On Fri, Mar 22, 2024 at 9:07 AM Yonghong Song <yonghong.song@xxxxxxxxx> wrote:
>
>
> On 3/22/24 5:26 AM, Jiri Olsa wrote:
> > On Thu, Mar 21, 2024 at 01:01:24PM -0700, Yonghong Song wrote:
> >> The current kprobe_multi_bench_attach/kernel test
> >> reads sym names from /sys/kernel/tracing/available_filter_functions.
> >> Some names do not agree with the corresponding entries in /proc/kallsyms
> >> since the corresponding /proc/kallsyms syms have suffix '.llvm.<hash>'.
> >> Actually, if we pass symbol names in /proc/kallsyms,
> >> kprobe_multi_attach will be okay.
> >>
> >> This patch added a new subtest where addresses are retrieved from
> >> /sys/kernel/tracing/available_filter_functions_addrs, and use the
> >> address to consule /proc/kallsyms to get the function name.
> > hm, I don't understand the reason for this test.. AFAICS test_kprobe_multi_bench_attach
> > is doing that already, just reading available_filter_functions file
> >
> > both available_filter_functions_addrs and available_filter_functions have the
> > same functions, there's just extra addresses in available_filter_functions_addrs
>
> The goal is to include those kernel functions filtered in patch 4.
> But we cannot use the names from available_filter_functions[_addrs],
> and we need to get names from /proc/kallsyms. Hence this patch.
> This will test if we give names (<name>.llvm.<hash>) to kernel
> for kprobe_multi_attach, things will be okay.
>
for patch #4 it would be good to not skip those *.llvm.* functions,
but find the full name using kallsyms. While here we can use address
based multi-attachment, while getting addresses from
available_filter_functions_addrs? That way we'll have a test that
benchmarks both symbol lookup paths in the kernel (where user provides
symbol names as strings) and address-based lookup (where user provides
raw addresses).
> >
> >> + *symsp = syms;
> >> + *cntp = cnt;
> >> +
> >> +error:
> >> + fclose(f);
> >> + hashmap__free(map);
> >> + if (err) {
> >> + for (i = 0; i < cnt; i++)
> >> + free(syms[i]);
> >> + free(syms);
> >> + }
> >> + return err;
> >> +}
> >> +
[...]
