Re: Kernel v5.2+ on HiKey960?

From: Jerome Forissier <jerome@forissier.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: Kernel v5.2+ on HiKey960?
Date: Wed, 4 Dec 2019 14:15:48 +0100	[thread overview]
Message-ID: <1c5e497f-4be0-e1f3-4d6d-fed9470d0406@forissier.org> (raw)
In-Reply-To: <20191204101851.GC13081@arrakis.emea.arm.com>

Hi Catalin,

On 12/4/19 11:18 AM, Catalin Marinas wrote:
> On Tue, Dec 03, 2019 at 04:43:22PM +0100, Jerome Forissier wrote:
>> Has anyone successfully run kernel v5.2 or later on a HiKey960 board?
>>
>> For some reason, anything past v5.1 doesn't work for me and I could not
>> figure out why. The symptom is it never gets to the login prompt. The
>> root FS is a Buildroot-generated one, and prior to reaching the kernel
>> the board runs TF-A, OP-TEE, UEFI (edk2) and Grub.
>>
>> I tried replacing /init with a shell, in which case I can type a command
>> but whatever it is (even a simple "ls"), the command hangs on exit and I
>> never get back to the prompt.
>>
>> Then I started bisecting, that was quite painful but I found several
>> problematic commits. I ended up reverting the following (in this order)
>> to be able to boot v5.4:
>>
>> 1. "arm64: vdso: Substitute gettimeofday() with C implementation"
> 
> Commit 28b1a824a4f4, merged in 5.3
> 
>> 2. "arm64: vdso: Explicitly add build-id option"
> 
> Commit 7a0a93c51799, merged in 5.2
> 
>> 3. "arm64: arch_timer: Ensure counter register reads occur with seqlock
>>     held"
> 
> Commit 75a19a0202db, merged in 5.2.
> 
>> 4. "arm64: vdso: Remove stale files from old assembly implementation"
> 
> Commit 37a5076098c1, merged in 5.4.
> 
> The above is a pretty random set of reverts that doesn't really help
> pinpoint the issue.
> 
> Since 5.2 was the first kernel where the regression was noticed, could
> you try reverting commit 75a19a0202db in 5.2 and try that specific
> kernel version?

Ends up with a kernel panic [1].

> If this doesn't solve the issue, it may be simpler to
> bisect only between 5.1 and 5.2 rather than across multiple kernel
> versions.

75a19a0202db is the first bad commit. Its parent: commit 2f1d4e24d91b
("firmware: arm_sdei: Prohibit probing in '_sdei_handler'") boots fine
[2]. Since reverting 75a19a0202db in v5.2 does not work, I suspect we're
dealing with multiple problems. As I said, the set of reverts above is
the best I could figure out, and believe me I spent several days trying
to troubleshoot this :-/ (that being said, I know nothing about the VDSO
or the arch timer so I could not try anything meaningful other than
reverting some commits).

[1] https://pastebin.com/U4iHLrc8
[2] https://pastebin.com/bLgzJYwE

-- 
Jerome

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