOOLEAN(0,		 "stats", &opts.stats, "print statistics"),

	OPT_STRING(0,		 "trace", &opts.trace, "func", "trace function validation"),

	OPT_BOOLEAN('v',	 "verbose", &opts.verbose, "verbose warnings"),

	OPT_BOOLEAN(0,		 "werror", &opts.werror, "return error on warnings"),

tools/objtool/check.c

+87 −17
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
 */



#define _GNU_SOURCE /* memmem() */

#include <fnmatch.h>

#include <string.h>

#include <stdlib.h>

#include <inttypes.h>
@@ -15,6 +16,7 @@ 
#include <objtool/disas.h>

#include <objtool/check.h>

#include <objtool/special.h>

#include <objtool/trace.h>

#include <objtool/warn.h>

#include <objtool/checksum.h>

#include <objtool/util.h>
@@ -37,7 +39,9 @@ static struct cfi_state init_cfi; 
static struct cfi_state func_cfi;

static struct cfi_state force_undefined_cfi;



static size_t sym_name_max_len;

struct disas_context *objtool_disas_ctx;



size_t sym_name_max_len;



struct instruction *find_insn(struct objtool_file *file,

			      struct section *sec, unsigned long offset)
@@ -3556,8 +3560,10 @@ static bool skip_alt_group(struct instruction *insn) 
		return false;



	/* ANNOTATE_IGNORE_ALTERNATIVE */

	if (insn->alt_group->ignore)

	if (insn->alt_group->ignore) {

		TRACE_INSN(insn, "alt group ignored");

		return true;

	}



	/*

	 * For NOP patched with CLAC/STAC, only follow the latter to avoid
@@ -3663,6 +3669,8 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func, 


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

			   struct instruction *insn, struct insn_state state);

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

			      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,
@@ -3684,8 +3692,10 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
		if (!insn->hint && !insn_cfi_match(insn, &statep->cfi))

			return 1;



		if (insn->visited & visited)

		if (insn->visited & visited) {

			TRACE_INSN(insn, "already visited");

			return 0;

		}

	} else {

		nr_insns_visited++;

	}
@@ -3722,8 +3732,10 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
				 * It will be seen later via the

				 * straight-line path.

				 */

				if (!prev_insn)

				if (!prev_insn) {

					TRACE_INSN(insn, "defer restore");

					return 0;

				}



				WARN_INSN(insn, "objtool isn't smart enough to handle this CFI save/restore combo");

				return 1;
@@ -3751,13 +3763,23 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
		return 1;



	if (insn->alts) {

		int i, num_alts;



		num_alts = 0;

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

			num_alts++;



		i = 1;

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

			TRACE_INSN(insn, "alternative %d/%d", i, num_alts);

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

			if (ret) {

				BT_INSN(insn, "(alt)");

				return ret;

			}

			i++;

		}

		TRACE_INSN(insn, "alternative DEFAULT");

	}



	if (skip_alt_group(insn))
@@ -3769,10 +3791,16 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
	switch (insn->type) {



	case INSN_RETURN:

		TRACE_INSN(insn, "return");

		return validate_return(func, insn, statep);



	case INSN_CALL:

	case INSN_CALL_DYNAMIC:

		if (insn->type == INSN_CALL)

			TRACE_INSN(insn, "call");

		else

			TRACE_INSN(insn, "indirect call");



		ret = validate_call(file, insn, statep);

		if (ret)

			return ret;
@@ -3788,13 +3816,18 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
	case INSN_JUMP_CONDITIONAL:

	case INSN_JUMP_UNCONDITIONAL:

		if (is_sibling_call(insn)) {

			TRACE_INSN(insn, "sibling call");

			ret = validate_sibling_call(file, insn, statep);

			if (ret)

				return ret;



		} else if (insn->jump_dest) {

			ret = validate_branch(file, func,

					      insn->jump_dest, *statep);

			if (insn->type == INSN_JUMP_UNCONDITIONAL)

				TRACE_INSN(insn, "unconditional jump");

			else

				TRACE_INSN(insn, "jump taken");



