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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>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-mm@kvack.org
Subject: [PATCH v4 14/16] powerpc/32s: reorganise DSI handler.
Date: Tue, 26 Nov 2019 12:36:18 +0000 (UTC)	[thread overview]
Message-ID: <b07098858befd1384ff66a6cc13cbf7e09f3e5fa.1574771541.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1574771539.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 | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 449625b4ff03..7ec780858299 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -295,24 +295,20 @@ __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_2	/* 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)
-
+	b	handle_page_fault_tramp_1
+FTR_SECTION_ELSE
+	b	handle_page_fault_tramp_2
+ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)
 
 /* Instruction access exception. */
 	. = 0x400
@@ -642,6 +638,13 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
 
 	. = 0x3000
 
+handle_page_fault_tramp_1:
+	lwz	r4, _DAR(r11)
+	lwz	r5, _DSISR(r11)
+	/* fall through */
+handle_page_fault_tramp_2:
+	EXC_XFER_LITE(0x300, handle_page_fault)
+
 AltiVecUnavailable:
 	EXCEPTION_PROLOG
 #ifdef CONFIG_ALTIVEC
-- 
2.13.3



  parent reply	other threads:[~2019-11-26 12:36 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-26 12:36 [PATCH v4 00/16] Enable CONFIG_VMAP_STACK on PPC32 Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 01/16] powerpc/32: replace MTMSRD() by mtmsr Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 02/16] powerpc/32: Add EXCEPTION_PROLOG_0 in head_32.h Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 03/16] powerpc/32: save DEAR/DAR before calling handle_page_fault Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 04/16] powerpc/32: move MSR_PR test into EXCEPTION_PROLOG_0 Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 05/16] powerpc/32: add a macro to get and/or save DAR and DSISR on stack Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 06/16] powerpc/32: prepare for CONFIG_VMAP_STACK Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 07/16] powerpc: align stack to 2 * THREAD_SIZE with VMAP_STACK Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 08/16] powerpc/32: Add early stack overflow detection with VMAP stack Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 09/16] powerpc/8xx: Use alternative scratch registers in DTLB miss handler Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 10/16] powerpc/8xx: drop exception entries for non-existing exceptions Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 11/16] powerpc/8xx: move DataStoreTLBMiss perf handler Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 12/16] powerpc/8xx: split breakpoint exception Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 13/16] powerpc/8xx: Enable CONFIG_VMAP_STACK Christophe Leroy
2019-11-26 12:36 ` Christophe Leroy [this message]
2019-11-26 12:36 ` [PATCH v4 15/16] powerpc/32s: avoid crossing page boundary while changing SRR0/1 Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 16/16] powerpc/32s: Activate CONFIG_VMAP_STACK Christophe Leroy

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