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

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Message-ID: <CAPhsuW4UrhaYKj6pbAC9Cq1ZW+igFrA284nnCFsVdKdOfRpi6w@mail.gmail.com>
Date: Thu, 30 Jan 2025 09:59:19 -0800
From: Song Liu <song@...nel.org>
To: Weinan Liu <wnliu@...gle.com>
Cc: Josh Poimboeuf <jpoimboe@...nel.org>, 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

I missed this set before sending my RFC set. If this set works well, we
won't need the other set. I will give this one a try.

Thanks,
Song

On Mon, Jan 27, 2025 at 1:33 PM Weinan Liu <wnliu@...gle.com> wrote:
>
> This patchset implements a generic kernel sframe-based [1] unwinder.
> The main goal is to support reliable stacktraces on arm64.
>
> On x86 orc unwinder provides reliable stacktraces. But arm64 misses the
> required support from objtool: it cannot generate orc unwind tables for
> arm64.
>
> Currently, there's already a sframe unwinder proposed for userspace: [2].
> Since the sframe unwind table algorithm is similar, these two proposal
> could integrate common functionality in the future.
>
> There are some incomplete features or challenges:
>   - The unwinder doesn't yet work with kernel modules. The `start_addr` of
>     FRE from kernel modules doesn't appear correct, preventing us from
>     unwinding functions from kernel modules.
>   - Currently, only GCC supports sframe.
>
> Ref:
> [1]: https://sourceware.org/binutils/docs/sframe-spec.html
> [2]: https://lore.kernel.org/lkml/cover.1730150953.git.jpoimboe@kernel.org/
>
> Madhavan T. Venkataraman (1):
>   arm64: Define TIF_PATCH_PENDING for livepatch
>
> Weinan Liu (7):
>   unwind: build kernel with sframe info
>   arm64: entry: add unwind info for various kernel entries
>   unwind: add sframe v2 header
>   unwind: Implement generic sframe unwinder library
>   unwind: arm64: Add sframe unwinder on arm64
>   unwind: arm64: add reliable stacktrace support for arm64
>   arm64: Enable livepatch for ARM64
>
>  Makefile                                   |   6 +
>  arch/Kconfig                               |   8 +
>  arch/arm64/Kconfig                         |   3 +
>  arch/arm64/Kconfig.debug                   |  10 +
>  arch/arm64/include/asm/stacktrace/common.h |   6 +
>  arch/arm64/include/asm/thread_info.h       |   4 +-
>  arch/arm64/kernel/entry-common.c           |   4 +
>  arch/arm64/kernel/entry.S                  |  10 +
>  arch/arm64/kernel/setup.c                  |   2 +
>  arch/arm64/kernel/stacktrace.c             | 102 ++++++++++
>  include/asm-generic/vmlinux.lds.h          |  12 ++
>  include/linux/sframe_lookup.h              |  43 +++++
>  kernel/Makefile                            |   1 +
>  kernel/sframe.h                            | 215 +++++++++++++++++++++
>  kernel/sframe_lookup.c                     | 196 +++++++++++++++++++
>  15 files changed, 621 insertions(+), 1 deletion(-)
>  create mode 100644 include/linux/sframe_lookup.h
>  create mode 100644 kernel/sframe.h
>  create mode 100644 kernel/sframe_lookup.c
>
> --
> 2.48.1.262.g85cc9f2d1e-goog
>
>