[RFC PATCH v2 16/18] livepatch: store function sizes

[Josh Poimboeuf]

For the consistency model we'll need to know the sizes of the old and
new functions to determine if they're on the stacks of any tasks.

Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
 include/linux/livepatch.h |  3 +++
 kernel/livepatch/core.c   | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 9ba26c5..c38c694 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -37,6 +37,8 @@
  * @old_addr:  the address of the function being patched
  * @kobj:      kobject for sysfs resources
  * @stack_node:        list node for klp_ops func_stack list
+ * @old_size:  size of the old function
+ * @new_size:  size of the new function
  * @patched:   the func has been added to the klp_ops list
  */
 struct klp_func {
@@ -56,6 +58,7 @@ struct klp_func {
        unsigned long old_addr;
        struct kobject kobj;
        struct list_head stack_node;
+       unsigned long old_size, new_size;
        bool patched;
 };
 
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index f28504d..aa3dbdf 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -577,6 +577,22 @@ static int klp_init_object_loaded(struct klp_patch *patch,
                                             &func->old_addr);
                if (ret)
                        return ret;
+
+               ret = kallsyms_lookup_size_offset(func->old_addr,
+                                                 &func->old_size, NULL);
+               if (!ret) {
+                       pr_err("kallsyms size lookup failed for '%s'\n",
+                              func->old_name);
+                       return -ENOENT;
+               }
+
+               ret = kallsyms_lookup_size_offset((unsigned long)func->new_func,
+                                                 &func->new_size, NULL);
+               if (!ret) {
+                       pr_err("kallsyms size lookup failed for '%s' 
replacement\n",
+                              func->old_name);
+                       return -ENOENT;
+               }
        }
 
        return 0;
-- 
2.4.11

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