linux-kernel - [PATCH v2 01/11] objtool: Fix stack offset tracking for indirect CFAs

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Message-Id: <853d5d691b29e250333332f09b8e27410b2d9924.1587808742.git.jpoimboe@redhat.com>
Date:   Sat, 25 Apr 2020 05:03:00 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Vince Weaver <vincent.weaver@...ne.edu>,
        Dave Jones <dsj@...com>, Jann Horn <jannh@...gle.com>,
        Miroslav Benes <mbenes@...e.cz>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Joe Mario <jmario@...hat.com>
Subject: [PATCH v2 01/11] objtool: Fix stack offset tracking for indirect CFAs

When the current frame address (CFA) is stored on the stack (i.e.,
cfa->base == CFI_SP_INDIRECT), objtool neglects to adjust the stack
offset when there are subsequent pushes or pops.  This results in bad
ORC data at the end of the ENTER_IRQ_STACK macro, when it puts the
previous stack pointer on the stack and does a subsequent push.

This fixes the following unwinder warning:

  WARNING: can't dereference registers at 00000000f0a6bdba for ip interrupt_entry+0x9f/0xa0

Fixes: 627fce14809b ("objtool: Add ORC unwind table generation")
Reported-by: Vince Weaver <vincent.weaver@...ne.edu>
Reported-by: Dave Jones <dsj@...com>
Reported-by: Steven Rostedt <rostedt@...dmis.org>
Reported-by: Vegard Nossum <vegard.nossum@...cle.com>
Reported-by: Joe Mario <jmario@...hat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Reviewed-by: Miroslav Benes <mbenes@...e.cz>
---
 tools/objtool/check.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0d500767009b..0c732d586924 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1550,7 +1550,7 @@ static int update_cfi_state_regs(struct instruction *insn,
 {
 	struct cfi_reg *cfa = &cfi->cfa;
 
-	if (cfa->base != CFI_SP)
+	if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
 		return 0;
 
 	/* push */
-- 
2.21.1