* Copyright 1999, 2000, 2001 Bernie Innocenti <bernie@codewiz.org>
* -->
*
- * \version $Id$
* \author Bernie Innocenti <bernie@codewiz.org>
*
- * \brief i386 context switch
+ * \brief x86_64 context switch
+ *
+ * x86_64 function call convention:
+ * --------------------------------
+ * arguments | callee-saved | extra caller-saved | return
+ * [callee-clobbered] | | [callee-clobbered] |
+ * -------------------------------------------------------------------------
+ * rdi rsi rdx rcx r8-9 | rbx rbp [*] r12-15 | r10-11 | rax, rdx
+ *
+ * [*] 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.
*/
/* void asm_switch_context(void **new_sp [%rdi], void **save_sp [%rsi]) */
.globl asm_switch_context
asm_switch_context:
- pushq %rax
- pushq %rbx
- pushq %rcx
- pushq %rdx
- pushq %rsi
- pushq %rdi
pushq %rbp
+ pushq %rdi
+ pushq %rsi
+ pushq %rcx
+ pushq %r8
+ pushq %r9
+ pushq %r10
+ pushq %r11
movq %rsp,(%rsi) /* *save_sp = rsp */
movq (%rdi),%rsp /* rsp = *new_sp */
- popq %rbp
- popq %rdi
- popq %rsi
- popq %rdx
+ popq %r11
+ popq %r10
+ popq %r9
+ popq %r8
popq %rcx
- popq %rbx
- popq %rax
+ popq %rsi
+ popq %rdi
+ popq %rbp
ret