From: Sameeruddin shaik <sameeruddin.shaik8@xxxxxxxxx>
This new API will write the function filters into the
set_ftrace_filter file.
tracefs_function_filter()
https://bugzilla.kernel.org/show_bug.cgi?id=210643
Link: https://lore.kernel.org/linux-trace-devel/1616171938-18914-1-git-send-email-sameeruddin.shaik8@xxxxxxxxx
Link: https://lore.kernel.org/linux-trace-devel/20210323013224.729594322@xxxxxxxxxxx
Acked-by: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx>
Signed-off-by: Sameeruddin shaik <sameeruddin.shaik8@xxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
include/tracefs.h | 3 +-
src/tracefs-tools.c | 111 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 113 insertions(+), 1 deletion(-)
diff --git a/include/tracefs.h b/include/tracefs.h
index 05bd0ef4d404..9477fdb14c5a 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -145,5 +145,6 @@ bool tracefs_option_is_enabled(struct tracefs_instance *instance, enum tracefs_o
int tracefs_option_enable(struct tracefs_instance *instance, enum tracefs_option_id id);
int tracefs_option_diasble(struct tracefs_instance *instance, enum tracefs_option_id id);
const char *tracefs_option_name(enum tracefs_option_id id);
-
+int tracefs_function_filter(struct tracefs_instance *instance, const char **filters,
+ const char *module, bool reset, const char ***errs);
#endif /* _TRACE_FS_H */
diff --git a/src/tracefs-tools.c b/src/tracefs-tools.c
index e2dfc7b8acff..4f8bcdc299df 100644
--- a/src/tracefs-tools.c
+++ b/src/tracefs-tools.c
@@ -18,6 +18,7 @@
#include "tracefs-local.h"
#define TRACE_CTRL "tracing_on"
+#define TRACE_FILTER "set_ftrace_filter"
static const char * const options_map[] = {
"unknown",
@@ -387,3 +388,113 @@ void tracefs_option_clear(struct tracefs_options_mask *options, enum tracefs_opt
if (options && id > TRACEFS_OPTION_INVALID)
options->mask &= ~(1ULL << (id - 1));
}
+
+static int controlled_write(const char *filter_path, const char **filters,
+ const char *module, bool reset, const char ***errs)
+{
+ int flags = reset ? O_TRUNC : O_APPEND;
+ const char **temp = NULL;
+ const char **e = NULL;
+ char *each_str = NULL;
+ int write_size = 0;
+ int size = 0;
+ int fd = -1;
+ int ret = 0;
+ int j = 0;
+ int i;
+
+ fd = open(filter_path, O_WRONLY | flags);
+ if (fd < 0)
+ return 1;
+
+ for (i = 0; filters[i]; i++) {
+ if (module)
+ write_size = asprintf(&each_str, "%s:mod:%s ", filters[i], module);
+ else
+ write_size = asprintf(&each_str, "%s ", filters[i]);
+ if (write_size < 0) {
+ ret = 1;
+ goto error;
+ }
+ size = write(fd, each_str, write_size);
+ /* compare written bytes*/
+ if (size < write_size) {
+ if (errs) {
+ temp = realloc(e, (j + 1) * (sizeof(char *)));
+ if (!temp) {
+ free(e);
+ ret = 1;
+ goto error;
+ } else
+ e = temp;
+
+ e[j++] = filters[i];
+ ret -= 1;
+ }
+ }
+ free(each_str);
+ each_str = NULL;
+ }
+ if (errs) {
+ temp = realloc(e, (j + 1) * (sizeof(char *)));
+ if (!temp) {
+ free(e);
+ ret = 1;
+ goto error;
+ } else
+ e = temp;
+ e[j] = NULL;
+ *errs = e;
+ }
+ error:
+ if (each_str)
+ free(each_str);
+ close(fd);
+ return ret;
+}
+
+/**
+ * tracefs_function_filter - write to set_ftrace_filter file to trace
+ * particular functions
+ * @instance: ftrace instance, can be NULL for top tracing instance
+ * @filters: An array of function names ending with a NULL pointer
+ * @module: Module to be traced
+ * @reset: set to true to reset the file before applying the filter
+ * @errs: A pointer to array of constant strings that will be allocated
+ * on negative return of this function, pointing to the filters that
+ * failed.May be NULL, in which case this field will be ignored.
+ *
+ * The @filters is an array of strings, where each string will be used
+ * to set a function or functions to be traced.
+ *
+ * If @reset is true, then all functions in the filter are cleared
+ * before adding functions from @filters. Otherwise, the functions set
+ * by @filters will be appended to the filter file
+ *
+ * returns -x on filter errors (where x is number of failed filter
+ * srtings) and if @errs is not NULL will be an allocated string array
+ * pointing to the strings in @filters that failed and must be freed
+ * with free().
+ *
+ * returns 1 on general errors not realted to setting the filter.
+ * @errs is not set even if supplied.
+ *
+ * return 0 on success and @errs is not set.
+ */
+int tracefs_function_filter(struct tracefs_instance *instance, const char **filters,
+ const char *module, bool reset, const char ***errs)
+{
+ char *ftrace_filter_path;
+ int ret = 0;
+
+ if (!filters)
+ return 1;
+
+ ftrace_filter_path = tracefs_instance_get_file(instance, TRACE_FILTER);
+ if (!ftrace_filter_path)
+ return 1;
+
+ ret = controlled_write(ftrace_filter_path, filters, module, reset, errs);
+ tracefs_put_tracing_file(ftrace_filter_path);
+ return ret;
+}
--
2.30.1
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