From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
All for full "regex(3)" processing of setting functions in the
set_ftrace_filter file. Check if the filter passed in is just a glob
expression that the kernel can process, or if it is a regex that should look
at the available_filter_functions list instead.
If it is a regex, it will read the available_filter_functions and write in
each function as it finds it.
Link: https://lore.kernel.org/linux-trace-devel/20210323013225.451281989@xxxxxxxxxxx
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
Documentation/libtracefs-function-filter.txt | 10 ++
src/tracefs-tools.c | 139 ++++++++++++++++---
2 files changed, 128 insertions(+), 21 deletions(-)
diff --git a/Documentation/libtracefs-function-filter.txt b/Documentation/libtracefs-function-filter.txt
index c0c89f372c21..88aa3b923d54 100644
--- a/Documentation/libtracefs-function-filter.txt
+++ b/Documentation/libtracefs-function-filter.txt
@@ -32,6 +32,16 @@ _errs_, is a pointer to an array of strings, which will be allocated if
any of filters fail to match any available function, If _errs_ is NULL, it will
be ignored.
+A filter in the array of _filters_ may be either a straight match of a
+function, a glob or regex(3). a glob is where '*' matches zero or more
+characters, '?' will match zero or one character, and '.' only matches a
+period. If the filter is determined to be a regex (where it contains
+anything other than alpha numeric characters, or '.', '*', '?') the filter
+will be processed as a regex(3) following the rules of regex(3), and '.' is
+not a period, but will match any one character. To force a regular
+expression, either prefix the filter with a '^' or append it with a '$' as
+all filters will act as complete matches of functions anyway.
+
returns 0 on success, 1 or -x (where x is an integer) on error.
RETURN VALUE
diff --git a/src/tracefs-tools.c b/src/tracefs-tools.c
index 470502b07f7d..d1a448459c6f 100644
--- a/src/tracefs-tools.c
+++ b/src/tracefs-tools.c
@@ -18,8 +18,9 @@
#include "tracefs.h"
#include "tracefs-local.h"
-#define TRACE_CTRL "tracing_on"
-#define TRACE_FILTER "set_ftrace_filter"
+#define TRACE_CTRL "tracing_on"
+#define TRACE_FILTER "set_ftrace_filter"
+#define TRACE_FILTER_LIST "available_filter_functions"
static const char * const options_map[] = {
"unknown",
@@ -421,8 +422,53 @@ struct func_filter {
const char *filter;
regex_t re;
bool set;
+ bool is_regex;
};
+static bool is_regex(const char *str)
+{
+ int i;
+
+ for (i = 0; str[i]; i++) {
+ switch (str[i]) {
+ case 'a' ... 'z':
+ case 'A'...'Z':
+ case '_':
+ case '0'...'9':
+ case '*':
+ case '.':
+ /* Dots can be part of a function name */
+ case '?':
+ continue;
+ default:
+ return true;
+ }
+ }
+ return false;
+}
+
+static char *update_regex(const char *reg)
+{
+ int len = strlen(reg);
+ char *str;
+
+ if (reg[0] == '^' && reg[len - 1] == '$')
+ return strdup(reg);
+
+ str = malloc(len + 3);
+ if (reg[0] == '^') {
+ strcpy(str, reg);
+ } else {
+ str[0] = '^';
+ strcpy(str + 1, reg);
+ len++; /* add ^ */
+ }
+ if (str[len - 1] != '$')
+ str[len++]= '$';
+ str[len] = '\0';
+ return str;
+}
+
/*
* Convert a glob into a regular expression.
