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/* uctx-setjmp.h - setjmp based user-space context switching
*
* Copyright (C) 2009 Timo Teräs <timo.teras@iki.fi>
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 or later as
* published by the Free Software Foundation.
*
* See http://www.gnu.org/ for details.
*/
#include <libtf/fiber.h>
#include <stdio.h>
#include <stdlib.h>
#include <setjmp.h>
#ifdef VALGRIND
#include <valgrind/valgrind.h>
#endif
#define STACK_GUARD 0xbad57ac4
struct tf_uctx {
int *stack_guard;
void *alloc;
jmp_buf jmpbuf;
#ifdef VALGRIND
unsigned int stack_id;
#endif
struct tf_fiber fiber;
};
#define set_stack(ptr) ({ __asm__("movl %0, %%esp" : : "r"(ptr)); })
#define get_stack() ({ void *ptr; __asm__("movl %%esp, %0" : "=r"(ptr)); ptr; })
attribute_never_inline
static void *tf_uctx_start(tf_fiber_proc fiber_main, size_t private_size)
{
struct tf_uctx *uctx;
uctx = alloca(private_size);
if (setjmp(uctx->jmpbuf) != 0) {
fiber_main(uctx->fiber.data);
tf_exit();
}
return uctx;
}
static inline
struct tf_fiber *tf_uctx_create(tf_fiber_proc fiber_main, int private_size)
{
size_t size = TF_STACK_SIZE;
struct tf_uctx *uctx;
void *stack, *old_stack, *stack_head, *stack_tail;
#ifdef VALGRIND
int stack_id;
#endif
stack = malloc(size);
if (stack == NULL)
return NULL;
#ifdef VALGRIND
stack_id = VALGRIND_STACK_REGISTER(stack, size);
#endif
/* Assumes stack grows up */
stack_head = stack + size - 8;
stack_tail = stack;
old_stack = get_stack();
set_stack(stack_head);
uctx = tf_uctx_start(fiber_main, private_size + sizeof(struct tf_uctx));
set_stack(old_stack);
#ifdef VALGRIND
uctx->stack_id = stack_id;
#endif
uctx->alloc = stack;
uctx->stack_guard = stack_tail;
*uctx->stack_guard = STACK_GUARD;
return &uctx->fiber;
}
static inline
void tf_uctx_destroy(struct tf_fiber *fiber)
{
struct tf_uctx *uctx = container_of(fiber, struct tf_uctx, fiber);
#ifdef VALGRIND
VALGRIND_STACK_DEREGISTER(uctx->stack_id);
#endif
free(uctx->alloc);
}
static inline
int tf_uctx_transfer(struct tf_fiber *from, struct tf_fiber *to, int value)
{
struct tf_uctx *ufrom = container_of(from, struct tf_uctx, fiber);
struct tf_uctx *uto = container_of(to, struct tf_uctx, fiber);
int r;
TF_BUG_ON(unlikely(*ufrom->stack_guard != STACK_GUARD));
r = setjmp(ufrom->jmpbuf);
if (r == 0)
longjmp(uto->jmpbuf, value);
return r;
}
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