From: Dirk Behme <dirk.behme@gmail.com>
To: Lior Weintraub <liorw@pliops.com>,
"linux-embedded@vger.kernel.org" <linux-embedded@vger.kernel.org>
Subject: Re: Debugging early SError exception
Date: Thu, 21 Dec 2023 09:29:31 +0100 [thread overview]
Message-ID: <b139c136-0417-4ac5-b99a-ba999d7418a0@gmail.com> (raw)
In-Reply-To: <PR3P195MB05553792B68C8A71BC08E4A5C395A@PR3P195MB0555.EURP195.PROD.OUTLOOK.COM>
Am 21.12.23 um 08:43 schrieb Lior Weintraub:
> Hi Dirk,
>
> We found that the issue was at the early stages of Barebox (a.k.a U-BOOT v2).
Glad to hear that! :)
> Our implementation of putc_ll (on debug_ll) was writing into the UART Tx FIFO without checking if the FIFO is full.
> Once the fifo got full it caused this SError probably because the UART IP generated an apberror signal.
Thanks for the report!
> Now the Linux is running and doesn't report the SError again but now we face another issue.
> We see that the PC is getting into a "report_bug" function.
> The Linux doesn't print anything to the UART (probably since it hasn't got to the point where the console is configured?).
For cases like this using earlyprintk is usually a good option. Check
the Linux kernel serial console (UART) dirver of you SoC if it
supports it. In the end it should be "just" a function in the serial
console driver which outputs the console data via polling before
(later) the interrupt driven console part takes over.
Best regards
Dirk
> Since our debug means are limited it can take some time to find the root cause.
>
> I will keep you posted and update our findings.
> Love to hear your thoughts,
>
> Cheers,
> Lior.
>
>
>> -----Original Message-----
>> From: Dirk Behme <dirk.behme@gmail.com>
>> Sent: Tuesday, December 19, 2023 3:37 PM
>> To: Lior Weintraub <liorw@pliops.com>; linux-embedded@vger.kernel.org
>> Subject: Re: Debugging early SError exception
>>
>> [You don't often get email from dirk.behme@gmail.com. Learn why this is
>> important at https://aka.ms/LearnAboutSenderIdentification ]
>>
>> CAUTION: External Sender
>>
>> Am 19.12.23 um 14:23 schrieb Lior Weintraub:
>>> Thanks Dirk,
>>
>> Welcome :)
>>
>> In case you find the root cause it would be nice to get some generic
>> description of it so that we can learn something :)
>>
>> Best regards
>>
>> Dirk
>>
>>
>>>> -----Original Message-----
>>>> From: Dirk Behme <dirk.behme@gmail.com>
>>>> Sent: Tuesday, December 19, 2023 9:09 AM
>>>> To: Lior Weintraub <liorw@pliops.com>; linux-embedded@vger.kernel.org
>>>> Subject: Re: Debugging early SError exception
>>>>
>>>> [You don't often get email from dirk.behme@gmail.com. Learn why this is
>>>> important at https://aka.ms/LearnAboutSenderIdentification ]
>>>>
>>>> CAUTION: External Sender
>>>>
>>>> Am 17.12.23 um 22:32 schrieb Lior Weintraub:
>>>>> Hi,
>>>>>
>>>>> We have a new SoC with eLinux porting (kernel v6.5).
>>>>> This SoC is ARM64 (A53) single core based device.
>>>>> It runs correctly on QEMU but fails with SError on emulation platform
>>>> (Synopsys Zebu running our SoC model).
>>>>> There is no debugger connected to this emulation but there are several
>>>> debug capabilities we can use:
>>>>> 1. Generating wave dump of CPU signals
>>>>> 2. Generate a Tarmac log
>>>>> 3. UART
>>>>>
>>>>> Since the SError happens at early stages of Linux boot the UART is not
>>>> enabled yet.
