Re: ARM64 boot failure on espressobin with 5.0.0-rc6 (1f947a7a011fcceb14cb912f5481a53b18f1879a)

[Robin Murphy <robin.murphy@arm.com>]

On 14/02/2019 16:09, John David Anglin wrote:
> Starting kernel ...
> 
> [    0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd034]
> [    0.000000] Linux version 5.0.0-rc6+ (root@espressobin) (gcc version 6.3.0 20170516 (Debian 6.3.0-18+deb9u1)) #1 SMP PREEMPT Wed Feb 13
> 16:17:46 EST 2019
> [    0.000000] Machine model: Globalscale Marvell ESPRESSOBin Board
> [    0.000000] earlycon: ar3700_uart0 at MMIO 0x00000000d0012000 (options '')
> [    0.000000] printk: bootconsole [ar3700_uart0] enabled
> [    3.219693] Internal error: Oops: 96000005 [#1] PREEMPT SMP
> [    3.225349] Modules linked in:
> [    3.228489] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.0.0-rc6+ #1
> [    3.234936] Hardware name: Globalscale Marvell ESPRESSOBin Board (DT)
> [    3.241568] pstate: 20000005 (nzCv daif -PAN -UAO)
> [    3.246505] pc : dma_direct_map_page+0x48/0x1d8
> [    3.251159] lr : mv_xor_channel_add+0x3b0/0xb28
> [    3.255812] sp : ffffff8010033a60
> [    3.259217] x29: ffffff8010033a60 x28: ffffffc03befec80
> [    3.264682] x27: ffffff8010e97068 x26: 0000000000000000
> [    3.270148] x25: 0000000000000029 x24: 0000000000000083
> [    3.275613] x23: 0000000000000000 x22: 0000000000000002
> [    3.281079] x21: 0000000000000080 x20: ffffff8010ecd000
> [    3.286544] x19: 0000000000000000 x18: ffffffffffffffff
> [    3.292010] x17: 00000000f8f63085 x16: 0000000074242664
> [    3.297476] x15: ffffff8010ecd6c8 x14: ffffffc03bed9e83
> [    3.302941] x13: ffffffc03bed9e82 x12: 0000000000000038
> [    3.308407] x11: 0000000000001fff x10: 0000000000000001
> [    3.313872] x9 : 0000000000000000 x8 : ffffff8010dbe000
> [    3.319338] x7 : ffffff8010fbe000 x6 : ffffffbf00000000
> [    3.324804] x5 : 0000000000000000 x4 : 0000000000000002
> [    3.330269] x3 : 0000000000000002 x2 : 0000000000000eac
> [    3.335735] x1 : ffffffbf00efbf80 x0 : 0000000000000000
> [    3.341202] Process swapper/0 (pid: 1, stack limit = 0x(____ptrval____))
> [    3.348100] Call trace:
> [    3.350612]  dma_direct_map_page+0x48/0x1d8
> [    3.354912]  mv_xor_channel_add+0x3b0/0xb28
> [    3.359213]  mv_xor_probe+0x20c/0x4b8
> [    3.362978]  platform_drv_probe+0x50/0xb0
> [    3.367097]  really_probe+0x1fc/0x2c0
> [    3.370860]  driver_probe_device+0x58/0x100
> [    3.375160]  __driver_attach+0xd8/0xe0
> [    3.379016]  bus_for_each_dev+0x68/0xc8
> [    3.382957]  driver_attach+0x20/0x28
> [    3.386631]  bus_add_driver+0x108/0x228
> [    3.390572]  driver_register+0x60/0x110
> [    3.394515]  __platform_driver_register+0x44/0x50
> [    3.399357]  mv_xor_driver_init+0x18/0x20
> [    3.403477]  do_one_initcall+0x58/0x170
> [    3.407419]  kernel_init_freeable+0x190/0x234
> [    3.411900]  kernel_init+0x10/0x108
> [    3.415482]  ret_from_fork+0x10/0x1c
> [    3.419157] Code: 2a0403f6 934cfc00 aa0503f7 7100047f (f9412663)
> [    3.425438] ---[ end trace f62a451df663a071 ]---
> [    3.430228] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> [    3.438060] SMP: stopping secondary CPUs
> [    3.442093] Kernel Offset: disabled
> [    3.445676] CPU features: 0x002,2000200c
> [    3.449706] Memory Limit: none
> [    3.452846] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---
> 
> The same error occurs with linux-net 5.0.0-rc5 (91986ee166cf0816ae92668476ea7872d51b0c6e).  v4.20.x
> boots okay.  Seems to be a hard failure.

Oh wow, that driver has possibly the most inventive way of passing a 
NULL device to the DMA API that I've ever seen, and on arm64 it will 
certainly have been failing since 4.2, but of course there's also no 
error checking for anyone to notice...

This crash will be a fallout from 356da6d0cd (plus the subsequent fix in 
9ab91e7c5c51) that's otherwise missed Christoph's big cleanup. Obviously 
the right thing to do is for someone to try to figure out the steaming 
pile of mess in that driver, but if necessary I think the quick fix 
below should probably suffice to mitigate the change in the short term.

Robin.

----->8-----
diff --git a/arch/arm64/include/asm/dma-mapping.h 
b/arch/arm64/include/asm/dma-mapping.h
index 95dbf3ef735a..f530edfe5678 100644
--- a/arch/arm64/include/asm/dma-mapping.h
+++ b/arch/arm64/include/asm/dma-mapping.h
@@ -26,7 +26,7 @@

  static inline const struct dma_map_ops *get_arch_dma_ops(struct 
bus_type *bus)
  {
-	return NULL;
+	return bus ? NULL : &dma_dummy_ops;
  }

  void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,

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