Hi Alan,

On 1/31/22 5:12 PM, Alan Maguire wrote:

This patch series is a refinement of the RFC patchset [1], focusing
on support for attach by name for uprobes and uretprobes. v3
because there was an earlier RFC [2].

Currently attach for such probes is done by determining the offset
manually, so the aim is to try and mimic the simplicity of kprobe
attach, making use of uprobe opts to specify a name string.
Patch 1 adds the "func_name" option to allow uprobe attach by
name; the mechanics are described there.

Having name-based support allows us to support auto-attach for
uprobes; patch 2 adds auto-attach support while attempting
to handle backwards-compatibility issues that arise.  The format
supported is

u[ret]probe//path/2/binary:[raw_offset|function[+offset]]

For example, to attach to libc malloc:

SEC("uprobe//usr/lib64/libc.so.6:malloc")

Patch 3 introduces a helper function to trace_helpers, allowing
us to retrieve the path to a library by reading /proc/self/maps.

Finally patch 4 add tests to the attach_probe selftests covering
attach by name, auto-attach and auto-attach failure.

Looks like the selftest in the series fails the BPF CI (test_progs & test_progs-no_alu32):

https://github.com/kernel-patches/bpf/runs/5012260907?check_suite_focus=true

   [...]
   test_attach_probe:PASS:uprobe_offset 0 nsec
   test_attach_probe:PASS:ref_ctr_offset 0 nsec
   test_attach_probe:PASS:skel_open 0 nsec
   test_attach_probe:PASS:check_bss 0 nsec
   test_attach_probe:PASS:attach_kprobe 0 nsec
   test_attach_probe:PASS:attach_kretprobe 0 nsec
   test_attach_probe:PASS:uprobe_ref_ctr_before 0 nsec
   test_attach_probe:PASS:attach_uprobe 0 nsec
   test_attach_probe:PASS:uprobe_ref_ctr_after 0 nsec
   test_attach_probe:PASS:attach_uretprobe 0 nsec
   test_attach_probe:PASS:auto-attach should fail for old-style name 0 nsec
   test_attach_probe:PASS:attach_uprobe_byname 0 nsec
   test_attach_probe:PASS:attach_uretprobe_byname 0 nsec
   test_attach_probe:PASS:get path to libc 0 nsec
   test_attach_probe:PASS:find libc path in /proc/self/maps 0 nsec
   libbpf: failed to open 7f55b225c000-7f55b2282000 r--p 00000000 fe:00 3381                       /usr/lib/libc-2.32.so: No such file or directory
   test_attach_probe:FAIL:attach_uprobe_byname2 unexpected error: -2
   test_attach_probe:PASS:uprobe_ref_ctr_cleanup 0 nsec
   #4 attach_probe:FAIL
   [...]

Thanks,
Daniel