>>>>> From the Tarmac log we can see:
>>>>> 3824884521 ps ES (ffff800080760888:d65f03c0) O el1h_ns: ret
>>>> (parse_early_param)
>>>>> 3824884522 ps ES (ffff800080763a60:d2801800) O el1h_ns: mov
>> x0,
>>>> #0xc0 // #192 (setup_arch)
>>>>> R X0 (AARCH64) 00000000 000000c0
>>>>> 3824884523 ps ES (ffff800080763a64:d51b4220) O el1h_ns: msr
>>>> daif, x0 (setup_arch)
>>>>> R CPSR 600000c5
>>>>> 3824884529 ps ES System Error (Abort)
>>>>> EXC [0x380] SError/vSError Current EL with SP_ELx
>>>>> R ESR_EL1 (AARCH64) bf000002
>>>>> R CPSR 600003c5
>>>>> R SPSR_EL1 (AARCH64) 600000c5
>>>>> R ELR_EL1 (AARCH64) ffff8000 80763a68
>>>>> 3824884925 ps ES (ffff800080010b80:d10543ff) O el1h_ns: sub
>> sp,
>>>> sp, #0x150 (vectors)
>>>>> R SP_EL1 (AARCH64) ffff8000 808f3c50
>>>>> 3824884925 ps ES (ffff800080010b84:8b2063ff) O el1h_ns: add
>> sp,
>>>> sp, x0 (vectors)
>>>>> R SP_EL1 (AARCH64) ffff8000 808f3d10
>>>>> 3824884926 ps ES (ffff800080010b88:cb2063e0) O el1h_ns: sub
>> x0,
>>>> sp, x0 (vectors)
>>>>> R X0 (AARCH64) ffff8000 808f3c50
>>>>> 3824884927 ps ES (ffff800080010b8c:37700080) O el1h_ns: tbnz
>> w0,
>>>> #14, ffff800080010b9c <vectors+0x39c> (vectors)
>>>>> 3824884935 ps ES (ffff800080010b90:cb2063e0) O el1h_ns: sub
>> x0,
>>>> sp, x0 (vectors)
>>>>> R X0 (AARCH64) 00000000 000000c0
>>>>> 3824884937 ps ES (ffff800080010b94:cb2063ff) O el1h_ns: sub sp,
>>>> sp, x0 (vectors)
>>>>> R SP_EL1 (AARCH64) ffff8000 808f3c50
>>>>> 3824884938 ps ES (ffff800080010b98:140001ef) O el1h_ns: b
>>>> ffff800080011354 <el1h_64_error> (vectors)
>>>>>
>>>>> If I understand correctly, the exception happened sometime earlier and
>> only
>>>> now Linux boot code (setup_arch) opened the exception handling and as a
>>>> result we immediately jump to the SError exception handler.
>>>>
>>>>
>>>> Yes, that sounds reasonable. If I understood correctly, you are
>>>> running something "quite new" on some software (QEMU) and hardware
>>>> (Synopsis) simulators.
>>>>
>>>> That would mean that you have new hardware with e.g. new memory map
>>>> not used before. What you describe might sound like in the code before
>>>> Linux (boot loader) there is anything resulting in the SError. This
>>>> might be an access to non-existing or non-enabled hardware. I.e. it
>>>> might be that you try to access (read/write) an address what is not
>>>> available, yet (or just invalid). It's hard to debug that. In case you
>>>> are able to modify the code before Linux (the boot loader?) you might
>>>> try to enable SError exceptions, there, too. To get it earlier and
>>>> with that make the search window smaller. I'm not that familiar with
>>>> QEMU, but could you try to trace which (all?) hardware accesses your
>>>> code does. And with that analyse all accesses and with that check if
>>>> all these accesses are valid even on the hardware (Synopsis) emulation
>>>> system? That should be checked from valid address and from hardware
>>>> subsystem enablement point of view.
>>>>
>>>> Hth,
>>>>
>>>> Dirk
>>>>
>>>>
>>>>> From the Linux source:
>>>>> parse_early_param();
>>>>>
>>>>> dynamic_scs_init();
>>>>>
>>>>> /*
>>>>> * Unmask asynchronous aborts and fiq after bringing up possible
>>>>> * earlycon. (Report possible System Errors once we can report this
>>>>> * occurred).
>>>>> */
>>>>> local_daif_restore(DAIF_PROCCTX_NOIRQ); <---- This is when we get
>> the
>>>> exception.
