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

[Aaro Koskinen]

Hi,

Kirill A. Shutemov wrote:
> It needed for proper prefetch abort handling on ARMv7.
> 
> Instruction fault status register (IFSR) was introduced on ARMv7.

According to the ARMv7-AR reference manual it's available in ARMv6
(see chapter G.7).

> 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);
>  }