From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
To: Josh Poimboeuf <jpoimboe@redhat.com>,
Chen Zhongjin <chenzhongjin@huawei.com>
Cc: mark.rutland@arm.com, broonie@kernel.org, ardb@kernel.org,
nobuta.keiya@fujitsu.com, sjitindarsingh@gmail.com,
catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org,
linux-arm-kernel@lists.infradead.org,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v1 0/9] arm64: livepatch: Use DWARF Call Frame Information for frame pointer validation
Date: Mon, 18 Apr 2022 13:38:51 -0500 [thread overview]
Message-ID: <e787031d-81fd-b1bc-4619-e8236a938d5c@linux.microsoft.com> (raw)
In-Reply-To: <20220418161145.hj3ahxqjdgqd3qn2@treble>
On 4/18/22 11:11, Josh Poimboeuf wrote:
> On Mon, Apr 18, 2022 at 08:28:33PM +0800, Chen Zhongjin wrote:
>> Hi Josh,
>>
>> IIUC, ORC on x86 can make reliable stack unwind for this scenario
>> because objtool validates BP state.
>>
>> I'm thinking that on arm64 there's no guarantee that LR will be pushed
>> onto stack. When we meet similar scenario on arm64, we should recover
>> (LR, FP) on pt_regs and continue to unwind the stack. And this is
>> reliable only after we validate (LR, FP).
>>
>> So should we track LR on arm64 additionally as track BP on x86? Or can
>> we just treat (LR, FP) as a pair? because as I know they are always set
>> up together.
>
> Does the arm64 unwinder have a way to detect kernel pt_regs on the
> stack? If so, the simplest solution is to mark all stacks with kernel
> regs as unreliable. That's what the x86 FP unwinder does.
>
AFAICT, only the task pt_regs can be detected. For detecting the other pt_regs,
we would have to set a bit in the FP. IIRC, I had a proposal where I set the LSB in
the FP stored on the stack. The arm64 folks did not like that approach as it
would be indistinguishable from a corrupted FP, however unlikely the corruption
may be.
Unwind hints can be used for these cases to unwind reliably through them. That is
probably the current thinking. Mark Rutland can confirm.
Madhavan
next prev parent reply other threads:[~2022-04-18 18:39 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <95691cae4f4504f33d0fc9075541b1e7deefe96f>
2022-01-17 14:55 ` [PATCH v13 00/11] arm64: Reorganize the unwinder and implement stack trace reliability checks madvenka
2022-01-17 14:55 ` [PATCH v13 01/11] arm64: Remove NULL task check from unwind_frame() madvenka
2022-01-17 14:55 ` [PATCH v13 02/11] arm64: Rename unwinder functions madvenka
2022-01-17 14:56 ` [PATCH v13 03/11] arm64: Rename stackframe to unwind_state madvenka
2022-01-17 14:56 ` [PATCH v13 04/11] arm64: Split unwind_init() madvenka
2022-02-02 18:44 ` Mark Brown
2022-02-03 0:26 ` Madhavan T. Venkataraman
2022-02-03 0:39 ` Madhavan T. Venkataraman
2022-02-03 11:29 ` Mark Brown
2022-02-15 13:07 ` Mark Rutland
2022-02-15 18:04 ` Madhavan T. Venkataraman
2022-01-17 14:56 ` [PATCH v13 05/11] arm64: Copy the task argument to unwind_state madvenka
2022-02-02 18:45 ` Mark Brown
2022-02-15 13:22 ` Mark Rutland
2022-02-22 16:53 ` Madhavan T. Venkataraman
2022-01-17 14:56 ` [PATCH v13 06/11] arm64: Use stack_trace_consume_fn and rename args to unwind() madvenka
2022-02-02 18:46 ` Mark Brown
2022-02-03 0:34 ` Madhavan T. Venkataraman
2022-02-03 11:30 ` Mark Brown
2022-02-03 14:45 ` Madhavan T. Venkataraman
