livepatch: Fix crash when access the global variable in hook

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4IH1G
CVE: NA

---------------------------

Livepatch allows users to call hook functions to perform some customized
operations when insmod the .ko. During the test, it is found that in the
ARM64 architecture, if accesses the global variables defined by other ko in
hook functions, a crash occurs.

Since relocation is performed during the livepatch insertion, instructions
in the icache should be invalid. If the instructions in the icache are
directly obtained, incorrect addresses may be obtained, caseing crash.
Therefore, flush the icache before calling the hook functions.
Signed-off-by: NYe Weihua <yeweihua4@huawei.com>
Reviewed-by: NJian Cheng <cj.chengjian@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NYe Weihua <yeweihua4@huawei.com>
Reviewed-by: NYang Jihong <yangjihong1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

include/linux/moduleloader.h

@@ -96,6 +96,8 @@ void module_arch_cleanup(struct module *mod);
 /* Any cleanup before freeing mod->module_init */
 void module_arch_freeing_init(struct module *mod);
 
+void flush_module_icache(const struct module *mod);
+
 #if defined(CONFIG_KASAN) && !defined(CONFIG_KASAN_VMALLOC)
 #include <linux/kasan.h>
 #define MODULE_ALIGN (PAGE_SIZE << KASAN_SHADOW_SCALE_SHIFT)

kernel/livepatch/core.c

@@ -1214,6 +1214,7 @@ static int klp_init_patch(struct klp_patch *patch)
 			goto out;
 	}
 
+	flush_module_icache(patch->mod);
 	set_mod_klp_rel_state(patch->mod, MODULE_KLP_REL_DONE);
 	module_disable_ro(patch->mod);
 	jump_label_apply_nops(patch->mod);

kernel/module.c

@@ -3523,7 +3523,7 @@ static int check_module_license_and_versions(struct module *mod)
 	return 0;
 }
 
-static void flush_module_icache(const struct module *mod)
+void flush_module_icache(const struct module *mod)
 {
 	/*
 	 * Flush the instruction cache, since we've played with text.