[RFC PATCH 4/9] livepatch: get 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 any task stacks.

Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
 include/linux/livepatch.h |  3 +++
 kernel/livepatch/core.c   | 19 ++++++++++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 22a67d1..0e65b4d 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -37,6 +37,8 @@
  * @kobj:      kobject for sysfs resources
  * @state:     tracks function-level patch application state
  * @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 {
        /* internal */
        struct kobject kobj;
        struct list_head stack_node;
+       unsigned long old_size, new_size;
        int patched;
 };
 
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 0c09eba..85d4ef7 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -197,8 +197,25 @@ static int klp_find_verify_func_addr(struct klp_object 
*obj,
        else
                ret = klp_verify_vmlinux_symbol(func->old_name,
                                                func->old_addr);
+       if (ret)
+               return ret;
 
-       return ret;
+       ret = kallsyms_lookup_size_offset(func->old_addr, &func->old_size,
+                                         NULL);
+       if (!ret) {
+               pr_err("kallsyms lookup failed for '%s'\n", func->old_name);
+               return -EINVAL;
+       }
+
+       ret = kallsyms_lookup_size_offset((unsigned long)func->new_func,
+                                         &func->new_size, NULL);
+       if (!ret) {
+               pr_err("kallsyms lookup failed for '%s' replacement\n",
+                      func->old_name);
+               return -EINVAL;
+       }
+
+       return 0;
 }
 
 /*
-- 
2.1.0

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