Re: [Xen-devel] Dom0 kernel panic when porting xen to new arm soc

[Peng Fan <van.freenix@xxxxxxxxx>]

Hi

On 6/20/2015 10:08 PM, Peng Fan wrote:
> Hi Julien,
> 
> On 6/20/2015 6:19 PM, Julien Grall wrote:
>> Hi,
>>
>> On 19/06/2015 14:22, Peng Fan wrote:
>>> diff --git a/kernel/timer.c b/kernel/timer.c
>>> index 38f0d40..4a025cc 100644
>>> --- a/kernel/timer.c
>>> +++ b/kernel/timer.c
>>> @@ -1175,6 +1175,10 @@ static inline void __run_timers(struct tvec_base
>>> *base)
>>>
>>>                          base->running_timer = timer;
>>>                          detach_expired_timer(timer, base);
>>> +                       if (!fn) {
>>> +                               printk("fn is null why????\n"); ---->
>>> This log only shows once. Not sure why fn is null and only once.
>>> +                               continue;
>>> +                       }
>>>
>>>                          if (irqsafe) {
>>>                                  spin_unlock(&base->lock);
>>
>> By any chance, does your board has a another timer (i.e other than the
>> generic timer)?
> 
> Yeah. There is a another timer whose rating is lower that generic timer.
>>
>> I would also track down to see who is adding this timer.
>>
>>> But after apply the above kernel patch, Dom0 Linux can handle shell
>>> input.
>>> Just have another question, How can Dom0 handle DMA for arm.
>>
>> When Xen is allocating the RAM bank for DOM0 we use a direct mapping
>> (i.e the Physical Address = Intermediate Address for the RAM). So DOM0
>> can perform DMA as on baremetal.
> Thanks. Current, without using rootfs in sd card, my Dom0 kernel can
> boot using ramfs. But if with sdhc which use ADMA, Dom0 kernel will
> panic. Below is the log:
> 
> sdhci: Secure Digital Host Controller Interface driver
> sdhci: Copyright(c) Pierre Ossman
> sdhci-pltfm: SDHCI platform and OF driver helper
> Unable to handle kernel NULL pointer dereference at virtual address 00000000
> pgd = 80004000
> [00000000] *pgd=00000000
> Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.38-02383-g5ccf32b-dirty #22
> task: 84074000 ti: 84078000 task.ti: 84078000
> PC is at bitmap_clear+0xc0/0xdc
> LR is at bitmap_clear+0x54/0xdc
> pc : [<8029deb8>]    lr : [<8029de4c>]    psr: 20000193
> sp : 84079d80  ip : 00000001  fp : 00000000
> r10: 00077fff  r9 : 00000404  r8 : 00000001
> r7 : 00000001  r6 : 00000001  r5 : 00000000  r4 : ffffffff
> r3 : 00000001  r2 : 00000001  r1 : 20000193  r0 : 00000015
> Flags: nzCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
> Control: 10c53c7d  Table: 8800406a  DAC: 00000015
> Process swapper/0 (pid: 1, stack limit = 0x84078238)
> Stack: (0x84079d80 to 0x8407a000)
> 9d80: 80000113 00000000 87efa000 81109918 00001000 800197f8 84128558
> 00080008
> 9da0: 84079dec 000000d0 84bfeac0 84126c10 84126c10 ffffffff 00000404
> ffffffff
> 9dc0: 00000000 00000402 00000000 00000000 84126c10 80310ba8 ffffffff
> 00000000
> 9de0: 00000000 00000524 84078000 00000000 00000000 ffffffff ffffffff
> 84bfeac0
> 9e00: 84bfe800 8000b407 07eb0000 8116e0f8 00000000 804ee81c ffffffff
> ffffffff
> 9e20: 00000000 84126c10 84c92010 84bfeac0 00000000 84126c10 84126c00
> 84bfeac0
> 9e40: 84078030 804f08e4 804f03d8 84126c10 fffffdfb 8115401c 8115401c
> 00000000
> 9e60: 0000010f 80362330 803622ec 84126c10 811c8098 00000000 8115401c
> 80360b1c
> 9e80: 84126c10 8115401c 84126c44 00000000 80de1888 80360d28 00000000
> 8115401c
> 9ea0: 80360c9c 8035f10c 8406965c 84123634 8115401c 84c8bf80 8112f3c8
> 803602bc
> 9ec0: 80d08314 8115401c 00000006 8115401c 00000006 8116e080 8116e080
> 8036130c
> 9ee0: 00000000 80e00f78 00000006 800088dc 8400f900 80c94fe0 840bd480
> 80735184
