tracing/selftests: Add test for event filtering on function name

With the new filter logic of passing in the name of a function to match an
instruction pointer (or the address of the function), add a test to make
sure that it is functional.

This is also the first test to test plain filtering. The filtering has
been tested via the trigger logic, which uses the same code, but there was
nothing to test just the event filter, so this test is the first to add
such a case.

Link: https://lkml.kernel.org/r/20221219183214.075559302@goodmis.org

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Zheng Yejian <zhengyejian1@huawei.com>
Cc: linux-kselftest@vger.kernel.org
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Ross Zwisler <zwisler@google.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc

+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event filter function - test event filtering on functions
+# requires: set_event events/kmem/kmem_cache_free/filter
+# flags: instance
+
+fail() { #msg
+    echo $1
+    exit_fail
+}
+
+echo "Test event filter function name"
+echo 0 > tracing_on
+echo 0 > events/enable
+echo > trace
+echo 'call_site.function == exit_mmap' > events/kmem/kmem_cache_free/filter
+echo 1 > events/kmem/kmem_cache_free/enable
+echo 1 > tracing_on
+ls > /dev/null
+echo 0 > events/kmem/kmem_cache_free/enable
+
+hitcnt=`grep kmem_cache_free trace| grep exit_mmap | wc -l`
+misscnt=`grep kmem_cache_free trace| grep -v exit_mmap | wc -l`
+
+if [ $hitcnt -eq 0 ]; then
+	exit_fail
+fi
+
+if [ $misscnt -gt 0 ]; then
+	exit_fail
+fi
+
+address=`grep ' exit_mmap$' /proc/kallsyms | cut -d' ' -f1`
+
+echo "Test event filter function address"
+echo 0 > tracing_on
+echo 0 > events/enable
+echo > trace
+echo "call_site.function == 0x$address" > events/kmem/kmem_cache_free/filter
+echo 1 > events/kmem/kmem_cache_free/enable
+echo 1 > tracing_on
+sleep 1
+echo 0 > events/kmem/kmem_cache_free/enable
+
+hitcnt=`grep kmem_cache_free trace| grep exit_mmap | wc -l`
+misscnt=`grep kmem_cache_free trace| grep -v exit_mmap | wc -l`
+
+if [ $hitcnt -eq 0 ]; then
+	exit_fail
+fi
+
+if [ $misscnt -gt 0 ]; then
+	exit_fail
+fi
+
+reset_events_filter
+
+exit 0