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authorChristophe Leroy <christophe.leroy@c-s.fr>2019-04-26 18:23:37 +0200
committerMichael Ellerman <mpe@ellerman.id.au>2019-05-02 17:20:26 +0200
commitda3a3b0a0e38377c98946420acdc7d4ca38cff47 (patch)
tree56962be152c3046b9e791ff5a9867da9b4a0ba7c
parentpowerpc/32s: set up an early static hash table for KASAN. (diff)
downloadlinux-da3a3b0a0e38377c98946420acdc7d4ca38cff47.tar.xz
linux-da3a3b0a0e38377c98946420acdc7d4ca38cff47.zip
powerpc/32s: map kasan zero shadow with PAGE_READONLY instead of PAGE_KERNEL_RO
For hash32, the zero shadow page gets mapped with PAGE_READONLY instead of PAGE_KERNEL_RO, because the PP bits don't provide a RO kernel, so PAGE_KERNEL_RO is equivalent to PAGE_KERNEL. By using PAGE_READONLY, the page is RO for both kernel and user, but this is not a security issue as it contains only zeroes. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
-rw-r--r--arch/powerpc/mm/kasan/kasan_init_32.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index ba8361487075..0d62be3cba47 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -39,7 +39,10 @@ static int kasan_init_shadow_page_tables(unsigned long k_start, unsigned long k_
if (!new)
return -ENOMEM;
- kasan_populate_pte(new, PAGE_KERNEL_RO);
+ if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
+ kasan_populate_pte(new, PAGE_READONLY);
+ else
+ kasan_populate_pte(new, PAGE_KERNEL_RO);
pmd_populate_kernel(&init_mm, pmd, new);
}
return 0;
@@ -84,7 +87,10 @@ static int __ref kasan_init_region(void *start, size_t size)
static void __init kasan_remap_early_shadow_ro(void)
{
- kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL_RO);
+ if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
+ kasan_populate_pte(kasan_early_shadow_pte, PAGE_READONLY);
+ else
+ kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL_RO);
flush_tlb_kernel_range(KASAN_SHADOW_START, KASAN_SHADOW_END);
}