From: Nick Desaulniers <ndesaulniers@google.com>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Bill Wendling <morbo@google.com>,
linux-efi <linux-efi@vger.kernel.org>,
Julien Thierry <jthierry@redhat.com>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Peter Zijlstra <peterz@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Yonghyun Hwang <yonghyun@google.com>,
LKML <linux-kernel@vger.kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
raphael.gault@arm.com, Mark Brown <broonie@kernel.org>,
linux-hardening@vger.kernel.org, Pete Swain <swine@google.com>,
live-patching@vger.kernel.org, Will Deacon <will@kernel.org>,
Ard Biesheuvel <ardb@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Kees Cook <keescook@chromium.org>
Subject: Re: [RFC PATCH 12/17] gcc-plugins: objtool: Add plugin to detect switch table on arm64
Date: Tue, 2 Feb 2021 15:52:04 -0800 [thread overview]
Message-ID: <CAKwvOdnr5LcVbv2=2h+j8-ekvoB6PezmSOWhPzZdMaDG6eniag@mail.gmail.com> (raw)
In-Reply-To: <20210202233636.nvbl6wivgnhacbvg@treble>
On Tue, Feb 2, 2021 at 3:36 PM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>
> On Tue, Feb 02, 2021 at 02:33:38PM -0800, Nick Desaulniers wrote:
> > On Mon, Feb 1, 2021 at 4:02 PM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > >
> > > On Mon, Feb 01, 2021 at 03:17:40PM -0800, Nick Desaulniers wrote:
> > > And yes, objtool has been pretty good at finding compiler bugs, so the
> > > more coverage the better.
> > > > The idea of rebuilding control flow from binary analysis and using
> > > > that to find codegen bugs is a really cool idea (novel, even? idk),
> > > > and I wish we had some analog for userspace binaries that could
> > > > perform similar checks.
> > >
> > > Objtool is generic in many ways -- in fact I recently heard from a PhD
> > > candidate who used it successfully on another kernel for an ORC
> > > unwinder.
> >
> > That's pretty cool! Reuse outside the initial context is always a
> > good sign that something was designed right.
>
> So basically you're saying objtool is both useful and well-designed. I
> will quote you on that!
Haha, all I'm saying is that while I'm not proud that it did find bugs
in LLVM (and I do have existing bugs found by it to fix on my plate),
I don't see who else or how else those would have been spotted, and I
can appreciate that. I think the tools given to us are broken (by
design, perhaps), so anything that can help us spot issues might help
our code live longer than we do.
I also think that there's room for improvement and experimentation in
debug info formats, though there is currently a proliferation to
support. Live patching and eBPF seem to have some functional overlap
IIUC, strengths/weaknesses, and their own unique debug info formats to
go with it. Supporting each one does require some level of toolchain
support or coordination (or complexity, even).
--
Thanks,
~Nick Desaulniers
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next prev parent reply other threads:[~2021-02-02 23:53 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 17:37 [RFC PATCH 00/17] objtool: add base support for arm64 Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 01/17] tools: Add some generic functions and headers Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 02/17] tools: arm64: Make aarch64 instruction decoder available to tools Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 03/17] tools: bug: Remove duplicate definition Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 04/17] objtool: arm64: Add base definition for arm64 backend Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 05/17] objtool: arm64: Decode add/sub instructions Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 06/17] objtool: arm64: Decode jump and call related instructions Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 07/17] objtool: arm64: Decode other system instructions Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 08/17] objtool: arm64: Decode load/store instructions Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 09/17] objtool: arm64: Decode LDR instructions Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 10/17] objtool: arm64: Accept padding in code sections Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 11/17] efi: libstub: Ignore relocations for .discard sections Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 12/17] gcc-plugins: objtool: Add plugin to detect switch table on arm64 Julien Thierry
2021-01-27 22:15 ` Nick Desaulniers
2021-01-27 23:26 ` Josh Poimboeuf
2021-01-29 18:10 ` Nick Desaulniers
2021-02-01 21:44 ` Josh Poimboeuf
2021-02-01 23:17 ` Nick Desaulniers
2021-02-02 0:02 ` Josh Poimboeuf
2021-02-02 14:24 ` David Laight
2021-02-02 22:33 ` Nick Desaulniers
2021-02-02 23:36 ` Josh Poimboeuf
2021-02-02 23:52 ` Nick Desaulniers [this message]
2021-02-02 8:57 ` Julien Thierry
2021-02-02 23:01 ` Nick Desaulniers
2021-02-03 0:14 ` Josh Poimboeuf
2021-02-03 11:57 ` Peter Zijlstra
2021-02-03 13:04 ` Mark Brown
2021-02-03 13:58 ` Mark Rutland
2021-02-03 8:11 ` Julien Thierry
2021-02-09 16:30 ` Daniel Kiss
2021-01-20 17:37 ` [RFC PATCH 13/17] objtool: arm64: Implement functions to add switch tables alternatives Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 14/17] objtool: arm64: Cache section with switch table information Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 15/17] objtool: arm64: Handle supported relocations in alternatives Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 16/17] objtool: arm64: Ignore replacement section for alternative callback Julien Thierry
2021-01-20 17:38 ` [RFC PATCH 17/17] objtool: arm64: Enable stack validation for arm64 Julien Thierry
2021-01-21 9:03 ` [RFC PATCH 00/17] objtool: add base support " Ard Biesheuvel
2021-01-21 10:26 ` Julien Thierry
2021-01-21 11:08 ` Ard Biesheuvel
2021-01-21 11:23 ` Peter Zijlstra
2021-01-21 11:48 ` Ard Biesheuvel
2021-01-21 18:54 ` Josh Poimboeuf
2021-01-22 17:43 ` Mark Brown
2021-01-22 17:54 ` Ard Biesheuvel
2021-01-28 22:10 ` Madhavan T. Venkataraman
2021-01-29 15:47 ` Mark Brown
2021-01-22 21:15 ` Madhavan T. Venkataraman
2021-01-22 21:43 ` Ard Biesheuvel
2021-01-22 21:44 ` Madhavan T. Venkataraman
2021-01-25 21:19 ` Josh Poimboeuf
2021-01-22 21:16 ` Madhavan T. Venkataraman
2021-01-21 13:23 ` Julien Thierry
2021-01-21 14:23 ` Mark Brown
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