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arm: mm: retry on QSD icache parity errors

RFC PATCH New Daniel Walker 4 participants 7 messages Jan 28, 2010 – Feb 23, 2010 Arm (32-bit)

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Daniel Walker

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#0 lore raw

RFC PATCH 5/12 arm: mm: retry on QSD icache parity errors

From: Steve Muckle <[email protected]>

Parity errors in the icache on QSD can be worked around either by retrying the access, or invalidating the icache. The whole icache must be invalidated since the data abort is imprecise (the faulting address is not known).

Signed-off-by Steve Muckle <[email protected]>
Signed-off-by Daniel Walker <[email protected]>
---
 arch/arm/mm/fault.c |   36 +++++++++++++++++++++++++++++++++++-
 1 files changed, 35 insertions(+), 1 deletions(-)
arch/arm/mm/fault.c +35 -1
index 10e0680..bea3e75 100644
@@ -2,6 +2,7 @@
  *  linux/arch/arm/mm/fault.c
  *
  *  Copyright (C) 1995  Linus Torvalds
+ *  Copyright (c) 2009, Code Aurora Forum. All rights reserved.
  *  Modifications for ARM processor (c) 1995-2004 Russell King
  *
  * This program is free software; you can redistribute it and/or modify

@@ -442,6 +443,39 @@ do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	return 1;
 }
 
+static int
+do_imprecise_ext(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+#ifdef CONFIG_ARCH_MSM_SCORPION
+	unsigned int regval;
+	static unsigned char flush_toggle;
+
+	asm("mrc p15, 0, %0, c5, c1, 0\n" /* read adfsr for fault status */
+	    : "=r" (regval));
+	if (regval == 0x2) {
+		/* Fault was caused by icache parity error. Alternate
+		 * simply retrying the access and flushing the icache. */
+		flush_toggle ^= 1;
+		if (flush_toggle)
+			asm("mcr p15, 0, %0, c7, c5, 0\n"
+			    :
+			    : "r" (regval)); /* input value is ignored */
+		/* Clear fault in EFSR. */
+		asm("mcr p15, 7, %0, c15, c0, 1\n"
+		    :
+		    : "r" (regval));
+		/* Clear fault in ADFSR. */
+		regval = 0;
+		asm("mcr p15, 0, %0, c5, c1, 0\n"
+		    :
+		    : "r" (regval));
+		return 0;
+	}
+#endif
+
+	return 1;
+}
+
 static struct fsr_info {
 	int	(*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
 	int	sig;

@@ -479,7 +513,7 @@ static struct fsr_info {
 	{ do_bad,		SIGBUS,  0,		"unknown 19"			   },
 	{ do_bad,		SIGBUS,  0,		"lock abort"			   }, /* xscale */
 	{ do_bad,		SIGBUS,  0,		"unknown 21"			   },
-	{ do_bad,		SIGBUS,  BUS_OBJERR,	"imprecise external abort"	   }, /* xscale */
+	{ do_imprecise_ext,	SIGBUS,  BUS_OBJERR,	"imprecise external abort"	   }, /* xscale */
 	{ do_bad,		SIGBUS,  0,		"unknown 23"			   },
 	{ do_bad,		SIGBUS,  0,		"dcache parity error"		   }, /* xscale */
 	{ do_bad,		SIGBUS,  0,		"unknown 25"			   },
Signature · 1 line
1.6.3.3
#1 lore raw

RFC PATCH 5/12 arm: mm: retry on QSD icache parity errors

Hi!

Quoted 32 lines

Parity errors in the icache on QSD can be worked around either by retrying the access, or invalidating the icache. The whole icache must be invalidated since the data abort is imprecise (the faulting address is not known).

Signed-off-by Steve Muckle <[email protected]>
Signed-off-by Daniel Walker <[email protected]>
arch/arm/mm/fault.c +19 -0
@@ -442,6 +443,39 @@ do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	return 1;
 }
 
+static int
+do_imprecise_ext(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+#ifdef CONFIG_ARCH_MSM_SCORPION
+	unsigned int regval;
+	static unsigned char flush_toggle;
+
+	asm("mrc p15, 0, %0, c5, c1, 0\n" /* read adfsr for fault status */
+	    : "=r" (regval));
+	if (regval == 0x2) {
+		/* Fault was caused by icache parity error. Alternate
+		 * simply retrying the access and flushing the icache. */
+		flush_toggle ^= 1;
+		if (flush_toggle)
+			asm("mcr p15, 0, %0, c7, c5, 0\n"
+			    :
+			    : "r" (regval)); /* input value is ignored */
+		/* Clear fault in EFSR. */
+		asm("mcr p15, 7, %0, c15, c0, 1\n"

arch/arm/mm/fault.c do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs) · line 474

Quoted 10 lines
arch/arm/mm/fault.c +10 -0
+		    :
+		    : "r" (regval));
+		/* Clear fault in ADFSR. */
+		regval = 0;
+		asm("mcr p15, 0, %0, c5, c1, 0\n"
+		    :
+		    : "r" (regval));
+		return 0;
+	}
+#endif

Tell the user or at least keep the count, so cache going bad can be recognized?

Also you probably need asm volatile, and probably do not need those \n-s.

