Date: Tue, 18 Jun 2024 11:44:16 +0100
From: James Clark <james.clark@....com>
To: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
 linux-perf-users <linux-perf-users@...r.kernel.org>,
 linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>, akanksha@...ux.ibm.com,
 Madhavan Srinivasan <maddy@...ux.ibm.com>, Kajol Jain <kjain@...ux.ibm.com>,
 Disha Goel <disgoel@...ux.vnet.ibm.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
 Adrian Hunter <adrian.hunter@...el.com>, Ian Rogers <irogers@...gle.com>,
 Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH] tools/perf: Handle perftool-testsuite_probe testcases
 fail when kernel debuginfo is not present



On 17/06/2024 17:47, Athira Rajeev wrote:
> 
> 
>> On 17 Jun 2024, at 8:30 PM, James Clark <james.clark@....com> wrote:
>>
>>
>>
>> On 17/06/2024 13:21, Athira Rajeev wrote:
>>> Running "perftool-testsuite_probe" fails as below:
>>>
>>> ./perf test -v "perftool-testsuite_probe"
>>> 83: perftool-testsuite_probe  : FAILED
>>>
>>> There are three fails:
>>>
>>> 1. Regexp not found: "\s*probe:inode_permission(?:_\d+)?\s+\(on inode_permission(?:[:\+][0-9A-Fa-f]+)?@.+\)"
>>>   -- [ FAIL ] -- perf_probe :: test_adding_kernel :: listing added probe :: perf probe -l (output regexp parsing)
>>>
>>
>> On a machine where NO_DEBUGINFO gets set, this one skips for me. But on
>> a machine where there _is_ debug info this test still fails.
>>
>> But in both cases the probe looks like it was added successfully. So I'm
>> wondering if this one does need to be skipped, or it's just always
>> failing? Do you have this test passing anywhere where there is debug info?
>>
>> The list command looks like it successfully lists the probe for me in
>> both cases, it just doesn't have an address on the end:
>>
>> perf list 'probe:*'
>>
>>   probe:inode_permission (on inode_permission)
>>
>> Does the missing address mean anything or is it just not handled
>> properly by the test?
>>
>> Ironically the machine that _does_ pass the debug info test also prints
>> this, but it looks like it still adds and lists the probe correctly:
>>
>>  perf probe -l probe:*
>>
>>  Failed to find debug information for address 0xffff80008047ac30
>>    probe:inode_permission (on inode_permission)
> 
> Hi James,
> 
> Thanks for checking this patch.
> 
> In environment where kernel is compiled with debuginfo:
> 
> 1) Add probe point
> 
> # ./perf probe --add inode_permission
> Added new event:
>   probe:inode_permission (on inode_permission)
> 
> You can now use it in all perf tools, such as:
> 
> perf record -e probe:inode_permission -aR sleep 1
> 
> 
> 2) Check using perf probe -l
> 
> # ./perf probe -l
> probe:inode_permission (on inode_permission:2@...namei.c)
> 
> With debuginfo, the result has additional info.
>  The test looks for matching pattern "\s*probe:inode_permission(?:_\d+)?\s+\(on inode_permission(?:[:\+][0-9A-Fa-f]+)?@.+\)” in result
> where it is expecting "inode_permission:2@...namei.c” . The “@fs/namei.c” info needs debuginfo here.
> 

Hi Athira,

Maybe there is a real bug and this patch is ok to go in and we should leave
it as failing. Probe -L shows there is debug info available for inode_permission:

   $ ./perf probe -L inode_permission

  <inode_permission@...ux/fs/namei.c:0>
      0  int inode_permission(struct mnt_idmap *idmap,
                             struct inode *inode, int mask)
  ... more source code ...

But probe -l has an error which could be related to the following
line not showing the filename details:

  $ ./perf probe -l
  
  Failed to find debug information for address 0xffff80008047ac30
    probe:inode_permission (on inode_permission)

I'm running a clang kernel and sometimes I see issues with debug
info or toolchain stuff, that could be the reason.

