objtool: Add retpoline validation (b5bc2231) · Commits · 戴 / test

scripts/Makefile.build

+4 −0

Original line number	Diff line number	Diff line
		@@ -264,6 +264,10 @@ objtool_args += --no-unreachable
		else
		objtool_args += $(call cc-ifversion, -lt, 0405, --no-unreachable)
		endif
		ifdef CONFIG_RETPOLINE
		objtool_args += --retpoline
		endif


		ifdef CONFIG_MODVERSIONS
		objtool_o = $(@D)/.tmp_$(@F)

tools/objtool/builtin-check.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -29,7 +29,7 @@
		#include "builtin.h"
		#include "check.h"

		bool no_fp, no_unreachable;
		bool no_fp, no_unreachable, retpoline;

		static const char * const check_usage[] = {
		"objtool check [<options>] file.o",
		@@ -39,6 +39,7 @@ static const char * const check_usage[] = {
		const struct option check_options[] = {
		OPT_BOOLEAN('f', "no-fp", &no_fp, "Skip frame pointer validation"),
		OPT_BOOLEAN('u', "no-unreachable", &no_unreachable, "Skip 'unreachable instruction' warnings"),
		OPT_BOOLEAN('r', "retpoline", &retpoline, "Validate retpoline assumptions"),
		OPT_END(),
		};

tools/objtool/builtin.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -20,7 +20,7 @@
		#include <subcmd/parse-options.h>

		extern const struct option check_options[];
		extern bool no_fp, no_unreachable;
		extern bool no_fp, no_unreachable, retpoline;

		extern int cmd_check(int argc, const char **argv);
		extern int cmd_orc(int argc, const char **argv);

tools/objtool/check.c

+85 −1

Original line number	Diff line number	Diff line
		@@ -497,6 +497,7 @@ static int add_jump_destinations(struct objtool_file *file)
		* disguise, so convert them accordingly.
		*/
		insn->type = INSN_JUMP_DYNAMIC;
		insn->retpoline_safe = true;
		continue;
		} else {
		/* sibling call */
		@@ -548,6 +549,7 @@ static int add_call_destinations(struct objtool_file *file)
		if (!insn->call_dest && !insn->ignore) {
		WARN_FUNC("unsupported intra-function call",
		insn->sec, insn->offset);
		if (retpoline)
		WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE.");
		return -1;
		}
		@@ -1108,6 +1110,54 @@ static int read_unwind_hints(struct objtool_file *file)
		return 0;
		}

		static int read_retpoline_hints(struct objtool_file *file)
		{
		struct section sec, relasec;
		struct instruction *insn;
		struct rela *rela;
		int i;

		sec = find_section_by_name(file->elf, ".discard.retpoline_safe");
		if (!sec)
		return 0;

		relasec = sec->rela;
		if (!relasec) {
		WARN("missing .rela.discard.retpoline_safe section");
		return -1;
		}

		if (sec->len % sizeof(unsigned long)) {
		WARN("retpoline_safe size mismatch: %d %ld", sec->len, sizeof(unsigned long));
		return -1;
		}

		for (i = 0; i < sec->len / sizeof(unsigned long); i++) {
		rela = find_rela_by_dest(sec, i * sizeof(unsigned long));
		if (!rela) {
		WARN("can't find rela for retpoline_safe[%d]", i);
		return -1;
		}

		insn = find_insn(file, rela->sym->sec, rela->addend);
		if (!insn) {
		WARN("can't find insn for retpoline_safe[%d]", i);
		return -1;
		}

		if (insn->type != INSN_JUMP_DYNAMIC &&
		insn->type != INSN_CALL_DYNAMIC) {
		WARN_FUNC("retpoline_safe hint not a indirect jump/call",
		insn->sec, insn->offset);
		return -1;
		}

		insn->retpoline_safe = true;
		}

		return 0;
		}

		static int decode_sections(struct objtool_file *file)
		{
		int ret;
		@@ -1146,6 +1196,10 @@ static int decode_sections(struct objtool_file *file)
		if (ret)
		return ret;

		ret = read_retpoline_hints(file);
		if (ret)
		return ret;

		return 0;
		}

		@@ -1891,6 +1945,29 @@ static int validate_unwind_hints(struct objtool_file *file)
		return warnings;
		}

		static int validate_retpoline(struct objtool_file *file)
		{
		struct instruction *insn;
		int warnings = 0;

		for_each_insn(file, insn) {
		if (insn->type != INSN_JUMP_DYNAMIC &&
		insn->type != INSN_CALL_DYNAMIC)
		continue;

		if (insn->retpoline_safe)
		continue;

		WARN_FUNC("indirect %s found in RETPOLINE build",
		insn->sec, insn->offset,
		insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");

		warnings++;
		}

		return warnings;
		}

		static bool is_kasan_insn(struct instruction *insn)
		{
		return (insn->type == INSN_CALL &&
		@@ -2051,6 +2128,13 @@ int check(const char *_objname, bool orc)
		if (list_empty(&file.insn_list))
		goto out;

		if (retpoline) {
		ret = validate_retpoline(&file);
		if (ret < 0)
		return ret;
		warnings += ret;
		}

		ret = validate_functions(&file);
		if (ret < 0)
		goto out;

tools/objtool/check.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -45,6 +45,7 @@ struct instruction {
		unsigned char type;
		unsigned long immediate;
		bool alt_group, visited, dead_end, ignore, hint, save, restore, ignore_alts;
		bool retpoline_safe;
		struct symbol *call_dest;
		struct instruction *jump_dest;
		struct instruction *first_jump_src;

Admin message