Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754363Ab0FYJUy (ORCPT ); Fri, 25 Jun 2010 05:20:54 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:63304 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753416Ab0FYJUw (ORCPT ); Fri, 25 Jun 2010 05:20:52 -0400 Message-ID: <4C2474EF.4050902@cn.fujitsu.com> Date: Fri, 25 Jun 2010 17:20:47 +0800 From: Lai Jiangshan User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@linux.intel.com CC: linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/alternatives] x86, alternatives: Use 16-bit numbers for cpufeature index References: In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3238 Lines: 87 tip-bot for H. Peter Anvin wrote: > Commit-ID: f88731e3068f9d1392ba71cc9f50f035d26a0d4f > Gitweb: http://git.kernel.org/tip/f88731e3068f9d1392ba71cc9f50f035d26a0d4f > Author: H. Peter Anvin > AuthorDate: Wed, 9 Jun 2010 16:03:09 -0700 > Committer: H. Peter Anvin > CommitDate: Wed, 9 Jun 2010 16:03:09 -0700 > > x86, alternatives: Use 16-bit numbers for cpufeature index > > We already have cpufeature indicies above 255, so use a 16-bit number > for the alternatives index. This consumes a padding field and so > doesn't add any size, but it means that abusing the padding field to > create assembly errors on overflow no longer works. We can retain the > test simply by redirecting it to the .discard section, however. > My machine hits "invalid opcode" at *prepare_to_copy+0x79, and it can't boot up. (gdb) l *prepare_to_copy+0x79 0xc0101789 is in prepare_to_copy (/home/njubee/work/linux-2.6-tip/arch/x86/include/asm/xsave.h:118). 113 114 static inline void fpu_xsave(struct fpu *fpu) 115 { 116 /* This, however, we can work around by forcing the compiler to select 117 an addressing mode that doesn't require extended registers. */ 118 __asm__ __volatile__(".byte " REX_PREFIX "0x0f,0xae,0x27" 119 : : "D" (&(fpu->state->xsave)), 120 "a" (-1), "d"(-1) : "memory"); 121 } 122 #endif It can boot up if this patch is reverted. Does this patch change the return value of "use_xsave()" cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 15 model : 4 model name : Intel(R) Pentium(R) D CPU 2.80GHz stepping : 8 cpu MHz : 2800.120 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 5 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss constant_tsc pebs bts tsc_reliable pni ds_cpl bogomips : 5600.24 clflush size : 64 cache_alignment : 128 address sizes : 36 bits physical, 48 bits virtual power management: processor : 1 vendor_id : GenuineIntel cpu family : 15 model : 4 model name : Intel(R) Pentium(R) D CPU 2.80GHz stepping : 8 cpu MHz : 2800.120 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 5 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss constant_tsc pebs bts tsc_reliable pni ds_cpl bogomips : 5574.36 clflush size : 64 cache_alignment : 128 address sizes : 36 bits physical, 48 bits virtual power management: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/