The challenge with book3s/32 is that the hash table management has to be set up before being able to use KASAN.
This patch adds a kasan_arch_is_ready() helper to defer the activation of KASAN until paging is ready. This limits KASAN to KASAN_MINIMAL mode. The downside of it is that the 603, which doesn't use hash table, also gets downgraded to KASAN_MINIMAL because this is no way to activate full support dynamically because that's compiled-in. Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr> --- arch/powerpc/Makefile | 2 ++ arch/powerpc/include/asm/kasan.h | 13 +++++++++++++ arch/powerpc/mm/kasan/kasan_init_32.c | 27 +++++++++++++++++++++++++-- 3 files changed, 40 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index f0738099e31e..06d085558d21 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -428,11 +428,13 @@ endif endif ifdef CONFIG_KASAN +ifndef CONFIG_PPC_BOOK3S_32 prepare: kasan_prepare kasan_prepare: prepare0 $(eval KASAN_SHADOW_OFFSET = $(shell awk '{if ($$2 == "KASAN_SHADOW_OFFSET") print $$3;}' include/generated/asm-offsets.h)) endif +endif # Check toolchain versions: # - gcc-4.6 is the minimum kernel-wide version so nothing required. diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h index 0bc9148f5d87..97b5ccf0702f 100644 --- a/arch/powerpc/include/asm/kasan.h +++ b/arch/powerpc/include/asm/kasan.h @@ -16,6 +16,7 @@ #include <asm/page.h> #include <asm/pgtable-types.h> +#include <linux/jump_label.h> #define KASAN_SHADOW_SCALE_SHIFT 3 @@ -34,5 +35,17 @@ void kasan_early_init(void); void kasan_init(void); +extern struct static_key_false powerpc_kasan_enabled_key; + +static inline bool kasan_arch_is_ready(void) +{ + if (!IS_ENABLED(CONFIG_BOOK3S_32)) + return true; + if (static_branch_likely(&powerpc_kasan_enabled_key)) + return true; + return false; +} +#define kasan_arch_is_ready kasan_arch_is_ready + #endif /* __ASSEMBLY */ #endif diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c index 495c908d6ee6..f24f8f56d450 100644 --- a/arch/powerpc/mm/kasan/kasan_init_32.c +++ b/arch/powerpc/mm/kasan/kasan_init_32.c @@ -9,6 +9,9 @@ #include <linux/vmalloc.h> #include <asm/pgalloc.h> +/* Used by BOOK3S_32 only */ +DEFINE_STATIC_KEY_FALSE(powerpc_kasan_enabled_key); + void __init kasan_early_init(void) { unsigned long addr = KASAN_SHADOW_START; @@ -21,7 +24,7 @@ void __init kasan_early_init(void) BUILD_BUG_ON(KASAN_SHADOW_START & ~PGDIR_MASK); if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE)) - panic("KASAN not supported with Hash MMU\n"); + return; for (i = 0; i < PTRS_PER_PTE; i++) __set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page, @@ -32,6 +35,22 @@ void __init kasan_early_init(void) next = pgd_addr_end(addr, end); pmd_populate_kernel(&init_mm, pmd, kasan_early_shadow_pte); } while (pmd++, addr = next, addr != end); + + if (IS_ENABLED(CONFIG_PPC_BOOK3S_32)) { + jump_label_init(); + static_branch_enable(&powerpc_kasan_enabled_key); + } +} + +static void __init kasan_late_init(void) +{ + unsigned long addr; + phys_addr_t pa = __pa(kasan_early_shadow_page); + + for (addr = KASAN_SHADOW_START; addr < KASAN_SHADOW_END; addr += PAGE_SIZE) + map_kernel_page(addr, pa, PAGE_KERNEL_RO); + + static_branch_enable(&powerpc_kasan_enabled_key); } static void __ref *kasan_get_one_page(void) @@ -113,6 +132,9 @@ void __init kasan_init(void) { struct memblock_region *reg; + if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE)) + kasan_late_init(); + for_each_memblock(memory, reg) { int ret = kasan_init_region(__va(reg->base), reg->size); @@ -120,7 +142,8 @@ void __init kasan_init(void) panic("kasan: kasan_init_region() failed"); } - kasan_remap_early_shadow_ro(); + if (!early_mmu_has_feature(MMU_FTR_HPTE_TABLE)) + kasan_remap_early_shadow_ro(); clear_page(kasan_early_shadow_page); -- 2.13.3