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Date:   Fri, 22 Jan 2021 17:43:42 +0000
From:   Mark Brown <broonie@kernel.org>
To:     Josh Poimboeuf <jpoimboe@redhat.com>
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Julien Thierry <jthierry@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Mark Rutland <mark.rutland@arm.com>,
        linux-efi <linux-efi@vger.kernel.org>,
        linux-hardening@vger.kernel.org, live-patching@vger.kernel.org
Subject: Re: [RFC PATCH 00/17] objtool: add base support for arm64
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On Thu, Jan 21, 2021 at 12:54:52PM -0600, Josh Poimboeuf wrote:

> 2) The shadow stack idea sounds promising -- how hard would it be to
>    make a prototype reliable unwinder?

In theory it doesn't look too hard and I can't see a particular reason
not to try doing this - there's going to be edge cases but hopefully for
reliable stack trace they're all in areas where we would be happy to
just decide the stack isn't reliable anyway, things like nesting which
allocates separate shadow stacks for each nested level for example.
I'll take a look.

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