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

			if (ret) {

				BT_INSN(insn, "(branch)");

				return ret;
@@ -3804,10 +3837,12 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
		if (insn->type == INSN_JUMP_UNCONDITIONAL)

			return 0;



		TRACE_INSN(insn, "jump not taken");

		break;



	case INSN_JUMP_DYNAMIC:

	case INSN_JUMP_DYNAMIC_CONDITIONAL:

		TRACE_INSN(insn, "indirect jump");

		if (is_sibling_call(insn)) {

			ret = validate_sibling_call(file, insn, statep);

			if (ret)
@@ -3820,6 +3855,7 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
		break;



	case INSN_SYSCALL:

		TRACE_INSN(insn, "syscall");

		if (func && (!next_insn || !next_insn->hint)) {

			WARN_INSN(insn, "unsupported instruction in callable function");

			return 1;
@@ -3828,6 +3864,7 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
		break;



	case INSN_SYSRET:

		TRACE_INSN(insn, "sysret");

		if (func && (!next_insn || !next_insn->hint)) {

			WARN_INSN(insn, "unsupported instruction in callable function");

			return 1;
@@ -3836,6 +3873,7 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
		return 0;



	case INSN_STAC:

		TRACE_INSN(insn, "stac");

		if (!opts.uaccess)

			break;
@@ -3848,6 +3886,7 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
		break;



	case INSN_CLAC:

		TRACE_INSN(insn, "clac");

		if (!opts.uaccess)

			break;
@@ -3865,6 +3904,7 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
		break;



	case INSN_STD:

		TRACE_INSN(insn, "std");

		if (statep->df) {

			WARN_INSN(insn, "recursive STD");

			return 1;
@@ -3874,6 +3914,7 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
		break;



	case INSN_CLD:

		TRACE_INSN(insn, "cld");

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

			WARN_INSN(insn, "redundant CLD");

			return 1;
@@ -3886,8 +3927,10 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
		break;

	}



	*dead_end = insn->dead_end;

	if (insn->dead_end)

		TRACE_INSN(insn, "dead end");



	*dead_end = insn->dead_end;

	return 0;

}
@@ -3897,7 +3940,7 @@ static int validate_insn(struct objtool_file *file, struct symbol *func, 
 * 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,

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

			      struct instruction *insn, struct insn_state state)

{

	struct instruction *next_insn, *prev_insn = NULL;
@@ -3907,7 +3950,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 
	if (func && func->ignore)

		return 0;



	while (1) {

	do {

		insn->trace = 0;

		next_insn = next_insn_to_validate(file, insn);



		if (opts.checksum && func && insn->sec)
@@ -3930,10 +3974,15 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 


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

				    &dead_end);

		if (dead_end)

			break;



		if (!next_insn) {

		if (!insn->trace) {

			if (ret)

				TRACE_INSN(insn, "warning (%d)", ret);

			else

				TRACE_INSN(insn, NULL);

		}



		if (!dead_end && !next_insn) {

			if (state.cfi.cfa.base == CFI_UNDEFINED)

				return 0;

			if (file->ignore_unreachables)
@@ -3947,8 +3996,21 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 


		prev_insn = insn;

		insn = next_insn;



	} while (!dead_end);



	return ret;

}



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

			   struct instruction *insn, struct insn_state state)

{

	int ret;



	trace_depth_inc();

	ret = do_validate_branch(file, func, insn, state);

	trace_depth_dec();



	return ret;

}
@@ -4408,10 +4470,18 @@ static int validate_symbol(struct objtool_file *file, struct section *sec, 
	if (opts.checksum)

		checksum_init(func);



	if (opts.trace && !fnmatch(opts.trace, sym->name, 0)) {

		trace_enable();

		TRACE("%s: validation begin\n", sym->name);

	}



	ret = validate_branch(file, func, insn, *state);

	if (ret)

		BT_INSN(insn, "<=== (sym)");



	TRACE("%s: validation %s\n\n", sym->name, ret ? "failed" : "end");

	trace_disable();



	if (opts.checksum)

		checksum_finish(func);
@@ -4823,8 +4893,6 @@ static void free_insns(struct objtool_file *file) 
		free(chunk->addr);

}



static struct disas_context *objtool_disas_ctx;



const char *objtool_disas_insn(struct instruction *insn)

{

	struct disas_context *dctx = objtool_disas_ctx;
@@ -4846,8 +4914,10 @@ int check(struct objtool_file *file) 
	 * disassembly context to disassemble instruction or function

	 * on warning or backtrace.

