linux-kernel - [PATCH] Revert "objtool: Support addition to set CFA base"

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Message-Id: <c00ee7bc5791229d6db22e9485b9c65cba0e83c6.1681320526.git.jpoimboe@kernel.org>
Date:   Wed, 12 Apr 2023 10:29:01 -0700
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Miroslav Benes <mbenes@...e.cz>,
        kernel test robot <lkp@...el.com>
Subject: [PATCH] Revert "objtool: Support addition to set CFA base"

Commit 468af56a7bba ("objtool: Support addition to set CFA base") was
added as a preparatory patch for arm64 support, but that support never
came.  It triggers a false positive warning on x86, so just revert it
for now.

Fixes the following warning:

  vmlinux.o: warning: objtool: cdce925_regmap_i2c_write+0xdb: stack state mismatch: cfa1=4+120 cfa2=5+40

Fixes: 468af56a7bba ("objtool: Support addition to set CFA base")
Reported-by: kernel test robot <lkp@...el.com>
Link: https://lore.kernel.org/oe-kbuild-all/202304080538.j5G6h1AB-lkp@intel.com/
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 tools/objtool/check.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 34bd6a11bddd..7b78ffdc55fe 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2978,17 +2978,6 @@ static int update_cfi_state(struct instruction *insn,
 				break;
 			}
 
-			if (!cfi->drap && op->src.reg == CFI_SP &&
-			    op->dest.reg == CFI_BP && cfa->base == CFI_SP &&
-			    check_reg_frame_pos(&regs[CFI_BP], -cfa->offset + op->src.offset)) {
-
-				/* lea disp(%rsp), %rbp */
-				cfa->base = CFI_BP;
-				cfa->offset -= op->src.offset;
-				cfi->bp_scratch = false;
-				break;
-			}
-
 			if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
 
 				/* drap: lea disp(%rsp), %drap */
-- 
2.39.2