[PATCH v3 1/2] ARM: Pass IFSR register to do_PrefetchAbort()

[Kirill A. Shutemov]

It needed for proper prefetch abort handling on ARMv7.

Instruction fault status register (IFSR) was introduced on ARMv7.
For older CPU we simulate IFSR with translation fault status. It
allows to generalize code.

Signed-off-by: Kirill A. Shutemov <kirill at shutemov.name>
---
 arch/arm/include/asm/glue.h    |   10 ++++++++--
 arch/arm/kernel/entry-armv.S   |   14 ++++----------
 arch/arm/kernel/entry-common.S |    8 ++++++--
 arch/arm/mm/fault.c            |    2 +-
 4 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/arch/arm/include/asm/glue.h b/arch/arm/include/asm/glue.h
index a0e39d5..5bfaf6f 100644
--- a/arch/arm/include/asm/glue.h
+++ b/arch/arm/include/asm/glue.h
@@ -130,7 +130,10 @@
 # ifdef CPU_PABORT_HANDLER
 #  define MULTI_PABORT 1
 # else
-#  define CPU_PABORT_HANDLER(reg, insn)	mrc p15, 0, reg, cr6, cr0, 2
+#  define CPU_PABORT_HANDLER(addr, ifsr, insn) \
+	mrc	p15, 0, addr, c6, c0, 2 ; \
+	mrc	p15, 0, ifsr, c5, c0, 1
+
 # endif
 #endif
 
@@ -138,7 +141,10 @@
 # ifdef CPU_PABORT_HANDLER
 #  define MULTI_PABORT 1
 # else
-#  define CPU_PABORT_HANDLER(reg, insn)	mov reg, insn
+#define __hash_5 #5
+#  define CPU_PABORT_HANDLER(addr, ifsr, insn) \
+	mov	addr, insn ; \
+	mov	ifsr, __hash_5
 # endif
 #endif
 
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 3d727a8..335ae58 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -303,22 +303,16 @@ __pabt_svc:
 	tst	r3, #PSR_I_BIT
 	biceq	r9, r9, #PSR_I_BIT
 
-	@
-	@ set args, then call main handler
-	@
-	@  r0 - address of faulting instruction
-	@  r1 - pointer to registers on stack
-	@
 #ifdef MULTI_PABORT
 	mov	r0, r2			@ pass address of aborted instruction.
 	ldr	r4, .LCprocfns
 	mov	lr, pc
 	ldr	pc, [r4, #PROCESSOR_PABT_FUNC]
 #else
-	CPU_PABORT_HANDLER(r0, r2)
+	CPU_PABORT_HANDLER(r0, r1, r2)
 #endif
 	msr	cpsr_c, r9			@ Maybe enable interrupts
-	mov	r1, sp				@ regs
+	mov	r2, sp				@ regs
 	bl	do_PrefetchAbort		@ call abort handler
 
 	@
@@ -697,10 +691,10 @@ __pabt_usr:
 	mov	lr, pc
 	ldr	pc, [r4, #PROCESSOR_PABT_FUNC]
 #else
-	CPU_PABORT_HANDLER(r0, r2)
+	CPU_PABORT_HANDLER(r0, r1, r2)
 #endif
 	enable_irq				@ Enable interrupts
-	mov	r1, sp				@ regs
+	mov	r2, sp				@ regs
 	bl	do_PrefetchAbort		@ call abort handler
  UNWIND(.fnend		)
 	/* fall through */
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 807cfeb..931ab9a 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -426,10 +426,14 @@ sys_mmap2:
 ENDPROC(sys_mmap2)
 
 ENTRY(pabort_ifar)
-		mrc	p15, 0, r0, cr6, cr0, 2
-ENTRY(pabort_noifar)
+		mrc	p15, 0, r0, c6, c0, 2		@ get IFAR
+		mrc	p15, 0, r1, c5, c0, 1		@ get IFSR
 		mov	pc, lr
 ENDPROC(pabort_ifar)
+ENTRY(pabort_noifar)
+		/* simulate IFSR with section translation fault status */
+		mov	r1, #5
+		mov	pc, lr
 ENDPROC(pabort_noifar)
 
 #ifdef CONFIG_OABI_COMPAT
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index cc8829d..5e27462 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -506,7 +506,7 @@ do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 }
 
 asmlinkage void __exception
-do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
+do_PrefetchAbort(unsigned long addr, int ifsr, struct pt_regs *regs)
 {
 	do_translation_fault(addr, 0, regs);
 }
-- 
1.6.4.4