ftrace: Support full glob matching

Use glob_match() to support flexible glob wildcards (*,?)
and character classes ([) for ftrace.
Since the full glob matching is slower than the current
partial matching routines(*pat, pat*, *pat*), this leaves
those routines and just add MATCH_GLOB for complex glob
expression.

e.g.
----
[root@localhost tracing]# echo 'sched*group' > set_ftrace_filter
[root@localhost tracing]# cat set_ftrace_filter
sched_free_group
sched_change_group
sched_create_group
sched_online_group
sched_destroy_group
sched_offline_group
[root@localhost tracing]# echo '[Ss]y[Ss]_*' > set_ftrace_filter
[root@localhost tracing]# head set_ftrace_filter
sys_arch_prctl
sys_rt_sigreturn
sys_ioperm
SyS_iopl
sys_modify_ldt
SyS_mmap
SyS_set_thread_area
SyS_get_thread_area
SyS_set_tid_address
sys_fork
----

Link: http://lkml.kernel.org/r/147566869501.29136.6462645009894738056.stgit@devboxAcked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Documentation/trace/events.txt

@@ -189,16 +189,13 @@ And for string fields they are:
 
 ==, !=, ~
 
-The glob (~) only accepts a wild card character (*) at the start and or
-end of the string. For example:
+The glob (~) accepts a wild card character (*,?) and character classes
+([). For example:
 
   prev_comm ~ "*sh"
   prev_comm ~ "sh*"
   prev_comm ~ "*sh*"
-
-But does not allow for it to be within the string:
-
-  prev_comm ~ "ba*sh"   <-- is invalid
+  prev_comm ~ "ba*sh"
 
 5.2 Setting filters
 -------------------

Documentation/trace/ftrace.txt

@@ -2218,16 +2218,13 @@ hrtimer_interrupt
 sys_nanosleep
 
 
-Perhaps this is not enough. The filters also allow simple wild
-cards. Only the following are currently available
+Perhaps this is not enough. The filters also allow glob(7) matching.
 
   <match>*  - will match functions that begin with <match>
   *<match>  - will match functions that end with <match>
   *<match>* - will match functions that have <match> in it
-
-These are the only wild cards which are supported.
-
-  <match>*<match> will not work.
+  <match1>*<match2> - will match functions that begin with
+                      <match1> and end with <match2>
 
 Note: It is better to use quotes to enclose the wild cards,
       otherwise the shell may expand the parameters into names

kernel/trace/Kconfig

@@ -70,6 +70,7 @@ config FTRACE_NMI_ENTER
 
 config EVENT_TRACING
 	select CONTEXT_SWITCH_TRACER
+        select GLOB
 	bool
 
 config CONTEXT_SWITCH_TRACER
@@ -133,6 +134,7 @@ config FUNCTION_TRACER
 	select KALLSYMS
 	select GENERIC_TRACER
 	select CONTEXT_SWITCH_TRACER
+        select GLOB
 	help
 	  Enable the kernel to trace every kernel function. This is done
 	  by using a compiler feature to insert a small, 5-byte No-Operation

kernel/trace/ftrace.c

@@ -3511,6 +3511,10 @@ static int ftrace_match(char *str, struct ftrace_glob *g)
 		    memcmp(str + slen - g->len, g->search, g->len) == 0)
 			matched = 1;
 		break;
+	case MATCH_GLOB:
+		if (glob_match(g->search, str))
+			matched = 1;
+		break;
 	}
 
 	return matched;

kernel/trace/trace.c

@@ -4065,7 +4065,7 @@ static const char readme_msg[] =
 	"\n  available_filter_functions - list of functions that can be filtered on\n"
 	"  set_ftrace_filter\t- echo function name in here to only trace these\n"
 	"\t\t\t  functions\n"
-	"\t     accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
+	"\t     accepts: func_full_name or glob-matching-pattern\n"
 	"\t     modules: Can select a group via module\n"
 	"\t      Format: :mod:<module-name>\n"
 	"\t     example: echo :mod:ext3 > set_ftrace_filter\n"

kernel/trace/trace.h

@@ -15,6 +15,7 @@
 #include <linux/trace_events.h>
 #include <linux/compiler.h>
 #include <linux/trace_seq.h>
+#include <linux/glob.h>
 
 #ifdef CONFIG_FTRACE_SYSCALLS
 #include <asm/unistd.h>		/* For NR_SYSCALLS	     */
@@ -1257,6 +1258,7 @@ enum regex_type {
 	MATCH_FRONT_ONLY,
 	MATCH_MIDDLE_ONLY,
 	MATCH_END_ONLY,
+	MATCH_GLOB,
 };
 
 struct regex {

kernel/trace/trace_events_filter.c

@@ -344,6 +344,12 @@ static int regex_match_end(char *str, struct regex *r, int len)
 	return 0;
 }
 
+static int regex_match_glob(char *str, struct regex *r, int len __maybe_unused)
+{
+	if (glob_match(r->pattern, str))
+		return 1;
+	return 0;
+}
 /**
  * filter_parse_regex - parse a basic regex
  * @buff:   the raw regex
@@ -380,14 +386,20 @@ enum regex_type filter_parse_regex(char *buff, int len, char **search, int *not)
 			if (!i) {
 				*search = buff + 1;
 				type = MATCH_END_ONLY;
-			} else {
+			} else if (i == len - 1) {
 				if (type == MATCH_END_ONLY)
 					type = MATCH_MIDDLE_ONLY;
 				else
 					type = MATCH_FRONT_ONLY;
 				buff[i] = 0;
 				break;
+			} else {	/* pattern continues, use full glob */
+				type = MATCH_GLOB;
+				break;
 			}
+		} else if (strchr("[?\\", buff[i])) {
+			type = MATCH_GLOB;
+			break;
 		}
 	}
 
@@ -420,6 +432,9 @@ static void filter_build_regex(struct filter_pred *pred)
 	case MATCH_END_ONLY:
 		r->match = regex_match_end;
 		break;
+	case MATCH_GLOB:
+		r->match = regex_match_glob;
+		break;
 	}
 
 	pred->not ^= not;