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Fix up allocation of stack space for a cothread. Previous code did not allow for the underlying threading model to i...

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Original commit message from CVS:
Fix up allocation of stack space for a cothread.  Previous code did
not allow for the underlying threading model to insert an unmapped
guard page.
This commit is contained in:
David Schleef 2002-11-14 11:14:52 +00:00
parent 2556b83528
commit 5fa7e059eb
1 changed files with 8 additions and 25 deletions
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33
gst/cothreads.c
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@ -175,8 +175,7 @@ cothread_create (cothread_context *ctx)
{
cothread_state *cothread;
void *sp;
void *mmaped = 0;
guchar *stack_end;
unsigned long stack_top;
gint slot = 0;
g_return_val_if_fail (ctx != NULL, NULL);
@ -204,32 +203,16 @@ cothread_create (cothread_context *ctx)
* could use casts to uintptr_t from inttypes.h
* if only all platforms had inttypes.h
*/
/* FIXME: a little explanation on what this REALLY means would be nice ;) */
stack_end = (guchar *) ((gulong) sp & ~(STACK_SIZE - 1));
/* stack_top is the address of th first byte past our stack segment. */
/* FIXME: an assumption is made that the stack segment is STACK_SIZE
* aligned. */
stack_top = ((gulong) sp | (STACK_SIZE - 1)) + 1;
GST_DEBUG(GST_CAT_COTHREADS, "stack top is %lu", stack_top);
/* cothread stack space of the thread is mapped in reverse, with cothread 0
* stack space at the top */
cothread = (cothread_state *) (stack_end + ((slot - 1) * COTHREAD_STACKSIZE));
GST_DEBUG (GST_CAT_COTHREADS,
"mmap cothread slot stack from %p to %p (size 0x%lx)",
cothread, cothread + COTHREAD_STACKSIZE,
(long) COTHREAD_STACKSIZE);
GST_DEBUG (GST_CAT_COTHREADS, "going into mmap");
/* the mmap is used to reserve part of the stack
* ie. we state explicitly that we are going to use it */
mmaped = mmap ((void *) cothread, COTHREAD_STACKSIZE,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
GST_DEBUG (GST_CAT_COTHREADS, "coming out of mmap");
if (mmaped == MAP_FAILED) {
perror ("mmap'ing cothread stack space");
return NULL;
}
if (mmaped != cothread) {
g_warning ("could not mmap requested memory for cothread");
return NULL;
}
cothread = (cothread_state *) (stack_top - (slot + 1) * COTHREAD_STACKSIZE);
GST_DEBUG(GST_CAT_COTHREADS, "cothread pointer is %p", cothread);
cothread->magic_number = COTHREAD_MAGIC_NUMBER;
GST_DEBUG (GST_CAT_COTHREADS, "create cothread %d with magic number 0x%x",