Subject: [PATCH v2 1/2] ARM: mmu: Add debug_ll_io_init() mappings to early mappings

From: [email-masked] (Stephen Boyd)
Date: Wed, 26 Jun 2013 10:02:59 -0700

Russell,

Shall I put these two patches in the patch tracker for 3.11?

On 06/14/13 13:32, Stephen Boyd wrote:
> Failure to add the mapping created in debug_ll_io_init() can lead
> to the BUG_ON() triggering in lib/ioremap.c:27 if the static
> virtual address decided for the debug_ll mapping overlaps with
> another mapping that is created later. This happens because the
> generic ioremap code has no idea there is a mapping there and it
> tries to place a mapping in the same location and blows up when
> it sees that there is a pte already present.
>
> kernel BUG at lib/ioremap.c:27!
> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.10.0-rc2-00042-g2af0c67-dirty #316
> task: ef088000 ti: ef082000 task.ti: ef082000
> PC is at ioremap_page_range+0x16c/0x198
> LR is at ioremap_page_range+0xf0/0x198
> pc : [<c04cb874>]    lr : [<c04cb7f8>]    psr: 20000113
> sp : ef083e78  ip : af140000  fp : ef083ebc
> r10: ef7fc100  r9 : ef7fc104  r8 : 000af174
> r7 : 00000647  r6 : beffffff  r5 : f004c000  r4 : f0040000
> r3 : af173417  r2 : 16440653  r1 : af173e07  r0 : ef7fc8fc
> Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
> Control: 10c5787d  Table: 8020406a  DAC: 00000015
> Process swapper/0 (pid: 1, stack limit = 0xef082238)
> Stack: (0xef083e78 to 0xef084000)
> 3e60:                                                       00040000 ef083eec
> 3e80: bf134000 f004bfff c0207c00 f004c000 c02fc120 f000c000 c15e7800 00040000
> 3ea0: ef083eec 00000647 c098ba9c c0953544 ef083edc ef083ec0 c021b82c c04cb714
> 3ec0: c09cdc50 00000040 ef0f1e00 ef1003c0 ef083f14 ef083ee0 c09535bc c021b7bc
> 3ee0: c0953544 c04d0c6c c094e2cc c1600be4 c07440c4 c09a6888 00000002 c0a15f00
> 3f00: ef082000 00000000 ef083f54 ef083f18 c0208728 c0953550 00000002 c1600bfc
> 3f20: c08e3fac c0839918 ef083f54 c1600b80 c09a6888 c0a15f00 0000008b c094e2cc
> 3f40: c098ba9c c098bab8 ef083f94 ef083f58 c094ea0c c020865c 00000002 00000002
> 3f60: c094e2cc 00000000 c025b674 00000000 c06ff860 00000000 00000000 00000000
> 3f80: 00000000 00000000 ef083fac ef083f98 c06ff878 c094e910 00000000 00000000
> 3fa0: 00000000 ef083fb0 c020efe8 c06ff86c 00000000 00000000 00000000 00000000
> 3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 3fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 c0595108
> [<c04cb874>] (ioremap_page_range+0x16c/0x198) from [<c021b82c>] (__alloc_remap_buffer.isra.18+0x7c/0xc4)
> [<c021b82c>] (__alloc_remap_buffer.isra.18+0x7c/0xc4) from [<c09535bc>] (atomic_pool_init+0x78/0x128)
> [<c09535bc>] (atomic_pool_init+0x78/0x128) from [<c0208728>] (do_one_initcall+0xd8/0x198)
> [<c0208728>] (do_one_initcall+0xd8/0x198) from [<c094ea0c>] (kernel_init_freeable+0x108/0x1d0)
> [<c094ea0c>] (kernel_init_freeable+0x108/0x1d0) from [<c06ff878>] (kernel_init+0x18/0xf4)
> [<c06ff878>] (kernel_init+0x18/0xf4) from [<c020efe8>] (ret_from_fork+0x14/0x20)
> Code: e50b0040 ebf54b2f e51b0040 eaffffee (e7f001f2)
>
> Fix it by telling generic layers about the static mapping via
> iotable_init().  This also has the nice side effect of letting
> you see the mapping in procfs' vmallocinfo file.
>
> Cc: Rob Herring <[email-masked]>
> Cc: Stephen Warren <[email-masked]>
> Signed-off-by: Stephen Boyd <[email-masked]>
> ---
>
> Changes since v1:
>  * Use iotable_init() instead of open coding it
>
>  arch/arm/mm/mmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index e0d8565..18b8aeb 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -947,7 +947,7 @@ void __init debug_ll_io_init(void)
>  	map.virtual &= PAGE_MASK;
>  	map.length = PAGE_SIZE;
>  	map.type = MT_DEVICE;
> -	create_mapping(&map);
> +	iotable_init(&map, 1);
>  }
>  #endif
>  

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