On Fri, Oct 22, 2021 at 4:48 PM Song Liu [off-list ref] wrote:

Function in modules could appear in /proc/kallsyms in random order.

ffffffffa02608a0 t bpf_testmod_loop_test
ffffffffa02600c0 t __traceiter_bpf_testmod_test_writable_bare
ffffffffa0263b60 d __tracepoint_bpf_testmod_test_write_bare
ffffffffa02608c0 T bpf_testmod_test_read
ffffffffa0260d08 t __SCT__tp_func_bpf_testmod_test_writable_bare
ffffffffa0263300 d __SCK__tp_func_bpf_testmod_test_read
ffffffffa0260680 T bpf_testmod_test_write
ffffffffa0260860 t bpf_testmod_test_mod_kfunc

Therefore, we cannot reliably use kallsyms_find_next() to find the end of
a function. Replace it with a simple guess (start + 128). This is good
enough for this test.

It's so annoying that sizes of all those symbols are known and
available in ELF, yet kallsyms don't expose them :( I've applied this
"fix", but it makes me very sad.

Signed-off-by: Song Liu <redacted>
---
 .../bpf/prog_tests/get_branch_snapshot.c      |  7 ++--
 tools/testing/selftests/bpf/trace_helpers.c   | 36 -------------------
 tools/testing/selftests/bpf/trace_helpers.h   |  5 ---
 3 files changed, 4 insertions(+), 44 deletions(-)

[...]