[PATCH v6 2/2] tracing/selftests: Add tests for hist trigger expression parsing

[Kalesh Singh <kaleshsingh@google.com>]

Add tests for the parsing of hist trigger expressions; and to
validate expression evaluation.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
Changes in v6:
  - Read the expression result from the trigger file,
    instead of creating a histogram to print the value.

Changes in v5:
  - Add README pattern to requires tag, per Masami

Changes in v3:
  - Remove .sym-offset error check tests

Changes in v2:
  - Add Namhyung's Reviewed-by
  - Update comment to clarify err_pos in "Too many subexpressions" test


 .../trigger/trigger-hist-expressions.tc       | 65 +++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc

diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc
new file mode 100644
index 000000000000..33eb79589b32
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc
@@ -0,0 +1,65 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test histogram expression parsing
+# requires: set_event events/sched/sched_process_fork/trigger events/sched/sched_process_fork/hist error_log "<var1>=<field|var_ref|numeric_literal>":README
+
+
+fail() { #msg
+    echo $1
+    exit_fail
+}
+
+test_hist_expr() { # test_name expression expected_val
+    trigger="events/sched/sched_process_fork/trigger"
+
+    reset_trigger_file $trigger
+
+    echo "Test hist trigger expressions - $1"
+
+    echo "hist:keys=common_pid:x=$2" > $trigger
+
+    for i in `seq 1 10` ; do ( echo "forked" > /dev/null); done
+
+    x=`grep -o 'x=[[:digit:]]*' $trigger | awk -F= '{ print $2 }'`
+    actual=$(( x + 0 )) # To print negative numbers correctly
+
+    if [ $actual != $3 ]; then
+        fail "Failed hist trigger expression evaluation: Expression: $2 Expected: $3, Actual: $actual"
+    fi
+
+    reset_trigger_file $trigger
+}
+
+check_error() { # test_name command-with-error-pos-by-^
+    trigger="events/sched/sched_process_fork/trigger"
+
+    echo "Test hist trigger expressions - $1"
+    ftrace_errlog_check 'hist:sched:sched_process_fork' "$2" $trigger
+}
+
+test_hist_expr "Variable assignment" "123" "123"
+
+test_hist_expr "Subtraction not associative" "16-8-4-2" "2"
+
+test_hist_expr "Division not associative" "64/8/4/2" "1"
+
+test_hist_expr "Same precedence operators (+,-) evaluated left to right" "16-8+4+2" "14"
+
+test_hist_expr "Same precedence operators (*,/) evaluated left to right" "4*3/2*2" "12"
+
+test_hist_expr "Multiplication evaluated before addition/subtraction" "4+3*2-2" "8"
+
+test_hist_expr "Division evaluated before addition/subtraction" "4+6/2-2" "5"
+
+# Division by zero returns -1
+test_hist_expr "Handles division by zero" "3/0" "-1"
+
+# err pos for "too many subexpressions" is dependent on where
+# the last subexpression was detected. This can vary depending
+# on how the expression tree was generated.
+check_error "Too many subexpressions" 'hist:keys=common_pid:x=32+^10*3/20-4'
+check_error "Too many subexpressions" 'hist:keys=common_pid:x=^1+2+3+4+5'
+
+check_error "Unary minus not supported in subexpression" 'hist:keys=common_pid:x=-(^1)+2'
+
+exit 0
-- 
2.33.0.1079.g6e70778dc9-goog