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authorMax Filippov <jcmvbkbc@gmail.com>2017-12-03 13:28:52 -0800
committerMax Filippov <jcmvbkbc@gmail.com>2017-12-16 22:37:12 -0800
commitc633544a6154146a210cf158157a1ae7c55473b6 (patch)
treed670a9984373622d991c382126f341b6f32154cd /Documentation/xtensa
parent1af1e8a39dc0fab5e50f10462c636da8c1e0cfbb (diff)
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xtensa: add support for KASAN
Cover kernel addresses above 0x90000000 by the shadow map. Enable HAVE_ARCH_KASAN when MMU is enabled. Provide kasan_early_init that fills shadow map with writable copies of kasan_zero_page. Call kasan_early_init right after mmu initialization in the setup_arch. Provide kasan_init that allocates proper shadow map pages from the memblock and puts these pages into the shadow map for addresses from VMALLOC area to the end of KSEG. Call kasan_init right after memblock initialization. Don't use KASAN for the boot code, MMU and KASAN initialization and page fault handler. Make kernel stack size 4 times larger when KASAN is enabled to avoid stack overflows. GCC 7.3, 8 or newer is required to build the xtensa kernel with KASAN. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Diffstat (limited to 'Documentation/xtensa')
-rw-r--r--Documentation/xtensa/mmu.txt6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/xtensa/mmu.txt b/Documentation/xtensa/mmu.txt
index 16921393e366..318114de63f3 100644
--- a/Documentation/xtensa/mmu.txt
+++ b/Documentation/xtensa/mmu.txt
@@ -71,6 +71,8 @@ Default MMUv2-compatible layout.
+------------------+
| Page table | XCHAL_PAGE_TABLE_VADDR 0x80000000 XCHAL_PAGE_TABLE_SIZE
+------------------+
+| KASAN shadow map | KASAN_SHADOW_START 0x80400000 KASAN_SHADOW_SIZE
++------------------+ 0x8e400000
+------------------+
| VMALLOC area | VMALLOC_START 0xc0000000 128MB - 64KB
+------------------+ VMALLOC_END
@@ -111,6 +113,8 @@ Default MMUv2-compatible layout.
+------------------+
| Page table | XCHAL_PAGE_TABLE_VADDR 0x80000000 XCHAL_PAGE_TABLE_SIZE
+------------------+
+| KASAN shadow map | KASAN_SHADOW_START 0x80400000 KASAN_SHADOW_SIZE
++------------------+ 0x8e400000
+------------------+
| VMALLOC area | VMALLOC_START 0xa0000000 128MB - 64KB
+------------------+ VMALLOC_END
@@ -152,6 +156,8 @@ Default MMUv2-compatible layout.
+------------------+
| Page table | XCHAL_PAGE_TABLE_VADDR 0x80000000 XCHAL_PAGE_TABLE_SIZE
+------------------+
+| KASAN shadow map | KASAN_SHADOW_START 0x80400000 KASAN_SHADOW_SIZE
++------------------+ 0x8e400000
+------------------+
| VMALLOC area | VMALLOC_START 0x90000000 128MB - 64KB
+------------------+ VMALLOC_END