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author | Max Filippov <jcmvbkbc@gmail.com> | 2017-12-03 22:28:52 +0100 |
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committer | Max Filippov <jcmvbkbc@gmail.com> | 2017-12-17 07:37:12 +0100 |
commit | c633544a6154146a210cf158157a1ae7c55473b6 (patch) | |
tree | d670a9984373622d991c382126f341b6f32154cd /arch/xtensa/mm | |
parent | xtensa: move fixmap and kmap just above the KSEG (diff) | |
download | linux-c633544a6154146a210cf158157a1ae7c55473b6.tar.xz linux-c633544a6154146a210cf158157a1ae7c55473b6.zip |
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 'arch/xtensa/mm')
-rw-r--r-- | arch/xtensa/mm/Makefile | 5 | ||||
-rw-r--r-- | arch/xtensa/mm/init.c | 7 | ||||
-rw-r--r-- | arch/xtensa/mm/kasan_init.c | 95 |
3 files changed, 107 insertions, 0 deletions
diff --git a/arch/xtensa/mm/Makefile b/arch/xtensa/mm/Makefile index 0b3d296a016a..734888a00dc8 100644 --- a/arch/xtensa/mm/Makefile +++ b/arch/xtensa/mm/Makefile @@ -5,3 +5,8 @@ obj-y := init.o misc.o obj-$(CONFIG_MMU) += cache.o fault.o ioremap.o mmu.o tlb.o obj-$(CONFIG_HIGHMEM) += highmem.o +obj-$(CONFIG_KASAN) += kasan_init.o + +KASAN_SANITIZE_fault.o := n +KASAN_SANITIZE_kasan_init.o := n +KASAN_SANITIZE_mmu.o := n diff --git a/arch/xtensa/mm/init.c b/arch/xtensa/mm/init.c index 6fc1cb093fb3..0d980f05da82 100644 --- a/arch/xtensa/mm/init.c +++ b/arch/xtensa/mm/init.c @@ -100,6 +100,9 @@ void __init mem_init(void) mem_init_print_info(NULL); pr_info("virtual kernel memory layout:\n" +#ifdef CONFIG_KASAN + " kasan : 0x%08lx - 0x%08lx (%5lu MB)\n" +#endif #ifdef CONFIG_MMU " vmalloc : 0x%08lx - 0x%08lx (%5lu MB)\n" #endif @@ -108,6 +111,10 @@ void __init mem_init(void) " fixmap : 0x%08lx - 0x%08lx (%5lu kB)\n" #endif " lowmem : 0x%08lx - 0x%08lx (%5lu MB)\n", +#ifdef CONFIG_KASAN + KASAN_SHADOW_START, KASAN_SHADOW_START + KASAN_SHADOW_SIZE, + KASAN_SHADOW_SIZE >> 20, +#endif #ifdef CONFIG_MMU VMALLOC_START, VMALLOC_END, (VMALLOC_END - VMALLOC_START) >> 20, diff --git a/arch/xtensa/mm/kasan_init.c b/arch/xtensa/mm/kasan_init.c new file mode 100644 index 000000000000..6b532b6bd785 --- /dev/null +++ b/arch/xtensa/mm/kasan_init.c @@ -0,0 +1,95 @@ +/* + * Xtensa KASAN shadow map initialization + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 2017 Cadence Design Systems Inc. + */ + +#include <linux/bootmem.h> +#include <linux/init_task.h> +#include <linux/kasan.h> +#include <linux/kernel.h> +#include <linux/memblock.h> +#include <asm/initialize_mmu.h> +#include <asm/tlbflush.h> +#include <asm/traps.h> + +void __init kasan_early_init(void) +{ + unsigned long vaddr = KASAN_SHADOW_START; + pgd_t *pgd = pgd_offset_k(vaddr); + pmd_t *pmd = pmd_offset(pgd, vaddr); + int i; + + for (i = 0; i < PTRS_PER_PTE; ++i) + set_pte(kasan_zero_pte + i, + mk_pte(virt_to_page(kasan_zero_page), PAGE_KERNEL)); + + for (vaddr = 0; vaddr < KASAN_SHADOW_SIZE; vaddr += PMD_SIZE, ++pmd) { + BUG_ON(!pmd_none(*pmd)); + set_pmd(pmd, __pmd((unsigned long)kasan_zero_pte)); + } + early_trap_init(); +} + +static void __init populate(void *start, void *end) +{ + unsigned long n_pages = (end - start) / PAGE_SIZE; + unsigned long n_pmds = n_pages / PTRS_PER_PTE; + unsigned long i, j; + unsigned long vaddr = (unsigned long)start; + pgd_t *pgd = pgd_offset_k(vaddr); + pmd_t *pmd = pmd_offset(pgd, vaddr); + pte_t *pte = memblock_virt_alloc(n_pages * sizeof(pte_t), PAGE_SIZE); + + pr_debug("%s: %p - %p\n", __func__, start, end); + + for (i = j = 0; i < n_pmds; ++i) { + int k; + + for (k = 0; k < PTRS_PER_PTE; ++k, ++j) { + phys_addr_t phys = + memblock_alloc_base(PAGE_SIZE, PAGE_SIZE, + MEMBLOCK_ALLOC_ANYWHERE); + + set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL)); + } + } + + for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE) + set_pmd(pmd + i, __pmd((unsigned long)pte)); + + local_flush_tlb_all(); + memset(start, 0, end - start); +} + +void __init kasan_init(void) +{ + int i; + + BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START - + (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT)); + BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR); + + /* + * Replace shadow map pages that cover addresses from VMALLOC area + * start to the end of KSEG with clean writable pages. + */ + populate(kasan_mem_to_shadow((void *)VMALLOC_START), + kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR)); + + /* Write protect kasan_zero_page and zero-initialize it again. */ + for (i = 0; i < PTRS_PER_PTE; ++i) + set_pte(kasan_zero_pte + i, + mk_pte(virt_to_page(kasan_zero_page), PAGE_KERNEL_RO)); + + local_flush_tlb_all(); + memset(kasan_zero_page, 0, PAGE_SIZE); + + /* At this point kasan is fully initialized. Enable error messages. */ + current->kasan_depth = 0; + pr_info("KernelAddressSanitizer initialized\n"); +} |