Re: [PATCH v10 8/8] selftests/ftrace: Add funcgraph-retval test case

[Donglin Peng]

On 2023/4/3 13:01, Donglin Peng wrote:
> On 2023/4/3 10:33, Donglin Peng wrote:
> > On 2023/4/2 6:04, Masami Hiramatsu (Google) wrote:
> > > On Fri, 31 Mar 2023 05:47:44 -0700
> > > Donglin Peng <pengdonglin@xxxxxxxxxxxxxx> wrote:
> > >
> > > > Add a test case for the funcgraph-retval and funcgraph-retval-hex
> > > > trace options.
> > > >
> > > > Signed-off-by: Donglin Peng <pengdonglin@xxxxxxxxxxxxxx>
> > > > ---
> > > > v10:
> > > >   - Fix issues in selftest
> > > >
> > > > v8:
> > > >   - Fix issues in selftest
> > > > ---
> > > >   .../ftrace/test.d/ftrace/fgraph-retval.tc     | 43 
> > > > +++++++++++++++++++
> > > >   1 file changed, 43 insertions(+)
> > > >   create mode 100644 
> > > > tools/testing/selftests/ftrace/test.d/ftrace/fgraph-retval.tc
> > > >
> > > > diff --git 
> > > > a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-retval.tc 
> > > > b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-retval.tc
> > > > new file mode 100644
> > > > index 000000000000..5819aa2dd6ad
> > > > --- /dev/null
> > > > +++ b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-retval.tc
> > > > @@ -0,0 +1,43 @@
> > > > +#!/bin/sh
> > > > +# SPDX-License-Identifier: GPL-2.0
> > > > +# description: ftrace - function graph print function return value
> > > > +# requires: options/funcgraph-retval options/funcgraph-retval-hex 
> > > > function_graph:tracer
> > > > +
> > > > +# Make sure that funcgraph-retval works
> > > > +
> > > > +fail() { # msg
> > > > +    echo $1
> > > > +    exit_fail
> > > > +}
> > > > +
> > > > +disable_tracing
> > > > +clear_trace
> > > > +
> > > > +read PID _ < /proc/self/stat
> > >
> > > You can use "$$" for self pid.
> >
> > Yeah, I will fix it.
>
> I found that ftracetest used () to launch a new child process for
> executing a .tc script file, however the $$ value remains unchanged,
> so we can not use $$ here, because it is PPID. Therefore I think we
> have to get PID from /proc/self/stat.
>
> Here is the code from ftracetest that launches a child shell for 
> executing the .tc file.
>
> __run_test() { # testfile
>    # setup PID and PPID, $$ is *not* updated.
>    (cd $TRACING_DIR; read PID _ < /proc/self/stat; set -e; set -x;
>     checkreq $1; initialize_ftrace; . $1)
>    [ $? -ne 0 ] && kill -s $SIG_FAIL $SIG_PID
> }
>
> > > > +[ -f set_ftrace_pid ] && echo ${PID} > set_ftrace_pid
> > > > +[ -f set_ftrace_filter ] && echo proc_reg_write > set_ftrace_filter
> > > > +[ -f set_graph_function ] && echo proc_reg_write > set_graph_function
> > >
> > > You should set the required files for this test, so that the test result
> > > is always same. BTW, you need to set either 'set_ftrace_filter' or
> > > 'set_graph_function'.
> >
> > Yes, but I discovered that set_ftrace_filter and set_graph_function 
> > rely on the CONFIG_DYNAMIC_FTRACE configuration, which means that 
> > these two files are not present when CONFIG_DYNAMIC_FTRACE is 
> > disabled, even if CONFIG_FUNCTION_GRAPH_RETVAL is enabled. Therefore, 
> > I think that these two trace files are not necessary for this test.
> >
> > I will modify the above like this:
> >
> > [ -f set_ftrace_pid ] && echo $$ > set_ftrace_pid
> > [ -f set_ftrace_filter ] && echo proc_reg_write > set_ftrace_filter
> >
> > > > +echo function_graph > current_tracer
> > > > +echo funcgraph-retval > trace_options
> > > > +
> > > > +set +e
> > > > +enable_tracing
> > > > +echo > /proc/interrupts
> > > > +disable_tracing
> > > > +set -e
> > > > +
> > > > +: "Test printing the error code in signed decimal format"
> > > > +echo nofuncgraph-retval-hex > trace_options
> > >
> > > echo 0 > options/funcgraph-retval-hex
> > >
> > > If you require 'options/funcgraph-retval-hex' file, you can use the
> > > file to set it or clear it.
> >
> > Yeah.
> >
> > > > +count=`cat trace | grep 'proc_reg_write' | grep '= -5' | wc -l`
> > > > +if [ $count -eq 0 ]; then
> > > > +    fail "Return value can not be printed in signed decimal format"
> > > > +fi
> > > > +
> > > > +: "Test printing the error code in hexadecimal format"
> > > > +echo funcgraph-retval-hex > trace_options
> > >
> > > Ditto.
> >
> > Thanks.
> >
> > > Thanks,
> > >
> > > > +count=`cat trace | grep 'proc_reg_write' | grep 'fffffffb' | wc -l`
> > > > +if [ $count -eq 0 ]; then
> > > > +    fail "Return value can not be printed in hexadecimal format"
> > > > +fi
> > > > +
> > > > +exit 0
> > > > --
> > > > 2.25.1

Hi Masami,

I will update the selftest as follows, according to the comments:

#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
# description: ftrace - function graph print function return value
# requires: options/funcgraph-retval options/funcgraph-retval-hex 
function_graph:tracer

# Make sure that funcgraph-retval works

fail() { # msg
    echo $1
    exit_fail
}

disable_tracing
clear_trace

# get self PID, can not use $$, because it is PPID
read PID _ < /proc/self/stat

[ -f set_ftrace_filter ] && echo proc_reg_write > set_ftrace_filter
[ -f set_ftrace_pid ] && echo ${PID} > set_ftrace_pid
echo function_graph > current_tracer
echo 1 > options/funcgraph-retval

set +e
enable_tracing
echo > /proc/interrupts
disable_tracing
set -e

: "Test printing the error code in signed decimal format"
echo 0 > options/funcgraph-retval-hex
count=`cat trace | grep 'proc_reg_write' | grep '= -5' | wc -l`
if [ $count -eq 0 ]; then
    fail "Return value can not be printed in signed decimal format"
fi

: "Test printing the error code in hexadecimal format"
echo 1 > options/funcgraph-retval-hex
count=`cat trace | grep 'proc_reg_write' | grep 'fffffffb' | wc -l`
if [ $count -eq 0 ]; then
    fail "Return value can not be printed in hexadecimal format"
fi

exit 0