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 8D05DC433F5 for ; Tue, 7 Sep 2021 20:25:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7310161152 for ; Tue, 7 Sep 2021 20:25:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346719AbhIGU0c (ORCPT ); Tue, 7 Sep 2021 16:26:32 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:45908 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345769AbhIGU0I (ORCPT ); Tue, 7 Sep 2021 16:26:08 -0400 Message-ID: <20210907200848.991751342@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1631046301; 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: references:references; bh=ud9Rd1/fZ50YrK/Tfm/gE+UHE7gbflVrR9DwkiPTzFE=; b=pWo00YPKJ7F5mXtUUNvZTZTws7haHF4eIexTWQNfLtRo45CGeSAIYAXD1Ir1ngcmAipPsd A4Y/o8GBHTKhadPLcOEF6mk/yQPL6Jj7ZHXP+31Z82/04cgh0/HuWaMcGdKWwgPJ/bxwRj J7WG/4INyMSmwstxD5YoVCef5d5Ey9oa+Smrgw4x6spoAVHx7vkFg8H0lk0KReofRSaqOH Ekk20vRbIZUq2nkTD4kv349/N/Tt15r82fEUzen5stL126B0MtFEBpfVDdTYJZckNo0Sib waQvMqtS22sSqshwm0qVSTWHiFamiuz3BqHOB67AduRUGNq3P3VPRYHauo4xOw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1631046301; 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: references:references; bh=ud9Rd1/fZ50YrK/Tfm/gE+UHE7gbflVrR9DwkiPTzFE=; b=JiHjc+eT5CO3ldqOvZuvj3cK87FGsvUa145OqnN36jJZwWUjlSHUweJkCAomX2yEpBcKnb QmNeEwitNfIRMHAw== From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Al Viro , Linus Torvalds , Tony Luck , Song Liu , Alexei Starovoitov , Daniel Borkmann , Peter Ziljstra Subject: [patch V2.1 13/20] x86/fpu/signal: Move xstate clearing out of copy_fpregs_to_sigframe() References: <20210907200722.067068005@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Date: Tue, 7 Sep 2021 22:25:00 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When the direct saving of the FPU registers to the user space sigframe fails, copy_fpregs_to_sigframe() attempts to clear the user buffer. The most likely reason for such a fail is a page fault. As copy_fpregs_to_sigframe() is invoked with pagefaults disabled the chance that __clear_user() succeeds is minuscule. Move the clearing out into the caller which replaces the fault_in_pages_writeable() in that error handling path. The return value confusion will be cleaned up separately. Suggested-by: Al Viro Signed-off-by: Thomas Gleixner --- arch/x86/kernel/fpu/signal.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -136,18 +136,12 @@ static inline int save_xstate_epilog(voi static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf) { - int err; - if (use_xsave()) - err = xsave_to_user_sigframe(buf); - else if (use_fxsr()) - err = fxsave_to_user_sigframe((struct fxregs_state __user *) buf); + return xsave_to_user_sigframe(buf); + if (use_fxsr()) + return fxsave_to_user_sigframe((struct fxregs_state __user *) buf); else - err = fnsave_to_user_sigframe((struct fregs_state __user *) buf); - - if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size)) - err = -EFAULT; - return err; + return fnsave_to_user_sigframe((struct fregs_state __user *) buf); } /* @@ -218,9 +212,10 @@ int copy_fpstate_to_sigframe(void __user fpregs_unlock(); if (ret) { - if (!fault_in_pages_writeable(buf_fx, fpu_user_xstate_size)) + if (!__clear_user(buf_fx, fpu_user_xstate_size) && + ret == X86_TRAP_PF) goto retry; - return -EFAULT; + return -1; } /* Save the fsave header for the 32-bit frames. */