> The function I am using in patch to check for debuginfo (skip_if_no_debuginfo) is from "tests/shell/lib/probe_vfs_getname.sh"
> 
> skip_if_no_debuginfo() {
>         add_probe_vfs_getname -v 2>&1 | grep -E -q "^(Failed to find the path for the kernel|Debuginfo-analysis is not supported)|(file has no debug information)" && return 2
>         return 1
> }
> 
> So the debuginfo test passes in your case since the log has "Failed to find debug information” which is not present in above grep string. 
> 

It passes because there is debug info for getname_flags() which is what the
debug info check looks for. After some greps and seds it ultimately does this
which succeeds:

 $ perf probe "vfs_getname=getname_flags:72 pathname=result->name:string"

 Added new event:
    probe:vfs_getname    (on getname_flags:72 with pathname=result->name:string)

"Failed to find debug information for address" is only ever printed
with "perf probe -l" when there are probes added. The stderr
of that command is never piped into any grep anyway, which is why I
see it on the test output.

So "probe -L" is working but "probe -l" isn't. Ultimately it looks like a real
issue and we should leave the failure in.

> James,
> 
> Only “perf probe -l” subtest fails with debuginfo enabled or other two subtests as well? Can you also share result on how other two subtests behaves ? 
> 
> 1. Fail 2 :
>    perf probe -nf --max-probes=512 -a 'vfs_* $params’
>   
> 
> 2. Fail 3 :
>   perf probe 'vfs_read somenonexistingrandomstuffwhichisalsoprettylongorevenlongertoexceed64'
> 

Here's the full output:

$ sudo ./perf test -vvv "testsuite_probe"
 84: perftool-testsuite_probe:
--- start ---
test child forked, pid 4872
-- [ PASS ] -- perf_probe :: test_adding_kernel :: adding probe inode_permission :: 
-- [ PASS ] -- perf_probe :: test_adding_kernel :: adding probe inode_permission :: -a
-- [ PASS ] -- perf_probe :: test_adding_kernel :: adding probe inode_permission :: --add
-- [ PASS ] -- perf_probe :: test_adding_kernel :: listing added probe :: perf list
Failed to find debug information for address 0xffff80008047ac30
Regexp not found: "\s*probe:inode_permission(?:_\d+)?\s+\(on inode_permission(?:[:\+][0-9A-Fa-f]+)?@.+\)"
-- [ FAIL ] -- perf_probe :: test_adding_kernel :: listing added probe :: perf probe -l (output regexp parsing)
-- [ PASS ] -- perf_probe :: test_adding_kernel :: using added probe
-- [ PASS ] -- perf_probe :: test_adding_kernel :: deleting added probe
-- [ PASS ] -- perf_probe :: test_adding_kernel :: listing removed probe (should NOT be listed)
-- [ PASS ] -- perf_probe :: test_adding_kernel :: dry run :: adding probe
-- [ PASS ] -- perf_probe :: test_adding_kernel :: force-adding probes :: first probe adding
-- [ PASS ] -- perf_probe :: test_adding_kernel :: force-adding probes :: second probe adding (without force)
Failed to find debug information for address 0xffff80008047ac30
-- [ PASS ] -- perf_probe :: test_adding_kernel :: force-adding probes :: second probe adding (with force)
-- [ PASS ] -- perf_probe :: test_adding_kernel :: using doubled probe
-- [ PASS ] -- perf_probe :: test_adding_kernel :: removing multiple probes
-- [ PASS ] -- perf_probe :: test_adding_kernel :: wildcard adding support
-- [ PASS ] -- perf_probe :: test_adding_kernel :: non-existing variable
-- [ PASS ] -- perf_probe :: test_adding_kernel :: function with retval :: add
Regexp not found: "^\[\s+perf\s+record:\s+Woken up [0-9\.]+ times? to write data\s+\].*$"
Regexp not found: "^\[\s+perf\s+record:\s+Captured and wrote [0-9\.]+\s*MB\s+(?:[\w\+\.-]*(?:(?:[\w\+\.-]+)?(?:\/[\w\+\.-]+)+)?\/)?perf\.data(?:\.\d+)?\s*\(~?[0-9\.]+ samples\)\s+\].*$"
-- [ FAIL ] -- perf_probe :: test_adding_kernel :: function with retval :: record (command exitcode + output regexp parsing)
zero-sized data (/tmp/perftool-testsuite_probe.VMU/perf_probe/perf.data), nothing to do!
Regexp not found: "\s*cat\s+[0-9\.]+\s+\[[0-9\.]+\]\s+[0-9\.]+:\s+probe:inode_permission\w*:\s+\([0-9A-Fa-f]+\s+<\-\s+[0-9A-Fa-f]+\)\s+arg1=[0-9A-Fa-f]+"
-- [ FAIL ] -- perf_probe :: test_adding_kernel :: function argument probing :: script (command exitcode + output regexp parsing)
## [ FAIL ] ## perf_probe :: test_adding_kernel SUMMARY :: 3 failures found
---- end(-1) ----
 84: perftool-testsuite_probe                                        : FAILED!


