[newlib-cygwin] Move definition of wsadata into wsock_init
Corinna Vinschen
corinna@sourceware.org
Wed Mar 9 21:55:00 GMT 2016
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=264b5e137e20d0a8062497f8555759eb8bf8cc02
commit 264b5e137e20d0a8062497f8555759eb8bf8cc02
Author: Corinna Vinschen <corinna@vinschen.de>
Date: Wed Mar 9 22:55:28 2016 +0100
Move definition of wsadata into wsock_init
The problem this patch fixes showed up after updating to gcc-5.3.0. The
cuplrit is a change in gcc when emitting section attributes. It only
shows up when building without optimization. Effect in Cygwin: ws2_32
functions failed to load.
In the original code the definition of "NO_COPY wsadata" was preceeding
an __asm__ block (the definition of the _wsock_init wrapper), while the
definition of "NO_COPY here" immediately follows the same assembler
block. When gcc-5.3.0 emits assembler code for the wsadata definition,
it emits the .data_cygwin_nocopy section attribute.
Next it emits the assembler output for the __asm_ block, entirely ignoring
its content. The __asm__ block adds a .text section definition.
Eventually gcc emits assembler code for the here definition. However,
apparently gcc still "knows" that it just emitted the .data_cygwin_nocopy
section attribute and so doesn't redefine it. Remember the __asm__? It
changed the section to .text.
So with gcc-4.9.3 we got:
.section .data_cygwin_nocopy,"w"
wsadata:
__asm__ block:
.text
.section .data_cygwin_nocopy,"w"
here:
With gcc 5.3.0 we now get:
.section .data_cygwin_nocopy,"w"
wsadata:
__asm__ block:
.text
here:
So "here" is now in the .text segment which is read-only. Hilarity ensues.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Diff:
---
winsup/cygwin/autoload.cc | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/autoload.cc b/winsup/cygwin/autoload.cc
index bc13e07..422e2c98 100644
--- a/winsup/cygwin/autoload.cc
+++ b/winsup/cygwin/autoload.cc
@@ -480,7 +480,6 @@ std_dll_init ()
}
/* Initialization function for winsock stuff. */
-WSADATA NO_COPY wsadata;
#ifdef __x86_64__
/* See above comment preceeding std_dll_init. */
@@ -493,6 +492,10 @@ __attribute__ ((used, noinline)) static two_addr_t
wsock_init ()
#endif
{
+ /* CV 2016-03-09: Moved wsadata into wsock_init to workaround a problem
+ with the NO_COPY definition of wsadata and here starting with gcc-5.3.0.
+ See the git log for a description. */
+ static WSADATA NO_COPY wsadata;
static LONG NO_COPY here = -1L;
#ifndef __x86_64__
struct func_info *func = (struct func_info *) __builtin_return_address (0);
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