From c633544a6154146a210cf158157a1ae7c55473b6 Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Sun, 3 Dec 2017 13:28:52 -0800 Subject: 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 --- Documentation/xtensa/mmu.txt | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation/xtensa') 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 -- cgit v1.2.3