Subject: [PATCH] ARM: mmu: Add debug_ll_io_init() mappings to early mappings

From: [email-masked] (Stephen Boyd)
Date: Tue, 11 Jun 2013 18:30:07 -0700

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. 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]>
---
 arch/arm/mm/mmu.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index e0d8565..04fe160 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -938,8 +938,12 @@ static void __init pci_reserve_io(void)
 #ifdef CONFIG_DEBUG_LL
 void __init debug_ll_io_init(void)
 {
+	struct vm_struct *vm;
+	struct static_vm *svm;
 	struct map_desc map;
 
+	svm = early_alloc_aligned(sizeof(*svm), __alignof__(*svm));
+
 	debug_ll_addr(&map.pfn, &map.virtual);
 	if (!map.pfn || !map.virtual)
 		return;
@@ -948,6 +952,15 @@ void __init debug_ll_io_init(void)
 	map.length = PAGE_SIZE;
 	map.type = MT_DEVICE;
 	create_mapping(&map);
+
+	vm = &svm->vm;
+	vm->addr = (void *)map.virtual;
+	vm->size = map.length;
+	vm->phys_addr = __pfn_to_phys(map.pfn);
+	vm->flags = VM_IOREMAP | VM_ARM_STATIC_MAPPING;
+	vm->flags |= VM_ARM_MTYPE(map.type);
+	vm->caller = debug_ll_io_init;
+	add_static_vm_early(svm);
 }
 #endif
 
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