perf test trace: Remove set -e for BTF general tests

Remove set -e and print error messages in BTF general tests.

Before:
$ sudo /tmp/perf test btf -vv
108: perf trace BTF general tests:
108: perf trace BTF general tests : Running
--- start ---
test child forked, pid 889299
Checking if vmlinux BTF exists
Testing perf trace's string augmentation
String augmentation test failed
---- end(-1) ----
108: perf trace BTF general tests : FAILED!

After:
$ sudo /tmp/perf test btf -vv
108: perf trace BTF general tests:
108: perf trace BTF general tests : Running
--- start ---
test child forked, pid 886551
Checking if vmlinux BTF exists
Testing perf trace's string augmentation
String augmentation test failed, output:
:886566/886566 renameat2(CWD, "/tmp/file1_RcMa", CWD, "/tmp/file2_RcMa", NOREPLACE) = 0---- end(-1) ----
108: perf trace BTF general tests : FAILED!

Signed-off-by: Howard Chu <[e-mail]>
Tested-by: Namhyung Kim <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/tests/shell/trace_btf_general.sh

···
 # SPDX-License-Identifier: GPL-2.0
 
 err=0
-set -e
 
 # shellcheck source=lib/probe.sh
 . "$(dirname $0)"/lib/probe.sh
···
 
 trace_test_string() {
   echo "Testing perf trace's string augmentation"
-  if ! perf trace -e renameat* --max-events=1 -- mv ${file1} ${file2} 2>&1 | \
-    grep -q -E "^mv/[0-9]+ renameat(2)?\(.*, \"${file1}\", .*, \"${file2}\", .*\) += +[0-9]+$"
+  output="$(perf trace -e renameat* --max-events=1 -- mv ${file1} ${file2} 2>&1)"
+  if ! echo "$output" | grep -q -E "^mv/[0-9]+ renameat(2)?\(.*, \"${file1}\", .*, \"${file2}\", .*\) += +[0-9]+$"
   then
-    echo "String augmentation test failed"
+    printf "String augmentation test failed, output:\n$output\n"
     err=1
   fi
 }
···
 trace_test_buffer() {
   echo "Testing perf trace's buffer augmentation"
   # echo will insert a newline (\10) at the end of the buffer
-  if ! perf trace -e write --max-events=1 -- echo "${buffer}" 2>&1 | \
-    grep -q -E "^echo/[0-9]+ write\([0-9]+, ${buffer}.*, [0-9]+\) += +[0-9]+$"
+  output="$(perf trace -e write --max-events=1 -- echo "${buffer}" 2>&1)"
+  if ! echo "$output" | grep -q -E "^echo/[0-9]+ write\([0-9]+, ${buffer}.*, [0-9]+\) += +[0-9]+$"
   then
-    echo "Buffer augmentation test failed"
+    printf "Buffer augmentation test failed, output:\n$output\n"
     err=1
   fi
 }
 
 trace_test_struct_btf() {
   echo "Testing perf trace's struct augmentation"
-  if ! perf trace -e clock_nanosleep --force-btf --max-events=1 -- sleep 1 2>&1 | \
-    grep -q -E "^sleep/[0-9]+ clock_nanosleep\(0, 0, \{1,\}, 0x[0-9a-f]+\) += +[0-9]+$"
+  output="$(perf trace -e clock_nanosleep --force-btf --max-events=1 -- sleep 1 2>&1)"
+  if ! echo "$output" | grep -q -E "^sleep/[0-9]+ clock_nanosleep\(0, 0, \{1,\}, 0x[0-9a-f]+\) += +[0-9]+$"
   then
-    echo "BTF struct augmentation test failed"
+	printf "BTF struct augmentation test failed, output:\n$output\n"
     err=1
   fi
 }