Non-SFI NaCl: Fix browser_tests based on libc_free.c

chrome/test/data/nacl/nacl_test_data.gyp

Index: chrome/test/data/nacl/nacl_test_data.gyp
diff --git a/chrome/test/data/nacl/nacl_test_data.gyp b/chrome/test/data/nacl/nacl_test_data.gyp
index ea5e198cde0f3a5b8971e9d2d0648e2fef286092..d37a1c4ab650518c63613dacef8d6bb114e5c841 100644
--- a/chrome/test/data/nacl/nacl_test_data.gyp
+++ b/chrome/test/data/nacl/nacl_test_data.gyp
@@ -1152,6 +1152,14 @@
           'ldflags': [
             '-nostdlib',
             '-shared',
+            # This binary cannot relocate itself, so we should have no
+            # undefined references left.
+            '-Wl,--no-undefined',
+            # Clang emits .data.rel.ro.local for local struct values
+            # with initializers, and let the linker emit a few
+            # relocation info. We work around this issue by not using
+            # GNU_RELRO.
+            '-Wl,-z,norelro',

[Mark Seaborn, 2014/07/10 17:17:45]

I don't think adding "norelro" works.

For example:

struct S {
  int *x[6];
};

struct S global1;
struct S global2;

static int val1;
static int val2;

void foo1() {
  struct S local = {
    &val1, &val1, &val1, &val1, &val1, &val1
  };
  global1 = local;
}

void foo2() {
  int i = 0;
  global2.x[i++] = &val2;
  global2.x[i++] = &val2;
  global2.x[i++] = &val2;
  global2.x[i++] = &val2;
  global2.x[i++] = &val2;
  global2.x[i++] = &val2;
}

If you run:

clang libc_free_reloc.c -shared -fPIC -Wl,-z,norelro && objdump -R a.out

then you'll see there are still R_X86_64_RELATIVE relocs on 'local' that refer
to val1.  The linker can't make those go away when producing a
position-independent binary.

[hamaji, 2014/07/11 05:16:48]

True. I might have been testing this in a wrong way. Removed.

           ],
           'ldflags!': [
             # Explicitly remove the -pthread flag to avoid a link time warning.