[PATCH] powerpc/32s: Fix kasan_early_hash_table() for CONFIG_VMAP_STACK

[PATCH] powerpc/32s: Fix kasan_early_hash_table() for CONFIG_VMAP_STACK

[Christophe Leroy]

On book3s/32 CPUs that are handling MMU through a hash table,
MMU_init_hw() function was adapted for VMAP_STACK in order to
handle virtual addresses instead of physical addresses in the
low level hash functions.

When using KASAN, the same adaptations are required for the
early hash table set up by kasan_early_hash_table() function.

Fixes: cd08f109e262 ("powerpc/32s: Enable CONFIG_VMAP_STACK")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/mm/kasan/kasan_init_32.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index d3cacd462560..16dd95bd0749 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -185,8 +185,11 @@ u8 __initdata early_hash[256 << 10] __aligned(256 << 10) = {0};
 
 static void __init kasan_early_hash_table(void)
 {
-	modify_instruction_site(&patch__hash_page_A0, 0xffff, __pa(early_hash) >> 16);
-	modify_instruction_site(&patch__flush_hash_A0, 0xffff, __pa(early_hash) >> 16);
+	unsigned int hash = IS_ENABLED(CONFIG_VMAP_STACK) ? (unsigned int)early_hash :
+							    __pa(early_hash);
+
+	modify_instruction_site(&patch__hash_page_A0, 0xffff, hash >> 16);
+	modify_instruction_site(&patch__flush_hash_A0, 0xffff, hash >> 16);
 
 	Hash = (struct hash_pte *)early_hash;
 }
-- 
2.25.0

Re: [PATCH] powerpc/32s: Fix kasan_early_hash_table() for CONFIG_VMAP_STACK

[Michael Ellerman]

On Wed, 2020-01-29 at 12:34:36 UTC, Christophe Leroy wrote:
> On book3s/32 CPUs that are handling MMU through a hash table,
> MMU_init_hw() function was adapted for VMAP_STACK in order to
> handle virtual addresses instead of physical addresses in the
> low level hash functions.
> 
> When using KASAN, the same adaptations are required for the
> early hash table set up by kasan_early_hash_table() function.
> 
> Fixes: cd08f109e262 ("powerpc/32s: Enable CONFIG_VMAP_STACK")
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/41196224883a64e56e0ef237c19eb837058df071

cheers