	 */

	if (opts.verbose || opts.backtrace) {

	if (opts.verbose || opts.backtrace || opts.trace) {

		disas_ctx = disas_context_create(file);

		if (!disas_ctx)

			opts.trace = false;

		objtool_disas_ctx = disas_ctx;

	}

tools/objtool/disas.c

+115 −0
Original line number Diff line number Diff line
@@ -308,6 +308,121 @@ char *disas_result(struct disas_context *dctx) 
	return dctx->result;

}



#define DISAS_INSN_OFFSET_SPACE		10

#define DISAS_INSN_SPACE		60



/*

 * Print a message in the instruction flow. If insn is not NULL then

 * the instruction address is printed in addition of the message,

 * otherwise only the message is printed. In all cases, the instruction

 * itself is not printed.

 */

static int disas_vprint(FILE *stream, struct section *sec, unsigned long offset,

			int depth, const char *format, va_list ap)

{

	const char *addr_str;

	int i, n;

	int len;



	len = sym_name_max_len + DISAS_INSN_OFFSET_SPACE;

	if (depth < 0) {

		len += depth;

		depth = 0;

	}



	n = 0;



	if (sec) {

		addr_str = offstr(sec, offset);

		n += fprintf(stream, "%6lx:  %-*s  ", offset, len, addr_str);

		free((char *)addr_str);

	} else {

		len += DISAS_INSN_OFFSET_SPACE + 1;

		n += fprintf(stream, "%-*s", len, "");

	}



	/* print vertical bars to show the code flow */

	for (i = 0; i < depth; i++)

		n += fprintf(stream, "| ");



	if (format)

		n += vfprintf(stream, format, ap);



	return n;

}



/*

 * Print a message in the instruction flow. If insn is not NULL then

 * the instruction address is printed in addition of the message,

 * otherwise only the message is printed. In all cases, the instruction

 * itself is not printed.

 */

void disas_print_info(FILE *stream, struct instruction *insn, int depth,

		      const char *format, ...)

{

	struct section *sec;

	unsigned long off;

	va_list args;



	if (insn) {

		sec = insn->sec;

		off = insn->offset;

	} else {

		sec = NULL;

		off = 0;

	}



	va_start(args, format);

	disas_vprint(stream, sec, off, depth, format, args);

	va_end(args);

}



/*

 * Print an instruction address (offset and function), the instruction itself

 * and an optional message.

 */

void disas_print_insn(FILE *stream, struct disas_context *dctx,

		      struct instruction *insn, int depth,

		      const char *format, ...)

{

	char fake_nop_insn[32];

	const char *insn_str;

	bool fake_nop;

	va_list args;

	int len;



	/*

	 * Alternative can insert a fake nop, sometimes with no

	 * associated section so nothing to disassemble.

	 */

	fake_nop = (!insn->sec && insn->type == INSN_NOP);

	if (fake_nop) {

		snprintf(fake_nop_insn, 32, "<fake nop> (%d bytes)", insn->len);

		insn_str = fake_nop_insn;

	} else {

		disas_insn(dctx, insn);

		insn_str = disas_result(dctx);

	}



	/* print the instruction */

	len = (depth + 1) * 2 < DISAS_INSN_SPACE ? DISAS_INSN_SPACE - (depth+1) * 2 : 1;

	disas_print_info(stream, insn, depth, "%-*s", len, insn_str);



	/* print message if any */

	if (!format)

		return;



	if (strcmp(format, "\n") == 0) {

		fprintf(stream, "\n");

		return;

	}



	fprintf(stream, " - ");

	va_start(args, format);

	vfprintf(stream, format, args);

	va_end(args);

}



/*

 * Disassemble a single instruction. Return the size of the instruction.

 */

tools/objtool/include/objtool/builtin.h

+1 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ struct opts { 
	const char *output;

	bool sec_address;

	bool stats;

	const char *trace;

	bool verbose;

	bool werror;

};