perf test cs-etm: Make disassembly test use kcore

Hits in modules return empty disassembly with vmlinux as an input to
objdump. Make the disassembly test more reliable by always using kcore.
And update the comments to say that this is supported by the script.

Signed-off-by: James Clark <james.clark@linaro.org>
Cc: Amir Ayupov <aaupov@meta.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Mike Leach <mike.leach@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paschalis Mpeis <Paschalis.Mpeis@arm.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 10 insertions, 10 deletions

diff --git a/tools/perf/scripts/python/arm-cs-trace-disasm.py b/tools/perf/scripts/python/arm-cs-trace-disasm.py
index ba208c90d631..8f6fa4a007b4 100755
--- a/tools/perf/scripts/python/arm-cs-trace-disasm.py
+++ b/tools/perf/scripts/python/arm-cs-trace-disasm.py
@@ -18,29 +18,29 @@ from perf_trace_context import perf_sample_srccode, perf_config_get
 
 # Below are some example commands for using this script.
 # Note a --kcore recording is required for accurate decode
-# due to the alternatives patching mechanism. However this
-# script only supports reading vmlinux for disassembly dump,
-# meaning that any patched instructions will appear
-# as unpatched, but the instruction ranges themselves will
-# be correct. In addition to this, source line info comes
-# from Perf, and when using kcore there is no debug info. The
-# following lists the supported features in each mode:
+# due to the alternatives patching mechanism. In addition to this,
+# source line info comes from Perf, and when using kcore there is
+# no debug info. The following lists the supported features in each mode:
 #
 # +-----------+-----------------+------------------+------------------+
 # | Recording | Accurate decode | Source line dump | Disassembly dump |
 # +-----------+-----------------+------------------+------------------+
 # | --kcore   | yes             | no               | yes              |
-# | normal    | no              | yes              | yes              |
+# | normal    | no              | yes (inaccurate) | yes (inaccurate) |
 # +-----------+-----------------+------------------+------------------+
 #
 # Output disassembly with objdump and auto detect vmlinux
-# (when running on same machine.)
+# (when running on same machine.):
 #  perf script -s scripts/python/arm-cs-trace-disasm.py -d
 #
 # Output disassembly with llvm-objdump:
 #  perf script -s scripts/python/arm-cs-trace-disasm.py \
 #		-- -d llvm-objdump-11 -k path/to/vmlinux
 #
+# Output accurate disassembly by passing kcore to script:
+#  perf script -s scripts/python/arm-cs-trace-disasm.py \
+#		-- -d -k perf.data/kcore_dir/kcore
+#
 # Output only source line and symbols:
 #  perf script -s scripts/python/arm-cs-trace-disasm.py
 
@@ -57,7 +57,7 @@ def int_arg(v):
 
 args = argparse.ArgumentParser()
 args.add_argument("-k", "--vmlinux",
-		  help="Set path to vmlinux file. Omit to autodetect if running on same machine")
+		  help="Set path to vmlinux or kcore file. Omit to autodetect if running on same machine")
 args.add_argument("-d", "--objdump", nargs="?", const=default_objdump(),
 		  help="Show disassembly. Can also be used to change the objdump path"),
 args.add_argument("-v", "--verbose", action="store_true", help="Enable debugging log")