eglibc-2.15-fix-neon-libdl.patch 1.31 KB
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When compiled for arm with -mfpu=neon, the .init_array section declared
here becomes 64-bit aligned. Since the dynamic linker expects an array of
32-bit function pointers with no gaps, this causes an immediate SIGSEGV
for any application linked with libdl.

I suspect the default array alignment becomes 64 bits because the neon
has 64-bit registers, but I'm not sure. The explicit aligned attribute
does not help because it can only increase the alignment.

Fortunately, the whole declaration can be replaced with a constructor
attribute on the init function, which also adds it to the init_array
table and does the right thing with alignment.

(Why wasn't it this way already? I don't know, but maybe the constructor
attribute wasn't available yet when this code was written.)

Richard Braakman
richard.braakman@jollamobile.com

--- eglibc-2.15/dlfcn/dlfcn.c	2006-08-17 04:18:26.000000000 +0300
+++ glibc-fixed/dlfcn/dlfcn.c	2013-06-10 13:20:34.846885906 +0300
@@ -24,16 +24,9 @@
 char **__dlfcn_argv attribute_hidden;
 
 
-static void
+static void __attribute ((constructor))
 init (int argc, char *argv[])
 {
   __dlfcn_argc = argc;
   __dlfcn_argv = argv;
 }
-
-static void (*const init_array []) (int argc, char *argv[])
-     __attribute__ ((section (".init_array"), aligned (sizeof (void *))))
-     __attribute_used__ =
-{
-  init
-};