ARM: mmu: Add debug_ll_io_init() mappings to early mappings

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.

---

Changes since v1:
* Use iotable_init() instead of open coding it

 arch/arm/mm/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index e0d8565..18b8aeb 100644
@@ -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
 

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

Now that debug_ll_io_init() maps memory via iotable_init() we don't get much information in vmallocinfo about what the mapping corresponds to. Introduce iotable_init_caller() that does the same thing as iotable_init() except that it allows us to specify the function that should appear in vmallocinfo. This allows us to differentiate the debug_ll mapping from the other iotable_init() mappings.

---

I'm ok without this patch. Using __builtin_return_address(0) seems to do alright on framepointer builds but fails on unwind table builds so I went with this approach.

 arch/arm/mm/mmu.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

index 18b8aeb..0699bee 100644
@@ -811,10 +811,8 @@ static void __init create_mapping(struct map_desc *md)
 	} while (pgd++, addr != end);
 }
 
-/*
- * Create the architecture specific mappings
- */
-void __init iotable_init(struct map_desc *io_desc, int nr)
+static void __init
+iotable_init_caller(struct map_desc *io_desc, int nr, void *caller)
 {
 	struct map_desc *md;
 	struct vm_struct *vm;

@@ -834,11 +832,19 @@ void __init iotable_init(struct map_desc *io_desc, int nr)
 		vm->phys_addr = __pfn_to_phys(md->pfn);
 		vm->flags = VM_IOREMAP | VM_ARM_STATIC_MAPPING;
 		vm->flags |= VM_ARM_MTYPE(md->type);
-		vm->caller = iotable_init;
+		vm->caller = caller;
 		add_static_vm_early(svm++);
 	}
 }
 
+/*
+ * Create the architecture specific mappings
+ */
+void __init iotable_init(struct map_desc *io_desc, int nr)
+{
+	iotable_init_caller(io_desc, nr, iotable_init);
+}
+
 void __init vm_reserve_area_early(unsigned long addr, unsigned long size,
 				  void *caller)
 {

@@ -947,7 +953,7 @@ void __init debug_ll_io_init(void)
 	map.virtual &= PAGE_MASK;
 	map.length = PAGE_SIZE;
 	map.type = MT_DEVICE;
-	iotable_init(&map, 1);
+	iotable_init_caller(&map, 1, debug_ll_io_init);
 }
 #endif
 

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hosted by The Linux Foundation

Russell,

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

Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation