Function fpugetregs

freebsd/amd64/amd64/fpu.c:868–914

* Get the user state of the FPU into pcb->pcb_user_save without * dropping ownership (if possible). It returns the FPU ownership * status. */

 * status.
 */
int
fpugetregs(struct thread *td)
{
	struct pcb *pcb;
	uint64_t *xstate_bv, bit;
	char *sa;
	int max_ext_n, i, owned;

	pcb = td->td_pcb;
	critical_enter();
	if ((pcb->pcb_flags & PCB_USERFPUINITDONE) == 0) {
		bcopy(fpu_initialstate, get_pcb_user_save_pcb(pcb),
		    cpu_max_ext_state_size);
		get_pcb_user_save_pcb(pcb)->sv_env.en_cw =
		    pcb->pcb_initial_fpucw;
		fpuuserinited(td);
		critical_exit();
		return (_MC_FPOWNED_PCB);
	}
	if (td == PCPU_GET(fpcurthread) && PCB_USER_FPU(pcb)) {
		fpusave(get_pcb_user_save_pcb(pcb));
		owned = _MC_FPOWNED_FPU;
	} else {
		owned = _MC_FPOWNED_PCB;
	}
	if (use_xsave) {
		/*
		 * Handle partially saved state.
		 */
		sa = (char *)get_pcb_user_save_pcb(pcb);
		xstate_bv = (uint64_t *)(sa + sizeof(struct savefpu) +
		    offsetof(struct xstate_hdr, xstate_bv));
		max_ext_n = flsl(xsave_mask);
		for (i = 0; i < max_ext_n; i++) {
			bit = 1ULL << i;
			if ((xsave_mask & bit) == 0 || (*xstate_bv & bit) != 0)
				continue;
			bcopy((char *)fpu_initialstate +
			    xsave_area_desc[i].offset,
			    sa + xsave_area_desc[i].offset,
			    xsave_area_desc[i].size);
			*xstate_bv |= bit;
		}
	}
	critical_exit();
	return (owned);
}

void
fpuuserinited(struct thread *td)