Commit 753da417 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Peter Zijlstra
Browse files

objtool: Remove --lto and --vmlinux in favor of --link 



The '--lto' option is a confusing way of telling objtool to do stack
validation despite it being a linked object.  It's no longer needed now
that an explicit '--stackval' option exists.  The '--vmlinux' option is
also redundant.

Remove both options in favor of a straightforward '--link' option which
identifies a linked object.

Also, implicitly set '--link' with a warning if the user forgets to do
so and we can tell that it's a linked object.  This makes it easier for
manual vmlinux runs.

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarMiroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/dcd3ceffd15a54822c6183e5766d21ad06082b45.1650300597.git.jpoimboe@redhat.com
parent 489e355b

scripts/Makefile.build

+3 −1
Original line number Diff line number Diff line
@@ -229,7 +229,7 @@ objtool := $(objtree)/tools/objtool/objtool 
objtool_args =								\

	$(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label)	\

	$(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr)		\

	$(if $(CONFIG_X86_KERNEL_IBT), --lto --ibt)			\

	$(if $(CONFIG_X86_KERNEL_IBT), --ibt)				\

	$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount)		\

	$(if $(CONFIG_UNWINDER_ORC), --orc)				\

	$(if $(CONFIG_RETPOLINE), --retpoline)				\
@@ -237,6 +237,7 @@ objtool_args = \ 
	$(if $(CONFIG_STACK_VALIDATION), --stackval)			\

	$(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call)		\

	$(if $(CONFIG_X86_SMAP), --uaccess)				\

	$(if $(linked-object), --link)					\

	$(if $(part-of-module), --module)				\

	$(if $(CONFIG_GCOV_KERNEL), --no-unreachable)
@@ -306,6 +307,7 @@ quiet_cmd_cc_prelink_modules = LD [M] $@ 
# modules into native code

$(obj)/%.prelink.o: objtool-enabled = y

$(obj)/%.prelink.o: part-of-module := y

$(obj)/%.prelink.o: linked-object := y



$(obj)/%.prelink.o: $(obj)/%.o FORCE

	$(call if_changed,cc_prelink_modules)

scripts/link-vmlinux.sh

+3 −5
Original line number Diff line number Diff line
@@ -114,8 +114,8 @@ objtool_link() 


	if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then



		# Don't perform vmlinux validation unless explicitly requested,

		# but run objtool on vmlinux.o now that we have an object file.

		# For LTO and IBT, objtool doesn't run on individual

		# translation units.  Run everything on vmlinux instead.



		if is_enabled CONFIG_HAVE_JUMP_LABEL_HACK; then

			objtoolopt="${objtoolopt} --hacks=jump_label"
@@ -156,8 +156,6 @@ objtool_link() 
		if is_enabled CONFIG_X86_SMAP; then

			objtoolopt="${objtoolopt} --uaccess"

		fi



		objtoolopt="${objtoolopt} --lto"

	fi



	if is_enabled CONFIG_NOINSTR_VALIDATION; then
@@ -170,7 +168,7 @@ objtool_link() 
			objtoolopt="${objtoolopt} --no-unreachable"

		fi



		objtoolopt="${objtoolopt} --vmlinux"

		objtoolopt="${objtoolopt} --link"



		info OBJTOOL ${1}

		tools/objtool/objtool ${objtoolopt} ${1}

tools/objtool/builtin-check.c

+35 −4
Original line number Diff line number Diff line
@@ -9,6 +9,11 @@ 
#include <objtool/builtin.h>

#include <objtool/objtool.h>



#define ERROR(format, ...)				\

	fprintf(stderr,					\

		"error: objtool: " format "\n",		\

		##__VA_ARGS__)



struct opts opts;



static const char * const check_usage[] = {
@@ -73,12 +78,11 @@ const struct option check_options[] = { 
	OPT_BOOLEAN(0, "backtrace", &opts.backtrace, "unwind on error"),

	OPT_BOOLEAN(0, "backup", &opts.backup, "create .orig files before modification"),

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

	OPT_BOOLEAN(0, "lto", &opts.lto, "whole-archive like runs"),

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

	OPT_BOOLEAN(0, "module", &opts.module, "object is part of a kernel module"),

	OPT_BOOLEAN(0, "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),

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

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

	OPT_BOOLEAN(0, "vmlinux", &opts.vmlinux, "vmlinux.o validation"),



	OPT_END(),

};
@@ -124,7 +128,7 @@ static bool opts_valid(void) 
	    opts.static_call		||

	    opts.uaccess) {

		if (opts.dump_orc) {

			fprintf(stderr, "--dump can't be combined with other options\n");

			ERROR("--dump can't be combined with other options");

			return false;

		}
@@ -134,10 +138,34 @@ static bool opts_valid(void) 
	if (opts.dump_orc)

		return true;



	fprintf(stderr, "At least one command required\n");

	ERROR("At least one command required");

	return false;

