linux-kernel - [PATCH 0/2] x86 unwind fixes (1 unwinder fix, 1 missing entry ORC annotation)

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Message-Id: <20250325-2025-03-unwind-fixes-v1-0-acd774364768@google.com>
Date: Tue, 25 Mar 2025 03:01:21 +0100
From: Jann Horn <jannh@...gle.com>
To: x86@...nel.org, Andy Lutomirski <luto@...nel.org>, 
 Josh Poimboeuf <jpoimboe@...nel.org>, Peter Zijlstra <peterz@...radead.org>
Cc: linux-kernel@...r.kernel.org, 
 Dominik Brodowski <linux@...inikbrodowski.net>, 
 Ingo Molnar <mingo@...nel.org>, Oleg Nesterov <oleg@...hat.com>, 
 Vernon Lovejoy <vlovejoy@...hat.com>, Jann Horn <jannh@...gle.com>
Subject: [PATCH 0/2] x86 unwind fixes (1 unwinder fix, 1 missing entry ORC
 annotation)

While doing some kernel development, I managed to cause a recursive #PF
ending in a #DF, as one does... Thanks Andy for adding guard stacks and
such nice error handling for them years ago.

Unfortunately, instead of a nice stack trace, I just got a pile of guess
unwind lines, caused by two bugs.

Here are fixes I came up with for these issues. The issues were
introduced in 2018 and 2023 - if nobody else noticed them since then,
I guess the fixes aren't particularly urgent.

To: Andy Lutomirski <luto@...nel.org>

Cc: Dominik Brodowski <linux@...inikbrodowski.net>
Cc: Ingo Molnar <mingo@...nel.org>

To: Josh Poimboeuf <jpoimboe@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>

Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Vernon Lovejoy <vlovejoy@...hat.com>

Signed-off-by: Jann Horn <jannh@...gle.com>
---
Jann Horn (2):
      x86/entry: Fix ORC for PUSH_REGS with save_ret=1
      x86/dumpstack: Fix broken unwinding from exception stacks

 arch/x86/entry/calling.h    | 2 ++
 arch/x86/kernel/dumpstack.c | 5 ++---
 2 files changed, 4 insertions(+), 3 deletions(-)
---
base-commit: bcb044256d3f5d9f5bb61d1eac6492f77883bd60
change-id: 20250325-2025-03-unwind-fixes-a367c54be822

-- 
Jann Horn <jannh@...gle.com>