* [PATCH v5 bpf-next 0/4] bpf: introduce bpf_get_task_stack()
@ 2020-06-30 6:28 Song Liu
2020-07-01 15:34 ` Alexei Starovoitov
0 siblings, 1 reply; 2+ messages in thread
From: Song Liu @ 2020-06-30 6:28 UTC (permalink / raw)
To: bpf, netdev, linux-kernel
Cc: peterz, ast, daniel, kernel-team, john.fastabend, kpsingh, Song Liu
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@fb.com/
Changes v4 => v5:
1. Rebase and work around git-am issue. (Alexei)
2. Update commit log for 4/4. (Yonghong)
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 | 77 ++++++++++++++++++-
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, 221 insertions(+), 16 deletions(-)
create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
--
2.24.1
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v5 bpf-next 0/4] bpf: introduce bpf_get_task_stack()
2020-06-30 6:28 [PATCH v5 bpf-next 0/4] bpf: introduce bpf_get_task_stack() Song Liu
@ 2020-07-01 15:34 ` Alexei Starovoitov
0 siblings, 0 replies; 2+ messages in thread
From: Alexei Starovoitov @ 2020-07-01 15:34 UTC (permalink / raw)
To: Song Liu
Cc: bpf, Network Development, LKML, Peter Zijlstra,
Alexei Starovoitov, Daniel Borkmann, Kernel Team, John Fastabend,
KP Singh
On Mon, Jun 29, 2020 at 11:28 PM Song Liu <songliubraving@fb.com> 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@fb.com/
>
> Changes v4 => v5:
> 1. Rebase and work around git-am issue. (Alexei)
> 2. Update commit log for 4/4. (Yonghong)
Applied. Thanks
I've added /* */ tweak to BPF_FUNC_MAPPER, so we stop having
ongoing merge conflicts and preserve better 'git blame' for helpers.
^ permalink raw reply [flat|nested] 2+ messages in thread
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