From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELv0ktrAtK1P3ac3EHnk9e9L67guD+lPz57eF/M1ENNNg+I6UZJmo8itw+Ty6bllQknX9eI/ ARC-Seal: i=1; a=rsa-sha256; t=1521228600; cv=none; d=google.com; s=arc-20160816; b=wvTL87p9VgmNNDIoQEXG8nb3y2SijSQ6rqxIM9qrOx7LjVynE/v1j4nHw1yizu1QWO Ze+8QLuv5d/4UM6rO3/bXIrDKINSWlXwnRgxv7pxVkpgK9v9iJvnDaantzMjoey9RJ37 WBrdWRzPEZjDdgWC7QVdGzqUPUMit/TgLbVIlauvAVLVZmJ1p8YZnAIB2EyYn7U9Vfnx TFbC4YdSbxpmh9g/VccmneDNeNxZPIoOXsn1te99kG6ENQbp0PJhPV7A2tSqktI4CjHV B5UhQLUj4frixquy6dCAhs+zxG5wqLN1R3Bn523S+E7PAmJFvwECyNJEIOt+RVUx9Dw/ azFw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature:arc-authentication-results; bh=NTVb4LONHnLz6w99SoQtjWWuv+4gRfgau5jr8PemZlw=; b=hWRUCg4BWmTqzq83SEuiMcdW6P4KW2Iia3WCmNuqNa0vQuGQTj/V/fCtKgO0b+c4T7 siYT3RuOaK/ajwuP5haHZMEfPUi7vE7E68lm7O1Zxsq6L0a4hW4VkvB8ppsKy59D9sO4 +wUvVRhetmtg6cJcpfOseFyYAKBZqQRlchxpyS3lvETbnVPcgJXUtZoGFL5yXRInvSaq FMRkaPdncR82vKOmkRa4fWix9qBTz3gP5XrNGAH9Ic59FIDsz+8YAS+LFGLklEj9w+B9 juJsxoTQ5UyMnFULfAcNNrEeRIYzoLrqzBv7n6rDrIRBadkuvFHC9pDkwm2tu7t1cdGa Q4Ng== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=NthVvN3U; spf=pass (google.com: domain of joro@8bytes.org designates 81.169.241.247 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org Authentication-Results: mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=NthVvN3U; spf=pass (google.com: domain of joro@8bytes.org designates 81.169.241.247 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org 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 , jroedel@suse.de, joro@8bytes.org Subject: [PATCH 03/35] x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler Date: Fri, 16 Mar 2018 20:29:21 +0100 Message-Id: <1521228593-3820-4-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521228593-3820-1-git-send-email-joro@8bytes.org> References: <1521228593-3820-1-git-send-email-joro@8bytes.org> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1595123801347660556?= X-GMAIL-MSGID: =?utf-8?q?1595123801347660556?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 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 | 2 +- arch/x86/kernel/process_32.c | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c index f452bfd..b97e48c 100644 --- a/arch/x86/kernel/asm-offsets_32.c +++ b/arch/x86/kernel/asm-offsets_32.c @@ -47,7 +47,7 @@ void foo(void) BLANK(); /* Offset from the sysenter stack to tss.sp0 */ - DEFINE(TSS_entry_stack, offsetof(struct cpu_entry_area, tss.x86_tss.sp0) - + DEFINE(TSS_entry_stack, offsetof(struct cpu_entry_area, tss.x86_tss.sp1) - offsetofend(struct cpu_entry_area, entry_stack_page.stack)); #ifdef CONFIG_CC_STACKPROTECTOR diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 5224c60..097d36a 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -292,6 +292,8 @@ __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