}



static bool link_opts_valid(struct objtool_file *file)

{

	if (opts.link)

		return true;



	if (has_multiple_files(file->elf)) {

		ERROR("Linked object detected, forcing --link");

		opts.link = true;

		return true;

	}



	if (opts.noinstr) {

		ERROR("--noinstr requires --link");

		return false;

	}



	if (opts.ibt) {

		ERROR("--ibt requires --link");

		return false;

	}



	return true;

}



int objtool_run(int argc, const char **argv)

{

	const char *objname;
@@ -157,6 +185,9 @@ int objtool_run(int argc, const char **argv) 
	if (!file)

		return 1;



	if (!link_opts_valid(file))

		return 1;



	ret = check(file);

	if (ret)

		return ret;

tools/objtool/check.c

+14 −26
Original line number Diff line number Diff line
@@ -263,7 +263,8 @@ static void init_cfi_state(struct cfi_state *cfi) 
	cfi->drap_offset = -1;

}



static void init_insn_state(struct insn_state *state, struct section *sec)

static void init_insn_state(struct objtool_file *file, struct insn_state *state,

			    struct section *sec)

{

	memset(state, 0, sizeof(*state));

	init_cfi_state(&state->cfi);
@@ -273,7 +274,7 @@ static void init_insn_state(struct insn_state *state, struct section *sec) 
	 * not correctly determine insn->call_dest->sec (external symbols do

	 * not have a section).

	 */

	if (opts.vmlinux && opts.noinstr && sec)

	if (opts.link && opts.noinstr && sec)

		state->noinstr = sec->noinstr;

}
@@ -3405,7 +3406,7 @@ static int validate_unwind_hints(struct objtool_file *file, struct section *sec) 
	if (!file->hints)

		return 0;



	init_insn_state(&state, sec);

	init_insn_state(file, &state, sec);



	if (sec) {

		insn = find_insn(file, sec, 0);
@@ -3491,14 +3492,14 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio 
		return true;



	/*

	 * Whole archive runs might encounder dead code from weak symbols.

	 * Whole archive runs might encounter dead code from weak symbols.

	 * This is where the linker will have dropped the weak symbol in

	 * favour of a regular symbol, but leaves the code in place.

	 *

	 * In this case we'll find a piece of code (whole function) that is not

	 * covered by a !section symbol. Ignore them.

	 */

	if (!insn->func && opts.lto) {

	if (opts.link && !insn->func) {

		int size = find_symbol_hole_containing(insn->sec, insn->offset);

		unsigned long end = insn->offset + size;
@@ -3620,7 +3621,7 @@ static int validate_section(struct objtool_file *file, struct section *sec) 
		if (func->type != STT_FUNC)

			continue;



		init_insn_state(&state, sec);

		init_insn_state(file, &state, sec);

		set_func_state(&state.cfi);



		warnings += validate_symbol(file, sec, func, &state);
@@ -3629,7 +3630,7 @@ static int validate_section(struct objtool_file *file, struct section *sec) 
	return warnings;

}



static int validate_vmlinux_functions(struct objtool_file *file)

static int validate_noinstr_sections(struct objtool_file *file)

{

	struct section *sec;

	int warnings = 0;
@@ -3890,16 +3891,6 @@ int check(struct objtool_file *file) 
{

	int ret, warnings = 0;



	if (opts.lto && !(opts.vmlinux || opts.module)) {

		fprintf(stderr, "--lto requires: --vmlinux or --module\n");

		return 1;

	}



	if (opts.ibt && !opts.lto) {

		fprintf(stderr, "--ibt requires: --lto\n");

		return 1;

	}



	arch_initial_func_cfi_state(&initial_func_cfi);

	init_cfi_state(&init_cfi);

	init_cfi_state(&func_cfi);
@@ -3920,15 +3911,6 @@ int check(struct objtool_file *file) 
	if (list_empty(&file->insn_list))

		goto out;



	if (opts.vmlinux && !opts.lto) {

		ret = validate_vmlinux_functions(file);

		if (ret < 0)

			goto out;



		warnings += ret;

		goto out;

	}



	if (opts.retpoline) {

		ret = validate_retpoline(file);

		if (ret < 0)
@@ -3953,6 +3935,12 @@ int check(struct objtool_file *file) 
				goto out;

			warnings += ret;

		}



	} else if (opts.noinstr) {

		ret = validate_noinstr_sections(file);

		if (ret < 0)

			goto out;

		warnings += ret;

	}



	if (opts.ibt) {

tools/objtool/elf.c

+3 −0
Original line number Diff line number Diff line
@@ -377,6 +377,9 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym) 
	sym->type = GELF_ST_TYPE(sym->sym.st_info);

	sym->bind = GELF_ST_BIND(sym->sym.st_info);



	if (sym->type == STT_FILE)

		elf->num_files++;



	sym->offset = sym->sym.st_value;

	sym->len = sym->sym.st_size;