[PATCH] powerpc/32s: fix boot failure with DEBUG_PAGEALLOC without KASAN.

[PATCH] powerpc/32s: fix boot failure with DEBUG_PAGEALLOC without KASAN.

[Christophe Leroy]

When KASAN is selected, the definitive hash table has to be
set up later, but there is already an early temporary one.

When KASAN is not selected, there is no early hash table,
so the setup of the definitive hash table cannot be delayed.

Reported-by: Jonathan Neuschafer <j.neuschaefer@gmx.net>
Fixes: 72f208c6a8f7 ("powerpc/32s: move hash code patching out of MMU_init_hw()")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/kernel/head_32.S  | 2 ++
 arch/powerpc/mm/book3s32/mmu.c | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index f255e22184b4..c8b4f7ed318c 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -897,9 +897,11 @@ start_here:
 	bl	machine_init
 	bl	__save_cpu_setup
 	bl	MMU_init
+#ifdef CONFIG_KASAN
 BEGIN_MMU_FTR_SECTION
 	bl	MMU_init_hw_patch
 END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
+#endif
 
 /*
  * Go back to running unmapped so we can load up new values
diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index e249fbf6b9c3..6ddcbfad5c9e 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -358,6 +358,11 @@ void __init MMU_init_hw(void)
 	hash_mb2 = hash_mb = 32 - LG_HPTEG_SIZE - lg_n_hpteg;
 	if (lg_n_hpteg > 16)
 		hash_mb2 = 16 - LG_HPTEG_SIZE;
+
+	if (IS_ENABLED(CONFIG_KASAN))
+		return;
+
+	MMU_init_hw_patch();
 }
 
 void __init MMU_init_hw_patch(void)
-- 
2.13.3

Re: [PATCH] powerpc/32s: fix boot failure with DEBUG_PAGEALLOC without KASAN.

[Christoph Hellwig]

On Wed, Aug 14, 2019 at 05:28:35AM +0000, Christophe Leroy wrote:
> When KASAN is selected, the definitive hash table has to be
> set up later, but there is already an early temporary one.
> 
> When KASAN is not selected, there is no early hash table,
> so the setup of the definitive hash table cannot be delayed.

I think you also want to add this information to the code itself
as comments..

Re: [PATCH] powerpc/32s: fix boot failure with DEBUG_PAGEALLOC without KASAN.

[Jonathan Neuschäfer]

[-- Attachment #1: Type: text/plain, Size: 661 bytes --]

On Wed, Aug 14, 2019 at 05:28:35AM +0000, Christophe Leroy wrote:
> When KASAN is selected, the definitive hash table has to be
> set up later, but there is already an early temporary one.
> 
> When KASAN is not selected, there is no early hash table,
> so the setup of the definitive hash table cannot be delayed.
> 
> Reported-by: Jonathan Neuschafer <j.neuschaefer@gmx.net>
> Fixes: 72f208c6a8f7 ("powerpc/32s: move hash code patching out of MMU_init_hw()")
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---

Thanks. This does fix the DEBUG_PAGEALLOC-without-KASAN case.

Tested-by: Jonathan Neuschafer <j.neuschaefer@gmx.net>

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]