>>>>>
>>>>> After some kernel hacking (replacing printk) we could extract the logs:
>>>>> 6Booting Linux on physical CPU 0x0000000000 [0x410fd034]
>>>>> 5Linux version 6.5.0 (pliops@dev-liorw) (aarch64-buildroot-linux-gnu-
>>>> gcc.br_real (Buildroot 2023.02.1-95-g8391404e23) 11.3.0, GNU ld (GNU
>>>> Binutils) 2.38) #101 SMP Sun Dec 17 20:09:06 IST 2023
>>>>> 6Machine model: Pliops Spider MK-I EVK
>>>>> 2SError Interrupt on CPU0, code 0x00000000bf000002 -- SError
>>>>> CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0 #101
>>>>> Hardware name: Pliops Spider MK-I EVK (DT)
>>>>> pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>>>>> pc : setup_arch+0x13c/0x5ac
>>>>> lr : setup_arch+0x134/0x5ac
>>>>> sp : ffff8000808f3da0
>>>>> x29: ffff8000808f3da0c x28: 0000000008758074c x27:
>>>> 0000000005e31b58c
>>>>> x26: 0000000000000001c x25: 0000000007e5f728c x24:
>>>> ffff8000808f8000c
>>>>> x23: ffff8000808f8600c x22: ffff8000807b6000c x21:
>> ffff800080010000c
>>>>> x20: ffff800080a1e000c x19: fffffbfffddfe190c x18: 000000002266684ac
>>>>> x17: 00000000fcad60bbc x16: 0000000000001800c x15:
>>>> 0000000000000008c
>>>>> x14: ffffffffffffffffc x13: 0000000000000000c x12: 0000000000000003c
>>>>> x11: 0101010101010101c x10: ffffffffffee87dfc x9 :
>> 0000000000000038c
>>>>> x8 : 0101010101010101c x7 : 7f7f7f7f7f7f7f7fc x6 :
>> 0000000000000001c
>>>>> x5 : 0000000000000000c x4 : 8000000000000000c x3 :
>>>> 0000000000000065c
>>>>> x2 : 0000000000000000c x1 : 0000000000000000c x0 :
>>>> 00000000000000c0c
>>>>> 0Kernel panic - not syncing: Asynchronous SError Interrupt
>>>>> CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0 #101
>>>>> Hardware name: Pliops Spider MK-I EVK (DT)
>>>>> Call trace:
>>>>> dump_backtrace+0x9c/0xd0
>>>>> show_stack+0x14/0x1c
>>>>> dump_stack_lvl+0x44/0x58
>>>>> dump_stack+0x14/0x1c
>>>>> panic+0x2e0/0x33c
>>>>> nmi_panic+0x68/0x6c
>>>>> arm64_serror_panic+0x68/0x78
>>>>> do_serror+0x24/0x54
>>>>> el1h_64_error_handler+0x2c/0x40
>>>>> el1h_64_error+0x64/0x68
>>>>> setup_arch+0x13c/0x5ac
>>>>> start_kernel+0x5c/0x5b8
>>>>> __primary_switched+0xb4/0xbc
>>>>> 0---[ end Kernel panic - not syncing: Asynchronous SError Interrupt ]---
>>>>>
>>>>> Can you please advice how to proceed with debugging?
>>>>>
>>>>> Thanks in advanced,
>>>>> Cheers,
>>>>> Lior.
>>>>>
>>>>>
>>>>
>>>
>
next prev parent reply other threads:[~2023-12-21 8:29 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-17 21:32 Debugging early SError exception Lior Weintraub
2023-12-19 7:09 ` Dirk Behme
2023-12-19 13:23 ` Lior Weintraub
2023-12-19 13:37 ` Dirk Behme
2023-12-21 7:43 ` Lior Weintraub
2023-12-21 8:29 ` Dirk Behme [this message]
2023-12-21 10:04 ` Lior Weintraub
2023-12-21 11:19 ` Dirk Behme
2023-12-21 11:36 ` Heiko Schocher
2023-12-21 12:04 ` Lior Weintraub
2023-12-22 7:03 ` Lior Weintraub
2023-12-22 7:48 ` Dirk Behme
2023-12-22 8:04 ` Heiko Schocher
2023-12-24 15:41 ` Lior Weintraub
2023-12-24 19:12 ` Lior Weintraub
2023-12-26 7:48 ` Lior Weintraub
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=b139c136-0417-4ac5-b99a-ba999d7418a0@gmail.com \
--to=dirk.behme@gmail.com \
--cc=linux-embedded@vger.kernel.org \
--cc=liorw@pliops.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).