linux-kernel - Re: [PATCH 0/8] unwind, arm64: add sframe unwinder for kernel

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Message-ID: <20250214080848.5xpi2y2omk4vxyoj@jpoimboe>
Date: Fri, 14 Feb 2025 00:08:48 -0800
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Song Liu <song@...nel.org>
Cc: Puranjay Mohan <puranjay@...nel.org>, Weinan Liu <wnliu@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Indu Bhagat <indu.bhagat@...cle.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Mark Rutland <mark.rutland@....com>, roman.gushchin@...ux.dev,
	Will Deacon <will@...nel.org>, Ian Rogers <irogers@...gle.com>,
	linux-toolchains@...r.kernel.org, linux-kernel@...r.kernel.org,
	live-patching@...r.kernel.org, joe.lawrence@...hat.com,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/8] unwind, arm64: add sframe unwinder for kernel

On Thu, Feb 13, 2025 at 11:40:43AM -0800, Song Liu wrote:
> Yeah, objdump does show the same disassembly. However, if
> I open the file with gdb, and do "disassemble copy_process",
> the one in livepatch-special-static.o looks very weird.

The symbol table looks ok.  I'm not sure why gdb is getting confused,
but that could possibly be a red herring.  Maybe it doesn't like the
-ffunction-sections for some reason.

It's really weird the function length reported by kallsyms is so wrong.
Can you share the .ko?

The refcount warning might indicate it's passing some bogus memory to
tty_kref_get().  Any chance you have struct randomization enabled?

Are you sure there's no code or .config mismatch between the built
kernel and the running kernel?

Ignorant arm64 question: is the module's text further away from slab
memory than vmlinux text, thus requiring a different instruction (or
GOT/TOC) to access memory further away in the address space?

-- 
Josh