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 A543DC25B47 for ; Mon, 23 Oct 2023 21:17:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231443AbjJWVRm (ORCPT ); Mon, 23 Oct 2023 17:17:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230483AbjJWVRj (ORCPT ); Mon, 23 Oct 2023 17:17:39 -0400 Received: from mail-ot1-x32d.google.com (mail-ot1-x32d.google.com [IPv6:2607:f8b0:4864:20::32d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 074EB10A for ; Mon, 23 Oct 2023 14:17:38 -0700 (PDT) Received: by mail-ot1-x32d.google.com with SMTP id 46e09a7af769-6ce2988d62eso2416994a34.1 for ; Mon, 23 Oct 2023 14:17:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1698095857; x=1698700657; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=RjuCpZkTOQea0lODerpoBhUBPsuFVkeaJK9dO2sch2U=; b=P8nEBo+/FJO88zARo8MrYpwquNuXA5LnkT+jrDoVzglCyxNYnJFmc49OFTC1KYEFmT AeO16lxgOcdCdtfv2ceLGFyNE37AkB+0xhSniRD+uiPvq1t6XtpugE0vxF+2T7FRCXi5 ZDNd3rtRlT7fr8/g0kywJkBOWxfMj3Y0TZO1HQCZ55hesLsQOuQAm6YCE1rAEluEBiM6 v6jLSsn19zN69j+HtbkvuT/V/ZUSIiktvQ4PUecCbRa/QxDfMXYqiUC6BqroDqXDdWLq k6pyEZXdpoPjqOsWJQMjjDDZaEdA4W7d7/jEvAn4RZWuh2fFLgKNbXEc4S5SPmu1I4X8 t3sw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698095857; x=1698700657; 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=RjuCpZkTOQea0lODerpoBhUBPsuFVkeaJK9dO2sch2U=; b=PpIMeFaHMQiY8at7ohkRcfzCDduzv/I+tgVjSKUL+8mO5lnM0jczPbCWp1fWh12WoS m/B3Km5tOaynV7U4nq97z/tCNc2c16XXGDxzMgbqSAxmD5K/c6PkEz52b11Nn6LKvhZx n3Ozp4g5gkoscwp2pje32lEAQvytPU06zDDIgVlS6Pbfayjwe3MSjBegT4kct1VaZvR/ 8+H1iGwtW4Ct0LaMWO3FjjtLBjCkz7RzKKu3glkp87JQt2j/NCqpiu1NCincjq1vFXOX Wkw0Pb5Wk6KJGZ0t/c4Bkf6zX7ReE4k+VHzjQ9VsspNqVGWuAGfNB+PASI381U6pP+9E GOUA== X-Gm-Message-State: AOJu0Yxl13hVnek1cLytYQXP21QEswbRjY5gfWQzDEFE0piig46OQcVk s1cRS8Vgg997Dd79ayK7y/m9bDK9RA== X-Google-Smtp-Source: AGHT+IHPczHusIo0syP63L85pDXFu9VHkCbL4GggPRnet55dLTKKwgYLPLohQCSMK3b2EOsc6wWbPw== X-Received: by 2002:a9d:6a13:0:b0:6bf:df:66d5 with SMTP id g19-20020a9d6a13000000b006bf00df66d5mr10673224otn.35.1698095856874; Mon, 23 Oct 2023 14:17:36 -0700 (PDT) Received: from citadel.lan ([2600:6c4a:4d3f:6d5c::1019]) by smtp.gmail.com with ESMTPSA id o139-20020a0dcc91000000b00583e52232f1sm3485430ywd.112.2023.10.23.14.17.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Oct 2023 14:17:36 -0700 (PDT) From: Brian Gerst To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: Ingo Molnar , Thomas Gleixner , Borislav Petkov , "H . Peter Anvin" , Peter Zijlstra , Uros Bizjak , Brian Gerst Subject: [PATCH 0/9] x86-64: Stack protector and percpu improvements Date: Mon, 23 Oct 2023 17:17:21 -0400 Message-ID: <20231023211730.40566-1-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 Currently, x86-64 uses an unusual per-cpu layout, where the percpu section is linked at absolute address 0. The reason behind this is that older GCC versions placed the stack protector (if enabled) at a fixed offset from the GS segment base. Since the GS segement is also used for percpu variables, this forced the current layout. GCC since version 8.1 supports a configurable location for the stack protector value, which allows removal of the restriction on how the percpu section is linked. This allows the percpu section to be linked normally, like most other architectures. In turn, this allows removal of code that was needed to support the zero-based percpu section. P.S.: I posted this series back in 2021, and at the time it appeared that GCC 8.1 was too recent (released May 2, 2018) to be a requirement to keep stack protector support. Two years later, support for the new compiler options should be much more widespread. Brian Gerst (9): x86/stackprotector/32: Remove stack protector test script x86/boot: Disable stack protector for early boot code x86/stackprotector/64: Convert stack protector to normal percpu variable x86/percpu/64: Remove fixed_percpu_data x86/percpu/64: Use relative percpu offsets x86/boot/64: Remove inverse relocations x86/percpu/64: Remove INIT_PER_CPU macros percpu: Remove PER_CPU_FIRST_SECTION kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU arch/x86/Kconfig | 7 +- arch/x86/Makefile | 19 +-- arch/x86/boot/compressed/misc.c | 14 +-- arch/x86/entry/entry_64.S | 2 +- arch/x86/include/asm/percpu.h | 22 ---- arch/x86/include/asm/processor.h | 28 +---- arch/x86/include/asm/stackprotector.h | 37 ++---- arch/x86/kernel/Makefile | 2 + arch/x86/kernel/asm-offsets_64.c | 6 - arch/x86/kernel/cpu/common.c | 8 +- arch/x86/kernel/head_64.S | 10 +- arch/x86/kernel/irq_64.c | 1 - arch/x86/kernel/setup_percpu.c | 12 +- arch/x86/kernel/vmlinux.lds.S | 35 ------ arch/x86/tools/relocs.c | 136 +--------------------- arch/x86/xen/xen-head.S | 6 +- include/asm-generic/vmlinux.lds.h | 1 - include/linux/percpu-defs.h | 12 -- init/Kconfig | 11 +- kernel/kallsyms.c | 12 +- scripts/gcc-x86_32-has-stack-protector.sh | 8 -- scripts/gcc-x86_64-has-stack-protector.sh | 4 - scripts/kallsyms.c | 80 +++---------- scripts/link-vmlinux.sh | 4 - 24 files changed, 60 insertions(+), 417 deletions(-) delete mode 100755 scripts/gcc-x86_32-has-stack-protector.sh delete mode 100755 scripts/gcc-x86_64-has-stack-protector.sh -- 2.41.0