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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 5760DC49361 for ; Fri, 18 Jun 2021 15:20:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FB73613EE for ; Fri, 18 Jun 2021 15:20:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235136AbhFRPWf (ORCPT ); Fri, 18 Jun 2021 11:22:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235014AbhFRPVp (ORCPT ); Fri, 18 Jun 2021 11:21:45 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0F010C0617AD for ; Fri, 18 Jun 2021 08:19:36 -0700 (PDT) Message-Id: <20210618143445.869339459@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1624029574; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=EFWP0kL3mzs5vMeQuyAKSIlrs3/tsfT7zciJy9J5rIE=; b=rvqx60HhNyC2RFGEf+B6yrtCsWAQG2EvrBBTZgD67y59eqSe1YnGSmBd5fr3PaoM5ynwhr YbkRJH3iWAdv6aw7bO1UiGfWd3pkhCLG2pee4Yb42wuHiQ51rGh4Wly56yLtnhkELHJ5F6 rGPCa+/fHHXoO86AI4daX8nSj2pp39KUcTONhkqNUtlg2zjcgsfSlKQ3PLaDVHjZMYrjV+ ep8dHBNk8JF+UwEv8UfSvNFz+qJDlliaRbib6dKqGoFC1cmmLgf/570GjaeR9I6Xozovuu GZPHA/GXIZ1b5gIrLECSapyxdc6u/AsxaEyNJWuJR8S1MPohzT56A7zlON994Q== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1624029574; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=EFWP0kL3mzs5vMeQuyAKSIlrs3/tsfT7zciJy9J5rIE=; b=lqwpi82u7BVPb/Qe6RaI7F8njCyz5eBU/ynXwXyXvTpB4+JOynJtTRVrfed7ZJ/25O7j0B kshl3SrO/pLdVaAw== Date: Fri, 18 Jun 2021 16:18:36 +0200 From: Thomas Gleixner To: LKML Cc: Andy Lutomirski , Dave Hansen , Fenghua Yu , Tony Luck , Yu-cheng Yu , Sebastian Andrzej Siewior , Borislav Petkov , Peter Zijlstra , Kan Liang Subject: [patch V3 13/66] x86/fpu: Simplify PTRACE_GETREGS code References: <20210618141823.161158090@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen ptrace() has interfaces that let a ptracer inspect a ptracee's register state. This includes XSAVE state. The ptrace() ABI includes a hardware-format XSAVE buffer for both the SETREGS and GETREGS interfaces. In the old days, the kernel buffer and the ptrace() ABI buffer were the same boring non-compacted format. But, since the advent of supervisor states and the compacted format, the kernel buffer has diverged from the format presented in the ABI. This leads to two paths in the kernel: 1. Effectively a verbatim copy_to_user() which just copies the kernel buffer out to userspace. This is used when the kernel buffer is kept in the non-compacted form which means that it shares a format with the ptrace ABI. 2. A one-state-at-a-time path: copy_xstate_to_kernel(). This is theoretically slower since it does a bunch of piecemeal copies. Remove the verbatim copy case. Speed probably does not matter in this path, and the vast majority of new hardware will use the one-state-at-a-time path anyway. This ensures greater testing for the "slow" path. This also makes enabling PKRU in this interface easier since a single path can be patched instead of two. Signed-off-by: Dave Hansen Signed-off-by: Thomas Gleixner Reviewed-by: Andy Lutomirski Reviewed-by: Borislav Petkov --- arch/x86/kernel/fpu/regset.c | 24 +++--------------------- arch/x86/kernel/fpu/xstate.c | 6 +++--- 2 files changed, 6 insertions(+), 24 deletions(-) --- a/arch/x86/kernel/fpu/regset.c +++ b/arch/x86/kernel/fpu/regset.c @@ -77,32 +77,14 @@ int xstateregs_get(struct task_struct *t struct membuf to) { struct fpu *fpu = &target->thread.fpu; - struct xregs_state *xsave; - if (!boot_cpu_has(X86_FEATURE_XSAVE)) + if (!cpu_feature_enabled(X86_FEATURE_XSAVE)) return -ENODEV; - xsave = &fpu->state.xsave; - fpu__prepare_read(fpu); - if (using_compacted_format()) { - copy_xstate_to_kernel(to, xsave); - return 0; - } else { - fpstate_sanitize_xstate(fpu); - /* - * Copy the 48 bytes defined by the software into the xsave - * area in the thread struct, so that we can copy the whole - * area to user using one user_regset_copyout(). - */ - memcpy(&xsave->i387.sw_reserved, xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes)); - - /* - * Copy the xstate memory layout. - */ - return membuf_write(&to, xsave, fpu_user_xstate_size); - } + copy_xstate_to_kernel(to, &fpu->state.xsave); + return 0; } int xstateregs_set(struct task_struct *target, const struct user_regset *regset, --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1069,11 +1069,11 @@ static void copy_feature(bool from_xstat } /* - * Convert from kernel XSAVES compacted format to standard format and copy - * to a kernel-space ptrace buffer. + * Convert from kernel XSAVE or XSAVES compacted format to UABI + * non-compacted format and copy to a kernel-space ptrace buffer. * * It supports partial copy but pos always starts from zero. This is called - * from xstateregs_get() and there we check the CPU has XSAVES. + * from xstateregs_get() and there we check the CPU has XSAVE. */ void copy_xstate_to_kernel(struct membuf to, struct xregs_state *xsave) {