[PATCH 11/23] ARM: entry: avoid enabling interrupts in prefetch/data abort handlers

[Will Deacon]

Hi Russell,

This looks good, thanks. Minor comment inline.

On Wed, Jun 29, 2011 at 10:22:35AM +0100, Russell King - ARM Linux wrote:
> Avoid enabling interrupts if the parent context had interrupts enabled
> in the abort handler assembly code, and move this into the breakpoint/
> page/alignment fault handlers instead.
> 
> This gets rid of some special-casing for the breakpoint fault handlers
> from the low level abort handler path.
> 
> Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
> ---
>  arch/arm/kernel/entry-armv.S    |   43 +++++++++++++++++---------------------
>  arch/arm/kernel/entry-header.S  |   19 -----------------
>  arch/arm/kernel/hw_breakpoint.c |    6 +++-
>  arch/arm/mm/alignment.c         |    3 ++
>  arch/arm/mm/fault.c             |    4 +++
>  5 files changed, 30 insertions(+), 45 deletions(-)

[...]

> diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
> index 87acc25..b813e1e 100644
> --- a/arch/arm/kernel/hw_breakpoint.c
> +++ b/arch/arm/kernel/hw_breakpoint.c
> @@ -804,8 +804,10 @@ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
>  	int ret = 0;
>  	u32 dscr;
>  
> -	/* We must be called with preemption disabled. */
> -	WARN_ON(preemptible());
> +	preempt_disable();
> +
> +	if (interrupts_enabled(regs))
> +		local_irq_enable();
>  
>  	/* We only handle watchpoints and hardware breakpoints. */
>  	ARM_DBG_READ(c1, 0, dscr);

Could you also update the comments for this function too please? There's one
immediately before the function that states we are called with preemption
disabled and there's another one where we re-enable preemption stating that
it was disabled by the low-level exception handling code.

With those two extra changes:

Acked-by: Will Deacon <will.deacon at arm.com>

Cheers,

Will