[PATCH 1/5] ftrace: Support full glob matching

Masami Hiramatsu
2016-10-19T04:53:57Z

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
----

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
Documentation/trace/events.txt | 9 +++------
Documentation/trace/ftrace.txt | 9 +++------
kernel/trace/Kconfig | 2 ++
kernel/trace/ftrace.c | 4 ++++
kernel/trace/trace.c | 2 +-
kernel/trace/trace.h | 2 ++
kernel/trace/trace_events_filter.c | 17 ++++++++++++++++-
7 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/Documentation/trace/events.txt b/Documentation/trace/events.txt
index 08d74d7..2cc08d4 100644
--- a/Documentation/trace/events.txt
+++ b/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
-------------------
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index a6b3705..b26abc7 100644
--- a/Documentation/trace/ftrace.txt
+++ b/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
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index ba33267..aa6eb15 100644
--- a/kernel/trace/Kconfig
+++ b/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
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 84752c8..5741184 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3493,6 +3493,10 @@ 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;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 37824d9..ae343e7 100644
--- a/kernel/trace/trace.c
+++ b/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"
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f783df4..eac2eda 100644
--- a/kernel/trace/trace.h
+++ b/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 */
@@ -1252,6 +1253,7 @@ enum regex_type {
MATCH_FRONT_ONLY,
MATCH_MIDDLE_ONLY,
MATCH_END_ONLY,
+ MATCH_GLOB,
};

struct regex {
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 9daa9b3..e1c7e2c 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/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;