| /* |
| * |
| * verify_cpu.S - Code for cpu long mode and SSE verification. This |
| * code has been borrowed from boot/setup.S and was introduced by |
| * Andi Kleen. |
| * |
| * Copyright (c) 2007 Andi Kleen (ak@suse.de) |
| * Copyright (c) 2007 Eric Biederman (ebiederm@xmission.com) |
| * Copyright (c) 2007 Vivek Goyal (vgoyal@in.ibm.com) |
| * |
| * This source code is licensed under the GNU General Public License, |
| * Version 2. See the file COPYING for more details. |
| * |
| * This is a common code for verification whether CPU supports |
| * long mode and SSE or not. It is not called directly instead this |
| * file is included at various places and compiled in that context. |
| * Following are the current usage. |
| * |
| * This file is included by both 16bit and 32bit code. |
| * |
| * arch/x86_64/boot/setup.S : Boot cpu verification (16bit) |
| * arch/x86_64/boot/compressed/head.S: Boot cpu verification (32bit) |
| * arch/x86_64/kernel/trampoline.S: secondary processor verfication (16bit) |
| * arch/x86_64/kernel/acpi/wakeup.S:Verfication at resume (16bit) |
| * |
| * verify_cpu, returns the status of cpu check in register %eax. |
| * 0: Success 1: Failure |
| * |
| * The caller needs to check for the error code and take the action |
| * appropriately. Either display a message or halt. |
| */ |
| |
| #include <asm/cpufeature.h> |
| |
| verify_cpu: |
| pushfl # Save caller passed flags |
| pushl $0 # Kill any dangerous flags |
| popfl |
| |
| pushfl # standard way to check for cpuid |
| popl %eax |
| movl %eax,%ebx |
| xorl $0x200000,%eax |
| pushl %eax |
| popfl |
| pushfl |
| popl %eax |
| cmpl %eax,%ebx |
| jz verify_cpu_no_longmode # cpu has no cpuid |
| |
| movl $0x0,%eax # See if cpuid 1 is implemented |
| cpuid |
| cmpl $0x1,%eax |
| jb verify_cpu_no_longmode # no cpuid 1 |
| |
| xor %di,%di |
| cmpl $0x68747541,%ebx # AuthenticAMD |
| jnz verify_cpu_noamd |
| cmpl $0x69746e65,%edx |
| jnz verify_cpu_noamd |
| cmpl $0x444d4163,%ecx |
| jnz verify_cpu_noamd |
| mov $1,%di # cpu is from AMD |
| |
| verify_cpu_noamd: |
| movl $0x1,%eax # Does the cpu have what it takes |
| cpuid |
| andl $REQUIRED_MASK0,%edx |
| xorl $REQUIRED_MASK0,%edx |
| jnz verify_cpu_no_longmode |
| |
| movl $0x80000000,%eax # See if extended cpuid is implemented |
| cpuid |
| cmpl $0x80000001,%eax |
| jb verify_cpu_no_longmode # no extended cpuid |
| |
| movl $0x80000001,%eax # Does the cpu have what it takes |
| cpuid |
| andl $REQUIRED_MASK1,%edx |
| xorl $REQUIRED_MASK1,%edx |
| jnz verify_cpu_no_longmode |
| |
| verify_cpu_sse_test: |
| movl $1,%eax |
| cpuid |
| andl $SSE_MASK,%edx |
| cmpl $SSE_MASK,%edx |
| je verify_cpu_sse_ok |
| test %di,%di |
| jz verify_cpu_no_longmode # only try to force SSE on AMD |
| movl $0xc0010015,%ecx # HWCR |
| rdmsr |
| btr $15,%eax # enable SSE |
| wrmsr |
| xor %di,%di # don't loop |
| jmp verify_cpu_sse_test # try again |
| |
| verify_cpu_no_longmode: |
| popfl # Restore caller passed flags |
| movl $1,%eax |
| ret |
| verify_cpu_sse_ok: |
| popfl # Restore caller passed flags |
| xorl %eax, %eax |
| ret |
