From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756434AbYGJXY3 (ORCPT ); Thu, 10 Jul 2008 19:24:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753175AbYGJXYV (ORCPT ); Thu, 10 Jul 2008 19:24:21 -0400 Received: from gw.goop.org ([64.81.55.164]:48991 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752985AbYGJXYU (ORCPT ); Thu, 10 Jul 2008 19:24:20 -0400 Message-ID: <48769A18.4030402@goop.org> Date: Thu, 10 Jul 2008 16:24:08 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Ingo Molnar CC: the arch/x86 maintainers , Linux Kernel Mailing List Subject: [PATCH 2/2] xen64: disable 32-bit syscall/sysenter if not supported. X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Old versions of Xen (3.1 and before) don't support sysenter or syscall from 32-bit compat userspaces. If we can't set the appropriate syscall callback, then disable the corresponding feature bit, which will cause the vdso32 setup to fall back appropriately. Linux assumes that syscall is always available to 32-bit userspace, and installs it by default if sysenter isn't available. In that case, we just disable vdso altogether, forcing userspace libc to fall back to int $0x80. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/xen/setup.c | 38 +++++++++++++++++++------------------- 1 file changed, 19 insertions(+), 19 deletions(-) =================================================================== --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -106,46 +106,46 @@ static __cpuinit int register_callback(u void __cpuinit xen_enable_sysenter(void) { - int cpu = smp_processor_id(); extern void xen_sysenter_target(void); int ret; + unsigned sysenter_feature; #ifdef CONFIG_X86_32 - if (!boot_cpu_has(X86_FEATURE_SEP)) { - return; - } + sysenter_feature = X86_FEATURE_SEP; #else - if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL && - boot_cpu_data.x86_vendor != X86_VENDOR_CENTAUR) { - return; - } + sysenter_feature = X86_FEATURE_SYSENTER32; #endif + if (!boot_cpu_has(sysenter_feature)) + return; + ret = register_callback(CALLBACKTYPE_sysenter, xen_sysenter_target); - if(ret != 0) { - clear_cpu_cap(&cpu_data(cpu), X86_FEATURE_SEP); - clear_cpu_cap(&boot_cpu_data, X86_FEATURE_SEP); - } + if(ret != 0) + setup_clear_cpu_cap(sysenter_feature); } void __cpuinit xen_enable_syscall(void) { #ifdef CONFIG_X86_64 - int cpu = smp_processor_id(); int ret; extern void xen_syscall_target(void); extern void xen_syscall32_target(void); ret = register_callback(CALLBACKTYPE_syscall, xen_syscall_target); if (ret != 0) { - printk("failed to set syscall: %d\n", ret); - clear_cpu_cap(&cpu_data(cpu), X86_FEATURE_SYSCALL); - clear_cpu_cap(&boot_cpu_data, X86_FEATURE_SYSCALL); - } else { + printk(KERN_ERR "Failed to set syscall: %d\n", ret); + /* Pretty fatal; 64-bit userspace has no other + mechanism for syscalls. */ + } + + if (boot_cpu_has(X86_FEATURE_SYSCALL32)) { ret = register_callback(CALLBACKTYPE_syscall32, xen_syscall32_target); - if (ret != 0) - printk("failed to set 32-bit syscall: %d\n", ret); + if (ret != 0) { + printk(KERN_INFO "Xen: 32-bit syscall not supported: disabling vdso\n"); + setup_clear_cpu_cap(X86_FEATURE_SYSCALL32); + sysctl_vsyscall32 = 0; + } } #endif /* CONFIG_X86_64 */ }