[sparc64] Question about loop interations in trampoline_64.S

From: Kirill Tkhai <tkhai@yandex.ru>
Date: Sat, 17 Aug 2013 04:52:22 +0400

> %l5 iterates from 0 to %l6, where %l6 is (num_kernel_image_mappings + 1).
> 
> The loop is equal to:
> 
> for (l5 = 0; l5 < num_kernel_image_mappings + 1; l5++).
> 
> Is there no error? Looks like we don't have to lock 4MB page, which  number
> is num_kernel_image_mappings. Or prom call has any side effect?

That definitely looks like an off-by-one error, could you test the
following obvious fix?

--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

21.08.2013, 23:30, "David Miller" <davem@davemloft.net>:
> From: Kirill Tkhai <tkhai@yandex.ru>
> Date: Sat, 17 Aug 2013 04:52:22 +0400
>
>>  %l5 iterates from 0 to %l6, where %l6 is (num_kernel_image_mappings + 1).
>>
>>  The loop is equal to:
>>
>>  for (l5 = 0; l5 < num_kernel_image_mappings + 1; l5++).
>>
>>  Is there no error? Looks like we don't have to lock 4MB page, which  number
>>  is num_kernel_image_mappings. Or prom call has any side effect?
>
> That definitely looks like an off-by-one error, could you test the
> following obvious fix?

This had worked for me, but I doubted about all of TLB types...

So, now I confirm the patch.

> diff --git a/arch/sparc/kernel/trampoline_64.S b/arch/sparc/kernel/trampoline_64.S
> index e0b1e13..ad4bde3 100644
> --- a/arch/sparc/kernel/trampoline_64.S
> +++ b/arch/sparc/kernel/trampoline_64.S
> @@ -129,7 +129,6 @@ startup_continue:
>          clr %l5
>          sethi %hi(num_kernel_image_mappings), %l6
>          lduw [%l6 + %lo(num_kernel_image_mappings)], %l6
> - add %l6, 1, %l6
>
>          mov 15, %l7
>          BRANCH_IF_ANY_CHEETAH(g1,g5,2f)
> @@ -222,7 +221,6 @@ niagara_lock_tlb:
>          clr %l5
>          sethi %hi(num_kernel_image_mappings), %l6
>          lduw [%l6 + %lo(num_kernel_image_mappings)], %l6
> - add %l6, 1, %l6
>
>  1:
>          mov HV_FAST_MMU_MAP_PERM_ADDR, %o5
--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html