*/
@@ -488,8 +534,13 @@ static int write_filter(int fd, const char *filter, const char *module)
return 0;
}
-static int check_available_filters(struct func_filter *func_filters,
- const char *module, const char ***errs)
+enum match_type {
+ FILTER_CHECK,
+ FILTER_WRITE,
+};
+
+static int match_filters(int fd, struct func_filter *func_filters,
+ const char *module, enum match_type type)
{
char *line = NULL;
size_t size = 0;
@@ -499,7 +550,7 @@ static int check_available_filters(struct func_filter *func_filters,
int mlen;
int i;
- path = tracefs_get_tracing_file("available_filter_functions");
+ path = tracefs_get_tracing_file(TRACE_FILTER_LIST);
if (!path)
return 1;
@@ -530,39 +581,76 @@ static int check_available_filters(struct func_filter *func_filters,
(mtok[mlen + 1] != ']'))
goto next;
}
- for (i = 0; func_filters[i].filter; i++) {
- if (match(tok, &func_filters[i]))
- func_filters[i].set = true;
+ switch (type) {
+ case FILTER_CHECK:
+ /* Check, checks a list of filters */
+ for (i = 0; func_filters[i].filter; i++) {
+ if (match(tok, &func_filters[i]))
+ func_filters[i].set = true;
+ }
+ break;
+ case FILTER_WRITE:
+ /* Writes only have one filter */
+ if (match(tok, func_filters)) {
+ ret = write_filter(fd, tok, module);
+ if (ret)
+ goto out;
+ }
+ break;
}
next:
free(line);
line = NULL;
len = 0;
}
+ out:
+ free(line);
fclose(fp);
+ return ret;
+}
+
+static int check_available_filters(struct func_filter *func_filters,
+ const char *module, const char ***errs)
+{
+ int ret;
+ int i;
+
+ ret = match_filters(-1, func_filters, module, FILTER_CHECK);
+ /* Return here if success or non filter error */
+ if (ret >= 0)
+ return ret;
+
+ /* Failed on filter, set the errors */
ret = 0;
for (i = 0; func_filters[i].filter; i++) {
if (!func_filters[i].set)
add_errors(errs, func_filters[i].filter, ret--);
}
-
return ret;
}
-static int controlled_write(int fd, const char **filters,
+static int set_regex_filter(int fd, struct func_filter *func_filter,
+ const char *module)
+{
+ return match_filters(fd, func_filter, module, FILTER_WRITE);
+}
+
+static int controlled_write(int fd, struct func_filter *func_filters,
const char *module, const char ***errs)
{
int ret = 0;
int i;
- for (i = 0; filters[i]; i++) {
+ for (i = 0; func_filters[i].filter; i++) {
+ const char *filter = func_filters[i].filter;
int r;
- r = write_filter(fd, filters[i], module);
- if (r < 0) {
- add_errors(errs, filters[i], ret--);
- } else if (r > 0) {
+ if (func_filters[i].is_regex)
+ r = set_regex_filter(fd, &func_filters[i], module);
+ else
+ r = write_filter(fd, filter, module);
+ if (r > 0) {
/* Not filter error */
if (errs) {
free(*errs);
@@ -570,6 +658,8 @@ static int controlled_write(int fd, const char **filters,
}
return 1;
}
+ if (r < 0)
+ add_errors(errs, filter, ret--);
}
return ret;
}
@@ -579,7 +669,11 @@ static int init_func_filter(struct func_filter *func_filter, const char *filter)
char *str;
int ret;
- str = make_regex(filter);
+ if (!(func_filter->is_regex = is_regex(filter)))
+ str = make_regex(filter);
+ else
+ str = update_regex(filter);
+
if (!str)
return -1;
@@ -679,24 +773,27 @@ int tracefs_function_filter(struct tracefs_instance *instance, const char **filt
*errs = NULL;
ret = check_available_filters(func_filters, module, errs);
- free_func_filters(func_filters);
if (ret)
- return ret;
+ goto out_free;
+ ret = 1;
ftrace_filter_path = tracefs_instance_get_file(instance, TRACE_FILTER);
if (!ftrace_filter_path)
- return 1;
+ goto out_free;
flags = reset ? O_TRUNC : O_APPEND;
fd = open(ftrace_filter_path, O_WRONLY | flags);
tracefs_put_tracing_file(ftrace_filter_path);
if (fd < 0)
- return 1;
+ goto out_free;
- ret = controlled_write(fd, filters, module, errs);
+ ret = controlled_write(fd, func_filters, module, errs);
close(fd);
+ out_free:
+ free_func_filters(func_filters);
+
return ret;
}
--
2.30.1
|