From 7613f5a66becfd0e43a0f34de8518695888f5458 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 17 Dec 2020 11:53:06 +1100 Subject: [PATCH] powerpc/64s/kuap: Use mmu_has_feature() In commit 8150a153c013 ("powerpc/64s: Use early_mmu_has_feature() in set_kuap()") we switched the KUAP code to use early_mmu_has_feature(), to avoid a bug where we called set_kuap() before feature patching had been done, leading to recursion and crashes. That path, which called probe_kernel_read() from printk(), has since been removed, see commit 2ac5a3bf7042 ("vsprintf: Do not break early boot with probing addresses"). Additionally probe_kernel_read() no longer invokes any KUAP routines, since commit fe557319aa06 ("maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault") and c33165253492 ("powerpc: use non-set_fs based maccess routines"). So it should now be safe to use mmu_has_feature() in the KUAP routines, because we shouldn't invoke them prior to feature patching. This is essentially a revert of commit 8150a153c013 ("powerpc/64s: Use early_mmu_has_feature() in set_kuap()"), but we've since added a second usage of early_mmu_has_feature() in get_kuap(), so we convert that to use mmu_has_feature() as well. Reported-by: Christophe Leroy Signed-off-by: Michael Ellerman Depends-on: c33165253492 ("powerpc: use non-set_fs based maccess routines"). Link: https://lore.kernel.org/r/20201217005306.895685-1-mpe@ellerman.id.au --- arch/powerpc/include/asm/book3s/64/kup.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h index f50f72e535aa..2298eac49763 100644 --- a/arch/powerpc/include/asm/book3s/64/kup.h +++ b/arch/powerpc/include/asm/book3s/64/kup.h @@ -333,7 +333,7 @@ static inline unsigned long get_kuap(void) * This has no effect in terms of actually blocking things on hash, * so it doesn't break anything. */ - if (!early_mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) + if (!mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) return AMR_KUAP_BLOCKED; return mfspr(SPRN_AMR); @@ -341,7 +341,7 @@ static inline unsigned long get_kuap(void) static inline void set_kuap(unsigned long value) { - if (!early_mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) + if (!mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) return; /* -- 2.11.0