From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53C94ECE564 for ; Tue, 18 Sep 2018 23:10:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D44E20C0E for ; Tue, 18 Sep 2018 23:10:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0D44E20C0E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730538AbeISEof (ORCPT ); Wed, 19 Sep 2018 00:44:35 -0400 Received: from mga14.intel.com ([192.55.52.115]:3122 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725875AbeISEof (ORCPT ); Wed, 19 Sep 2018 00:44:35 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Sep 2018 16:09:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,391,1531810800"; d="scan'208";a="87288053" Received: from chang-linux-2.sc.intel.com ([10.3.52.139]) by fmsmga002.fm.intel.com with ESMTP; 18 Sep 2018 16:09:40 -0700 From: "Chang S. Bae" To: Ingo Molnar , Thomas Gleixner , Andy Lutomirski , "H . Peter Anvin" Cc: Andi Kleen , Dave Hansen , Markus T Metzger , Ravi Shankar , "Chang S . Bae" , LKML Subject: [PATCH v6 3/8] x86/fsgsbase/64: Make ptrace use correct FS/GS base helpers Date: Tue, 18 Sep 2018 16:08:54 -0700 Message-Id: <1537312139-5580-4-git-send-email-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1537312139-5580-1-git-send-email-chang.seok.bae@intel.com> References: <1537312139-5580-1-git-send-email-chang.seok.bae@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The FS/GS base helper functions are used on ptrace APIs (PTRACE_ARCH_PRCTL, PTRACE_SETREG, PTRACE_GETREG, etc). The FS/GS-update mechanism is now a bit organized. Based-on-code-from: Andy Lutomirski Signed-off-by: Chang S. Bae Cc: Andy Lutomirski Cc: H. Peter Anvin Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Andi Kleen Cc: Dave Hansen --- arch/x86/include/asm/fsgsbase.h | 3 --- arch/x86/kernel/process_64.c | 49 +++++++++-------------------------------- arch/x86/kernel/ptrace.c | 27 +++++++---------------- 3 files changed, 18 insertions(+), 61 deletions(-) diff --git a/arch/x86/include/asm/fsgsbase.h b/arch/x86/include/asm/fsgsbase.h index 0404dab..949eefc 100644 --- a/arch/x86/include/asm/fsgsbase.h +++ b/arch/x86/include/asm/fsgsbase.h @@ -8,9 +8,6 @@ #include -unsigned long x86_fsgsbase_read_task(struct task_struct *task, - unsigned short selector); - /* * Read/write a task's fsbase or gsbase. This returns the value that * the FS/GS base would have (if the task were to be resumed). These diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 52af8c1..710f639 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -285,8 +285,8 @@ static __always_inline void load_seg_legacy(unsigned short prev_index, } } -unsigned long x86_fsgsbase_read_task(struct task_struct *task, - unsigned short selector) +static unsigned long x86_fsgsbase_read_task(struct task_struct *task, + unsigned short selector) { unsigned short idx = selector >> 3; unsigned long base; @@ -749,54 +749,25 @@ static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr) long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) { int ret = 0; - int doit = task == current; - int cpu; switch (option) { - case ARCH_SET_GS: - if (arg2 >= TASK_SIZE_MAX) - return -EPERM; - cpu = get_cpu(); - task->thread.gsindex = 0; - task->thread.gsbase = arg2; - if (doit) { - load_gs_index(0); - ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, arg2); - } - put_cpu(); + case ARCH_SET_GS: { + ret = x86_gsbase_write_task(task, arg2); break; - case ARCH_SET_FS: - /* Not strictly needed for fs, but do it for symmetry - with gs */ - if (arg2 >= TASK_SIZE_MAX) - return -EPERM; - cpu = get_cpu(); - task->thread.fsindex = 0; - task->thread.fsbase = arg2; - if (doit) { - /* set the selector to 0 to not confuse __switch_to */ - loadsegment(fs, 0); - ret = wrmsrl_safe(MSR_FS_BASE, arg2); - } - put_cpu(); + } + case ARCH_SET_FS: { + ret = x86_fsbase_write_task(task, arg2); break; + } case ARCH_GET_FS: { - unsigned long base; + unsigned long base = x86_fsbase_read_task(task); - if (doit) - rdmsrl(MSR_FS_BASE, base); - else - base = task->thread.fsbase; ret = put_user(base, (unsigned long __user *)arg2); break; } case ARCH_GET_GS: { - unsigned long base; + unsigned long base = x86_gsbase_read_task(task); - if (doit) - rdmsrl(MSR_KERNEL_GS_BASE, base); - else - base = task->thread.gsbase; ret = put_user(base, (unsigned long __user *)arg2); break; } diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index fbde2a7..d8f49c7 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -397,12 +397,11 @@ static int putreg(struct task_struct *child, if (value >= TASK_SIZE_MAX) return -EIO; /* - * When changing the segment base, use do_arch_prctl_64 - * to set either thread.fs or thread.fsindex and the - * corresponding GDT slot. + * When changing the FS base, use the same + * mechanism as for do_arch_prctl_64(). */ if (child->thread.fsbase != value) - return do_arch_prctl_64(child, ARCH_SET_FS, value); + return x86_fsbase_write_task(child, value); return 0; case offsetof(struct user_regs_struct,gs_base): /* @@ -411,7 +410,7 @@ static int putreg(struct task_struct *child, if (value >= TASK_SIZE_MAX) return -EIO; if (child->thread.gsbase != value) - return do_arch_prctl_64(child, ARCH_SET_GS, value); + return x86_gsbase_write_task(child, value); return 0; #endif } @@ -435,20 +434,10 @@ static unsigned long getreg(struct task_struct *task, unsigned long offset) return get_flags(task); #ifdef CONFIG_X86_64 - case offsetof(struct user_regs_struct, fs_base): { - if (task->thread.fsindex == 0) - return task->thread.fsbase; - else - return x86_fsgsbase_read_task(task, - task->thread.fsindex); - } - case offsetof(struct user_regs_struct, gs_base): { - if (task->thread.gsindex == 0) - return task->thread.gsbase; - else - return x86_fsgsbase_read_task(task, - task->thread.gsindex); - } + case offsetof(struct user_regs_struct, fs_base): + return x86_fsbase_read_task(task); + case offsetof(struct user_regs_struct, gs_base): + return x86_gsbase_read_task(task); #endif } -- 2.7.4