[PATCH 4/4] perf trace: Add option to specify machine type

[David Ahern <dsahern@gmail.com>]

Perhaps there is a better way to do this; I could not think of one and
I don't see any field in the tracepoint that can be leveraged. So ...

perf-trace autodetects the machine type (e.g., i386, x86_64, etc) via
libaudit. When running 32-bit apps on a 64-bit kernel the wrong machine
type is used to convert syscall numbers to names leading to wrong information
getting displayed to the user. This option allows the user to override
the machine type to use.

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/builtin-trace.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 0203324fe585..4a78a39b684a 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -2274,6 +2274,7 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
 	};
 	const char *output_name = NULL;
 	const char *ev_qualifier_str = NULL;
+	const char *machine_str = NULL;
 	const struct option trace_options[] = {
 	OPT_BOOLEAN(0, "comm", &trace.show_comm,
 		    "show the thread COMM next to its id"),
@@ -2308,6 +2309,8 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
 		    "Show only syscall summary with statistics"),
 	OPT_BOOLEAN('S', "with-summary", &trace.summary,
 		    "Show all syscalls and summary with statistics"),
+	OPT_STRING('M', NULL, &machine_str, "x86|x86_64",
+		     "Advanced: machine type for converting system calls: x86, x86_64"),
 	OPT_END()
 	};
 	int err;
@@ -2318,6 +2321,17 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
 
 	argc = parse_options(argc, argv, trace_options, trace_usage, 0);
 
+	if (machine_str) {
+		if (strcmp(machine_str, "x86") == 0)
+			trace.audit.machine = MACH_X86;
+		else if (strcmp(machine_str, "x86_64") == 0)
+			trace.audit.machine = MACH_86_64;
+		else {
+			pr_err("Invalid machine type\n");
+			return -EINVAL;
+		}
+	}
+
 	/* summary_only implies summary option, but don't overwrite summary if set */
 	if (trace.summary_only)
 		trace.summary = trace.summary_only;
-- 
1.8.3.4 (Apple Git-47)