> 
> Also since you mentioned this gets skipped when debuginfo is not enabled, curious to know what is debuginfo message from your setup with debuginfo disabled.
> 

  $ sudo ./perf probe -L getname_flags
  Failed to find the path for the kernel: Invalid ELF file
    Error: Failed to show lines.

> Thanks again for checking.
> 
> Athira
> 
>>
> 
> 
>>
>>> 2. Regexp not found: "probe:vfs_mknod"
>>>   Regexp not found: "probe:vfs_create"
>>>   Regexp not found: "probe:vfs_rmdir"
>>>   Regexp not found: "probe:vfs_link"
>>>   Regexp not found: "probe:vfs_write"
>>>   -- [ FAIL ] -- perf_probe :: test_adding_kernel :: wildcard adding support (command exitcode + output regexp parsing)
>>>
>>> 3. Regexp not found: "Failed to find"
>>>   Regexp not found: "somenonexistingrandomstuffwhichisalsoprettylongorevenlongertoexceed64"
>>>   Regexp not found: "in this function|at this address"
>>>   Line did not match any pattern: "The /boot/vmlinux file has no debug information."
>>>   Line did not match any pattern: "Rebuild with CONFIG_DEBUG_INFO=y, or install an appropriate debuginfo package."
>>>
>>> These three tests depends on kernel debug info.
>>> 1. Fail 1 expects file name along with probe which needs debuginfo
>>> 2. Fail 2 :
>>>    perf probe -nf --max-probes=512 -a 'vfs_* $params'
>>>    Debuginfo-analysis is not supported.
>>>     Error: Failed to add events.
>>>
>>> 3. Fail 3 :
>>>   perf probe 'vfs_read somenonexistingrandomstuffwhichisalsoprettylongorevenlongertoexceed64'
>>>   Debuginfo-analysis is not supported.
>>>   Error: Failed to add events.
>>>
>>> There is already helper function skip_if_no_debuginfo in
>>> lib/probe_vfs_getname.sh which does perf probe and returns
>>> "2" if debug info is not present. Use the skip_if_no_debuginfo
>>> function and skip only the three tests which needs debuginfo
>>> based on the result.
>>>
>>> With the patch:
>>>
>>>    83: perftool-testsuite_probe:
>>>   --- start ---
>>>   test child forked, pid 3927
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: adding probe inode_permission ::
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: adding probe inode_permission :: -a
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: adding probe inode_permission :: --add
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: listing added probe :: perf list
>>>   Regexp not found: "\s*probe:inode_permission(?:_\d+)?\s+\(on inode_permission(?:[:\+][0-9A-Fa-f]+)?@.+\)"
>>>   -- [ SKIP ] -- perf_probe :: test_adding_kernel :: 2 2 Skipped due to missing debuginfo :: testcase skipped
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: using added probe
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: deleting added probe
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: listing removed probe (should NOT be listed)
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: dry run :: adding probe
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: force-adding probes :: first probe adding
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: force-adding probes :: second probe adding (without force)
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: force-adding probes :: second probe adding (with force)
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: using doubled probe
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: removing multiple probes
>>>   Regexp not found: "probe:vfs_mknod"
>>>   Regexp not found: "probe:vfs_create"
>>>   Regexp not found: "probe:vfs_rmdir"
>>>   Regexp not found: "probe:vfs_link"
>>>   Regexp not found: "probe:vfs_write"
>>>   -- [ SKIP ] -- perf_probe :: test_adding_kernel :: 2 2 Skipped due to missing debuginfo :: testcase skipped
>>>   Regexp not found: "Failed to find"
