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From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	 npiggin@gmail.com, dja@axtens.net
Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v3 14/15] powerpc/32s: reorganise DSI handler.
Date: Tue, 10 Sep 2019 09:16:33 +0000 (UTC)
Message-ID: <106a755225eabfcaa1ed3bed39f763c0a3292cce.1568106758.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1568106758.git.christophe.leroy@c-s.fr>

The part decidated to handling hash_page() is fully unneeded for
processors not having real hash pages like the 603.

Lets enlarge the content of the feature fixup, and provide
an alternative which jumps directly instead of getting NIPs.

Also, in preparation of VMAP stacks, the end of DSI handler has moved
to later in the code as it won't fit anymore once VMAP stacks
are there.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/kernel/head_32.S | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 449625b4ff03..5bda6a092673 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -295,24 +295,22 @@ __secondary_hold_acknowledge:
 	DO_KVM  0x300
 DataAccess:
 	EXCEPTION_PROLOG
-	mfspr	r10,SPRN_DSISR
-	stw	r10,_DSISR(r11)
+	get_and_save_dar_dsisr_on_stack	r4, r5, r11
+BEGIN_MMU_FTR_SECTION
 #ifdef CONFIG_PPC_KUAP
-	andis.	r0,r10,(DSISR_BAD_FAULT_32S | DSISR_DABRMATCH | DSISR_PROTFAULT)@h
+	andis.	r0, r5, (DSISR_BAD_FAULT_32S | DSISR_DABRMATCH | DSISR_PROTFAULT)@h
 #else
-	andis.	r0,r10,(DSISR_BAD_FAULT_32S|DSISR_DABRMATCH)@h
+	andis.	r0, r5, (DSISR_BAD_FAULT_32S | DSISR_DABRMATCH)@h
 #endif
-	bne	1f			/* if not, try to put a PTE */
-	mfspr	r4,SPRN_DAR		/* into the hash table */
-	rlwinm	r3,r10,32-15,21,21	/* DSISR_STORE -> _PAGE_RW */
-BEGIN_MMU_FTR_SECTION
+	bne	handle_page_fault_tramp	/* if not, try to put a PTE */
+	rlwinm	r3, r5, 32 - 15, 21, 21	/* DSISR_STORE -> _PAGE_RW */
 	bl	hash_page
-END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
-1:	lwz	r5,_DSISR(r11)		/* get DSISR value */
-	mfspr	r4,SPRN_DAR
-	stw	r4, _DAR(r11)
-	EXC_XFER_LITE(0x300, handle_page_fault)
-
+	lwz	r5, _DSISR(r11)		/* get DSISR value */
+	lwz	r4, _DAR(r11)
+	b	handle_page_fault_tramp
+FTR_SECTION_ELSE
+	b	handle_page_fault_tramp
+ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)
 
 /* Instruction access exception. */
 	. = 0x400
@@ -642,6 +640,9 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
 
 	. = 0x3000
 
+handle_page_fault_tramp:
+	EXC_XFER_LITE(0x300, handle_page_fault)
+
 AltiVecUnavailable:
 	EXCEPTION_PROLOG
 #ifdef CONFIG_ALTIVEC
-- 
2.13.3


  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-10  9:16 [PATCH v3 00/15] Enable CONFIG_VMAP_STACK on PPC32 Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 01/15] powerpc/32: replace MTMSRD() by mtmsr Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 02/15] powerpc/32: Add EXCEPTION_PROLOG_0 in head_32.h Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 03/15] powerpc/32: save DEAR/DAR before calling handle_page_fault Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 04/15] powerpc/32: move MSR_PR test into EXCEPTION_PROLOG_0 Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 05/15] powerpc/32: add a macro to get and/or save DAR and DSISR on stack Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 06/15] powerpc/32: prepare for CONFIG_VMAP_STACK Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 07/15] powerpc: align stack to 2 * THREAD_SIZE with VMAP_STACK Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 08/15] powerpc/32: Add early stack overflow detection with VMAP stack Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 09/15] powerpc/8xx: Use alternative scratch registers in DTLB miss handler Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 10/15] powerpc/8xx: drop exception entries for non-existing exceptions Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 11/15] powerpc/8xx: move DataStoreTLBMiss perf handler Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 12/15] powerpc/8xx: split breakpoint exception Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 13/15] powerpc/8xx: Enable CONFIG_VMAP_STACK Christophe Leroy
2019-09-10  9:16 ` Christophe Leroy [this message]
2019-09-10  9:16 ` [PATCH v3 15/15] powerpc/32s: Activate CONFIG_VMAP_STACK Christophe Leroy

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