linux-kernel - Re: [PATCH -next v1 0/3] kernel/events/uprobes: uprobe_write

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Message-ID: <e34433c3-6e7c-490e-a334-92800db0d190@redhat.com>
Date: Wed, 5 Mar 2025 21:53:20 +0100
From: David Hildenbrand <david@...hat.com>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Oleg Nesterov <oleg@...hat.com>, Andrii Nakryiko <andrii@...nel.org>,
 Jiri Olsa <jolsa@...nel.org>, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org,
 linux-trace-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
 Andrew Morton <akpm@...ux-foundation.org>,
 Matthew Wilcox <willy@...radead.org>, Russell King <linux@...linux.org.uk>,
 Masami Hiramatsu <mhiramat@...nel.org>, Peter Zijlstra
 <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
 "Liang, Kan" <kan.liang@...ux.intel.com>,
 Tong Tiangen <tongtiangen@...wei.com>
Subject: Re: [PATCH -next v1 0/3] kernel/events/uprobes: uprobe_write_opcode()
 rewrite

On 05.03.25 20:58, Andrii Nakryiko wrote:
> On Wed, Mar 5, 2025 at 11:47 AM David Hildenbrand <david@...hat.com> wrote:
>>
>> On 05.03.25 20:43, Andrii Nakryiko wrote:
>>> On Wed, Mar 5, 2025 at 7:22 AM Oleg Nesterov <oleg@...hat.com> wrote:
>>>>
>>>> On 03/04, David Hildenbrand wrote:
>>>>>
>>>>> Currently, uprobe_write_opcode() implements COW-breaking manually, which is
>>>>> really far from ideal.
>>>>
>>>> To say at least ;)
>>>>
>>>> David, thanks for doing this. I'll try to read 3/3 tomorrow, but I don't
>>>> think I can really help. Let me repeat, this code was written many years
>>>> ago, I forgot everything, and today my understanding of mm/ is very poor.
>>>> But I'll try anyway.
>>>>
>>>>> Are there any uprobe tests / benchmarks that are worth running?
>>>>
>>>> All I know about uprobe tests is that bpf people run a lot of tests which
>>>> use uprobes.
>>>>
>>>> Andrii, Jiri, what you advise?
>>>>
>>>
>>> We do have a bunch of tests within BPF selftests:
>>>
>>> cd tools/testing/selftest/bpf && make -j$(nproc) && sudo ./test_progs -t uprobe
>>
>> I stumbled over them, but was so far not successful in building them in
>> my test VM (did not try too hard, though). Will try harder now that I
>> know that it actually tests uprobe properly :)
> 
> If you have decently recent Clang and pahole, then just make sure you
> have kernel built before you build selftests. So above instructions
> are more like:
> 
> 1. cd <linux-repo>
> 2. cat tools/testing/selftests/bpf/{config, config.<your_arch>} >> .config

^ that did the trick

> 3. make -j$(nproc) # build kernel with that adjusted config
> 4. cd tools/testing/selftests/bpf
> 5. make -j$(nproc) # build BPF selftests
> 6. sudo ./test_progs -t uprobe # run selftests with "uprobe" in their name

#444     uprobe:OK
#445     uprobe_autoattach:OK
#446/1   uprobe_multi_test/skel_api:OK
#446/2   uprobe_multi_test/attach_api_pattern:OK
#446/3   uprobe_multi_test/attach_api_syms:OK
#446/4   uprobe_multi_test/link_api:OK
#446/5   uprobe_multi_test/bench_uprobe:OK
#446/6   uprobe_multi_test/bench_usdt:OK
#446/7   uprobe_multi_test/attach_api_fails:OK
#446/8   uprobe_multi_test/attach_uprobe_fails:OK
#446/9   uprobe_multi_test/consumers:OK
#446/10  uprobe_multi_test/filter_fork:OK
#446/11  uprobe_multi_test/filter_clone_vm:OK
#446/12  uprobe_multi_test/session:OK
#446/13  uprobe_multi_test/session_single:OK
#446/14  uprobe_multi_test/session_cookie:OK
#446/15  uprobe_multi_test/session_cookie_recursive:OK
#446/16  uprobe_multi_test/uprobe_sesison_return_0:OK
#446/17  uprobe_multi_test/uprobe_sesison_return_1:OK
#446/18  uprobe_multi_test/uprobe_sesison_return_2:OK
#446     uprobe_multi_test:OK
#447/1   uprobe_syscall/uretprobe_regs_equal:OK
#447/2   uprobe_syscall/uretprobe_regs_change:OK
#447/3   uprobe_syscall/uretprobe_syscall_call:OK
#447/4   uprobe_syscall/uretprobe_shadow_stack:SKIP
#447     uprobe_syscall:OK (SKIP: 1/4)
Summary: 4/21 PASSED, 1 SKIPPED, 0 FAILED


Looks promising, thanks!

-- 
Cheers,

David / dhildenb