/* * Copyright (c) 2008 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ #include <sys/appleapiopts.h> #include <machine/cpu_capabilities.h> #include <platfunc.h> /* * These platfunc routines provide fast access to the logical cpu number * of the calling processor assuming no pre-emption occurs. This number * is encoded in the bottom 12-bits of the limit field of the IDTR (the * Interrupt Descriptor Table Register). The SIDT instruction is used in * userspace to read this register and thus to gain access to the cpu number. * The IDTR is loaded by the kernel for each processor at startup - see * osfmk/i386/mp_desc.c. */ /* return logical cpu number in %eax */ .align 4 .private_extern _cpu_number _cpu_number: push %ebp mov %esp,%ebp sub $8, %esp // space to read IDTR sidt (%esp) // store limit:base on stack movw (%esp), %ax // get limit and $0xfff, %eax // mask off lower 12 bits to return mov %ebp,%esp pop %ebp ret