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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44E1FEB64D8 for ; Thu, 22 Jun 2023 12:08:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230137AbjFVMIO (ORCPT ); Thu, 22 Jun 2023 08:08:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229718AbjFVMIL (ORCPT ); Thu, 22 Jun 2023 08:08:11 -0400 Received: from mail-ot1-x330.google.com (mail-ot1-x330.google.com [IPv6:2607:f8b0:4864:20::330]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AF57A1731 for ; Thu, 22 Jun 2023 05:08:09 -0700 (PDT) Received: by mail-ot1-x330.google.com with SMTP id 46e09a7af769-6b5d5e6b086so376157a34.1 for ; Thu, 22 Jun 2023 05:08:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1687435688; x=1690027688; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=LWa68tYrGcCIa4PH1f5HyDq5yUUyzbHX4FuidyoLLdg=; b=Wj9biUC6F3xIauOs/udENeVtN3ReOt/xlt75pp1FHoixHWi4TIn2Tf5X9Pcig6xtdK lDgyofZaZ30tSAVxg1yMe1Cv+telZoZjyvJV2EhPDXUt4/4ekX0+Xqa7Mc65DVT1SuQJ 9AQbCgEa/TriCWs/cvBTA04hBj8rxEZwBHxTC8mpafV/ljnhbgjqfuilA4cbK+y/f4C8 jaS/EyYEmTSObK3emoQzhESKgQjW0YnkwrdY0iCSliDk6YO5d3QGG2U43eEnKyZoWKrw 9Et26iTN2zzyylmi3rrm8kJB+juF+noYx11PnvoLKWED1LyX81XLn1i4P2GBWu7yRmIc xiaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1687435688; x=1690027688; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=LWa68tYrGcCIa4PH1f5HyDq5yUUyzbHX4FuidyoLLdg=; b=Yi6p6G5vbFTpL6zSvTeiv8tijJQi34ZDVPjv6zQ7bPCND3U8xFYqVqvPmm+hlcs+Ia A6IMLmmNCw9OLpJ8nIS1umocsBIHjkvivxweG/HjgxqGLLlndhZxqIBnU5TmPLzFOkdu JMA2d9eLdA4QYWgk3zIxRjJXRoTkPVNDa+df0QuxyhmG4d2N0nl35TstZ9YOEAT0SFfR Fy9dXOoFJS0HYzY+qUA0SBa/rE2/KJMjA5rzeBYCfFGdILD5TMvjAPHO/beBoyLsB7NB FI6usw2A1Cu5e/Y47gVHdXTavAEJOJmfGgRXFiMy2WE850PalNEzaPFYQ2Bud+Vr0ddj uQjg== X-Gm-Message-State: AC+VfDw4/tjT0SKerGPF3KTsHhdJHSk6bHqNW2ZyRIVgY8tOvMAX6z3u PFI2FhEZ7amGvvIEmWcWTKrio6HRAw== X-Google-Smtp-Source: ACHHUZ7FiqBHDu9aDCmXeIOoeyZAZAbGO+lae4KwIvqrCJ/O56jrbmfR4N9Vukffrut+6vWxEcr6SA== X-Received: by 2002:a05:6830:4623:b0:6b7:1240:4511 with SMTP id ba35-20020a056830462300b006b712404511mr411060otb.0.1687435688054; Thu, 22 Jun 2023 05:08:08 -0700 (PDT) Received: from citadel.. (047-026-243-217.res.spectrum.com. [47.26.243.217]) by smtp.gmail.com with ESMTPSA id m2-20020a4ae842000000b0054f85f67f31sm2705773oom.46.2023.06.22.05.08.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jun 2023 05:08:07 -0700 (PDT) From: Brian Gerst To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: Thomas Gleixner , Borislav Petkov , "H . Peter Anvin" , Peter Zijlstra , Sami Tolvanen , alyssa.milburn@linux.intel.com, keescook@chromium.org, jpoimboe@kernel.org, joao@overdrivepizza.com, tim.c.chen@linux.intel.com, Brian Gerst Subject: [PATCH 0/2] x86: Rewrite ret_from_fork() in C Date: Thu, 22 Jun 2023 08:07:48 -0400 Message-ID: <20230622120750.5549-1-brgerst@gmail.com> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When kCFI is enabled, special handling is needed for the indirect call to the kernel thread function. Handling this in pure assembly is not simple, so moving it to C is more appropriate. Instead of moving just the indirect call to C as Peter Zijlstra has proposed, this patchset rewrites the whole ret_from_fork() function in C (other than some necessary asm glue remaning). Brian Gerst (2): x86/32: Remove schedule_tail_wrapper() x86: Rewrite ret_from_fork() in C arch/x86/entry/entry_32.S | 54 ++++++++------------------------ arch/x86/entry/entry_64.S | 35 ++++++--------------- arch/x86/include/asm/switch_to.h | 4 ++- arch/x86/kernel/process.c | 22 ++++++++++++- 4 files changed, 47 insertions(+), 68 deletions(-) -- 2.41.0