[PATCH v8 6/9] livepatch: Use kallsyms_on_each_match_symbol() to improve performance

Zhen Lei
2022-11-02T08:51:31Z

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>
---
kernel/livepatch/core.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 9ada0bc5247be5d..50bfc3481a4ee38 100644
--- 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;
--
2.25.1