On Mon, Jun 29, 2020 at 11:54 AM Song Liu <songliubraving@xxxxxx> wrote: > > This set introduces a new helper bpf_get_task_stack(). The primary use case > is to dump all /proc/*/stack to seq_file via bpf_iter__task. > > A few different approaches have been explored and compared: > > 1. A simple wrapper around stack_trace_save_tsk(), as v1 [1]. > > This approach introduces new syntax, which is different to existing > helper bpf_get_stack(). Therefore, this is not ideal. > > 2. Extend get_perf_callchain() to support "task" as argument. > > This approach reuses most of bpf_get_stack(). However, extending > get_perf_callchain() requires non-trivial changes to architecture > specific code. Which is error prone. > > 3. Current (v2) approach, leverages most of existing bpf_get_stack(), and > uses stack_trace_save_tsk() to handle architecture specific logic. > > [1] https://lore.kernel.org/netdev/20200623070802.2310018-1-songliubraving@xxxxxx/ > > Changes v3 => v4: > 1. Simplify the selftests with bpf_iter.h. (Yonghong) > 2. Add example output to commit log of 4/4. (Yonghong) > > Changes v2 => v3: > 1. Rebase on top of bpf-next. (Yonghong) > 2. Sanitize get_callchain_entry(). (Peter) > 3. Use has_callchain_buf for bpf_get_task_stack. (Andrii) > 4. Other small clean up. (Yonghong, Andrii). > > Changes v1 => v2: > 1. Reuse most of bpf_get_stack() logic. (Andrii) > 2. Fix unsigned long vs. u64 mismatch for 32-bit systems. (Yonghong) > 3. Add %pB support in bpf_trace_printk(). (Daniel) > 4. Fix buffer size to bytes. > > Song Liu (4): > perf: expose get/put_callchain_entry() > bpf: introduce helper bpf_get_task_stack() > bpf: allow %pB in bpf_seq_printf() and bpf_trace_printk() > selftests/bpf: add bpf_iter test with bpf_get_task_stack() > > include/linux/bpf.h | 1 + > include/linux/perf_event.h | 2 + > include/uapi/linux/bpf.h | 36 ++++++++- > kernel/bpf/stackmap.c | 75 ++++++++++++++++++- > kernel/bpf/verifier.c | 4 +- > kernel/events/callchain.c | 13 ++-- > kernel/trace/bpf_trace.c | 12 ++- > scripts/bpf_helpers_doc.py | 2 + > tools/include/uapi/linux/bpf.h | 36 ++++++++- > .../selftests/bpf/prog_tests/bpf_iter.c | 17 +++++ > .../selftests/bpf/progs/bpf_iter_task_stack.c | 37 +++++++++ > 11 files changed, 220 insertions(+), 15 deletions(-) > create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c > > -- > 2.24.1 Thanks for working on this! This will enable a whole new set of tools and applications. Acked-by: Andrii Nakryiko <andriin@xxxxxx>
