selftests/bpf: add test validating uprobe/uretprobe stack traces

Add a set of tests to validate that stack traces captured from or in the
presence of active uprobes and uretprobes are valid and complete.

For this we use BPF program that are installed either on entry or exit
of user function, plus deep-nested USDT. One of target funtions
(target_1) is recursive to generate two different entries in the stack
trace for the same uprobe/uretprobe, testing potential edge conditions.

If there is no fixes, we get something like this for one of the scenarios:

 caller: 0x758fff - 0x7595ab
 target_1: 0x758fd5 - 0x758fff
 target_2: 0x758fca - 0x758fd5
 target_3: 0x758fbf - 0x758fca
 target_4: 0x758fb3 - 0x758fbf
 ENTRY #0: 0x758fb3 (in target_4)
 ENTRY #1: 0x758fd3 (in target_2)
 ENTRY #2: 0x758ffd (in target_1)
 ENTRY #3: 0x7fffffffe000
 ENTRY #4: 0x7fffffffe000
 ENTRY #5: 0x6f8f39
 ENTRY #6: 0x6fa6f0
 ENTRY #7: 0x7f403f229590

Entry #3 and #4 (0x7fffffffe000) are uretprobe trampoline addresses
which obscure actual target_1 and another target_1 invocations. Also
note that between entry #0 and entry #1 we are missing an entry for
target_3.

With fixes, we get desired full stack traces:

 caller: 0x758fff - 0x7595ab
 target_1: 0x758fd5 - 0x758fff
 target_2: 0x758fca - 0x758fd5
 target_3: 0x758fbf - 0x758fca
 target_4: 0x758fb3 - 0x758fbf
 ENTRY #0: 0x758fb7 (in target_4)
 ENTRY #1: 0x758fc8 (in target_3)
 ENTRY #2: 0x758fd3 (in target_2)
 ENTRY #3: 0x758ffd (in target_1)
 ENTRY #4: 0x758ff3 (in target_1)
 ENTRY #5: 0x75922c (in caller)
 ENTRY #6: 0x6f8f39
 ENTRY #7: 0x6fa6f0
 ENTRY #8: 0x7f986adc4cd0

Now there is a logical and complete sequence of function calls.

Link: https://lore.kernel.org/all/20240522013845.1631305-5-andrii@kernel.org/



Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>