From patchwork Fri Feb 21 02:47:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Vincent Chen X-Patchwork-Id: 11395271 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 056FD1395 for ; Fri, 21 Feb 2020 02:48:23 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CB60624654 for ; Fri, 21 Feb 2020 02:48:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Djac/37J"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=sifive.com header.i=@sifive.com header.b="MlB7DS0O" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CB60624654 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sifive.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: Content-Transfer-Encoding:Content-Type:MIME-Version:Message-Id:Date:Subject: To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=qSX2UQu5IIhqMnlLqXpGYvxqIimPf5Ry/x+uqa3y+Jc=; b=Djac/37JCZPUYD vma7uCuNCDKVa6eaCT8vIWZVey3Hzcig+XhwTDGBtco6jJu6Oo6gCfQv2JL+L/gA1e96wLZbw3RhA ahARzkilMNfnxmfQOHK/jJXLL4DGcppSbpm8q6JlAwA+/HC//dkmxoTrx4CKZDzA2IUDkSTetqWD8 yckER7DS5M6ilc09LHccSCNxWpEYBChNLWLysSjIwLT4tsetvCRu7gKISwHcZ7JAYlOYSBULRvrLs ky53y50/MCrSMgvr8vWe+viwTLaO2Rv6smxyLvQDYRIu63A25BJ3rA9LgXc++HTUADFDhF/g7HkbZ wIIlX+Xr+bfWnkr+1oIA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4yMV-00068w-6c; Fri, 21 Feb 2020 02:48:19 +0000 Received: from mail-pj1-x1041.google.com ([2607:f8b0:4864:20::1041]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4yMS-00068N-9g for linux-riscv@lists.infradead.org; Fri, 21 Feb 2020 02:48:17 +0000 Received: by mail-pj1-x1041.google.com with SMTP id m13so87032pjb.2 for ; Thu, 20 Feb 2020 18:48:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sifive.com; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=qSX2UQu5IIhqMnlLqXpGYvxqIimPf5Ry/x+uqa3y+Jc=; b=MlB7DS0OMKms2cMMv3cMMV2YROR1Xm/OhKtpxaoecilkrWlLmYbVRRGe8freMcA59/ u1JVUP4BQnFjPpJkasHLEuqbSMmXZb8/9dEOBgasMGOjMRhMix1EVG5K4BhVnAmy/CTx Dk8phtV0UTw9g3yUq5SMxDFbd5AXyYAqZ5dca1tuvtjH2CX+xUfvClhXlEJTRonelbPM HOhz2W322Jfm8MV9SQWWgd4SOLUSInmo8sf1FMMmlzMhecuQscnrgVAhmE9fsGA4Ap6y lk8yihWpRLrCyH8aAfPBpCKWh3dayruNgApaHeCD0qzEDv+9UfKV/WADtdL+Xx99F+wD qZVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=qSX2UQu5IIhqMnlLqXpGYvxqIimPf5Ry/x+uqa3y+Jc=; b=WGbGA9ve0KNRX8s2mP+zpXvMg9TY1UFX7c9R1TlU2qVNHCWCalGh2RmV0LDssgoIMK GofoNAQutq6ANzkYFqB9sCaLi9P+wubHS5U8tvzVlIzLd7LTZOlUhyH3zMOqf89wM1fb MAd9Kuvqzx2r4tYmFUIW9zvtWny7M0Sk4rq2QJOhG7AD9i63mj8EYcYkwbQCtMUgOxS/ oOKBY30YNM8mg3SS7Sk+E14Z70ux4tmH6Nqfu0x2pZCoGzG0/OOUMMWFcFGdEOLBuq85 Fiu0ZIAmhJCvxNKLWh4uPs9hluFkd8MjfAdMkRtxitXpY2Yc2wV0BEH+lL9XNlXiRaao 2i9w== X-Gm-Message-State: APjAAAVJxz69r8PA5ZpvoEV6HZ+sTcisUUe/6AHRw/hdK7227vyvhMOG PTpeobBDHlW61NldJOH1obF278f/475G2Q== X-Google-Smtp-Source: APXvYqyWZRmaSzd4oe2BIZ8IWN9MjeQCE9nXqWiFqtH/nVo5BWBMD+KDbaKl0ebM/QGwsWh5vgtifg== X-Received: by 2002:a17:90a:f492:: with SMTP id bx18mr340292pjb.118.1582253295329; Thu, 20 Feb 2020 18:48:15 -0800 (PST) Received: from VincentChen-ThinkPad-T480s.internal.sifive.com (220-132-236-182.HINET-IP.hinet.net. [220.132.236.182]) by smtp.gmail.com with ESMTPSA id 28sm618810pgl.42.2020.02.20.18.48.13 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 20 Feb 2020 18:48:14 -0800 (PST) From: Vincent Chen To: paul.walmsley@sifive.com, palmer@dabbelt.com Subject: [PATCH 0/2] solve static percpu symbol issue in module and refine code model of module Date: Fri, 21 Feb 2020 10:47:53 +0800 Message-Id: <1582253275-28181-1-git-send-email-vincent.chen@sifive.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200220_184816_370670_8285C762 X-CRM114-Status: GOOD ( 11.49 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.3 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Vincent Chen , linux-riscv@lists.infradead.org, deanbo422@gmail.com Sender: "linux-riscv" Errors-To: linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@lists.infradead.org The compiler uses the PIC-relative method to access static variables instead of GOT when the code model is PIC. Therefore, the limitation of the access range from the instruction to the symbol address is +-2GB. Under this circumstance, the kernel cannot load a kernel module if this module has static per-CPU symbols declared by DEFINE_PER_CPU(). The reason is that kernel relocates the .data..percpu section of the kernel module to the end of kernel's .data..percpu. Hence, the distance between the per-CPU symbols and the instruction will exceed the 2GB limits. To solve this problem, the kernel should place the loaded module in the memory area [&_end-2G, VMALLOC_END]. Because the loaded module locates in the region [＆_end-2G，VMALLOC_END] at runtime, the distance from the module start to the end of the kernel image does not exceed 2GB. Hence, the second patch changes the code model of the kernel module from PIC to medany to improve the performance of data access. Changes from v1->v2 1. Unify the definition of VMALLOC_MODULE_START 2. Modify the indent Vincent Chen (2): riscv: avoid the PIC offset of static percpu data in module beyond 2G limits riscv: Replace PIC with medany to improve data accessing in module arch/riscv/Makefile | 6 ++++-- arch/riscv/kernel/module.c | 18 ++++++++++++++++++ 2 files changed, 22 insertions(+), 2 deletions(-)