From patchwork Mon Aug 8 10:10:50 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 73424 Delivered-To: patch@linaro.org Received: by 10.140.29.52 with SMTP id a49csp3135666qga; Mon, 8 Aug 2016 03:12:55 -0700 (PDT) X-Received: by 10.66.138.108 with SMTP id qp12mr160173550pab.65.1470651175579; Mon, 08 Aug 2016 03:12:55 -0700 (PDT) Return-Path: Received: from bombadil.infradead.org (bombadil.infradead.org. [2001:1868:205::9]) by mx.google.com with ESMTPS id o78si36310062pfi.291.2016.08.08.03.12.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 08 Aug 2016 03:12:55 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org designates 2001:1868:205::9 as permitted sender) client-ip=2001:1868:205::9; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org designates 2001:1868:205::9 as permitted sender) smtp.mailfrom=linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1bWhWq-0003Pg-E6; Mon, 08 Aug 2016 10:11:28 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1bWhWn-0003MV-6N for linux-arm-kernel@lists.infradead.org; Mon, 08 Aug 2016 10:11:26 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4A1C228; Mon, 8 Aug 2016 03:12:29 -0700 (PDT) Received: from leverpostej.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 2D2713F487; Mon, 8 Aug 2016 03:11:02 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] arm64: suspend: avoid potential TLB conflict Date: Mon, 8 Aug 2016 11:10:50 +0100 Message-Id: <1470651050-18291-1-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160808_031125_299905_C76B28FA X-CRM114-Status: GOOD ( 11.99 ) X-Spam-Score: -8.3 (--------) X-Spam-Report: SpamAssassin version 3.4.0 on bombadil.infradead.org summary: Content analysis details: (-8.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at http://www.dnswl.org/, high trust [217.140.101.70 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -1.4 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Catalin Marinas , Lorenzo Pieralisi , James Morse , Will Deacon MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org In create_safe_exec_page we install a set of global mappings in TTBR0, then subsequently invalidate TLBs. While TTBR0 points at the zero page, and the TLBs should be free of stale global entries, we may have stale ASID-tagged entries (e.g. from the EFI runtime services mappings) for the same VAs. Per the ARM ARM these ASID-tagged entries may conflict with newly-allocated global entries, and we must follow a Break-Before-Make approach to avoid issues resulting from this. This patch reworks create_safe_exec_page to invalidate TLBs while the zero page is still in place, ensuring that there are no potential conflicts when the new TTBR0 value is installed. As a single CPU is online while this code executes, we do not need to perform broadcast TLB maintenance, and can call local_flush_tlb_all(), which also subsumes some barriers. The remaining assembly is converted to use write_sysreg() and isb(). Other than this, we safely manipulate TTBRs in the hibernate dance. The code we install as part of the new TTBR0 mapping (the hibernated kernel's swsusp_arch_suspend_exit) installs a zero page into TTBR1, invalidates TLBs, then installs its preferred value. Upon being restored to the middle of swsusp_arch_suspend, the new image will call __cpu_suspend_exit, which will call cpu_uninstall_idmap, installing the zero page in TTBR0 and invalidating all TLB entries. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: James Morse Cc: Lorenzo Pieralisi Cc: Will Deacon Fixes: 82869ac57b5d3b55 ("arm64: kernel: Add support for hibernate/suspend-to-disk") --- arch/arm64/kernel/hibernate.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) -- 1.9.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c index 21ab5df..c59d3e4 100644 --- a/arch/arm64/kernel/hibernate.c +++ b/arch/arm64/kernel/hibernate.c @@ -35,6 +35,7 @@ #include #include #include +#include #include /* @@ -217,12 +218,16 @@ static int create_safe_exec_page(void *src_start, size_t length, set_pte(pte, __pte(virt_to_phys((void *)dst) | pgprot_val(PAGE_KERNEL_EXEC))); - /* Load our new page tables */ - asm volatile("msr ttbr0_el1, %0;" - "isb;" - "tlbi vmalle1is;" - "dsb ish;" - "isb" : : "r"(virt_to_phys(pgd))); + /* + * Load our new page tables. TTBR0 currently points to the zero page, + * and the TLBs should be free of global entries, but may contain stale + * ASID-tagged entries (e.g. from the EFI runtime services). A strict + * BBM approach requires that we destroy these before installing + * overlapping global mappings. + */ + local_flush_tlb_all(); + write_sysreg(virt_to_phys(pgd), ttbr0_el1); + isb(); *phys_dst_addr = virt_to_phys((void *)dst);