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SubjectRe: [RFC PATCH] ARM: Add imprecise abort enable/disable macro
On 02/10/2014 10:00 AM, Ben Dooks wrote:
> On 10/02/14 08:50, Fabrice Gasnier wrote:
>> On 02/07/2014 06:09 PM, Will Deacon wrote:
>>> On Fri, Feb 07, 2014 at 04:19:15PM +0000, Fabrice GASNIER wrote:
>>>> This patch adds imprecise abort enable/disable macros.
>>>> It also enables imprecise aborts when starting kernel.
>>>>
>>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
>>>> ---
>>>> arch/arm/include/asm/irqflags.h | 33
>>>> +++++++++++++++++++++++++++++++++
>>>> arch/arm/kernel/smp.c | 1 +
>>>> arch/arm/kernel/traps.c | 4 ++++
>>>> 3 files changed, 38 insertions(+)
>>>>
>>>> diff --git a/arch/arm/include/asm/irqflags.h
>>>> b/arch/arm/include/asm/irqflags.h
>>>> index 3b763d6..82e3834 100644
>>>> --- a/arch/arm/include/asm/irqflags.h
>>>> +++ b/arch/arm/include/asm/irqflags.h
>>>> @@ -51,6 +51,9 @@ static inline void arch_local_irq_disable(void)
>>>> #define local_fiq_enable() __asm__("cpsie f @ __stf" : : :
>>>> "memory", "cc")
>>>> #define local_fiq_disable() __asm__("cpsid f @ __clf" : : :
>>>> "memory", "cc")
>>>> +
>>>> +#define local_abt_enable() __asm__("cpsie a @ __sta" : : :
>>>> "memory", "cc")
>>>> +#define local_abt_disable() __asm__("cpsid a @ __cla" : : :
>>>> "memory", "cc")
>>>> #else
>>>> /*
>>>> @@ -130,6 +133,36 @@ static inline void arch_local_irq_disable(void)
>>>> : "memory", "cc"); \
>>>> })
>>>> +/*
>>>> + * Enable Aborts
>>>> + */
>>>> +#define local_abt_enable() \
>>>> + ({ \
>>>> + unsigned long temp; \
>>>> + __asm__ __volatile__( \
>>>> + "mrs %0, cpsr @ sta\n" \
>>>> +" bic %0, %0, %1\n" \
>>>> +" msr cpsr_c, %0" \
>>>> + : "=r" (temp) \
>>>> + : "r" (PSR_A_BIT) \
>>> Can you use "i" instead of a register for this constant?
>> Hi,
>>
>> Sure, I will change it in a future patch.
>>>
>>>> + : "memory", "cc"); \
>>> You don't need the "cc" clobber.
>> That surprises me: I think "orr" and "bic" instruction might change N
>> and Z bits, depending on the result.
>> So shouldn't "cc" be placed here ?
>> I also see that it is used in local_fiq_enable/disable macros just
>> above, that are similar:
>
> No, only if they have the S flag set on the instruction (ORRS,BICS)
>
>
Thank you for pointing that out!




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