On Sun, Feb 28, 2016 at 11:15 AM, Tom Herbert <t...@herbertland.com> wrote:
> On Sun, Feb 28, 2016 at 10:56 AM, Alexander Duyck
> <alexander.du...@gmail.com> wrote:
>> On Sat, Feb 27, 2016 at 12:30 AM, Alexander Duyck
>> <alexander.du...@gmail.com> wrote:
>>>> +{
>>>> + asm("lea 40f(, %[slen], 4), %%r11\n\t"
>>>> + "clc\n\t"
>>>> + "jmpq *%%r11\n\t"
>>>> + "adcq 7*8(%[src]),%[res]\n\t"
>>>> + "adcq 6*8(%[src]),%[res]\n\t"
>>>> + "adcq 5*8(%[src]),%[res]\n\t"
>>>> + "adcq 4*8(%[src]),%[res]\n\t"
>>>> + "adcq 3*8(%[src]),%[res]\n\t"
>>>> + "adcq 2*8(%[src]),%[res]\n\t"
>>>> + "adcq 1*8(%[src]),%[res]\n\t"
>>>> + "adcq 0*8(%[src]),%[res]\n\t"
>>>> + "nop\n\t"
>>>> + "40: adcq $0,%[res]"
>>>> + : [res] "=r" (sum)
>>>> + : [src] "r" (buff),
>>>> + [slen] "r" (-((unsigned long)(len >> 3))), "[res]"
>>>> (sum)
>>>> + : "r11");
>>>> +
>>>
>>> With this patch I cannot mix/match different length checksums without
>>> things failing. In perf the jmpq in the loop above seems to be set to
>>> a fixed value so perhaps it is something in how the compiler is
>>> interpreting the inline assembler.
>>
>> The perf thing was a red herring. Turns out the code is working
>> correctly there.
>>
>> I actually found the root cause. The problem is in add32_with_carry3.
>>
> Thanks for the follow-up. btw are you trying to build csum_partial in
> userspace for testing, or was this all in kernel?
It was in the kernel. I have been some user space work but all of the
problems I was having were in the kernel. My guess is that the
original sum value wasn't being used
- Alex
