nuclear@54: 	.text
nuclear@57: 	/* switch_stack(uint32_t new_stack, uint32_t *old_stack_ptr)
nuclear@57:      * switches to the new stack and returns the old stack pointer, which is
nuclear@57:      * also copied to the address passed as the second argument.
nuclear@54:      */
nuclear@54: 	.globl switch_stack
nuclear@54: switch_stack:
nuclear@57: 	movl %esp, %eax		/* old stack in eax */
nuclear@57: 	movl 8(%esp), %edx
nuclear@57: 	cmpl $0, %edx		/* if old_stack_ptr is null, skip ahead */
nuclear@57: 	jz oldp_is_null
nuclear@57: 	movl %eax, (%edx)	/* otherwise *old_stack_ptr = eax */
nuclear@57: oldp_is_null:
nuclear@57: 	movl 4(%esp), %esp	/* set the new stack */
nuclear@54: 	ret
nuclear@57: 
nuclear@57: 	/* get_instr_stack_ptr(uint32_t *eip, uint32_t *esp)
nuclear@57:      * returns the current instruction and stack pointers at the same
nuclear@57:      * point in execution, so that a newly-forked process with these
nuclear@57:      * values will just return from this function and continue on.
nuclear@57: 	 */
nuclear@57: 	.globl get_instr_stack_ptr
nuclear@57: get_instr_stack_ptr:
nuclear@57: 	call get_instr_ptr
nuclear@57: 	movl %eax, 4(%esp)
nuclear@57: 	movl %esp, 8(%esp)
nuclear@57: 	ret
nuclear@57: 
nuclear@57: 	/* get_instr_ptr(void)
nuclear@57: 	 * returns the address of the next instruction after the call to this function
nuclear@57: 	 */
nuclear@57: 	.globl get_instr_ptr
nuclear@57: get_instr_ptr:
nuclear@57: 	movl (%esp), %eax
nuclear@57: 	ret
nuclear@57: 
nuclear@57: 	/* get_caller_instr_ptr(void)
nuclear@57: 	 * returns the address of the next instruction after the call to the function that
nuclear@57: 	 * called this function.
nuclear@57:      * NOTE: will only work properly when called from a function that uses ebp to point
nuclear@57:      * to its stack frame, which means all of the C functions but pretty much none of
nuclear@57:      * our assembly functions.
nuclear@57: 	 */
nuclear@57: 	.globl get_caller_instr_ptr
nuclear@57: get_caller_instr_ptr:
nuclear@57: 	movl 4(%ebp), %eax
nuclear@57: 	ret
nuclear@57: 
nuclear@58: 	/* this is where we end up when we first context_switch to a newly forked
nuclear@58: 	 * process. The interrupt frame is already there, so we just call intr_ret
nuclear@58: 	 * to return to user space
nuclear@58: 	 */
nuclear@57: 	.globl just_forked
nuclear@57: just_forked:
nuclear@57: 	call intr_ret