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SubjectRe: [PATCH v9 perf,bpf 04/15] perf, bpf: synthesize bpf events with bpf_program__get_prog_info_linear()
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> On Mar 13, 2019, at 10:08 PM, Song Liu <songliubraving@fb.com> wrote:
>
>
>
>> On Mar 13, 2019, at 2:08 PM, Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> wrote:
>>
>> Em Wed, Mar 13, 2019 at 06:00:30PM -0300, Arnaldo Carvalho de Melo escreveu:
>>> Em Mon, Mar 11, 2019 at 10:30:40PM -0700, Song Liu escreveu:
>>>> -
>>>> /* Synthesize PERF_RECORD_KSYMBOL */
>>>> for (i = 0; i < sub_prog_cnt; i++) {
>>>> + u8 (*prog_tags)[BPF_TAG_SIZE] = (void *)(info->prog_tags);
>>>
>>> Need this:
>>>
>>> - u8 (*prog_tags)[BPF_TAG_SIZE] = (void *)(info->prog_tags);
>>> + u8 (*prog_tags)[BPF_TAG_SIZE] = (u8 *)(info->prog_tags);
>>>
>>>
>>> To overcome this on debian:experimental-x-mips, i.e. Debian Experimental
>>> cross building to MIPS 32-bit:
>>>
>>> util/bpf-event.c: In function 'perf_event__synthesize_one_bpf_prog':
>>> util/bpf-event.c:143:35: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>>> u8 (*prog_tags)[BPF_TAG_SIZE] = (void *)(info->prog_tags);
>>> ^
>>> util/bpf-event.c:144:22: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>>> __u32 *prog_lens = (__u32 *)(info->jited_func_lens);
>>> ^
>>> util/bpf-event.c:145:23: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>>> __u64 *prog_addrs = (__u64 *)(info->jited_ksyms);
>>> ^
>>> util/bpf-event.c:146:22: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>>> void *func_infos = (void *)(info->func_info);
>>> ^
>>> CC /tmp/build/perf/util/pmu.o
>>> CC /tmp/build/perf/util/pmu-flex.o
>>> cc1: all warnings being treated as errors
>>
>> Argh, hit the send button too fast, that is not the only case and then
>> my change just changed the error:
>>
>> util/bpf-event.c: In function 'perf_event__synthesize_one_bpf_prog':
>> util/bpf-event.c:143:35: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>> u8 (*prog_tags)[BPF_TAG_SIZE] = (u8 *)(info->prog_tags);
>> ^
>> util/bpf-event.c:143:35: error: initialization of 'u8 (*)[8]' {aka 'unsigned char (*)[8]'} from incompatible pointer type 'u8 *' {aka 'unsigned char *'} [-Werror=incompatible-pointer-types]
>> util/bpf-event.c:144:22: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>> __u32 *prog_lens = (__u32 *)(info->jited_func_lens);
>> ^
>> util/bpf-event.c:145:23: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>> __u64 *prog_addrs = (__u64 *)(info->jited_ksyms);
>> ^
>> util/bpf-event.c:146:22: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>> void *func_infos = (void *)(info->func_info);
>> ^
>> CC /tmp/build/perf/util/pmu.o
>> CC /tmp/build/perf/util/pmu-flex.o
>> cc1: all warnings being treated as errors
>> mv: cannot stat '/tmp/build/perf/util/.bpf-event.o.tmp': No such file or directory
>>
>
> We can fix it with the following:
>
> - u8 (*prog_tags)[BPF_TAG_SIZE] = (void *)(info->prog_tags);
> - __u32 *prog_lens = (__u32 *)(info->jited_func_lens);
> - __u64 *prog_addrs = (__u64 *)(info->jited_ksyms);
> - void *func_infos = (void *)(info->func_info);
> + u8 (*prog_tags)[BPF_TAG_SIZE] = (void *)(intptr_t)(info->prog_tags);
> + __u32 *prog_lens = (__u32 *)(intptr_t)(info->jited_func_lens);
> + __u64 *prog_addrs = (__u64 *)(intptr_t)(info->jited_ksyms);
> + void *func_infos = (void *)(intptr_t)(info->func_info);
>
> Thanks,
> Song

Actually, I think uintptr_t is better than intptr_t here.

Thanks,
Song
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