linux-kernel - [PATCH 1/3] livepatch: Move the initialization of old

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Message-Id: <20211119090327.12811-2-mbenes@suse.cz>
Date:   Fri, 19 Nov 2021 10:03:25 +0100
From:   Miroslav Benes <mbenes@...e.cz>
To:     jpoimboe@...hat.com, jikos@...nel.org, pmladek@...e.com,
        joe.lawrence@...hat.com
Cc:     peterz@...radead.org, linux-kernel@...r.kernel.org,
        live-patching@...r.kernel.org, shuah@...nel.org,
        linux-kselftest@...r.kernel.org, Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH 1/3] livepatch: Move the initialization of old_func to a new function

struct klp_func will be used not only for functions to be patched but
also for functions which must not be found on a stack. Move the
initialization of needed struct members to a separate function, so the
code can be reused.

Signed-off-by: Miroslav Benes <mbenes@...e.cz>
---
 kernel/livepatch/core.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 335d988bd811..3d8e3caf9f92 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -767,6 +767,28 @@ static int klp_apply_object_relocs(struct klp_patch *patch,
 	return 0;
 }
 
+static int klp_init_old_func(struct klp_object *obj,
+			     struct klp_func *func)
+{
+	int ret;
+
+	ret = klp_find_object_symbol(obj->name, func->old_name,
+				     func->old_sympos,
+				     (unsigned long *)&func->old_func);
+	if (ret)
+		return ret;
+
+	ret = kallsyms_lookup_size_offset((unsigned long)func->old_func,
+					  &func->old_size, NULL);
+	if (!ret) {
+		pr_err("kallsyms size lookup failed for '%s'\n",
+		       func->old_name);
+		return -ENOENT;
+	}
+
+	return 0;
+}
+
 /* parts of the initialization that is done only when the object is loaded */
 static int klp_init_object_loaded(struct klp_patch *patch,
 				  struct klp_object *obj)
@@ -787,20 +809,10 @@ static int klp_init_object_loaded(struct klp_patch *patch,
 	}
 
 	klp_for_each_func(obj, func) {
-		ret = klp_find_object_symbol(obj->name, func->old_name,
-					     func->old_sympos,
-					     (unsigned long *)&func->old_func);
+		ret = klp_init_old_func(obj, func);
 		if (ret)
 			return ret;
 
-		ret = kallsyms_lookup_size_offset((unsigned long)func->old_func,
-						  &func->old_size, NULL);
-		if (!ret) {
-			pr_err("kallsyms size lookup failed for '%s'\n",
-			       func->old_name);
-			return -ENOENT;
-		}
-
 		if (func->nop)
 			func->new_func = func->old_func;
 
-- 
2.33.1