module: fix BUG_ON() for powerpc (and other function descriptor archs)

The rarely-used symbol_put_addr() needs to use dereference_function_descriptor
on powerpc.

Reported-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/kernel/module.c b/kernel/module.c
index fd1411403558..07c80e68a6c4 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -909,16 +909,18 @@ void __symbol_put(const char *symbol)
 }
 EXPORT_SYMBOL(__symbol_put);
 
+/* Note this assumes addr is a function, which it currently always is. */
 void symbol_put_addr(void *addr)
 {
         struct module *modaddr;
+        unsigned long a = (unsigned long)dereference_function_descriptor(addr);
 
-        if (core_kernel_text((unsigned long)addr))
+        if (core_kernel_text(a))
                 return;
 
         /* module_text_address is safe here: we're supposed to have reference
          * to module from symbol_get, so it can't go away. */
-        modaddr = __module_text_address((unsigned long)addr);
+        modaddr = __module_text_address(a);
         BUG_ON(!modaddr);
         module_put(modaddr);
 }