On 18/01/2019 13:33, Mark Cave-Ayland wrote:
> On 03/01/2019 15:48, Corentin Labbe wrote:
>
>> Hello
>>
>> When using an initrd > 5M, I hit the following kernel crash:
>> qemu-system-sparc -kernel vmlinux -initrd rootfs.cpio.gz -nographic
>> Configuration device id QEMU version 1 machine id 32
>> Probing SBus slot 0 offset 0
>> Probing SBus slot 1 offset 0
>> Probing SBus slot 2 offset 0
>> Probing SBus slot 3 offset 0
>> Probing SBus slot 4 offset 0
>> Probing SBus slot 5 offset 0
>> Invalid FCode start byte
>> CPUs: 1 x FMI,MB86904
>> UUID: 00000000-0000-0000-0000-000000000000
>> Welcome to OpenBIOS v1.1 built on Oct 5 2018 08:20
>> Type 'help' for detailed information
>> [sparc] Kernel already loaded
>> switching to new context:
>> PROMLIB: obio_ranges 1
>> [ 0.000000] PROMLIB: Sun Boot Prom Version 3 Revision 2
>> [ 0.000000] Linux version 4.20.0-next-20190102+ (compile@Red) (gcc version 7.3.0 (Gentoo 7.3.0-r3 p1.4)) #148 Thu Jan 3 16:17:08 CET 2019
>> [ 0.000000] printk: bootconsole [earlyprom0] enabled
>> [ 0.000000] ARCH: SUN4M
>> [ 0.000000] TYPE: SPARCstation 5
>> [ 0.000000] Ethernet address: 52:54:00:12:34:56
>> [ 0.000000] Unable to handle kernel NULL pointer dereference
>> [ 0.000000] tsk->{mm,active_mm}->context = ffffffff
>> [ 0.000000] tsk->{mm,active_mm}->pgd = 00000000
>> [ 0.000000] \|/ ____ \|/
>> [ 0.000000] "@'/ ,. \`@"
>> [ 0.000000] /_| \__/ |_\
>> [ 0.000000] \__U_/
>> [ 0.000000] swapper(0): Oops [#1]
>> [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.20.0-next-20190102+ #148
>> [ 0.000000] PSR: 04001fc0 PC: f0010ef0 NPC: f0010ef4 Y: 00000000 Not tainted
>> [ 0.000000] PC: <do_sparc_fault+0x158/0x404>
>> [ 0.000000] %G: 0000000a 000003c4 f05ece08 f05ecc00 00000000 00e00000 f05d4000 00000001
>> [ 0.000000] %O: 00000000 00e00000 00800000 00e00000 00000000 00000002 f05d5bb8 f00bba58
>> [ 0.000000] RPC: <memblock_reserve+0x38/0x68>
>> [ 0.000000] %L: 00000040 f05dfaf8 f05d5c68 00000001 0003ffff 006951e0 f05ed014 f0674ab4
>> [ 0.000000] %I: f05d5c80 00000000 00000002 f1000000 ffffffff 00000000 f05d5c20 f0007fd8
>> [ 0.000000] Disabling lock debugging due to kernel taint
>> [ 0.000000] Caller[f0007fd8]: srmmu_fault+0x58/0x68
>> [ 0.000000] Caller[f0618598]: memblock_alloc_try_nid+0xb8/0xc8
>> [ 0.000000] Caller[f0611094]: srmmu_paging_init+0x174/0xaf8
>> [ 0.000000] Caller[f06106a8]: paging_init+0x4/0x24
>> [ 0.000000] Caller[f060e4f0]: setup_arch+0x3e8/0x480
>> [ 0.000000] Caller[f060ab50]: start_kernel+0x48/0x460
>> [ 0.000000] Caller[f060a43c]: continue_boot+0x324/0x334
>> [ 0.000000] Caller[00000000]: (null)
>> [ 0.000000] Instruction DUMP:
>> [ 0.000000] c800a024
>> [ 0.000000] 83286002
>> [ 0.000000] 073c17b3
>> [ 0.000000] <c4010001>
>> [ 0.000000] c600e22c
>> [ 0.000000] 8a08a003
>> [ 0.000000] 80a16001
>> [ 0.000000] 0280003b
>> [ 0.000000] c600c001
>> [ 0.000000]
>> [ 0.000000] Kernel panic - not syncing: Attempted to kill the idle task!
>> [ 0.000000] Press Stop-A (L1-A) from sun keyboard or send break
>> [ 0.000000] twice on console to return to the boot prom
>> [ 0.000000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---
>> qemu-system-sparc: terminating on signal 15 from pid 13043 (killall)
>>
>> The NULL ptr dereference is done by memset() in srmmu_nocache_init() and memblock_alloc_try_nid().
>> If I comment both memset, the boot pass
>>
>> But since nothing explain the NULL ptr deref in memset(), I suspect something is overriden by the initrd
>
> Sorry about the delay in replying to this, I haven't been too well recently.
>
> Looking at the code I suspect the problem is that when loading a kernel directly,
> OpenBIOS isn't adding the kernel/initrd memory ranges to the DT properties, and so
> the kernel doesn't recreate its own mapping on boot.
>
> It shouldn't be too hard to make this happen, let me take and look and see how
> difficult this would be.
I think I now have a fix for this, with changes needed in both QEMU and OpenBIOS.
Firstly you'll need to apply the QEMU patch from
https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg06635.html and then you'll
need an updated OpenBIOS.
I've uploaded a pre-compiled openbios-sparc32 with the patches from
https://mail.coreboot.org/hyperkitty/list/openbios@xxxxxxxxxxxx/thread/E6IMJNUFRF7W6ALWSYBOOCEYLBFXXQEN/
to https://www.ilande.co.uk/tmp/qemu/openbios-sparc32-initrdfix for testing.
Please can you test and let me know if this solves the issue? If so, I'll see if I
can get them merged in time for the upcoming QEMU 4.0 release.
ATB,
Mark.
