pstore: Use global ftrace filters for function trace filtering

Currently, pstore doesn't have any filters setup for function tracing.
This has the associated overhead and may not be useful for users looking
for tracing specific set of functions.

ftrace's regular function trace filtering is done writing to
tracing/set_ftrace_filter however this is not available if not requested.
In order to be able to use this feature, the support to request global
filtering introduced earlier in the series should be requested before
registering the ftrace ops. Here we do the same.

Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c
index 31548cc09e7b6f8ef60d323a7b62fc99cedeb3e0..899d0ba0bd6cca44593f25be751efbe52a507d31 100644 (file)
--- a/fs/pstore/ftrace.c
+++ b/fs/pstore/ftrace.c
@@ -75,10 +75,13 @@ static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
        if (!on ^ pstore_ftrace_enabled)
                goto out;
 
-       if (on)
+       if (on) {
+               ftrace_ops_set_global_filter(&pstore_ftrace_ops);
                ret = register_ftrace_function(&pstore_ftrace_ops);
-       else
+       } else {
                ret = unregister_ftrace_function(&pstore_ftrace_ops);
+       }
+
        if (ret) {
                pr_err("%s: unable to %sregister ftrace ops: %zd\n",
                       __func__, on ? "" : "un", ret);