[BUG] "access dev->iommu_fwspec" cause crash on BPI-R2

[BUG] "access dev->iommu_fwspec" cause crash on BPI-R2

[Frank Wunderlich]

Hi,

the following Patch breaks hdmi (at least) on Bananapi R2 (mt7623):

a9bf2eec5a6fc01a0a5250eaf0bf61dfd382a78a "iommu/mediatek: Use helper functions to access dev->iommu_fwspec"

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/iommu/mtk_iommu_v1.c?id=a9bf2eec5a6fc01a0a5250eaf0bf61dfd382a78a

[    5.363509] Backtrace:                                                                      
[    5.365946] [<c05a6010>] (mtk_iommu_domain_free) from [<c05a1544>] (iommu_domain_free+0x20/)
[    5.374670]  r4:decd57a0                                                                    
[    5.377192] [<c05a1524>] (iommu_domain_free) from [<c011b85c>] (release_iommu_mapping+0x24/)
[    5.385922] [<c011b838>] (release_iommu_mapping) from [<c011b8cc>] (arm_iommu_release_mappi)
[    5.395943]  r7:00000000 r6:decd5780 r5:00000000 r4:decd57a0                                
[    5.401567] [<c011b89c>] (arm_iommu_release_mapping.part.0) from [<c011cb4c>] (arch_setup_d)
[    5.411412]  r5:00000000 r4:dead1410                                                        
[    5.414968] [<c011ca7c>] (arch_setup_dma_ops) from [<c07d2764>] (of_dma_configure+0x27c/0x3)
[    5.423521]  r6:c0b58e20 r5:00000000 r4:00000000                                            
[    5.428109] [<c07d24e8>] (of_dma_configure) from [<c060a63c>] (platform_dma_configure+0x28/)
[    5.436838]  r10:c107efdc r9:00000000 r8:c10c0008 r7:00000000 r6:c1117b34 r5:dead1410       
[    5.444612]  r4:c1117b30                                                                    
[    5.447131] [<c060a614>] (platform_dma_configure) from [<c06079ec>] (really_probe+0xc4/0x42)
[    5.455602] [<c0607928>] (really_probe) from [<c0607f70>] (driver_probe_device+0x88/0x1e0)  
[    5.463814]  r10:00000000 r9:c060a25c r8:00000000 r7:c1008c48 r6:c107efdc r5:c107efdc       
[    5.471588]  r4:dead1410                                                                    
[    5.474107] [<c0607ee8>] (driver_probe_device) from [<c06081fc>] (__driver_attach+0x134/0x1)
[    5.482663]  r9:c060a25c r8:00000000 r7:c1008c48 r6:c107efdc r5:dead1444 r4:dead1410        
[    5.490358] [<c06080c8>] (__driver_attach) from [<c0605510>] (bus_for_each_dev+0x84/0xc4)   
[    5.498480]  r7:c1008c48 r6:c06080c8 r5:c107efdc r4:00000000                                
[    5.504102] [<c060548c>] (bus_for_each_dev) from [<c0607344>] (driver_attach+0x2c/0x30)     
[    5.512052]  r7:c10bff30 r6:c107fad8 r5:decde780 r4:c107efdc                                
[    5.517675] [<c0607318>] (driver_attach) from [<c0606c68>] (bus_add_driver+0x1d0/0x274)     
[    5.525629] [<c0606a98>] (bus_add_driver) from [<c0608fa8>] (driver_register+0x84/0x118)    
[    5.533666]  r8:c060a20c r7:c0609c60 r6:c10c0230 r5:00000002 r4:c107efdc                    
[    5.540323] [<c0608f24>] (driver_register) from [<c060a538>] (__platform_register_drivers+0)

after reverting it i can boot without crash and start x-server

my repo just for reference (revert not pushed yet): https://github.com/frank-w/BPI-R2-4.14/tree/5.0-hdmi

i hope i had chosen the right way to report this...

regards Frank

Re: [BUG] "access dev->iommu_fwspec" cause crash on BPI-R2

[Joerg Roedel]

Hi Frank,

thanks for the report!

On Tue, Jan 22, 2019 at 05:09:09PM +0100, Frank Wunderlich wrote:
> Hi,
> 
> the following Patch breaks hdmi (at least) on Bananapi R2 (mt7623):
> 
> a9bf2eec5a6fc01a0a5250eaf0bf61dfd382a78a "iommu/mediatek: Use helper functions to access dev->iommu_fwspec"

Does the attached diff fix the issue for you?

Thanks,

	Joerg

diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index 6ede4286b835..f60bdb85c4c0 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -442,6 +442,10 @@ static int mtk_iommu_add_device(struct device *dev)
 		iommu_spec.args_count = count;
 
 		mtk_iommu_create_mapping(dev, &iommu_spec);
+
+		/* dev->iommu_fwspec might have changed */
+		fwspec = dev_iommu_fwspec_get(dev);
+
 		of_node_put(iommu_spec.np);
 	}
 

Aw: Re: [BUG] "access dev->iommu_fwspec" cause crash on BPI-R2

[Frank Wunderlich]

Hi,

thanks for quick reply, this seems to fix it

no crash, xserver works, like revert of the commit...pushed the fix to below github-repo

regards Frank


> Gesendet: Dienstag, 22. Januar 2019 um 17:49 Uhr
> Von: "Joerg Roedel" <joro@8bytes.org>
> An: "Frank Wunderlich" <frank-w@public-files.de>
> Cc: "Matthias Brugger" <matthias.bgg@gmail.com>, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, "Ryder Lee" <ryder.lee@mediatek.com>
> Betreff: Re: [BUG] "access dev->iommu_fwspec" cause crash on BPI-R2
>
> Hi Frank,
> 
> thanks for the report!
> 
> On Tue, Jan 22, 2019 at 05:09:09PM +0100, Frank Wunderlich wrote:
> > Hi,
> > 
> > the following Patch breaks hdmi (at least) on Bananapi R2 (mt7623):
> > 
> > a9bf2eec5a6fc01a0a5250eaf0bf61dfd382a78a "iommu/mediatek: Use helper functions to access dev->iommu_fwspec"
> 
> Does the attached diff fix the issue for you?
> 
> Thanks,
> 
> 	Joerg
> 
> diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
> index 6ede4286b835..f60bdb85c4c0 100644
> --- a/drivers/iommu/mtk_iommu_v1.c
> +++ b/drivers/iommu/mtk_iommu_v1.c
> @@ -442,6 +442,10 @@ static int mtk_iommu_add_device(struct device *dev)
>  		iommu_spec.args_count = count;
>  
>  		mtk_iommu_create_mapping(dev, &iommu_spec);
> +
> +		/* dev->iommu_fwspec might have changed */
> +		fwspec = dev_iommu_fwspec_get(dev);
> +
>  		of_node_put(iommu_spec.np);
>  	}
>  
>