[PATCH RFC 1/3] arm64/crypto: add shared macro to test for NEED_RESCHED

[Ard Biesheuvel]

On 29 March 2014 02:53, Nicolas Pitre <nicolas.pitre at linaro.org> wrote:
> On Fri, 28 Mar 2014, Ard Biesheuvel wrote:
>
>> This adds arch/arm64/crypto/preempt.h, currently containing just a single
>> asm macro definition 'b_if_no_resched' that will be shared between multiple
>> crypto algorithm implementations that need to test for preemption in the
>> inner loop.
>
> This file is a rather bad choice for this pretty generic macro.  There
> is nothing crypto specific about it, even if crypto might be the only
> user for now.  This should live in include/asm/assembler.h, or a
> separate file in that directory only if including <asm/asm-offsets.h>
> from assembler.h is considered a nuisance.
>

True, there is nothing crypto specific about it,

@Catalin: would you object to adding this macro (and the #include
asm-offsets.h) to assembler.h?
Or would you prefer to have it in a separate file?

-- 
Ard.



>
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
>> ---
>>  arch/arm64/crypto/preempt.h | 28 ++++++++++++++++++++++++++++
>>  1 file changed, 28 insertions(+)
>>  create mode 100644 arch/arm64/crypto/preempt.h
>>
>> diff --git a/arch/arm64/crypto/preempt.h b/arch/arm64/crypto/preempt.h
>> new file mode 100644
>> index 000000000000..94302d5b5ae9
>> --- /dev/null
>> +++ b/arch/arm64/crypto/preempt.h
>> @@ -0,0 +1,28 @@
>> +/*
>> + * preempt.h - shared macros to check preempt state
>> + *
>> + * Copyright (C) 2014 Linaro Ltd <ard.biesheuvel at linaro.org>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + */
>> +
>> +#include <asm/asm-offsets.h>
>> +#include <asm/thread_info.h>
>> +
>> +     /*
>> +      * Branch to 'lb' but only if we have not been tagged for preemption.
>> +      *
>> +      * Expects current->thread_info in ti, or NULL if running in interrupt
>> +      * context. reg is a scratch x register.
>> +      */
>> +     .macro          b_if_no_resched, ti, reg, lb
>> +#if defined(CONFIG_PREEMPT) || defined(CONFIG_PREEMPT_VOLUNTARY)
>> +     cbz             \ti, \lb                        // have thread_info?
>> +     ldr             \reg, [\ti, #TI_FLAGS]          // get flags
>> +     tbz             \reg, #TIF_NEED_RESCHED, \lb    // needs rescheduling?
>> +#else
>> +     b               \lb
>> +#endif
>> +     .endm
>> --
>> 1.8.3.2
>>
>>
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