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: Tue, 19 Dec 2023 14:37:22 +0100 [thread overview]
Message-ID: <375eeb75-dde5-4806-a2d7-7f4e97342ee8@gmail.com> (raw)
In-Reply-To: <PR3P195MB05550310B202221101564038C397A@PR3P195MB0555.EURP195.PROD.OUTLOOK.COM>
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:[~2023-12-19 13:37 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 [this message]
2023-12-21 7:43 ` Lior Weintraub
2023-12-21 8:29 ` Dirk Behme
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
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