Re: [PATCH v3 5/5] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature

[Masami Hiramatsu]

(2014/11/18 23:52), Will Deacon wrote:
> Hi David,
> 
> On Tue, Nov 18, 2014 at 06:32:55AM +0000, David Long wrote:
>> From: "David A. Long" <dave.long@xxxxxxxxxx>
>>
>> Add HAVE_REGS_AND_STACK_ACCESS_API feature for arm64.
> 
> [...]
> 
>> diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
>> index d3e782a..24cc048 100644
>> --- a/arch/arm64/include/asm/ptrace.h
>> +++ b/arch/arm64/include/asm/ptrace.h
>> @@ -111,6 +111,8 @@ struct pt_regs {
>>  	u64 syscallno;
>>  };
>>  
>> +#define MAX_REG_OFFSET (offsetof(struct pt_regs, orig_x0))
> 
> Is orig_x0 actually useful to this API? If not, we could instead operate on
> the user_pt_regs structure, and define the maximum offset in terms of sizeof
> that.

It depends on the architecture, but this patch provides the common interface
for kprobe-tracer. I think this code looks OK, since kprobe-tracer doesn't
use user_pt_regs.

> 
>> +#define ARM_cpsr	pstate
>> +#define ARM_pc		pc
>> +#define ARM_sp		sp
>> +#define ARM_lr		regs[30]
>> +#define ARM_fp		regs[29]
>> +#define ARM_x28		regs[28]
>> +#define ARM_x27		regs[27]
> 
> [...]
> 
> I don't think we need these #defines.

Agreed.

Thank you,


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@xxxxxxxxxxx


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