objtool: Make stack validation frame-pointer-specific

Now that CONFIG_STACK_VALIDATION is frame-pointer specific, do the same
for the '--stackval' option.  Now the '--no-fp' option is redundant and
can be removed.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/f563fa064b3b63d528de250c72012d49e14742a3.1650300597.git.jpoimboe@redhat.com

scripts/Makefile.build

@@ -235,7 +235,6 @@ objtool_args =								\
 	$(if $(CONFIG_STACK_VALIDATION), --stackval)			\
 	$(if $(CONFIG_X86_SMAP), --uaccess)				\
 	$(if $(part-of-module), --module)				\
-	$(if $(CONFIG_FRAME_POINTER),, --no-fp)				\
 	$(if $(CONFIG_GCOV_KERNEL), --no-unreachable)
 
 cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)

scripts/link-vmlinux.sh

@@ -155,10 +155,6 @@ objtool_link()
 
 	if [ -n "${objtoolopt}" ]; then
 
-		if ! is_enabled CONFIG_FRAME_POINTER; then
-			objtoolopt="${objtoolopt} --no-fp"
-		fi
-
 		if is_enabled CONFIG_GCOV_KERNEL; then
 			objtoolopt="${objtoolopt} --no-unreachable"
 		fi

tools/objtool/builtin-check.c

@@ -39,7 +39,7 @@ const struct option check_options[] = {
 	OPT_BOOLEAN('o', "orc", &opts.orc, "generate ORC metadata"),
 	OPT_BOOLEAN('r', "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
 	OPT_BOOLEAN('l', "sls", &opts.sls, "validate straight-line-speculation mitigations"),
-	OPT_BOOLEAN('s', "stackval", &opts.stackval, "validate stack unwinding rules"),
+	OPT_BOOLEAN('s', "stackval", &opts.stackval, "validate frame pointer rules"),
 	OPT_BOOLEAN('u', "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"),
 	OPT_CALLBACK_OPTARG(0, "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
 
@@ -49,7 +49,6 @@ const struct option check_options[] = {
 	OPT_BOOLEAN(0, "dry-run", &opts.dryrun, "don't write modifications"),
 	OPT_BOOLEAN(0, "lto", &opts.lto, "whole-archive like runs"),
 	OPT_BOOLEAN(0, "module", &opts.module, "object is part of a kernel module"),
-	OPT_BOOLEAN(0, "no-fp", &opts.no_fp, "skip frame pointer validation"),
 	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"),

tools/objtool/check.c

@@ -2806,7 +2806,7 @@ static int update_cfi_state(struct instruction *insn,
 		}
 
 		/* detect when asm code uses rbp as a scratch register */
-		if (!opts.no_fp && insn->func && op->src.reg == CFI_BP &&
+		if (opts.stackval && insn->func && op->src.reg == CFI_BP &&
 		    cfa->base != CFI_BP)
 			cfi->bp_scratch = true;
 		break;
@@ -3279,7 +3279,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 			if (ret)
 				return ret;
 
-			if (!opts.no_fp && func && !is_fentry_call(insn) &&
+			if (opts.stackval && func && !is_fentry_call(insn) &&
 			    !has_valid_stack_frame(&state)) {
 				WARN_FUNC("call without frame pointer save/setup",
 					  sec, insn->offset);

tools/objtool/include/objtool/builtin.h

@@ -27,7 +27,6 @@ struct opts {
 	bool dryrun;
 	bool lto;
 	bool module;
-	bool no_fp;
 	bool no_unreachable;
 	bool sec_address;
 	bool stats;