From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Subject: mm/CMA: fix boot regression due to physical address of high_memory
high_memory isn't direct mapped memory so retrieving it's physical address
isn't appropriate. But, it would be useful to check physical address of
highmem boundary so it's justfiable to get physical address from it. In
x86, there is a validation check if CONFIG_DEBUG_VIRTUAL and it triggers
following boot failure reported by Ingo.
...
BUG: Int 6: CR2 00f06f53
EDI (null) ESI 0665b000 EBP c1ed7edc EBX 40000000
ESP c1ed7ed8 ES 0000007b DS 0000007b
EDX c2022c18 ECX 37d34000 EAX (null)
vec 00000006 err (null) EIP c102b62e CS 00000060 flg 00210013
...
Call Trace:
[<c1902dfd>] dump_stack+0x41/0x52
[<c1fad1f7>] early_idt_handler+0x6b/0x6b
[<c102b62e>] ? __phys_addr+0x16/0x68
[<c1fccd26>] cma_declare_contiguous+0x33/0x212
[<c1fe9b6e>] dma_contiguous_reserve_area+0x31/0x4e
[<c1fe9ca8>] dma_contiguous_reserve+0x11d/0x125
[<c1faf2c8>] ? setup_real_mode+0x98/0xa3
[<c1fb00c8>] setup_arch+0x7b5/0xb63
[<c1fad802>] start_kernel+0xb8/0x3e6
[<c1fad2cb>] i386_start_kernel+0x79/0x7d
To fix boot regression, this patch implements workaround to avoid
validation check in x86 when retrieving physical address of high_memory.
__pa_nodebug() used by this patch is implemented only in x86 so there is
no choice but to use dirty #ifdef.
[akpm@xxxxxxxxxxxxxxxxxxxx: tweak comment]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Reported-by: Ingo Molnar <mingo@xxxxxxxxxx>
Tested-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/cma.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff -puN mm/cma.c~mm-cma-fix-boot-regression-due-to-physical-address-of-high_memory mm/cma.c
--- a/mm/cma.c~mm-cma-fix-boot-regression-due-to-physical-address-of-high_memory
+++ a/mm/cma.c
@@ -215,9 +215,21 @@ int __init cma_declare_contiguous(phys_a
bool fixed, struct cma **res_cma)
{
phys_addr_t memblock_end = memblock_end_of_DRAM();
- phys_addr_t highmem_start = __pa(high_memory);
+ phys_addr_t highmem_start;
int ret = 0;
+#ifdef CONFIG_X86
+ /*
+ * high_memory isn't direct mapped memory so retrieving its physical
+ * address isn't appropriate. But it would be useful to check the
+ * physical address of the highmem boundary so it's justfiable to get
+ * the physical address from it. On x86 there is a validation check for
+ * this case, so the following workaround is needed to avoid it.
+ */
+ highmem_start = __pa_nodebug(high_memory);
+#else
+ highmem_start = __pa(high_memory);
+#endif
pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
__func__, &size, &base, &limit, &alignment);
_
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