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* miscfuncs.cc (DEFAULT_STACKSIZE): Remove. 

(CygwinCreateThread): Simplify code by assuming that now stack-related
	input values are undefined.  Set stack protection to PAGE_READWRITE,
	as is default on Windows.  Add lengthy comment to explain POSIX
	guardpage.
	* thread.cc (pthread_attr::pthread_attr): Initialize stacksize as
	PTHREAD_DEFAULT_STACKSIZE.  Initialize guardsize as
	PTHREAD_DEFAULT_GUARDSIZE.
	* thread.h (PTHREAD_DEFAULT_STACKSIZE): Define.  Add comment to explain.
	(PTHREAD_DEFAULT_GUARDSIZE): Define.
This commit is contained in:
Corinna Vinschen 2012-02-11 17:37:02 +00:00
parent 793371f584
commit ce48510394
4 changed files with 35 additions and 23 deletions
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13
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,16 @@
2012-02-11 Corinna Vinschen <corinna@vinschen.de>
* miscfuncs.cc (DEFAULT_STACKSIZE): Remove.
(CygwinCreateThread): Simplify code by assuming that now stack-related
input values are undefined. Set stack protection to PAGE_READWRITE,
as is default on Windows. Add lengthy comment to explain POSIX
guardpage.
* thread.cc (pthread_attr::pthread_attr): Initialize stacksize as
PTHREAD_DEFAULT_STACKSIZE. Initialize guardsize as
PTHREAD_DEFAULT_GUARDSIZE.
* thread.h (PTHREAD_DEFAULT_STACKSIZE): Define. Add comment to explain.
(PTHREAD_DEFAULT_GUARDSIZE): Define.
2012-02-10 Corinna Vinschen <corinna@vinschen.de>
* miscfuncs.cc (DEFAULT_STACKSIZE): Set to 1 Megs. Drop comment about

35
winsup/cygwin/miscfuncs.cc
View File

@ -549,8 +549,6 @@ thread_wrapper (VOID *arg)
ExitThread (0);
}
#define DEFAULT_STACKSIZE (1024 * 1024)
HANDLE WINAPI
CygwinCreateThread (LPTHREAD_START_ROUTINE thread_func, PVOID thread_arg,
PVOID stackaddr, ULONG stacksize, ULONG guardsize,
@ -572,30 +570,19 @@ CygwinCreateThread (LPTHREAD_START_ROUTINE thread_func, PVOID thread_arg,
wrapper_arg->func = thread_func;
wrapper_arg->arg = thread_arg;
/* Set stacksize. */
real_stacksize = stacksize ?: DEFAULT_STACKSIZE;
if (real_stacksize < PTHREAD_STACK_MIN)
real_stacksize = PTHREAD_STACK_MIN;
if (stackaddr)
{
/* If the application provided the stack, just use it. */
wrapper_arg->stackaddr = (char *) stackaddr;
wrapper_arg->stackbase = (char *) stackaddr + real_stacksize;
wrapper_arg->stackbase = (char *) stackaddr + stacksize;
}
else
{
/* If not, we have to create the stack here. */
real_stacksize = roundup2 (real_stacksize, wincap.page_size ());
/* If no guardsize has been specified by the application, use the
system pagesize as default. */
real_guardsize = (guardsize != (ULONG) -1)
? guardsize : wincap.page_size ();
if (real_guardsize)
real_guardsize = roundup2 (real_guardsize, wincap.page_size ());
/* Add the guardsize to the stacksize, but only if the stacksize and
the guardsize have been explicitely specified. */
if (stacksize || guardsize != (ULONG) -1)
real_stacksize += real_guardsize;
real_stacksize = roundup2 (stacksize, wincap.page_size ());
real_guardsize = roundup2 (guardsize, wincap.page_size ());
/* Add the guardsize to the stacksize */
real_stacksize += real_guardsize;
/* Now roundup the result to the next allocation boundary. */
real_stacksize = roundup2 (real_stacksize,
wincap.allocation_granularity ());
@ -606,7 +593,7 @@ CygwinCreateThread (LPTHREAD_START_ROUTINE thread_func, PVOID thread_arg,
the Cygwin DLL comes to mind. */
real_stackaddr = VirtualAlloc (NULL, real_stacksize,
MEM_RESERVE | MEM_TOP_DOWN,
PAGE_EXECUTE_READWRITE);
PAGE_READWRITE);
if (!real_stackaddr)
return NULL;
/* Set up committed region. In contrast to the OS we commit 64K and
@ -615,13 +602,19 @@ CygwinCreateThread (LPTHREAD_START_ROUTINE thread_func, PVOID thread_arg,
+ real_stacksize
- wincap.allocation_granularity ();
if (!VirtualAlloc (commitaddr, wincap.page_size (), MEM_COMMIT,
PAGE_EXECUTE_READWRITE | PAGE_GUARD))
PAGE_READWRITE | PAGE_GUARD))
goto err;
commitaddr += wincap.page_size ();
if (!VirtualAlloc (commitaddr, wincap.allocation_granularity ()
- wincap.page_size (), MEM_COMMIT,
PAGE_EXECUTE_READWRITE))
PAGE_READWRITE))
goto err;
/* If the guardsize is != 0 (which is the default), set up a POSIX
guardpage at the end of the stack. This isn't the same as the
Windows guardpage, which is used to convert reserved stack to
commited stack if necessary. Rather, the POSIX guardpage consists
of one or more memory pages with NOACCESS protection. It's supposed
to safeguard memory areas beyond the stack against stack overflow. */
if (real_guardsize)
VirtualAlloc (real_stackaddr, real_guardsize, MEM_COMMIT,
PAGE_NOACCESS);

4
winsup/cygwin/thread.cc
View File

@ -1127,8 +1127,8 @@ pthread::resume ()
pthread_attr::pthread_attr ():verifyable_object (PTHREAD_ATTR_MAGIC),
joinable (PTHREAD_CREATE_JOINABLE), contentionscope (PTHREAD_SCOPE_PROCESS),
inheritsched (PTHREAD_INHERIT_SCHED), stackaddr (NULL), stacksize (0),
guardsize ((size_t) -1)
inheritsched (PTHREAD_INHERIT_SCHED), stackaddr (NULL),
stacksize (PTHREAD_DEFAULT_STACKSIZE), guardsize (PTHREAD_DEFAULT_GUARDSIZE)
{
schedparam.sched_priority = 0;
}

6
winsup/cygwin/thread.h
View File

@ -16,6 +16,12 @@ details. */
#define WRITE_LOCK 1
#define READ_LOCK 2
/* Default is a 1 Megs stack with a 4K guardpage. Since the pthread stacksize
does not include the guardpage size, but we don't want to waste another 64K,
subtract the default guardpage size from the stacksize. */
#define PTHREAD_DEFAULT_STACKSIZE (1024 * 1024 - wincap.page_size ())
#define PTHREAD_DEFAULT_GUARDSIZE (wincap.page_size ())
#include <pthread.h>
#include <limits.h>
#include "security.h"