From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
Julien Thierry <jthierry@redhat.com>,
Ard Biesheuvel <ardb@kernel.org>, Mark Brown <broonie@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Kees Cook <keescook@chromium.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
linux-efi <linux-efi@vger.kernel.org>,
linux-hardening@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
raphael.gault@arm.com, Will Deacon <will@kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Bill Wendling <morbo@google.com>,
swine@google.com, yonghyun@google.com
Subject: Re: [RFC PATCH 12/17] gcc-plugins: objtool: Add plugin to detect switch table on arm64
Date: Wed, 3 Feb 2021 12:57:27 +0100 [thread overview]
Message-ID: <YBqPp53EM/E+o5TA@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210203001414.idjrcrki7wmhndre@treble>
On Tue, Feb 02, 2021 at 06:14:14PM -0600, Josh Poimboeuf wrote:
> > Sure, but this is what production unwinders do, and they don't require
> > compiler plugins, right?
>
> What do you mean by "production unwinders"? Generally unwinders rely on
> either frame pointers or DWARF, but (without validation) those aren't
> robust enough for live patching in the kernel, so I'm not sure how this
> is relevant.
Not to mention that DWARF and consequently it's unders are horribly
large, complex and above all fragile things.
There's a reason ORC got invented, DWARF is simlpy unacceptable and
inadequate.
Now, one avenue that has been mentioned in the past, but I've not seen
recently, is to have objtool use DWARF as input to help it understand
the code. At least in userspace we can rely on DWARF libs. But I'm
fairly sure people aren't jumping up and down for having to always build
their kernel with DWARFs on, compile speed etc..
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
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>,
Catalin Marinas <catalin.marinas@arm.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Nick Desaulniers <ndesaulniers@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, swine@google.com,
yonghyun@google.com, 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: Wed, 3 Feb 2021 12:57:27 +0100 [thread overview]
Message-ID: <YBqPp53EM/E+o5TA@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210203001414.idjrcrki7wmhndre@treble>
On Tue, Feb 02, 2021 at 06:14:14PM -0600, Josh Poimboeuf wrote:
> > Sure, but this is what production unwinders do, and they don't require
> > compiler plugins, right?
>
> What do you mean by "production unwinders"? Generally unwinders rely on
> either frame pointers or DWARF, but (without validation) those aren't
> robust enough for live patching in the kernel, so I'm not sure how this
> is relevant.
Not to mention that DWARF and consequently it's unders are horribly
large, complex and above all fragile things.
There's a reason ORC got invented, DWARF is simlpy unacceptable and
inadequate.
Now, one avenue that has been mentioned in the past, but I've not seen
recently, is to have objtool use DWARF as input to help it understand
the code. At least in userspace we can rely on DWARF libs. But I'm
fairly sure people aren't jumping up and down for having to always build
their kernel with DWARFs on, compile speed etc..
