kernel: add support for init_array constructors

This adds the .init_array section as yet another section with constructors. This
is needed because gcc could add __gcov_init calls to .init_array or .ctors
section, depending on gcc (and binutils) version .

v2: - reuse mod->ctors for .init_array section for modules, because gcc uses
      .ctors or .init_array, but not both at the same time
v3: - fail to load if that does happen somehow.

Signed-off-by: Frantisek Hrbata <fhrbata@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 18 insertions, 2 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 947105fd4cab..5c9cf84017d5 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2708,7 +2708,7 @@ static int check_modinfo(struct module *mod, struct load_info *info, int flags)
         return 0;
 }
 
-static void find_module_sections(struct module *mod, struct load_info *info)
+static int find_module_sections(struct module *mod, struct load_info *info)
 {
         mod->kp = section_objs(info, "__param",
                                sizeof(*mod->kp), &mod->num_kp);
@@ -2738,6 +2738,18 @@ static void find_module_sections(struct module *mod, struct load_info *info)
 #ifdef CONFIG_CONSTRUCTORS
         mod->ctors = section_objs(info, ".ctors",
                                   sizeof(*mod->ctors), &mod->num_ctors);
+        if (!mod->ctors)
+                mod->ctors = section_objs(info, ".init_array",
+                                sizeof(*mod->ctors), &mod->num_ctors);
+        else if (find_sec(info, ".init_array")) {
+                /*
+                 * This shouldn't happen with same compiler and binutils
+                 * building all parts of the module.
+                 */
+                printk(KERN_WARNING "%s: has both .ctors and .init_array.\n",
+                       mod->name);
+                return -EINVAL;
+        }
 #endif
 
 #ifdef CONFIG_TRACEPOINTS
@@ -2776,6 +2788,8 @@ static void find_module_sections(struct module *mod, struct load_info *info)
 
         info->debug = section_objs(info, "__verbose",
                                    sizeof(*info->debug), &info->num_debug);
+
+        return 0;
 }
 
 static int move_module(struct module *mod, struct load_info *info)
@@ -3233,7 +3247,9 @@ static int load_module(struct load_info *info, const char __user *uargs,
 
         /* Now we've got everything in the final locations, we can
          * find optional sections. */
-        find_module_sections(mod, info);
+        err = find_module_sections(mod, info);
+        if (err)
+                goto free_unload;
 
         err = check_module_license_and_versions(mod);
         if (err)