linux-kernel - [PATCH v2] powerpc/32s: fix boot failure with DEBUG

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Message-Id: <b7860c5e1e784d6b96ba67edf47dd6cbc2e78ab6.1565776892.git.christophe.leroy@c-s.fr>
Date:   Wed, 14 Aug 2019 10:02:20 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, j.neuschaefer@....net,
        nch@...radead.org
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v2] powerpc/32s: fix boot failure with DEBUG_PAGEALLOC without
 KASAN.

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@....net>
Fixes: 72f208c6a8f7 ("powerpc/32s: move hash code patching out of MMU_init_hw()")
Tested-by: Jonathan Neuschafer <j.neuschaefer@....net>
Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 v2: Added a comment in MMU_init_hw()

 arch/powerpc/kernel/head_32.S  | 2 ++
 arch/powerpc/mm/book3s32/mmu.c | 9 +++++++++
 2 files changed, 11 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..8d68f03bf5a4 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -358,6 +358,15 @@ 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;
+
+	/*
+	 * When KASAN is selected, there is already an early temporary hash
+	 * table and the switch to the final hash table is done later.
+	 */
+	if (IS_ENABLED(CONFIG_KASAN))
+		return;
+
+	MMU_init_hw_patch();
 }
 
 void __init MMU_init_hw_patch(void)
-- 
2.13.3