Commit 9bb162fa authored Dec 07, 2021 by Christophe Leroy Committed by Michael Ellerman Feb 07, 2022

powerpc/603: Fix boot failure with DEBUG_PAGEALLOC and KFENCE

Allthough kernel text is always mapped with BATs, we still have
inittext mapped with pages, so TLB miss handling is required
when CONFIG_DEBUG_PAGEALLOC or CONFIG_KFENCE is set.

The final solution should be to set a BAT that also maps inittext
but that BAT then needs to be cleared at end of init, and it will
require more changes to be able to do it properly.

As DEBUG_PAGEALLOC or KFENCE are debugging, performance is not a big
deal so let's fix it simply for now to enable easy stable application.

Fixes: 035b19a1 ("powerpc/32s: Always map kernel text and rodata with BATs")
Cc: stable@vger.kernel.org # v5.11+
Reported-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/aea33b4813a26bdb9378b5f273f00bd5d4abe240.1638857364.git.christophe.leroy@csgroup.eu

parent 26291c54

arch/powerpc/kernel/head_book3s_32.S

+2 −2

Original line number	Diff line number	Diff line
		@@ -421,14 +421,14 @@ InstructionTLBMiss:
		*/
		/* Get PTE (linux-style) and check access */
		mfspr r3,SPRN_IMISS
		#ifdef CONFIG_MODULES
		#if defined(CONFIG_MODULES) \|\| defined(CONFIG_DEBUG_PAGEALLOC) \|\| defined(CONFIG_KFENCE)
		lis r1, TASK_SIZE@h /* check if kernel address */
		cmplw 0,r1,r3
		#endif
		mfspr r2, SPRN_SDR1
		li r1,_PAGE_PRESENT \| _PAGE_ACCESSED \| _PAGE_EXEC \| _PAGE_USER
		rlwinm r2, r2, 28, 0xfffff000
		#ifdef CONFIG_MODULES
		#if defined(CONFIG_MODULES) \|\| defined(CONFIG_DEBUG_PAGEALLOC) \|\| defined(CONFIG_KFENCE)
		bgt- 112f
		lis r2, (swapper_pg_dir - PAGE_OFFSET)@ha /* if kernel address, use */
		li r1,_PAGE_PRESENT \| _PAGE_ACCESSED \| _PAGE_EXEC