Em Mon, Jan 02, 2023 at 07:12:50PM +0530, Athira Rajeev escreveu:

quoted

On 14-Dec-2022, at 9:21 PM, Arnaldo Carvalho de Melo <acme@kernel.org <mailto:acme@kernel.org>> wrote:
Em Tue, Dec 13, 2022 at 03:21:03PM +0530, Athira Rajeev escreveu:

quoted

quoted

On 13-Dec-2022, at 12:27 AM, Arnaldo Carvalho de Melo <acme@kernel.org <mailto:acme@kernel.org>> wrote:
Em Thu, Nov 03, 2022 at 12:27:01PM +0530, Athira Rajeev escreveu:

quoted

quoted

On 28-Oct-2022, at 9:12 PM, Kajol Jain <kjain@linux.ibm.com <mailto:kjain@linux.ibm.com>> wrote:

Perf BPF filter test fails in environment where "kernel-debuginfo"
is not installed.

Test failure logs:
<<>>
42: BPF filter                            :
42.1: Basic BPF filtering                 : Ok
42.2: BPF pinning                         : Ok
42.3: BPF prologue generation             : FAILED!
<<>>

Enabling verbose option provided debug logs, which says debuginfo
needs to be installed. Snippet of verbose logs:

<<>>
42.3: BPF prologue generation                                       :

--- start ---

test child forked, pid 28218
<<>>
Rebuild with CONFIG_DEBUG_INFO=y, or install an appropriate debuginfo
package.
bpf_probe: failed to convert perf probe events
Failed to add events selected by BPF
test child finished with -1
---- end ----
BPF filter subtest 3: FAILED!
<<>>

Here subtest, "BPF prologue generation" failed and
logs shows debuginfo is needed. After installing
kernel-debuginfo package, testcase passes.

Subtest "BPF prologue generation" failed because, the "do_test"
function returns "TEST_FAIL" without checking the error type
returned by "parse_events_load_bpf_obj" function.
Function parse_events_load_bpf_obj can also return error of type
"-ENOENT" incase kernel-debuginfo package is not installed. Fix this
by adding check for -ENOENT error.

Test result after the patch changes:

Test failure logs:
<<>>
42: BPF filter                 :
42.1: Basic BPF filtering      : Ok
42.2: BPF pinning              : Ok
42.3: BPF prologue generation  : Skip (clang/debuginfo isn't
installed or environment missing BPF support)

Fixes: ba1fae431e74bb42 ("perf test: Add 'perf test BPF'")
Signed-off-by: Kajol Jain <kjain@linux.ibm.com <mailto:kjain@linux.ibm.com>>
Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com <mailto:maddy@linux.ibm.com>>
---
tools/perf/tests/bpf.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c
index 17c023823713..57cecadc1da2 100644
--- a/tools/perf/tests/bpf.c
+++ b/tools/perf/tests/bpf.c

@@ -126,6 +126,10 @@ static int do_test(struct bpf_object *obj, int (*func)(void),

	err = parse_events_load_bpf_obj(&parse_state, &parse_state.list, obj, NULL);
	parse_events_error__exit(&parse_error);
+	if (err == -ENOENT) {
+		pr_debug("Failed to add events selected by BPF, debuginfo package not installed\n");
+		return TEST_SKIP;
+	}

Hi Kajol,

Here, you have used ENOENT to skip the test. But there could be other places in the code path for “parse_events_load_bpf_obj”
which also returns ENOENT. In that case, for any exit that returns ENOENT, test will get skipped.

Can we look at the logs, example we have this in commit logs:

	Rebuild with CONFIG_DEBUG_INFO=y, or install an appropriate debuginfo
	package.

so as to decide whether to skip for debug info ?

Kajol?

quoted

Hi Arnaldo, looking for your suggestion on how to handle the case where debuginfo is missing.

quoted

Here the bpf test fails because of missing debuginfo. The function
which goes through the debuginfo check is "parse_events_load_bpf_obj"
. parse_events_load_bpf_obj internally calls "open_debuginfo" which
returns ENOENT when debuginfo is missing. The patch fix from Kajol is
to skip the test using error code ENOENT for debuginfo.

Lets see:

root@roc-rk3399-pc:~# uname -a
Linux roc-rk3399-pc 6.1.0-rc5-00123-g4dd7ff4a0311 #2 SMP PREEMPT Wed Nov 16 19:55:11 UTC 2022 aarch64 aarch64 aarch64 GNU/Linux
root@roc-rk3399-pc:~# perf probe -x ~/bin/perf open_debuginfo
Added new event:
probe_perf:open_debuginfo (on open_debuginfo in /home/acme/bin/perf)

You can now use it in all perf tools, such as:

	perf record -e probe_perf:open_debuginfo -aR sleep 1

root@roc-rk3399-pc:~#

root@roc-rk3399-pc:~# perf trace --call-graph=dwarf -a -e probe_perf:* perf test bpf
40: LLVM search and compile                                         :
40.1: Basic BPF llvm compile                                        : Ok
40.3: Compile source for BPF prologue generation                    : FAILED!
40.4: Compile source for BPF relocation                             : Ok
42: BPF filter                                                      :
42.1: Basic BPF filtering                                           :     0.000 perf/38363 probe_perf:open_debuginfo(__probe_ip: 187650778659428)
                                    open_debuginfo (/home/acme/bin/perf)
                                    try_to_find_probe_trace_events (inlined)
                                    convert_to_probe_trace_events (inlined)
                                    convert_perf_probe_events (/home/acme/bin/perf)
                                    bpf__probe (/home/acme/bin/perf)
                                    parse_events_load_bpf_obj (/home/acme/bin/perf)
                                    do_test (/home/acme/bin/perf)
FAILED!
42.2: BPF pinning                                                   :  5594.218 perf/38582 probe_perf:open_debuginfo(__probe_ip: 187650778659428)
                                    open_debuginfo (/home/acme/bin/perf)
                                    try_to_find_probe_trace_events (inlined)
                                    convert_to_probe_trace_events (inlined)
                                    convert_perf_probe_events (/home/acme/bin/perf)
                                    bpf__probe (/home/acme/bin/perf)
                                    parse_events_load_bpf_obj (/home/acme/bin/perf)
                                    do_test (/home/acme/bin/perf)
FAILED!
42.3: BPF prologue generation                                       : FAILED!
63: Test libpfm4 support                                            :
99: perf stat --bpf-counters test                                   : Skip
100: perf stat --bpf-counters --for-each-cgroup test                 : Skip
root@roc-rk3399-pc:~#

So that is the callchains leading to open_debuginfo(), perhaps we should
return ENODATA at try_to_find_probe_trace_events() when open_debuginfo()
fails?

Hi Arnaldo,

Thanks for the suggestions. I tried with changing return code to ENODATA when open_debuginfo fails and will
send a separate patch addressing this change.

quoted

⬢[acme@toolbox perf]$ find tools/perf/ -name "*.[ch]" | xargs grep try_to_find_probe_trace_events
tools/perf/util/probe-event.c:static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
tools/perf/util/probe-event.c:static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
tools/perf/util/probe-event.c:	ret = try_to_find_probe_trace_events(pev, tevs);
⬢[acme@toolbox perf]$ 

Also it returns ENOENT as well when not finding the probe point... There
we should return perhaps ENOSYM?

ENOSYM is not defined for all the archs. 

	arch/parisc/include/uapi/asm/errno.h:#define ENOSYM		215	/* symbol does not exist in executable */

So we need to make this error code generic to use in probe-event. Shall we make this error code
generic for all archs to use ?

Try to find some other errno that is available everywhere and use
instead, I think.

- Arnaldo