Pavel

Signature · 2 lines
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
#2 lore raw

RFC PATCH 5/12 arm: mm: retry on QSD icache parity errors

In reply to Daniel Walker
Quoted 4 lines · Daniel Walker
arch/arm/mm/fault.c +0 -0
index 10e0680..bea3e75 100644

[...]

arch/arm/mm/fault.c static struct fsr_info { · line 516

Quoted 9 lines
 static struct fsr_info {
        int     (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
        int     sig;
arch/arm/mm/fault.c +1 -1
@@ -479,7 +513,7 @@ static struct fsr_info {
        { do_bad,               SIGBUS,  0,             "unknown 19"                       },
        { do_bad,               SIGBUS,  0,             "lock abort"                       }, /* xscale */
        { do_bad,               SIGBUS,  0,             "unknown 21"                       },
-       { do_bad,               SIGBUS,  BUS_OBJERR,    "imprecise external abort"         }, /* xscale */
+       { do_imprecise_ext,     SIGBUS,  BUS_OBJERR,    "imprecise external abort"         }, /* xscale */

Can you not use hook_fault_code() and move the do_imprecise_ext() to a platform-specific file (under arch/arm/mach-* maybe)?

Signature · 1 line
Catalin
author
#3 lore raw

RFC PATCH 5/12 arm: mm: retry on QSD icache parity errors

Quoted 6 lines · Catalin Marinas
Quoted 4 lines · Daniel Walker
arch/arm/mm/fault.c +0 -0
index 10e0680..bea3e75 100644

[...]

Quoted 13 lines

arch/arm/mm/fault.c static struct fsr_info { · line 516

Quoted 9 lines
 static struct fsr_info {
        int     (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
        int     sig;
arch/arm/mm/fault.c +1 -1
@@ -479,7 +513,7 @@ static struct fsr_info {
        { do_bad,               SIGBUS,  0,             "unknown 19"                       },
        { do_bad,               SIGBUS,  0,             "lock abort"                       }, /* xscale */
        { do_bad,               SIGBUS,  0,             "unknown 21"                       },
-       { do_bad,               SIGBUS,  BUS_OBJERR,    "imprecise external abort"         }, /* xscale */
+       { do_imprecise_ext,     SIGBUS,  BUS_OBJERR,    "imprecise external abort"         }, /* xscale */

Can you not use hook_fault_code() and move the do_imprecise_ext() to a platform-specific file (under arch/arm/mach-* maybe)?

How do you mean? I'm not sure how we would move this into arch/arm/mach- ..

Daniel

#4 lore raw

RFC PATCH 5/12 arm: mm: retry on QSD icache parity errors

Quoted 21 lines · Daniel Walker
Quoted 6 lines · Catalin Marinas
Quoted 4 lines · Daniel Walker
arch/arm/mm/fault.c +0 -0
index 10e0680..bea3e75 100644

[...]

Quoted 13 lines

arch/arm/mm/fault.c static struct fsr_info { · line 516

Quoted 9 lines
 static struct fsr_info {
        int     (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
        int     sig;
arch/arm/mm/fault.c +1 -1
@@ -479,7 +513,7 @@ static struct fsr_info {
        { do_bad,               SIGBUS,  0,             "unknown 19"                       },
        { do_bad,               SIGBUS,  0,             "lock abort"                       }, /* xscale */
        { do_bad,               SIGBUS,  0,             "unknown 21"                       },
-       { do_bad,               SIGBUS,  BUS_OBJERR,    "imprecise external abort"         }, /* xscale */
+       { do_imprecise_ext,     SIGBUS,  BUS_OBJERR,    "imprecise external abort"         }, /* xscale */

Can you not use hook_fault_code() and move the do_imprecise_ext() to a platform-specific file (under arch/arm/mach-* maybe)?

Quoted 2 lines

How do you mean? I'm not sure how we would move this into arch/arm/mach- ..

Err, exactly as Catalin says. Use hook_fault_code() to hook into the fault table at run time, just like platforms which have to handle imprecise exceptions on PCI and the alignment fault handler do.

author
#5 lore raw

RFC PATCH 5/12 arm: mm: retry on QSD icache parity errors

Quoted 10 lines · Russell King - ARM Linux
Quoted 6 lines
Quoted 3 lines

Can you not use hook_fault_code() and move the do_imprecise_ext() to a platform-specific file (under arch/arm/mach-* maybe)?

How do you mean? I'm not sure how we would move this into arch/arm/mach- ..

Err, exactly as Catalin says. Use hook_fault_code() to hook into the fault table at run time, just like platforms which have to handle imprecise exceptions on PCI and the alignment fault handler do.

"Can you not use hook_fault_code()"

Typo maybe ?

Daniel

#6 lore raw

RFC PATCH 5/12 arm: mm: retry on QSD icache parity errors

Quoted 9 lines · Daniel Walker
Quoted 7 lines · Russell King - ARM Linux
Quoted 6 lines
Quoted 3 lines

Can you not use hook_fault_code() and move the do_imprecise_ext() to a platform-specific file (under arch/arm/mach-* maybe)?

How do you mean? I'm not sure how we would move this into arch/arm/mach- ..

Quoted 8 lines
Quoted 3 lines

Err, exactly as Catalin says. Use hook_fault_code() to hook into the fault table at run time, just like platforms which have to handle imprecise exceptions on PCI and the alignment fault handler do.

"Can you not use hook_fault_code()"

Typo maybe ?

I don't think so. It's a request for you to use hook_fault_code().