/*
* Finish a fork operation, with process p2 nearly set up.
* Copy and update the kernel stack and pcb, making the child
* ready to run, and marking it so that it can return differently
* than the parent.
*/
void
cpu_fork(struct proc *p1, struct proc *p2, void *stack, void *tcb,
void (*func)(void *), void *arg)
{
struct cpu_info *ci = curcpu();
struct pcb *pcb = &p2->p_addr->u_pcb;
struct pcb *pcb1 = &p1->p_addr->u_pcb;
struct trapframe *tf;
struct switchframe *sf;
/* Save the fpu h/w state to p1's pcb so that we can copy it. */
if (p1 != &proc0 && (ci->ci_flags & CPUF_USERXSTATE))
fpusave(&pcb1->pcb_savefpu);
p2->p_md.md_flags = p1->p_md.md_flags;
#ifdef DIAGNOSTIC
if (p1 != curproc && p1 != &proc0)
panic("cpu_fork: curproc");
#endif
*pcb = *pcb1;
/*
* Activate the address space.
*/
pmap_activate(p2);
/* Record where this process's kernel stack is */
pcb->pcb_kstack = (u_int64_t)p2->p_addr + USPACE - 16 -
(arc4random() & PAGE_MASK & ~_STACKALIGNBYTES);
/*
* Copy the trapframe.
*/
p2->p_md.md_regs = tf = (struct trapframe *)pcb->pcb_kstack - 1;
*tf = *p1->p_md.md_regs;
setguardpage(p2);
/*
* If specified, give the child a different stack and/or TCB
*/
if (stack != NULL)
tf->tf_rsp = (u_int64_t)stack;
if (tcb != NULL)
pcb->pcb_fsbase = (u_int64_t)tcb;
sf = (struct switchframe *)tf - 1;
sf->sf_r12 = (u_int64_t)func;
sf->sf_r13 = (u_int64_t)arg;
sf->sf_rip = (u_int64_t)proc_trampoline;
pcb->pcb_rsp = (u_int64_t)sf;
pcb->pcb_rbp = 0;
}
static void
save_guest_fpustate(struct vcpu *vcpu)
{
if ((rcr0() & CR0_TS) == 0)
panic("fpu emulation not enabled in host!");
/* save guest XCR0 and restore host XCR0 */
if (rcr4() & CR4_XSAVE) {
vcpu->guest_xcr0 = rxcr(0);
load_xcr(0, vmm_get_host_xcr0());
}
/* save guest FPU state */
fpu_stop_emulating();
fpusave(vcpu->guestfpu);
fpu_start_emulating();
}