2022-02-15 13:39 ` Mark Rutland
2022-02-15 18:12 ` Madhavan T. Venkataraman
2022-03-07 16:51 ` Madhavan T. Venkataraman
2022-03-07 17:01 ` Mark Brown
2022-03-08 22:00 ` Madhavan T. Venkataraman
2022-03-09 11:47 ` Mark Brown
2022-03-09 15:34 ` Madhavan T. Venkataraman
2022-03-10 8:33 ` Miroslav Benes
2022-03-10 12:36 ` Madhavan T. Venkataraman
2022-03-16 3:43 ` Josh Poimboeuf
2022-04-08 14:44 ` Mark Rutland
2022-04-08 17:58 ` Mark Rutland
2022-04-10 17:42 ` Madhavan T. Venkataraman
2022-04-10 17:33 ` Madhavan T. Venkataraman
2022-04-10 17:45 ` Madhavan T. Venkataraman
2022-01-17 14:56 ` [PATCH v13 07/11] arm64: Make the unwind loop in unwind() similar to other architectures madvenka
2022-01-17 14:56 ` [PATCH v13 08/11] arm64: Introduce stack trace reliability checks in the unwinder madvenka
2022-01-17 14:56 ` [PATCH v13 09/11] arm64: Create a list of SYM_CODE functions, check return PC against list madvenka
2022-01-17 14:56 ` [PATCH v13 10/11] arm64: Introduce arch_stack_walk_reliable() madvenka
2022-01-17 14:56 ` [PATCH v13 11/11] arm64: Select HAVE_RELIABLE_STACKTRACE madvenka
2022-01-25 5:21 ` nobuta.keiya
2022-01-25 13:43 ` Madhavan T. Venkataraman
2022-01-26 10:20 ` nobuta.keiya
2022-01-26 17:14 ` Madhavan T. Venkataraman
2022-01-27 1:13 ` nobuta.keiya
2022-01-26 17:16 ` Mark Brown
2022-04-07 20:25 ` [RFC PATCH v1 0/9] arm64: livepatch: Use DWARF Call Frame Information for frame pointer validation madvenka
2022-04-07 20:25 ` [RFC PATCH v1 1/9] objtool: Parse DWARF Call Frame Information in object files madvenka
2022-04-07 20:25 ` [RFC PATCH v1 2/9] objtool: Generate DWARF rules and place them in a special section madvenka
2022-04-07 20:25 ` [RFC PATCH v1 3/9] dwarf: Build the kernel with DWARF information madvenka
2022-04-07 20:25 ` [RFC PATCH v1 4/9] dwarf: Implement DWARF rule processing in the kernel madvenka
2022-04-07 20:25 ` [RFC PATCH v1 5/9] dwarf: Implement DWARF support for modules madvenka
2022-04-07 20:25 ` [RFC PATCH v1 6/9] arm64: unwinder: Add a reliability check in the unwinder based on DWARF CFI madvenka
2022-04-07 20:25 ` [RFC PATCH v1 7/9] arm64: dwarf: Implement unwind hints madvenka
2022-04-07 20:25 ` [RFC PATCH v1 8/9] dwarf: Miscellaneous changes required for enabling livepatch madvenka
2022-04-07 20:25 ` [RFC PATCH v1 9/9] dwarf: Enable livepatch for ARM64 madvenka
2022-04-08 0:21 ` [RFC PATCH v1 0/9] arm64: livepatch: Use DWARF Call Frame Information for frame pointer validation Josh Poimboeuf
2022-04-08 11:41 ` Peter Zijlstra
2022-04-11 17:26 ` Madhavan T. Venkataraman
2022-04-11 17:18 ` Madhavan T. Venkataraman
2022-04-12 8:32 ` Chen Zhongjin
2022-04-16 0:56 ` Josh Poimboeuf
2022-04-18 12:28 ` Chen Zhongjin
2022-04-18 16:11 ` Josh Poimboeuf
2022-04-18 18:38 ` Madhavan T. Venkataraman [this message]
[not found] ` <844b3ede-eddb-cbe6-80e0-3529e2da2eb6@huawei.com>
2022-04-12 17:27 ` Madhavan T. Venkataraman
2022-04-16 1:07 ` Josh Poimboeuf
2022-04-14 14:11 ` Madhavan T. Venkataraman
2022-04-08 10:55 ` Peter Zijlstra
2022-04-08 11:54 ` Peter Zijlstra
2022-04-08 14:34 ` Josh Poimboeuf
2022-04-10 17:47 ` Madhavan T. Venkataraman
2022-04-11 16:34 ` Josh Poimboeuf
2022-04-08 12:06 ` Peter Zijlstra
2022-04-11 17:35 ` Madhavan T. Venkataraman
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