On 05.03.25 20:58, Andrii Nakryiko wrote:

On Wed, Mar 5, 2025 at 11:47 AM David Hildenbrand [off-list ref] wrote:

quoted

On 05.03.25 20:43, Andrii Nakryiko wrote:

quoted

On Wed, Mar 5, 2025 at 7:22 AM Oleg Nesterov [off-list ref] wrote:

quoted

On 03/04, David Hildenbrand wrote:

quoted

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.

quoted

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