linux-kernel - [PATCH v2] powerpc/32s: Only build hash code when CONFIG_PPC_BOOK3S

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Message-Id: <62df436454ef06e104cc334a0859a2878d7888d5.1608274548.git.christophe.leroy@csgroup.eu>
Date:   Fri, 18 Dec 2020 06:56:05 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
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 v2] powerpc/32s: Only build hash code when
 CONFIG_PPC_BOOK3S_604 is selected

It is now possible to only build book3s/32 kernel for
CPUs without hash table.

Opt out hash related code when CONFIG_PPC_BOOK3S_604 is not selected.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
v2: Rebased
---
 arch/powerpc/kernel/head_book3s_32.S | 12 ++++++++++++
 arch/powerpc/mm/book3s32/Makefile    |  4 +++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 349bf3f0c3af..c02024bce544 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -286,6 +286,7 @@ MachineCheck:
 	DO_KVM  0x300
 DataAccess:
 #ifdef CONFIG_VMAP_STACK
+#ifdef CONFIG_PPC_BOOK3S_604
 BEGIN_MMU_FTR_SECTION
 	mtspr	SPRN_SPRG_SCRATCH2,r10
 	mfspr	r10, SPRN_SPRG_THREAD
@@ -302,12 +303,14 @@ BEGIN_MMU_FTR_SECTION
 MMU_FTR_SECTION_ELSE
 	b	1f
 ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)
+#endif
 1:	EXCEPTION_PROLOG_0 handle_dar_dsisr=1
 	EXCEPTION_PROLOG_1
 	b	handle_page_fault_tramp_1
 #else	/* CONFIG_VMAP_STACK */
 	EXCEPTION_PROLOG handle_dar_dsisr=1
 	get_and_save_dar_dsisr_on_stack	r4, r5, r11
+#ifdef CONFIG_PPC_BOOK3S_604
 BEGIN_MMU_FTR_SECTION
 	andis.	r0, r5, (DSISR_BAD_FAULT_32S | DSISR_DABRMATCH)@h
 	bne	handle_page_fault_tramp_2	/* if not, try to put a PTE */
@@ -315,8 +318,11 @@ BEGIN_MMU_FTR_SECTION
 	bl	hash_page
 	b	handle_page_fault_tramp_1
 MMU_FTR_SECTION_ELSE
+#endif
 	b	handle_page_fault_tramp_2
+#ifdef CONFIG_PPC_BOOK3S_604
 ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)
+#endif
 #endif	/* CONFIG_VMAP_STACK */
 
 /* Instruction access exception. */
@@ -332,12 +338,14 @@ InstructionAccess:
 	mfspr	r11, SPRN_SRR1		/* check whether user or kernel */
 	stw	r11, SRR1(r10)
 	mfcr	r10
+#ifdef CONFIG_PPC_BOOK3S_604
 BEGIN_MMU_FTR_SECTION
 	andis.	r11, r11, SRR1_ISI_NOPT@h	/* no pte found? */
 	bne	hash_page_isi
 .Lhash_page_isi_cont:
 	mfspr	r11, SPRN_SRR1		/* check whether user or kernel */
 END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
+#endif
 	andi.	r11, r11, MSR_PR
 
 	EXCEPTION_PROLOG_1
@@ -348,9 +356,11 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
 	beq	1f			/* if so, try to put a PTE */
 	li	r3,0			/* into the hash table */
 	mr	r4,r12			/* SRR0 is fault address */
+#ifdef CONFIG_PPC_BOOK3S_604
 BEGIN_MMU_FTR_SECTION
 	bl	hash_page
 END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
+#endif
 #endif	/* CONFIG_VMAP_STACK */
 1:	mr	r4,r12
 	andis.	r5,r9,DSISR_SRR1_MATCH_32S@h /* Filter relevant SRR1 bits */
@@ -683,6 +693,7 @@ handle_page_fault_tramp_2:
 	EXC_XFER_LITE(0x300, handle_page_fault)
 
 #ifdef CONFIG_VMAP_STACK
+#ifdef CONFIG_PPC_BOOK3S_604
 .macro save_regs_thread		thread
 	stw	r0, THR0(\thread)
 	stw	r3, THR3(\thread)
@@ -754,6 +765,7 @@ fast_hash_page_return:
 	mfspr	r11, SPRN_SPRG_SCRATCH1
 	mfspr	r10, SPRN_SPRG_SCRATCH0
 	rfi
+#endif /* CONFIG_PPC_BOOK3S_604 */
 
 stack_overflow:
 	vmap_stack_overflow_exception
diff --git a/arch/powerpc/mm/book3s32/Makefile b/arch/powerpc/mm/book3s32/Makefile
index 3f972db17761..446d9de88ce4 100644
--- a/arch/powerpc/mm/book3s32/Makefile
+++ b/arch/powerpc/mm/book3s32/Makefile
@@ -6,4 +6,6 @@ ifdef CONFIG_KASAN
 CFLAGS_mmu.o  		+= -DDISABLE_BRANCH_PROFILING
 endif
 
-obj-y += mmu.o hash_low.o mmu_context.o tlb.o nohash_low.o
+obj-y += mmu.o mmu_context.o
+obj-$(CONFIG_PPC_BOOK3S_603) += nohash_low.o
+obj-$(CONFIG_PPC_BOOK3S_604) += hash_low.o tlb.o
-- 
2.25.0