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/* $OpenBSD: rthread_stack.c,v 1.5 2011/11/06 11:48:59 guenther Exp $ */
/* $snafu: rthread_stack.c,v 1.12 2005/01/11 02:45:28 marc Exp $ */
/* PUBLIC DOMAIN: No Rights Reserved. Marco S Hyman <marc@snafu.org> */
#include <sys/types.h>
#include <sys/mman.h>
#include <machine/param.h>
#include <errno.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include "rthread.h"
struct stack *
_rthread_alloc_stack(pthread_t thread)
{
struct stack *stack;
caddr_t base;
caddr_t guard;
caddr_t start = NULL;
size_t pgsz;
size_t size;
/* guard pages are forced to a multiple of the page size */
pgsz = sysconf(_SC_PAGESIZE);
if (pgsz == (size_t)-1)
return NULL;
/* figure out the actual requested size, including guard size */
size = thread->attr.stack_size + thread->attr.guard_size;
size += pgsz - 1;
size &= ~(pgsz - 1);
/*
* Allocate some stack space unless an address was provided.
* A provided address is ASSUMED to be correct with respect to
* alignment constraints.
*/
if (size > thread->attr.guard_size) {
if (thread->attr.stack_addr)
base = thread->attr.stack_addr;
else {
base = mmap(NULL, size, PROT_READ | PROT_WRITE,
MAP_ANON, -1, 0);
if (base == MAP_FAILED)
return (NULL);
}
/* memory protect the guard region */
#ifdef MACHINE_STACK_GROWS_UP
guard = base + size - thread->attr.guard_size;
start = base;
#else
guard = base;
start = base + size;
#endif
if (mprotect(guard, thread->attr.guard_size, PROT_NONE) == -1) {
munmap(base, size);
return (NULL);
}
/* wrap up the info in a struct stack and return it */
stack = malloc(sizeof(*stack));
if (!stack) {
munmap(base, size);
return (NULL);
}
stack->sp = start;
stack->base = base;
stack->guard = guard;
stack->guardsize = thread->attr.guard_size;
stack->len = size;
return (stack);
}
errno = EINVAL;
return (NULL);
}
void
_rthread_free_stack(struct stack *stack)
{
munmap(stack->base, stack->len);
free(stack);
}
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