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-rw-r--r--kernel/trace/Kconfig28
-rw-r--r--kernel/trace/trace.c245
2 files changed, 269 insertions, 4 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index a5da09c..fedbdd7 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -599,6 +599,34 @@ config RING_BUFFER_STARTUP_TEST
If unsure, say N
+config TRACE_ENUM_MAP_FILE
+ bool "Show enum mappings for trace events"
+ depends on TRACING
+ help
+ The "print fmt" of the trace events will show the enum names instead
+ of their values. This can cause problems for user space tools that
+ use this string to parse the raw data as user space does not know
+ how to convert the string to its value.
+
+ To fix this, there's a special macro in the kernel that can be used
+ to convert the enum into its value. If this macro is used, then the
+ print fmt strings will have the enums converted to their values.
+
+ If something does not get converted properly, this option can be
+ used to show what enums the kernel tried to convert.
+
+ This option is for debugging the enum conversions. A file is created
+ in the tracing directory called "enum_map" that will show the enum
+ names matched with their values and what trace event system they
+ belong too.
+
+ Normally, the mapping of the strings to values will be freed after
+ boot up or module load. With this option, they will not be freed, as
+ they are needed for the "enum_map" file. Enabling this option will
+ increase the memory footprint of the running kernel.
+
+ If unsure, say N
+
endif # FTRACE
endif # TRACING_SUPPORT
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 28e6654..39e6956 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -123,6 +123,42 @@ enum ftrace_dump_mode ftrace_dump_on_oops;
/* When set, tracing will stop when a WARN*() is hit */
int __disable_trace_on_warning;
+#ifdef CONFIG_TRACE_ENUM_MAP_FILE
+/* Map of enums to their values, for "enum_map" file */
+struct trace_enum_map_head {
+ struct module *mod;
+ unsigned long length;
+};
+
+union trace_enum_map_item;
+
+struct trace_enum_map_tail {
+ /*
+ * "end" is first and points to NULL as it must be different
+ * than "mod" or "enum_string"
+ */
+ union trace_enum_map_item *next;
+ const char *end; /* points to NULL */
+};
+
+static DEFINE_MUTEX(trace_enum_mutex);
+
+/*
+ * The trace_enum_maps are saved in an array with two extra elements,
+ * one at the beginning, and one at the end. The beginning item contains
+ * the count of the saved maps (head.length), and the module they
+ * belong to if not built in (head.mod). The ending item contains a
+ * pointer to the next array of saved enum_map items.
+ */
+union trace_enum_map_item {
+ struct trace_enum_map map;
+ struct trace_enum_map_head head;
+ struct trace_enum_map_tail tail;
+};
+
+static union trace_enum_map_item *trace_enum_maps;
+#endif /* CONFIG_TRACE_ENUM_MAP_FILE */
+
static int tracing_set_tracer(struct trace_array *tr, const char *buf);
#define MAX_TRACER_SIZE 100
@@ -3908,7 +3944,169 @@ static const struct file_operations tracing_saved_cmdlines_size_fops = {
.write = tracing_saved_cmdlines_size_write,
};
-static void trace_insert_enum_map(struct trace_enum_map **start, int len)
+#ifdef CONFIG_TRACE_ENUM_MAP_FILE
+static union trace_enum_map_item *
+update_enum_map(union trace_enum_map_item *ptr)
+{
+ if (!ptr->map.enum_string) {
+ if (ptr->tail.next) {
+ ptr = ptr->tail.next;
+ /* Set ptr to the next real item (skip head) */
+ ptr++;
+ } else
+ return NULL;
+ }
+ return ptr;
+}
+
+static void *enum_map_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ union trace_enum_map_item *ptr = v;
+
+ /*
+ * Paranoid! If ptr points to end, we don't want to increment past it.
+ * This really should never happen.
+ */
+ ptr = update_enum_map(ptr);
+ if (WARN_ON_ONCE(!ptr))
+ return NULL;
+
+ ptr++;
+
+ (*pos)++;
+
+ ptr = update_enum_map(ptr);
+
+ return ptr;
+}
+
+static void *enum_map_start(struct seq_file *m, loff_t *pos)
+{
+ union trace_enum_map_item *v;
+ loff_t l = 0;
+
+ mutex_lock(&trace_enum_mutex);
+
+ v = trace_enum_maps;
+ if (v)
+ v++;
+
+ while (v && l < *pos) {
+ v = enum_map_next(m, v, &l);
+ }
+
+ return v;
+}
+
+static void enum_map_stop(struct seq_file *m, void *v)
+{
+ mutex_unlock(&trace_enum_mutex);
+}
+
+static int enum_map_show(struct seq_file *m, void *v)
+{
+ union trace_enum_map_item *ptr = v;
+
+ seq_printf(m, "%s %ld (%s)\n",
+ ptr->map.enum_string, ptr->map.enum_value,
+ ptr->map.system);
+
+ return 0;
+}
+
+static const struct seq_operations tracing_enum_map_seq_ops = {
+ .start = enum_map_start,
+ .next = enum_map_next,
+ .stop = enum_map_stop,
+ .show = enum_map_show,
+};
+
+static int tracing_enum_map_open(struct inode *inode, struct file *filp)
+{
+ if (tracing_disabled)
+ return -ENODEV;
+
+ return seq_open(filp, &tracing_enum_map_seq_ops);
+}
+
+static const struct file_operations tracing_enum_map_fops = {
+ .open = tracing_enum_map_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
+static inline union trace_enum_map_item *
+trace_enum_jmp_to_tail(union trace_enum_map_item *ptr)
+{
+ /* Return tail of array given the head */
+ return ptr + ptr->head.length + 1;
+}
+
+static void
+trace_insert_enum_map_file(struct module *mod, struct trace_enum_map **start,
+ int len)
+{
+ struct trace_enum_map **stop;
+ struct trace_enum_map **map;
+ union trace_enum_map_item *map_array;
+ union trace_enum_map_item *ptr;
+
+ stop = start + len;
+
+ /*
+ * The trace_enum_maps contains the map plus a head and tail item,
+ * where the head holds the module and length of array, and the
+ * tail holds a pointer to the next list.
