linux-kernel - Re: [PATCHv3 perf/core 0/6] uprobe,bpf: Allow to change app registers from uprobe registers

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Message-ID: <7f591ac9-d3e0-4404-987c-40eceaf51fbb@linux.dev>
Date: Fri, 12 Sep 2025 13:28:55 -0700
From: Ihor Solodrai <ihor.solodrai@...ux.dev>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>, Jiri Olsa <jolsa@...nel.org>
Cc: Oleg Nesterov <oleg@...hat.com>, Masami Hiramatsu <mhiramat@...nel.org>,
 Peter Zijlstra <peterz@...radead.org>, Andrii Nakryiko <andrii@...nel.org>,
 bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, x86@...nel.org,
 Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
 John Fastabend <john.fastabend@...il.com>, Hao Luo <haoluo@...gle.com>,
 Steven Rostedt <rostedt@...dmis.org>, Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCHv3 perf/core 0/6] uprobe,bpf: Allow to change app registers
 from uprobe registers

On 9/9/25 9:41 AM, Andrii Nakryiko wrote:
> On Tue, Sep 9, 2025 at 8:39 AM Jiri Olsa <jolsa@...nel.org> wrote:
>>
>> hi,
>> we recently had several requests for tetragon to be able to change
>> user application function return value or divert its execution through
>> instruction pointer change.
>>
>> This patchset adds support for uprobe program to change app's registers
>> including instruction pointer.
>>
>> v3 changes:
>> - deny attach of kprobe,multi with kprobe_write_ctx set [Alexei]
>> - added more tests for denied kprobe attachment
>>
>> thanks,
>> jirka
>>
>>
>> ---
>> Jiri Olsa (6):
>>        bpf: Allow uprobe program to change context registers
>>        uprobe: Do not emulate/sstep original instruction when ip is changed
>>        selftests/bpf: Add uprobe context registers changes test
>>        selftests/bpf: Add uprobe context ip register change test
>>        selftests/bpf: Add kprobe write ctx attach test
>>        selftests/bpf: Add kprobe multi write ctx attach test
>>
> 
> For the series:
> 
> Acked-by: Andrii Nakryiko <andrii@...nel.org>
> 
> Question is which tree will this go through? Most changes are in BPF,
> so probably bpf-next, right?

Hi Jiri.

This series does not apply to current bpf-next, see below.

Could you please respin it with bpf-next tag?
E.g. "[PATCH v4 bpf-next 0/6] ..."

Thanks!

$ git log -1 --oneline
a578b54a8ad2 (HEAD -> master, origin/master, origin/HEAD, 
kernel-patches/bpf-next) Merge branch 
'bpf-report-arena-faults-to-bpf-streams'
$ b4 am 20250909123857.315599-1-jolsa@...nel.org
[...]
$ git am 
./v3_20250909_jolsa_uprobe_bpf_allow_to_change_app_registers_from_uprobe_registers.mbx
Applying: bpf: Allow uprobe program to change context registers
Applying: uprobe: Do not emulate/sstep original instruction when ip is 
changed
error: patch failed: kernel/events/uprobes.c:2768
error: kernel/events/uprobes.c: patch does not apply
Patch failed at 0002 uprobe: Do not emulate/sstep original instruction 
when ip is changed
[...]

> 
>>   include/linux/bpf.h                                        |   1 +
>>   kernel/events/core.c                                       |   4 +++
>>   kernel/events/uprobes.c                                    |   7 +++++
>>   kernel/trace/bpf_trace.c                                   |   7 +++--
>>   tools/testing/selftests/bpf/prog_tests/attach_probe.c      |  28 +++++++++++++++++
>>   tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c |  27 ++++++++++++++++
>>   tools/testing/selftests/bpf/prog_tests/uprobe.c            | 156 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>>   tools/testing/selftests/bpf/progs/kprobe_write_ctx.c       |  22 +++++++++++++
>>   tools/testing/selftests/bpf/progs/test_uprobe.c            |  38 +++++++++++++++++++++++
>>   9 files changed, 287 insertions(+), 3 deletions(-)
>>   create mode 100644 tools/testing/selftests/bpf/progs/kprobe_write_ctx.c