From patchwork Tue Jan 16 14:08:32 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 124716 Delivered-To: patch@linaro.org Received: by 10.46.64.148 with SMTP id r20csp1025881lje; Tue, 16 Jan 2018 06:08:39 -0800 (PST) X-Google-Smtp-Source: ACJfBosvwVqruB6uZiMeYe+kpZxKWGulaLYVssZe4kpybq/KqRsO/1ER3ApCiK44b7Sm7v/gu9mS X-Received: by 10.99.67.197 with SMTP id q188mr21455946pga.255.1516111719587; Tue, 16 Jan 2018 06:08:39 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1516111719; cv=none; d=google.com; s=arc-20160816; b=V8Ly7xHZhJwshGRpGoYQykEfZQtXj8+ybZP99toV1vw7OxwnUsRrf7r4Dh2NdNNL/B L680mhYHixlpsbdNbMovMESHGvLkBt0A5K0HYhqOD/b8az87BFTe5LCVNIJJzwkwKdYv ObnKHHnw+Bc9/+7+yQ1np9LuqJ9IdVLK82eSz7EMpVHxbzRUT4ZaAXFVrDaTnQMEAWk7 itnI9SQMuo2/Mqw9mtVWR7WqSsGioKBV+jDYEJQwoqiRV1ryDu7/5H2j4bCkh00zRNZY 6g3qqFcOPiYAI8Y2GwWF/TnMvZPn1/a77iHvcox3WU2ykAgHyF9xYEc9WS/TMDg6DNZB HXvA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:message-id:date:subject:cc:to:from :arc-authentication-results; bh=dF5KH8X3T1hDGq/SQFbAHUhb2JmHOBI9j23HNWp5WaE=; b=axzfKZHFbZVf9w/o1hP7mr+KkmhStYDEz7+4ghRxcFx58QDnh+Pk7fTvcqeT2sopZe X6lRdFm+tGaq1PFRvc9btvOQXlYNGX57krbHTlsKjv2qP26R0CSI7FsdguMExNPaR5FJ GLFcNbft0fT/aXAvrvj1twfGZd2OsYiZ/Ios3aY1EK+Ta2HgEOzWXzZZ2ffWsdIxdteu IMA6Q0nabPMGRXmzW8WXF3YCXz0ipbvRi95YbB2TMsXTrFAZ6PX4I36csUai0oGUghgr OwndJz3BjsG9Pivm0WEha7r0kksSWhaw4bZQfDPpoYR43apIiNnpDORJciziodidKs0U GYFA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-efi-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-efi-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id f12si1669085pgo.493.2018.01.16.06.08.39; Tue, 16 Jan 2018 06:08:39 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-efi-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-efi-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-efi-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750876AbeAPOIi (ORCPT + 2 others); Tue, 16 Jan 2018 09:08:38 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:55500 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750825AbeAPOIi (ORCPT ); Tue, 16 Jan 2018 09:08:38 -0500 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 D16231435; Tue, 16 Jan 2018 06:08:37 -0800 (PST) Received: from lakrids.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 9B4AB3F557; Tue, 16 Jan 2018 06:08:36 -0800 (PST) From: Mark Rutland To: ard.biesheuvel@linaro.org Cc: linux-arm-kernel@lists.infradead.org, will.deacon@arm.com, Mark Rutland , linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] efi/arm*: Only register page tables when they exist Date: Tue, 16 Jan 2018 14:08:32 +0000 Message-Id: <20180116140832.26731-1-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Currently the arm/arm64 runtime code registers the runtime servies pagetables with ptdump regardless of whether runtime services page tables have been created. As efi_mm.pgd is NULL in these cases, attempting to dump the efi page tables results in a NULL pointer dereference in the ptdump code: /sys/kernel/debug# cat efi_page_tables [ 479.522600] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 479.522715] Mem abort info: [ 479.522764] ESR = 0x96000006 [ 479.522850] Exception class = DABT (current EL), IL = 32 bits [ 479.522899] SET = 0, FnV = 0 [ 479.522937] EA = 0, S1PTW = 0 [ 479.528200] Data abort info: [ 479.528230] ISV = 0, ISS = 0x00000006 [ 479.528317] CM = 0, WnR = 0 [ 479.528317] user pgtable: 4k pages, 48-bit VAs, pgd = 0000000064ab0cb0 [ 479.528449] [0000000000000000] *pgd=00000000fbbe4003, *pud=00000000fb66e003, *pmd=0000000000000000 [ 479.528600] Internal error: Oops: 96000006 [#1] PREEMPT SMP [ 479.528664] Modules linked in: [ 479.528699] CPU: 0 PID: 2457 Comm: cat Not tainted 4.15.0-rc3-00065-g2ad2ee7ecb5c-dirty #7 [ 479.528799] Hardware name: FVP Base (DT) [ 479.528899] pstate: 00400009 (nzcv daif +PAN -UAO) [ 479.528941] pc : walk_pgd.isra.1+0x20/0x1d0 [ 479.529011] lr : ptdump_walk_pgd+0x30/0x50 [ 479.529105] sp : ffff00000bf4bc20 [ 479.529185] x29: ffff00000bf4bc20 x28: 0000ffff9d22e000 [ 479.529271] x27: 0000000000020000 x26: ffff80007b4c63c0 [ 479.529358] x25: 00000000014000c0 x24: ffff80007c098900 [ 479.529445] x23: ffff00000bf4beb8 x22: 0000000000000000 [ 479.529532] x21: ffff00000bf4bd70 x20: 0000000000000001 [ 479.529618] x19: ffff00000bf4bcb0 x18: 0000000000000000 [ 479.529760] x17: 000000000041a1c8 x16: ffff0000082139d8 [ 479.529800] x15: 0000ffff9d3c6030 x14: 0000ffff9d2527f4 [ 479.529924] x13: 00000000000003f3 x12: 0000000000000038 [ 479.530000] x11: 0000000000000003 x10: 0101010101010101 [ 479.530099] x9 : 0000000017e94050 x8 : 000000000000003f [ 479.530226] x7 : 0000000000000000 x6 : 0000000000000000 [ 479.530313] x5 : 0000000000000001 x4 : 0000000000000000 [ 479.530416] x3 : ffff000009069fd8 x2 : 0000000000000000 [ 479.530500] x1 : 0000000000000000 x0 : 0000000000000000 [ 479.530599] Process cat (pid: 2457, stack limit = 0x000000005d1b0e6f) [ 479.530660] Call trace: [ 479.530746] walk_pgd.isra.1+0x20/0x1d0 [ 479.530833] ptdump_walk_pgd+0x30/0x50 [ 479.530907] ptdump_show+0x10/0x20 [ 479.530920] seq_read+0xc8/0x470 [ 479.531023] full_proxy_read+0x60/0x90 [ 479.531100] __vfs_read+0x18/0x100 [ 479.531180] vfs_read+0x88/0x160 [ 479.531267] SyS_read+0x48/0xb0 [ 479.531299] el0_svc_naked+0x20/0x24 [ 479.531400] Code: 91400420 f90033a0 a90707a2 f9403fa0 (f9400000) [ 479.531499] ---[ end trace bfe8e28d8acb2b67 ]--- Segmentation fault Let's avoid this problem by only registering the tables after their successful creation, which is also less confusing when EFI runtime services are not in use. Signed-off-by: Mark Rutland Reported-by: Will Deacon Cc: Ard Biesheuvel Cc: linux-efi@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- drivers/firmware/efi/arm-runtime.c | 3 +++ 1 file changed, 3 insertions(+) -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Acked-by: Will Deacon diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c index 1cc41c3d6315..86a1ad17a32e 100644 --- a/drivers/firmware/efi/arm-runtime.c +++ b/drivers/firmware/efi/arm-runtime.c @@ -54,6 +54,9 @@ static struct ptdump_info efi_ptdump_info = { static int __init ptdump_init(void) { + if (!efi_enabled(EFI_RUNTIME_SERVICES)) + return 0; + return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables"); } device_initcall(ptdump_init);