> 9f00: 00000000 8116e080 0000150c 8012d430 00000000 811105b0 60000113
> 00000001
> 9f20: 87ffc576 8075ca38 0000010f 8004b0f0 80d66884 00000006 87ffc583
> 00000006
> 9f40: 811105a0 80e00f78 00000006 8116e080 8116e080 80da150c 0000010f
> 80df4154
> 9f60: 80df4148 80da1c4c 00000006 00000006 80da150c 9355553c 84079f9c
> 80731338
> 9f80: 00000000 00000000 80727254 00000000 00000000 00000000 00000000
> 00000000
> 9fa0: 00000000 8072725c 00000000 8000ecf8 00000000 00000000 00000000
> 00000000
> 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 00000000
> 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000 9355553c
> 9355553c
> [<8029deb8>] (bitmap_clear) from [<800197f8>]
> (__arm_dma_free.isra.18+0xe4/0x228)
> [<800197f8>] (__arm_dma_free.isra.18) from [<80310ba8>]
> (xen_swiotlb_free_coherent+0xfc/0x140)
> [<80310ba8>] (xen_swiotlb_free_coherent) from [<804ee81c>]
> (sdhci_add_host+0xb34/0xe64)
> [<804ee81c>] (sdhci_add_host) from [<804f08e4>]
> (sdhci_esdhc_imx_probe+0x50c/0x808)
> [<804f08e4>] (sdhci_esdhc_imx_probe) from [<80362330>]
> (platform_drv_probe+0x44/0xa4)
> [<80362330>] (platform_drv_probe) from [<80360b1c>]
> (driver_probe_device+0x120/0x25c)
> [<80360b1c>] (driver_probe_device) from [<80360d28>]
> (__driver_attach+0x8c/0x90)
> [<80360d28>] (__driver_attach) from [<8035f10c>]
> (bus_for_each_dev+0x60/0x94)
> [<8035f10c>] (bus_for_each_dev) from [<803602bc>]
> (bus_add_driver+0x148/0x1f0)
> [<803602bc>] (bus_add_driver) from [<8036130c>] (driver_register+0x78/0xf8)
> [<8036130c>] (driver_register) from [<800088dc>]
> (do_one_initcall+0xf8/0x144)
> [<800088dc>] (do_one_initcall) from [<80da1c4c>]
> (kernel_init_freeable+0x138/0x1d8)
> [<80da1c4c>] (kernel_init_freeable) from [<8072725c>] (kernel_init+0x8/0xf0)
> [<8072725c>] (kernel_init) from [<8000ecf8>] (ret_from_fork+0x14/0x3c)
> Code: 10866003 1206601f 10633006 11e02312 (e5953000)
> ---[ end trace f6f103bb73cc0503 ]---
> note: swapper/0[1] exited with preempt_count 1
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> 
> The piece code is at here:
> if (host->flags & SDHCI_USE_ADMA) {
>          /*
>           * We need to allocate descriptors for all sg entries
>           * (128) and potentially one alignment transfer for
>           * each of those entries.
>           */
>          host->adma_desc = dma_alloc_coherent(mmc_dev(host->mmc),
>                                               ADMA_SIZE, &host->adma_addr,
>                                               GFP_KERNEL);
>          host->align_buffer = kmalloc(128 * 4, GFP_KERNEL);
>          printk("%p %p\n", host->adma_desc, host->align_buffer); --->
> Here host->adma_desc is NULL
>          if (!host->adma_desc || !host->align_buffer) {
>                  dma_free_coherent(mmc_dev(host->mmc), ADMA_SIZE,
> -->Trigger panic
>                                    host->adma_desc, host->adma_addr);
>                  kfree(host->align_buffer);
> 
> So dma_alloc_coherent failed, dma_free_coherent-->bitmap_clear trigger
> Dom0 panic. 128M memory is for Dom0, dma_alloc_coherent should not fail.
> Do you have any suggestions?
> 

In my Dom0 kernel configuration:CONFIG_CMA_SIZE_MBYTES=320. But Dom0
kernel memsize is only 128M. From Dom0 kernel boot info, we can see CMA
alloc 3200M failed. Anyway, I think this should not only change
CONFIG_CMD_SIZE_MBYTES that simple, kernel should handle such case, but
not panic. After change CONFIG_CMD_SIZE_MBYTES to 24M, the panic
disappears.
Another problem comes to me, with 128M for Dom0, Dom0 can printk msg to
serial, but with "dom0_mem=1024M", I see nothing from serial for Dom0.

>>
>> Regards,
>>
> Thanks,
> Peng.
> 
Thanks,
Peng.

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