+ */
+ map_array = kmalloc(sizeof(*map_array) * (len + 2), GFP_KERNEL);
+ if (!map_array) {
+ pr_warning("Unable to allocate trace enum mapping\n");
+ return;
+ }
+
+ mutex_lock(&trace_enum_mutex);
+
+ if (!trace_enum_maps)
+ trace_enum_maps = map_array;
+ else {
+ ptr = trace_enum_maps;
+ for (;;) {
+ ptr = trace_enum_jmp_to_tail(ptr);
+ if (!ptr->tail.next)
+ break;
+ ptr = ptr->tail.next;
+
+ }
+ ptr->tail.next = map_array;
+ }
+ map_array->head.mod = mod;
+ map_array->head.length = len;
+ map_array++;
+
+ for (map = start; (unsigned long)map < (unsigned long)stop; map++) {
+ map_array->map = **map;
+ map_array++;
+ }
+ memset(map_array, 0, sizeof(*map_array));
+
+ mutex_unlock(&trace_enum_mutex);
+}
+
+static void trace_create_enum_file(struct dentry *d_tracer)
+{
+ trace_create_file("enum_map", 0444, d_tracer,
+ NULL, &tracing_enum_map_fops);
+}
+
+#else /* CONFIG_TRACE_ENUM_MAP_FILE */
+static inline void trace_create_enum_file(struct dentry *d_tracer) { }
+static inline void trace_insert_enum_map_file(struct module *mod,
+ struct trace_enum_map **start, int len) { }
+#endif /* !CONFIG_TRACE_ENUM_MAP_FILE */
+
+static void trace_insert_enum_map(struct module *mod,
+ struct trace_enum_map **start, int len)
{
struct trace_enum_map **map;
@@ -3918,6 +4116,8 @@ static void trace_insert_enum_map(struct trace_enum_map **start, int len)
map = start;
trace_event_enum_update(map, len);
+
+ trace_insert_enum_map_file(mod, start, len);
}
static ssize_t
@@ -6562,7 +6762,7 @@ static void __init trace_enum_init(void)
int len;
len = __stop_ftrace_enum_maps - __start_ftrace_enum_maps;
- trace_insert_enum_map(__start_ftrace_enum_maps, len);
+ trace_insert_enum_map(NULL, __start_ftrace_enum_maps, len);
}
#ifdef CONFIG_MODULES
@@ -6578,9 +6778,41 @@ static void trace_module_add_enums(struct module *mod)
if (trace_module_has_bad_taint(mod))
return;
- trace_insert_enum_map(mod->trace_enums, mod->num_trace_enums);
+ trace_insert_enum_map(mod, mod->trace_enums, mod->num_trace_enums);
}
+#ifdef CONFIG_TRACE_ENUM_MAP_FILE
+static void trace_module_remove_enums(struct module *mod)
+{
+ union trace_enum_map_item *map;
+ union trace_enum_map_item **last = &trace_enum_maps;
+
+ if (!mod->num_trace_enums)
+ return;
+
+ mutex_lock(&trace_enum_mutex);
+
+ map = trace_enum_maps;
+
+ while (map) {
+ if (map->head.mod == mod)
+ break;
+ map = trace_enum_jmp_to_tail(map);
+ last = &map->tail.next;
+ map = map->tail.next;
+ }
+ if (!map)
+ goto out;
+
+ *last = trace_enum_jmp_to_tail(map)->tail.next;
+ kfree(map);
+ out:
+ mutex_unlock(&trace_enum_mutex);
+}
+#else
+static inline void trace_module_remove_enums(struct module *mod) { }
+#endif /* CONFIG_TRACE_ENUM_MAP_FILE */
+
static int trace_module_notify(struct notifier_block *self,
unsigned long val, void *data)
{
@@ -6590,6 +6822,9 @@ static int trace_module_notify(struct notifier_block *self,
case MODULE_STATE_COMING:
trace_module_add_enums(mod);
break;
+ case MODULE_STATE_GOING:
+ trace_module_remove_enums(mod);
+ break;
}
return 0;
@@ -6599,7 +6834,7 @@ static struct notifier_block trace_module_nb = {
.notifier_call = trace_module_notify,
.priority = 0,
};
-#endif
+#endif /* CONFIG_MODULES */
static __init int tracer_init_debugfs(void)
{
@@ -6627,6 +6862,8 @@ static __init int tracer_init_debugfs(void)
trace_enum_init();
+ trace_create_enum_file(d_tracer);
+
#ifdef CONFIG_MODULES
register_module_notifier(&trace_module_nb);
#endif
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