linux-kernel - [PATCH 2/5] objtool: More consistent use of arch_callee_saved

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Message-ID: <20210203120401.134132370@infradead.org>
Date:   Wed, 03 Feb 2021 13:02:24 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Miroslav Benes <mbenes@...e.cz>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Julien Thierry <jthierry@...hat.com>,
        Kees Cook <keescook@...omium.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org, peterz@...radead.org
Subject: [PATCH 2/5] objtool: More consistent use of arch_callee_saved_reg()

Since save_regs() will only ever set a reg when it is
arch_callee_saved_reg() all the other regs will always be unused and
are effectively scratch space.

No point in comparing them.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 tools/objtool/check.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1725,6 +1725,9 @@ static bool has_modified_stack_frame(str
 		return false;
 
 	for (i = 0; i < CFI_NUM_REGS; i++) {
+		if (!arch_callee_saved_reg(i))
+			continue;
+
 		if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
 		    cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
 			return true;
@@ -2248,6 +2251,9 @@ static bool insn_cfi_match(struct instru
 
 	} else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
 		for (i = 0; i < CFI_NUM_REGS; i++) {
+			if (!arch_callee_saved_reg(i))
+				continue;
+
 			if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
 				    sizeof(struct cfi_reg)))
 				continue;