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 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 132D5C48BE5 for ; Wed, 23 Jun 2021 12:24:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3B1561002 for ; Wed, 23 Jun 2021 12:24:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231288AbhFWM0U (ORCPT ); Wed, 23 Jun 2021 08:26:20 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:36406 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230479AbhFWM0G (ORCPT ); Wed, 23 Jun 2021 08:26:06 -0400 Message-Id: <20210623121452.408457100@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1624451028; 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=3IUsGsRRbXPflSH1zvTuy/TjG7uiiaUsCM89J4QRNN4uPEpLhelXWyl+tgnqJBrfGKSs7+ BVYsV8Rr10PAdzc0GJjbrIq/DUdIpFU6yAtRQZufvFTnZTkiEB/f4mfiTkFuj3U+VCmcml rCdVbCXY9J3Ns9n51qBvw6d374MIuY+5SzTRnTzpGT6ji0LfSb5it+Jv8FQLHWieWs4AXL NPbrY92Oh0d+Ea1nf9M7TXAEvGum95grVCXRgGpabZw8ljTO0Hq6RpyRGmEH572J2h+A1q mdwqZGX8kjOyNT7t+LOrNWyT9LNz1e++z5dLhJrgd4fhckHchbIEiqFSCfJqZw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1624451028; 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=3aN6/khEO1YoILvd676bh0z/Mhles/kEs6w4uSomK7aE0KEmZ2E50lfGZ5wjAXzudvNjku llyMyXmUMCPtBWAA== Date: Wed, 23 Jun 2021 14:01:38 +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 , "Chang Seok Bae" , Megha Dey , Oliver Sang Subject: [patch V4 11/65] x86/fpu: Simplify PTRACE_GETREGS code References: <20210623120127.327154589@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) {