Subject: [PATCH v4 21/21] powerpc/8xx: Invalidate non present TLB as early as possible

From: Christophe Leroy <[email-masked]>
Date: Fri, 19 Sep 2014 10:36:10 +0200 (CEST)

8xx sometimes need to load a invalid/non-present TLBs in
it DTLB asm handler.

These must be invalidated separaly as linux mm doesn't.
    
Commit 5efab4a02c89c252fb4cce097aafde5f8208dbfe was invalidating them in
arch/powerpc/mm/fault.c. 
This patch does the invalidation earlier in order to free the TLB as soon as
possible. This also has the advantage of removing some 8xx specific code from
fault.c

Signed-off-by: Christophe Leroy <[email-masked]>

---
Changes in v3:
- New

Changes in v4:
- None (but impacted by changes in patch 3 and 7)

 arch/powerpc/kernel/head_8xx.S | 15 ++++++++++-----
 arch/powerpc/mm/fault.c        |  7 -------
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 4964adf..3d4b8ee 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -475,8 +475,11 @@ InstructionTLBError1:
 	EXCEPTION_PROLOG_2
 	mr	r4,r12
 	mr	r5,r9
+	andis.	r10,r5,0x4000
+	beq+	1f
+	tlbie	r4
 	/* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
-	EXC_XFER_LITE(0x400, handle_page_fault)
+1:	EXC_XFER_LITE(0x400, handle_page_fault)
 
 /* This is the data TLB error on the MPC8xx.  This could be due to
  * many reasons, including a dirty update to a pte.  We bail out to
@@ -492,11 +495,13 @@ DataTLBError:
 DARFixed:/* Return from dcbx instruction bug workaround */
 	EXCEPTION_PROLOG_1
 	EXCEPTION_PROLOG_2
-	mfspr	r10,SPRN_DSISR
-	stw	r10,_DSISR(r11)
-	mr	r5,r10
+	mfspr	r5,SPRN_DSISR
+	stw	r5,_DSISR(r11)
 	mfspr	r4,SPRN_DAR
-	li	r10,RPN_PATTERN
+	andis.	r10,r5,0x4000
+	beq+	1f
+	tlbie	r4
+1:	li	r10,RPN_PATTERN
 	mtspr	SPRN_DAR,r10	/* Tag DAR, to be used in DTLB Error */
 	/* 0x300 is DataAccess exception, needed by bad_page_fault() */
 	EXC_XFER_LITE(0x300, handle_page_fault)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 51ab9e7..9885aad 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -43,7 +43,6 @@
 #include <asm/tlbflush.h>
 #include <asm/siginfo.h>
 #include <asm/debug.h>
-#include <mm/mmu_decl.h>
 
 #include "icswx.h"
 
@@ -368,12 +367,6 @@ good_area:
 		goto bad_area;
 #endif /* CONFIG_6xx */
 #if defined(CONFIG_8xx)
-	/* 8xx sometimes need to load a invalid/non-present TLBs.
-	 * These must be invalidated separately as linux mm don't.
-	 */
-	if (error_code & 0x40000000) /* no translation? */
-		_tlbil_va(address, 0, 0, 0);
-
         /* The MPC8xx seems to always set 0x80000000, which is
          * "undefined".  Of those that can be set, this is the only
          * one which seems bad.
-- 
2.1.0