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linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-02-03 11:58 UTC|newest]
Thread overview: 106+ 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 ` 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 ` 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 ` Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 03/17] tools: bug: Remove duplicate definition Julien Thierry
2021-01-20 17:37 ` 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 ` Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 05/17] objtool: arm64: Decode add/sub instructions Julien Thierry
2021-01-20 17:37 ` 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 ` Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 07/17] objtool: arm64: Decode other system instructions Julien Thierry
2021-01-20 17:37 ` Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 08/17] objtool: arm64: Decode load/store instructions Julien Thierry
2021-01-20 17:37 ` Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 09/17] objtool: arm64: Decode LDR instructions Julien Thierry
2021-01-20 17:37 ` 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 ` 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 ` Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 12/17] gcc-plugins: objtool: Add plugin to detect switch table on arm64 Julien Thierry
2021-01-20 17:37 ` Julien Thierry
2021-01-27 22:15 ` Nick Desaulniers
2021-01-27 22:15 ` Nick Desaulniers
2021-01-27 23:26 ` Josh Poimboeuf
2021-01-27 23:26 ` Josh Poimboeuf
2021-01-29 18:10 ` Nick Desaulniers
2021-01-29 18:10 ` Nick Desaulniers
2021-02-01 21:44 ` Josh Poimboeuf
2021-02-01 21:44 ` Josh Poimboeuf
2021-02-01 23:17 ` Nick Desaulniers
2021-02-01 23:17 ` Nick Desaulniers
2021-02-02 0:02 ` Josh Poimboeuf
2021-02-02 0:02 ` Josh Poimboeuf
2021-02-02 14:24 ` David Laight
2021-02-02 14:24 ` David Laight
2021-02-02 22:33 ` Nick Desaulniers
2021-02-02 22:33 ` Nick Desaulniers
2021-02-02 23:36 ` Josh Poimboeuf
2021-02-02 23:36 ` Josh Poimboeuf
2021-02-02 23:52 ` Nick Desaulniers
2021-02-02 23:52 ` Nick Desaulniers
2021-02-02 8:57 ` Julien Thierry
2021-02-02 8:57 ` Julien Thierry
2021-02-02 23:01 ` Nick Desaulniers
2021-02-02 23:01 ` Nick Desaulniers
2021-02-03 0:14 ` Josh Poimboeuf
2021-02-03 0:14 ` Josh Poimboeuf
2021-02-03 11:57 ` Peter Zijlstra [this message]
2021-02-03 11:57 ` Peter Zijlstra
2021-02-03 13:04 ` Mark Brown
2021-02-03 13:04 ` Mark Brown
2021-02-03 13:58 ` Mark Rutland
2021-02-03 13:58 ` Mark Rutland
2021-02-03 8:11 ` Julien Thierry
2021-02-03 8:11 ` Julien Thierry
2021-02-09 16:30 ` Daniel Kiss
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 ` 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 ` 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 ` Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 16/17] objtool: arm64: Ignore replacement section for alternative callback Julien Thierry
2021-01-20 17:37 ` Julien Thierry
2021-01-20 17:38 ` [RFC PATCH 17/17] objtool: arm64: Enable stack validation for arm64 Julien Thierry
2021-01-20 17:38 ` Julien Thierry
2021-01-21 5:39 ` kernel test robot
2021-01-21 9:03 ` [RFC PATCH 00/17] objtool: add base support " Ard Biesheuvel
2021-01-21 9:03 ` Ard Biesheuvel
2021-01-21 10:26 ` Julien Thierry
2021-01-21 10:26 ` Julien Thierry
2021-01-21 11:08 ` Ard Biesheuvel
2021-01-21 11:08 ` Ard Biesheuvel
2021-01-21 11:23 ` Peter Zijlstra
2021-01-21 11:23 ` Peter Zijlstra
2021-01-21 11:48 ` Ard Biesheuvel
2021-01-21 11:48 ` Ard Biesheuvel
2021-01-21 18:54 ` Josh Poimboeuf
2021-01-21 18:54 ` Josh Poimboeuf
2021-01-22 17:43 ` Mark Brown
2021-01-22 17:43 ` Mark Brown
2021-01-22 17:54 ` Ard Biesheuvel
2021-01-22 17:54 ` Ard Biesheuvel
2021-01-28 22:10 ` Madhavan T. Venkataraman
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 21:15 ` Madhavan T. Venkataraman
2021-01-22 21:43 ` Ard Biesheuvel
2021-01-22 21:43 ` Ard Biesheuvel
2021-01-22 21:44 ` Madhavan T. Venkataraman
2021-01-22 21:44 ` Madhavan T. Venkataraman
2021-01-25 21:19 ` Josh Poimboeuf
2021-01-25 21:19 ` Josh Poimboeuf
2021-01-22 21:16 ` Madhavan T. Venkataraman
2021-01-22 21:16 ` Madhavan T. Venkataraman
2021-01-21 13:23 ` Julien Thierry
2021-01-21 13:23 ` Julien Thierry
2021-01-21 14:23 ` Mark Brown
2021-01-21 14:23 ` Mark Brown
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