>>>   Regexp not found: "somenonexistingrandomstuffwhichisalsoprettylongorevenlongertoexceed64"
>>>   Regexp not found: "in this function|at this address"
>>>   Line did not match any pattern: "The /boot/vmlinux file has no debug information."
>>>   Line did not match any pattern: "Rebuild with CONFIG_DEBUG_INFO=y, or install an appropriate debuginfo package."
>>>   -- [ SKIP ] -- perf_probe :: test_adding_kernel :: 2 2 Skipped due to missing debuginfo :: testcase skipped
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: function with retval :: add
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: function with retval :: record
>>>   -- [ PASS ] -- perf_probe :: test_adding_kernel :: function argument probing :: script
>>>   ## [ PASS ] ## perf_probe :: test_adding_kernel SUMMARY
>>>   ---- end(0) ----
>>>   83: perftool-testsuite_probe                                        : Ok
>>>
>>> Only the three specific tests are skipped and remaining
>>> ran successfully.
>>>
>>> Signed-off-by: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
>>> ---
>>> .../shell/base_probe/test_adding_kernel.sh    | 31 +++++++++++++++++--
>>> 1 file changed, 28 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/tools/perf/tests/shell/base_probe/test_adding_kernel.sh b/tools/perf/tests/shell/base_probe/test_adding_kernel.sh
>>> index 63bb8974b38e..187dc8d4b163 100755
>>> --- a/tools/perf/tests/shell/base_probe/test_adding_kernel.sh
>>> +++ b/tools/perf/tests/shell/base_probe/test_adding_kernel.sh
>>> @@ -21,8 +21,18 @@
>>> THIS_TEST_NAME=`basename $0 .sh`
>>> TEST_RESULT=0
>>>
>>> +# shellcheck source=lib/probe_vfs_getname.sh
>>> +. "$(dirname "$0")/../lib/probe_vfs_getname.sh"
>>> +
>>> TEST_PROBE=${TEST_PROBE:-"inode_permission"}
>>>
>>> +# set NO_DEBUGINFO to skip testcase if debuginfo is not present
>>> +# skip_if_no_debuginfo returns 2 if debuginfo is not present
>>> +skip_if_no_debuginfo
>>> +if [ $? -eq 2 ]; then
>>> + NO_DEBUGINFO=1
>>> +fi
>>> +
>>> check_kprobes_available
>>> if [ $? -ne 0 ]; then
>>> print_overall_skipped
>>> @@ -67,7 +77,12 @@ PERF_EXIT_CODE=$?
>>> ../common/check_all_patterns_found.pl "\s*probe:${TEST_PROBE}(?:_\d+)?\s+\(on ${TEST_PROBE}(?:[:\+]$RE_NUMBER_HEX)?@.+\)" < $LOGS_DIR/adding_kernel_list-l.log
>>> CHECK_EXIT_CODE=$?
>>>
>>> -print_results $PERF_EXIT_CODE $CHECK_EXIT_CODE "listing added probe :: perf probe -l"
>>> +if [ $NO_DEBUGINFO ] ; then
>>> + print_testcase_skipped $NO_DEBUGINFO $NO_DEBUGINFO "Skipped due to missing debuginfo"
>>> +else
>>> + print_results $PERF_EXIT_CODE $CHECK_EXIT_CODE "listing added probe :: perf probe -l"
>>> +fi
>>> +
>>> (( TEST_RESULT += $? ))
>>>
>>>
>>> @@ -208,7 +223,12 @@ PERF_EXIT_CODE=$?
>>> ../common/check_all_patterns_found.pl "probe:vfs_mknod" "probe:vfs_create" "probe:vfs_rmdir" "probe:vfs_link" "probe:vfs_write" < $LOGS_DIR/adding_kernel_adding_wildcard.err
>>> CHECK_EXIT_CODE=$?
>>>
>>> -print_results $PERF_EXIT_CODE $CHECK_EXIT_CODE "wildcard adding support"
>>> +if [ $NO_DEBUGINFO ] ; then
>>> + print_testcase_skipped $NO_DEBUGINFO $NO_DEBUGINFO "Skipped due to missing debuginfo"
>>> +else
>>> + print_results $PERF_EXIT_CODE $CHECK_EXIT_CODE "wildcard adding support"
>>> +fi
>>> +
>>> (( TEST_RESULT += $? ))
>>>
>>>
>>> @@ -232,7 +252,12 @@ CHECK_EXIT_CODE=$?
>>> ../common/check_no_patterns_found.pl "$RE_SEGFAULT" < $LOGS_DIR/adding_kernel_nonexisting.err
>>> (( CHECK_EXIT_CODE += $? ))
>>>
>>> -print_results $PERF_EXIT_CODE $CHECK_EXIT_CODE "non-existing variable"
>>> +if [ $NO_DEBUGINFO ]; then
>>> + print_testcase_skipped $NO_DEBUGINFO $NO_DEBUGINFO "Skipped due to missing debuginfo"
>>> +else
>>> + print_results $PERF_EXIT_CODE $CHECK_EXIT_CODE "non-existing variable"
>>> +fi
>>> +
>>> (( TEST_RESULT += $? ))
>>>
>>>
> 

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