tools lib traceevent: Add plugin for decoding syscalls/sys_enter_futex

The futex syscall is a complicated one.  It supports thirteen
multiplexed operations, each with different semantics and encodings for
the syscalls six arguments.

Manually decoding these arguments is tedious and error prone.

This plugin provides symbolic names for futex operations, futex flags,
and tries to be intelligent about the intent of specific arguments (for
example, waking operations use 'val' as an integer count, not just an
arbitrary value).

It doesn't do a full decode of the FUTEX_WAKE_OP's 'val3' argument,
however, this is a good starting point.

Link: http://lkml.kernel.org/r/20171207025649.12160-1-julia@ni.com
Link: http://lore.kernel.org/linux-trace-devel/20200702174950.123454-3-tz.stoyanov@gmail.comSigned-off-by: Julia Cartwright <julia@ni.com>
[ Ported from trace-cmd.git ]
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200702185705.127175788@goodmis.orgSigned-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/plugins/Build

@@ -5,6 +5,7 @@ plugin_kvm-y          += plugin_kvm.o
 plugin_mac80211-y     += plugin_mac80211.o
 plugin_sched_switch-y += plugin_sched_switch.o
 plugin_function-y     += plugin_function.o
+plugin_futex-y        += plugin_futex.o
 plugin_xen-y          += plugin_xen.o
 plugin_scsi-y         += plugin_scsi.o
 plugin_cfg80211-y     += plugin_cfg80211.o

tools/lib/traceevent/plugins/Makefile

@@ -134,6 +134,7 @@ PLUGINS += plugin_kvm.so
 PLUGINS += plugin_mac80211.so
 PLUGINS += plugin_sched_switch.so
 PLUGINS += plugin_function.so
+PLUGINS += plugin_futex.so
 PLUGINS += plugin_xen.so
 PLUGINS += plugin_scsi.so
 PLUGINS += plugin_cfg80211.so

tools/lib/traceevent/plugins/plugin_futex.c

+/*
+ * Copyright (C) 2017 National Instruments Corp.
+ *
+ * Author: Julia Cartwright <julia@ni.com>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License (not later!)
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not,  see <http://www.gnu.org/licenses>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <linux/futex.h>
+
+#include "event-parse.h"
+
+#define ARRAY_SIZE(_a) (sizeof(_a) / sizeof((_a)[0]))
+
+struct futex_args {
+	unsigned long long	uaddr;
+	unsigned long long	op;
+	unsigned long long	val;
+	unsigned long long	utime; /* or val2 */
+	unsigned long long	uaddr2;
+	unsigned long long	val3;
+};
+
+struct futex_op {
+	const char	*name;
+	const char	*fmt_val;
+	const char	*fmt_utime;
+	const char	*fmt_uaddr2;
+	const char	*fmt_val3;
+};
+
+static const struct futex_op futex_op_tbl[] = {
+	{            "FUTEX_WAIT", " val=0x%08llx", " utime=0x%08llx",               NULL,             NULL },
+	{            "FUTEX_WAKE",     " val=%llu",              NULL,               NULL,             NULL },
+	{              "FUTEX_FD",     " val=%llu",              NULL,               NULL,             NULL },
+	{         "FUTEX_REQUEUE",     " val=%llu",      " val2=%llu", " uaddr2=0x%08llx",             NULL },
+	{     "FUTEX_CMP_REQUEUE",     " val=%llu",      " val2=%llu", " uaddr2=0x%08llx", " val3=0x%08llx" },
+	{         "FUTEX_WAKE_OP",     " val=%llu",      " val2=%llu", " uaddr2=0x%08llx", " val3=0x%08llx" },
+	{         "FUTEX_LOCK_PI",            NULL, " utime=0x%08llx",               NULL,             NULL },
+	{       "FUTEX_UNLOCK_PI",            NULL,              NULL,               NULL,             NULL },
+	{      "FUTEX_TRYLOCK_PI",            NULL,              NULL,               NULL,             NULL },
+	{     "FUTEX_WAIT_BITSET", " val=0x%08llx", " utime=0x%08llx",               NULL, " val3=0x%08llx" },
+	{     "FUTEX_WAKE_BITSET",     " val=%llu",              NULL,               NULL, " val3=0x%08llx" },
+	{ "FUTEX_WAIT_REQUEUE_PI", " val=0x%08llx", " utime=0x%08llx", " uaddr2=0x%08llx", " val3=0x%08llx" },
+	{  "FUTEX_CMP_REQUEUE_PI",     " val=%llu",      " val2=%llu", " uaddr2=0x%08llx", " val3=0x%08llx" },
+};
+
+
+static void futex_print(struct trace_seq *s, const struct futex_args *args,
+			const struct futex_op *fop)
+{
+	trace_seq_printf(s, " uaddr=0x%08llx", args->uaddr);
+
+	if (fop->fmt_val)
+		trace_seq_printf(s, fop->fmt_val, args->val);
+
+	if (fop->fmt_utime)
+		trace_seq_printf(s,fop->fmt_utime, args->utime);
+
+	if (fop->fmt_uaddr2)
+		trace_seq_printf(s, fop->fmt_uaddr2, args->uaddr2);
+
+	if (fop->fmt_val3)
+		trace_seq_printf(s, fop->fmt_val3, args->val3);
+}
+
+static int futex_handler(struct trace_seq *s, struct tep_record *record,
+			 struct tep_event *event, void *context)
+{
+	const struct futex_op *fop;
+	struct futex_args args;
+	unsigned long long cmd;
+
+	if (tep_get_field_val(s, event, "uaddr", record, &args.uaddr, 1))
+		return 1;
+
+	if (tep_get_field_val(s, event, "op", record, &args.op, 1))
+		return 1;
+
+	if (tep_get_field_val(s, event, "val", record, &args.val, 1))
+		return 1;
+
+	if (tep_get_field_val(s, event, "utime", record, &args.utime, 1))
+		return 1;
+
+	if (tep_get_field_val(s, event, "uaddr2", record, &args.uaddr2, 1))
+		return 1;
+
+	if (tep_get_field_val(s, event, "val3", record, &args.val3, 1))
+		return 1;
+
+	cmd = args.op & FUTEX_CMD_MASK;
+	if (cmd >= ARRAY_SIZE(futex_op_tbl))
+		return 1;
+
+	fop = &futex_op_tbl[cmd];
+
+	trace_seq_printf(s, "op=%s", fop->name);
+
+	if (args.op & FUTEX_PRIVATE_FLAG)
+		trace_seq_puts(s, "|FUTEX_PRIVATE_FLAG");
+
+	if (args.op & FUTEX_CLOCK_REALTIME)
+		trace_seq_puts(s, "|FUTEX_CLOCK_REALTIME");
+
+	futex_print(s, &args, fop);
+	return 0;
+}
+
+int TEP_PLUGIN_LOADER(struct tep_handle *tep)
+{
+	tep_register_event_handler(tep, -1, "syscalls", "sys_enter_futex",
+				   futex_handler, NULL);
+	return 0;
+}
+
+void TEP_PLUGIN_UNLOADER(struct tep_handle *tep)
+{
+	tep_unregister_event_handler(tep, -1, "syscalls", "sys_enter_futex",
+				     futex_handler, NULL);
+}