livepatch: Use kallsyms_on_each_match_symbol() to improve performance

Based on the test results of kallsyms_on_each_match_symbol() and
kallsyms_on_each_symbol(), the average performance can be improved by
more than 1500 times.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 9ada0bc..50bfc34 100644 (file)
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -153,6 +153,24 @@ static int klp_find_callback(void *data, const char *name,
        return 0;
 }
 
+static int klp_match_callback(void *data, unsigned long addr)
+{
+       struct klp_find_arg *args = data;
+
+       args->addr = addr;
+       args->count++;
+
+       /*
+        * Finish the search when the symbol is found for the desired position
+        * or the position is not defined for a non-unique symbol.
+        */
+       if ((args->pos && (args->count == args->pos)) ||
+           (!args->pos && (args->count > 1)))
+               return 1;
+
+       return 0;
+}
+
 static int klp_find_object_symbol(const char *objname, const char *name,
                                  unsigned long sympos, unsigned long *addr)
 {
@@ -167,7 +185,7 @@ static int klp_find_object_symbol(const char *objname, const char *name,
        if (objname)
                module_kallsyms_on_each_symbol(klp_find_callback, &args);
        else
-               kallsyms_on_each_symbol(klp_find_callback, &args);
+               kallsyms_on_each_match_symbol(klp_match_callback, name, &args);
 
        /*
         * Ensure an address was found. If sympos is 0, ensure symbol is unique;