* Copyright 1999, 2000, 2001 Bernie Innocenti <bernie@codewiz.org>
* -->
*
- * \version $Id$
* \author Bernie Innocenti <bernie@codewiz.org>
*
* \brief i386 context switch
+ *
+ * x86 function calling convention:
+ * --------------------------------
+ * arguments | callee-saved | extra caller-saved | return
+ * [callee-clobbered] | | [callee-clobbered] |
+ * -------------------------------------------------------------------------
+ * eax edx ecx | ebx edi esi ebp [*] | <none> | eax, edx
+ *
+ * [*] In the frame-pointers case rbp must hold a base address for the
+ * current stack frame.
+ *
+ * asm_switch_context() can be considered as a normal function call, so we need
+ * to save all the callee-clobbered registers minus the return registers.
*/
#ifdef __APPLE__
/* void asm_switch_context(void ** new_sp [sp+4], void ** save_sp [sp+8]) */
.globl SWITCH_CONTEXT
SWITCH_CONTEXT:
- pushl %eax
- pushl %ebx
- pushl %ecx
- pushl %edx
- pushl %esi
- pushl %edi
pushl %ebp
- movl 0x24(%esp),%ebp /* ebp = save_sp */
+ pushl %ecx
+ movl 0x10(%esp),%ebp /* ebp = save_sp */
movl %esp,(%ebp) /* *save_sp = esp */
- movl 0x20(%esp),%ebp /* ebp = new_sp */
+ movl 0x0c(%esp),%ebp /* ebp = new_sp */
movl (%ebp),%esp /* esp = *new_sp */
- popl %ebp
- popl %edi
- popl %esi
- popl %edx
popl %ecx
- popl %ebx
- popl %eax
+ popl %ebp
ret