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=-2.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, 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 9CCE1ECDFAA for ; Wed, 18 Jul 2018 09:41:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0D932086B for ; Wed, 18 Jul 2018 09:41:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=8bytes.org header.i=@8bytes.org header.b="XOVe/mQd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F0D932086B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=8bytes.org 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 S1731526AbeGRKSb (ORCPT ); Wed, 18 Jul 2018 06:18:31 -0400 Received: from 8bytes.org ([81.169.241.247]:53740 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731408AbeGRKSb (ORCPT ); Wed, 18 Jul 2018 06:18:31 -0400 Received: by theia.8bytes.org (Postfix, from userid 1000) id 8CFAF219; Wed, 18 Jul 2018 11:41:18 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=8bytes.org; s=mail-1; t=1531906879; bh=w4DXGqDHgCkivWXTkiZjSWhwcxxFw+CPZ35l4K1+2YU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XOVe/mQdTYm01PubZ4K7rGVa8RoLqKe0Jx3lHy3Wfil8L9zFTbo/7PmW08/XEbgPM sz0Y6yEInMf3qjwdfOe6iouzy0hj20g6k+FQFGETdXBdC10yEGu16A8JgI4jtAZLDe Dtdw1TZZzhKVKpf/gviM54XgvHND1aoqq/kt5l+NhC5AUfxycsf9L/lmUCBy/oQaaB gMfdDKptZX7xgeuNy8EkUpRO5j1TQDuHtrPzmc9Kk3Qi+hLUcxvZp4TWTXkE84IZgs dPszHouRBECsORYuyQrglC7092LNKqns5fah1YzL9bb2HeE08bwoQ9JZTqRswBjRVv Ja1uwElnZK7Kg== From: Joerg Roedel To: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Andrea Arcangeli , Waiman Long , Pavel Machek , "David H . Gutteridge" , jroedel@suse.de, joro@8bytes.org Subject: [PATCH 03/39] x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler Date: Wed, 18 Jul 2018 11:40:40 +0200 Message-Id: <1531906876-13451-4-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1531906876-13451-1-git-send-email-joro@8bytes.org> References: <1531906876-13451-1-git-send-email-joro@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joerg Roedel We want x86_tss.sp0 point to the entry stack later to use it as a trampoline stack for other kernel entry points besides SYSENTER. So store the task stack pointer in x86_tss.sp1, which is otherwise unused by the hardware, as Linux doesn't make use of Ring 1. Signed-off-by: Joerg Roedel --- arch/x86/kernel/asm-offsets_32.c | 9 +++++++-- arch/x86/kernel/process_32.c | 2 ++ 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c index 15b3f45..82826f2 100644 --- a/arch/x86/kernel/asm-offsets_32.c +++ b/arch/x86/kernel/asm-offsets_32.c @@ -46,9 +46,14 @@ void foo(void) OFFSET(saved_context_gdt_desc, saved_context, gdt_desc); BLANK(); - /* Offset from the entry stack to task stack stored in TSS */ + /* + * Offset from the entry stack to task stack stored in TSS. Kernel entry + * happens on the per-cpu entry-stack, and the asm code switches to the + * task-stack pointer stored in x86_tss.sp1, which is a copy of + * task->thread.sp0 where entry code can find it. + */ DEFINE(TSS_entry2task_stack, - offsetof(struct cpu_entry_area, tss.x86_tss.sp0) - + offsetof(struct cpu_entry_area, tss.x86_tss.sp1) - offsetofend(struct cpu_entry_area, entry_stack_page.stack)); #ifdef CONFIG_STACKPROTECTOR diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 0ae659d..ec62cc7 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -290,6 +290,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) this_cpu_write(cpu_current_top_of_stack, (unsigned long)task_stack_page(next_p) + THREAD_SIZE); + /* SYSENTER reads the task-stack from tss.sp1 */ + this_cpu_write(cpu_tss_rw.x86_tss.sp1, next_p->thread.sp0); /* * Restore %gs if needed (which is common) -- 2.7.4