Re: [PATCH bpf-next 1/2] bpf: Add bpf_task_cwd_from_pid() kfunc

On Wed, May 28, 2025 at 8:37 PM Rong Tao rtoax@foxmail.com wrote:

From: Rong Tao rongtao@cestc.cn

It is a bit troublesome to get cwd based on pid in bpf program, such as bpftrace example [1].

This patch therefore adds a new bpf_task_cwd_from_pid() kfunc which allows BPF programs to get cwd from a pid.

[1] https://github.com/bpftrace/bpftrace/issues/3314

Yes. This is cumbersome, but adding a very specific kfunc to the kernel is not a solution. This is tracing, no need for precise cwd. probe_read_kernel can do the job. bpftrace needs to have better C interop. Once that happens any kind of tracing extraction will be easy to write in C. Like this bpf_task_cwd_from_pid() can already be written as C bpf program.