linux-kernel - [PATCH] powerpc/mm: Eliminate not possible mmu features at compile time

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Date:   Fri, 16 Nov 2018 17:08:03 +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>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/mm: Eliminate not possible mmu features at compile
 time

Depending on the CONFIG selected, many of the MMU features are
not possible. Lets only get the possible ones in MMU_FTRS_POSSIBLE.

This allows gcc to get rid at compile time of code related to
not possible features.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/include/asm/mmu.h | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index eb20eb3b8fb0..b13d8e571dd9 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -131,16 +131,37 @@ DECLARE_PER_CPU(int, next_tlbcam_idx);
 #endif
 
 enum {
-	MMU_FTRS_POSSIBLE = MMU_FTR_HPTE_TABLE | MMU_FTR_TYPE_8xx |
-		MMU_FTR_TYPE_40x | MMU_FTR_TYPE_44x | MMU_FTR_TYPE_FSL_E |
-		MMU_FTR_TYPE_47x | MMU_FTR_USE_HIGH_BATS | MMU_FTR_BIG_PHYS |
-		MMU_FTR_USE_TLBIVAX_BCAST | MMU_FTR_USE_TLBILX |
-		MMU_FTR_LOCK_BCAST_INVAL | MMU_FTR_NEED_DTLB_SW_LRU |
+	MMU_FTRS_POSSIBLE =
+#ifdef CONFIG_PPC_BOOK3S
+		MMU_FTR_HPTE_TABLE |
+#endif
+#ifdef CONFIG_PPC_8xx
+		MMU_FTR_TYPE_8xx |
+#endif
+#ifdef CONFIG_40x
+		MMU_FTR_TYPE_40x |
+#endif
+#ifdef CONFIG_44x
+		MMU_FTR_TYPE_44x |
+#endif
+#if defined(CONFIG_E200) || defined(CONFIG_E500)
+		MMU_FTR_TYPE_FSL_E | MMU_FTR_BIG_PHYS | MMU_FTR_USE_TLBILX |
+#endif
+#ifdef CONFIG_PPC_47x
+		MMU_FTR_TYPE_47x | MMU_FTR_USE_TLBIVAX_BCAST | MMU_FTR_LOCK_BCAST_INVAL |
+#endif
+#ifdef CONFIG_PPC_BOOK3S_32
+		MMU_FTR_USE_HIGH_BATS | MMU_FTR_NEED_DTLB_SW_LRU |
+#endif
+#ifdef CONFIG_PPC_BOOK3E_64
 		MMU_FTR_USE_TLBRSRV | MMU_FTR_USE_PAIRED_MAS |
+#endif
+#ifdef CONFIG_PPC_BOOK3S_64
 		MMU_FTR_NO_SLBIE_B | MMU_FTR_16M_PAGE | MMU_FTR_TLBIEL |
 		MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_CI_LARGE_PAGE |
 		MMU_FTR_1T_SEGMENT | MMU_FTR_TLBIE_CROP_VA |
 		MMU_FTR_KERNEL_RO | MMU_FTR_68_BIT_VA |
+#endif
 #ifdef CONFIG_PPC_RADIX_MMU
 		MMU_FTR_TYPE_RADIX |
 #endif
-- 
2.13.3