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Re: [PATCH] ARC: Change ld.as instruction to regular ld.

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  Re: [PATCH] ARC: Change ld.as instruction to regular ld. Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-08-25 14:10 +0200
    Re: [PATCH] ARC: Change ld.as instruction to regular ld. Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-08-25 19:50 +0200

#1470097 — Re: [PATCH] ARC: Change ld.as instruction to regular ld.

Hi Liav,

On Wed, 2016-08-17 at 09:23 +0300, Liav Rehana wrote:
> From: Liav Rehana <liavr@mellanox.com>
> 
> User mode callee regs are explicitly collected before signal delivery
> or breakpoint trap. r25 is special for kernel as it serves as task
> pointer, so user mode value is clobbered very early. It is saved in
> pt_regs where generally only scratch (caller saved) res are saved.
> The code to access the corresponding pt_regs location had a subtle bug
> as it was using load/store with scaling of offset, whereas the offset
> was already byte wise correct. So fix this by replacing LD.AS with a
> standard LD
> 
> Signed-off-by: Liav Rehana <liavr@mellanox.com>

That nice patch really fixes quite annoying issue when r25 got
printed improperly in gdb!

So

Tested-by: Alexey Brodkin <abrodkin@synopsys.com>

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#1470304

On 08/25/2016 05:05 AM, Alexey Brodkin wrote:
> Hi Liav,
>
> On Wed, 2016-08-17 at 09:23 +0300, Liav Rehana wrote:
>> From: Liav Rehana <liavr@mellanox.com>
>>
>> User mode callee regs are explicitly collected before signal delivery
>> or breakpoint trap. r25 is special for kernel as it serves as task
>> pointer, so user mode value is clobbered very early. It is saved in
>> pt_regs where generally only scratch (caller saved) res are saved.
>> The code to access the corresponding pt_regs location had a subtle bug
>> as it was using load/store with scaling of offset, whereas the offset
>> was already byte wise correct. So fix this by replacing LD.AS with a
>> standard LD
>>
>> Signed-off-by: Liav Rehana <liavr@mellanox.com>
> That nice patch really fixes quite annoying issue when r25 got
> printed improperly in gdb!
>
> So
>
> Tested-by: Alexey Brodkin <abrodkin@synopsys.com>


Indeed this becomes even more important given that r25 is Thread pointer regs in
ARC ABI !
This patch is already merged upstream by Linus.

Thx,
-Vineet

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