Re: [PATCH Linux-next] perf test: Fix test case perf trace BTF general tests

Steven Rostedt
2025-11-18T18:24:28Z

On Mon, 17 Nov 2025 22:43:21 -0800
Namhyung Kim <namhyung@kernel.org> wrote:

> > bash-5.3# uname -a
> > Linux f43 6.18.0-rc5-next-20251114tmr-n #1 SMP PREEMPT_DYNAMIC Mon Nov 17 11:24:02 CET 2025 x86_64 GNU/Linux
> > bash-5.3# cat /sys/kernel/tracing/events/syscalls/sys_enter_write/format
> > name: sys_enter_write
> > ID: 758
> > format:
> > field:unsigned short common_type; offset:0; size:2; signed:0;
> > field:unsigned char common_flags; offset:2; size:1; signed:0;
> > field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
> > field:int common_pid; offset:4; size:4; signed:1;
> >
> > field:int __syscall_nr; offset:8; size:4; signed:1;
> > field:unsigned int fd; offset:16; size:8; signed:0;
> > field:const char * buf; offset:24; size:8; signed:0;
> > field:size_t count; offset:32; size:8; signed:0;
> > field:__data_loc char[] __buf_val; offset:40; size:4; signed:0;
>
> Indeed, I see this new field __buf_val.
>
> Steve, is this what you added recently for taking user contents?

Yes.

> Hmm.. this makes perf trace confused wrt the syscall parameters.
> Is it always __buf_val or has any patterns?

Really? It still uses libtraceevent right? I made sure that this didn't
break trace-cmd and thought that perf would work too.

-- Steve