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=-10.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 CCF29C4CEC9 for ; Thu, 12 Sep 2019 20:08:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB7F8208C2 for ; Thu, 12 Sep 2019 20:08:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727504AbfILUIF (ORCPT ); Thu, 12 Sep 2019 16:08:05 -0400 Received: from mga01.intel.com ([192.55.52.88]:35554 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727338AbfILUH5 (ORCPT ); Thu, 12 Sep 2019 16:07:57 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Sep 2019 13:07:57 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,489,1559545200"; d="scan'208";a="336688246" Received: from chang-linux-3.sc.intel.com ([172.25.66.185]) by orsmga004.jf.intel.com with ESMTP; 12 Sep 2019 13:07:56 -0700 From: "Chang S. Bae" To: linux-kernel@vger.kernel.org Cc: ravi.v.shankar@intel.com, chang.seok.bae@intel.com, Thomas Gleixner , Borislav Petkov , Andy Lutomirski , "H . Peter Anvin" , Dave Hansen , Tony Luck , Andi Kleen , Vegard Nossum Subject: [PATCH v8 10/17] x86/entry/64: Introduce the FIND_PERCPU_BASE macro Date: Thu, 12 Sep 2019 13:06:51 -0700 Message-Id: <1568318818-4091-11-git-send-email-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1568318818-4091-1-git-send-email-chang.seok.bae@intel.com> References: <1568318818-4091-1-git-send-email-chang.seok.bae@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org GS base is used to find per-CPU data in the kernel. But when GS base is unknown, the per-CPU base can be found from the per_cpu_offset table with a CPU NR. The CPU NR is extracted from the limit field of the CPUNODE entry in GDT, or by the RDPID instruction. This is a prerequisite for using FSGSBASE in the low level entry code. Also, add the GAS-compatible RDPID macro as binutils 2.21 does not support it. Support is added in version 2.27. Suggested-by: H. Peter Anvin Signed-off-by: Chang S. Bae Reviewed-by: Tony Luck Cc: Thomas Gleixner Cc: Borislav Petkov Cc: Andy Lutomirski Cc: H. Peter Anvin Cc: Dave Hansen Cc: Tony Luck Cc: Andi Kleen Cc: Vegard Nossum --- Changes from v7: * No code change * Massaged changelog by Thomas * Used 'GS base' consistently, instead of 'GSBASE' --- arch/x86/entry/calling.h | 34 ++++++++++++++++++++++++++++++++++ arch/x86/include/asm/inst.h | 15 +++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index 515c0ce..c222302 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -6,6 +6,7 @@ #include #include #include +#include /* @@ -347,6 +348,39 @@ For 32-bit we have the following conventions - kernel is built with #endif .endm +#ifdef CONFIG_SMP + +/* + * CPU/node NR is loaded from the limit (size) field of a special segment + * descriptor entry in GDT. + */ +.macro LOAD_CPU_AND_NODE_SEG_LIMIT reg:req + movq $__CPUNODE_SEG, \reg + lsl \reg, \reg +.endm + +/* + * Fetch the per-CPU GS base value for this processor and put it in @reg. + * We normally use %gs for accessing per-CPU data, but we are setting up + * %gs here and obviously can not use %gs itself to access per-CPU data. + */ +.macro GET_PERCPU_BASE reg:req + ALTERNATIVE \ + "LOAD_CPU_AND_NODE_SEG_LIMIT \reg", \ + "RDPID \reg", \ + X86_FEATURE_RDPID + andq $VDSO_CPUNODE_MASK, \reg + movq __per_cpu_offset(, \reg, 8), \reg +.endm + +#else + +.macro GET_PERCPU_BASE reg:req + movq pcpu_unit_offsets(%rip), \reg +.endm + +#endif /* CONFIG_SMP */ + /* * This does 'call enter_from_user_mode' unless we can avoid it based on * kernel config or using the static jump infrastructure. diff --git a/arch/x86/include/asm/inst.h b/arch/x86/include/asm/inst.h index f5a796d..d063841 100644 --- a/arch/x86/include/asm/inst.h +++ b/arch/x86/include/asm/inst.h @@ -306,6 +306,21 @@ .endif MODRM 0xc0 movq_r64_xmm_opd1 movq_r64_xmm_opd2 .endm + +.macro RDPID opd + REG_TYPE rdpid_opd_type \opd + .if rdpid_opd_type == REG_TYPE_R64 + R64_NUM rdpid_opd \opd + .else + R32_NUM rdpid_opd \opd + .endif + .byte 0xf3 + .if rdpid_opd > 7 + PFX_REX rdpid_opd 0 + .endif + .byte 0x0f, 0xc7 + MODRM 0xc0 rdpid_opd 0x7 +.endm #endif #endif -- 2.7.4