linux-kernel - Re: [PATCH 1/2] arm64: Implement arch_stack_walk

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Message-ID: <ifqn5txrr25ffky7lxtnjtb4b2gekq5jy4fmbiwtwfvofb4wgw@py7v7xpzaqxa>
Date: Tue, 18 Mar 2025 22:39:54 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Song Liu <song@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-toolchains@...r.kernel.org, live-patching@...r.kernel.org, indu.bhagat@...cle.com, 
	puranjay@...nel.org, wnliu@...gle.com, irogers@...gle.com, joe.lawrence@...hat.com, 
	mark.rutland@....com, peterz@...radead.org, roman.gushchin@...ux.dev, 
	rostedt@...dmis.org, will@...nel.org, kernel-team@...a.com
Subject: Re: [PATCH 1/2] arm64: Implement arch_stack_walk_reliable

On Tue, Mar 18, 2025 at 08:58:52PM -0700, Song Liu wrote:
> On a closer look, I think we also need some logic in unwind_find_stack()
> so that we can see when the unwinder hits the exception boundary. For
> this reason, we may still need unwind_state.unreliable. I will look into
> fixing this and send v2.

Isn't that what FRAME_META_TYPE_PT_REGS is for?

Maybe it can just tell kunwind_stack_walk() to set a bit in
kunwind_state which tells kunwind_next_frame_record_meta() to quit the
unwind early for the FRAME_META_TYPE_PT_REGS case.  That also has the
benefit of stopping the unwind as soon as the exception is encounterd.

-- 
Josh