On 7 November 2017 at 03:36, Suzuki K Poulose <suzuki.poul...@arm.com> wrote:
> On 06/11/17 19:07, Mathieu Poirier wrote:
>>
>> On Thu, Oct 19, 2017 at 06:15:42PM +0100, Suzuki K Poulose wrote:
>
>
> ...
>
>>> +/*
>>> + * tmc_etr_sg_offset_to_table_index : Translate a given data @offset
>>> + * to the index of the page table "entry". Data pointers always have
>>> + * a fixed location, with ETR_SG_PTRS_PER_PAGE - 1 entries in an
>>> + * ETR_SG_PAGE and 1 link entry per (ETR_SG_PTRS_PER_PAGE -1) entries.
>>> + */
>>> +static inline u32
>>> +tmc_etr_sg_offset_to_table_index(u64 offset)
>>> +{
>>> + u64 sgpage_idx = offset >> ETR_SG_PAGE_SHIFT;
>>> +
>>> + return sgpage_idx + sgpage_idx / (ETR_SG_PTRS_PER_PAGE - 1);
>>> +}
>>
>>
>> This function is the source of a bizarre linking error when compiling
>> [14/17] on
>> armv7 as pasted here:
>>
>> UPD include/generated/compile.h
>> CC init/version.o
>> AR init/built-in.o
>> AR built-in.o
>> LD vmlinux.o
>> MODPOST vmlinux.o
>> drivers/hwtracing/coresight/coresight-tmc-etr.o: In function
>> `tmc_etr_sg_offset_to_table_index':
>>
>> /home/mpoirier/work/linaro/coresight/kernel-maint/drivers/hwtracing/coresight/coresight-tmc-etr.c:553:
>> undefined reference to `__aeabi_uldivmod'
>>
>> /home/mpoirier/work/linaro/coresight/kernel-maint/drivers/hwtracing/coresight/coresight-tmc-etr.c:551:
>> undefined reference to `__aeabi_uldivmod'
>>
>> /home/mpoirier/work/linaro/coresight/kernel-maint/drivers/hwtracing/coresight/coresight-tmc-etr.c:553:
>> undefined reference to `__aeabi_uldivmod'
>> drivers/hwtracing/coresight/coresight-tmc-etr.o: In function
>> `tmc_etr_sg_table_rotate':
>>
>> /home/mpoirier/work/linaro/coresight/kernel-maint/drivers/hwtracing/coresight/coresight-tmc-etr.c:609:
>> undefined reference to `__aeabi_uldivmod'
>>
>> Please see if you can reproduce on your side.
>
>
> Uh ! I had gcc-7, which didn't complain about it. But if switch to 4.9, it
> does.
> It looks like division of 64bit entity on arm32 is triggering it. We don't
> need
> this to be u64 above, as it is the page_idx and could simply switch to
> "unsigned long"
> rather than explicitly using div64 helpers.
>
> The following change fixes the issue for me. Please could you check if it
> solves the problem
> for you ?
Unfortunately it doesn't.
Mathieu
>
>
> @@ -551,7 +553,7 @@ static void tmc_etr_sg_table_populate(struct
> etr_sg_table *etr_table)
> static inline u32
> tmc_etr_sg_offset_to_table_index(u64 offset)
> {
> - u64 sgpage_idx = offset >> ETR_SG_PAGE_SHIFT;
> + unsigned long sgpage_idx = offset >> ETR_SG_PAGE_SHIFT;
> return sgpage_idx + sgpage_idx / (ETR_SG_PTRS_PER_PAGE - 1);
> }
>
>
>
> Thanks for the testing !
>
> Suzuki
