From patchwork Sun Nov 4 13:53:09 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sasha Levin X-Patchwork-Id: 150111 Delivered-To: patch@linaro.org Received: by 2002:a2e:299d:0:0:0:0:0 with SMTP id p29-v6csp1538560ljp; Sun, 4 Nov 2018 05:53:44 -0800 (PST) X-Google-Smtp-Source: AJdET5cv5pLogqe8nqWgAJCFijjeLXCaOzRRWMLpkq9nLuYYuGWq82PJxAmEHbcXfhS9U8pCMbeK X-Received: by 2002:a62:adb:: with SMTP id 88-v6mr4878231pfk.121.1541339624297; Sun, 04 Nov 2018 05:53:44 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1541339624; cv=none; d=google.com; s=arc-20160816; b=LOtkdNr4KpytYIOJtO6rIGATHTFQbG0+jYEOYxXLQJCN1yOMGb115ArU13SvyL4pF2 QFrEHCYsH6ghNDGw59yGOowq1ReR1m9Yz0T1RfTzCvXw7dg+xeMXlHhA6nMUL//Rcl0Z +N+fI2mZ/Miz0oN6aH3jBRXjdLu7/zdY1OokVMOjI24AfbdAZ4ZKlM2+HVwBoVqCtXmH ze3DUAnJllSATymtiQlJWeNVXyPG1bWe9DBKQR+331abpj2ZFnAZ4JOml6WOtTMR92CW t6PxuJwdoQ1N/Dawc1H32xd7iXcXFfR6q4DKa3ClH/PTExVI8KPXNhXTJnjgeVnQBD1O nnOA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature; bh=lkbZMfD9Nv8TDi2C6BP0wmJkMT83YATED7jnjq3Vliw=; b=iFNZOH/bs5bPWQdQE3Nh83caQkj3KeTDCHJDRsFWwcFVSGxuUSkdrwvjrSIMlLpH6C 18OmnUFjrquXg0wbvqsbluUPTKuQPB7V8VxdM/7meVGlQYzg1eK4W9Nb39sHPRyQhL9h g8ehshLuuPak/7cCtOMd/HZJBj+pHlDJkizlsBLORHlbsrPlFEeEhE4REaCBOl7/TfYA n9ufdNkI8UGGYxvT6yYcBnwz7OPA+V/85bvo0zle+lyQpEkjdKYdtce4PhVQ3Dt9m9T3 ydlUuulVxejAD2rpQGuxFVVBm1OYJHFHYhbnJ5Thcw+BQERfsu4esetDEeu1Ms2UvpEE HJSA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=hM1OvUU9; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id 1-v6si14488277plx.91.2018.11.04.05.53.44; Sun, 04 Nov 2018 05:53:44 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=hM1OvUU9; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731291AbeKDXIq (ORCPT + 32 others); Sun, 4 Nov 2018 18:08:46 -0500 Received: from mail.kernel.org ([198.145.29.99]:47762 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731227AbeKDXIo (ORCPT ); Sun, 4 Nov 2018 18:08:44 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A60292086C; Sun, 4 Nov 2018 13:53:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541339620; bh=A6/X4YppExsa6bwHtOV0hd2CFF2T1ib/JdwbcAAfrFQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hM1OvUU95uSW1kpyYURjJdERNxOWIwgWla/AR6RpIdHmEYBtgkVUc75Fnegan3JZt +Tdikilfq+7vO+9U4GK7A+SuLhIoMDP1pfzbZ8RsK5N8pynArtDeiVC569Wjk7ehMT CVOzNh1ZQAepmmoEDuu0gEqNwZ/i/WUhTPVosCW0= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Tomi Valkeinen , Peter Ujfalusi , Sasha Levin Subject: [PATCH AUTOSEL 4.14 14/30] drm/omap: fix memory barrier bug in DMM driver Date: Sun, 4 Nov 2018 08:53:09 -0500 Message-Id: <20181104135325.88524-14-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181104135325.88524-1-sashal@kernel.org> References: <20181104135325.88524-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tomi Valkeinen [ Upstream commit 538f66ba204944470a653a4cccc5f8befdf97c22 ] A DMM timeout "timed out waiting for done" has been observed on DRA7 devices. The timeout happens rarely, and only when the system is under heavy load. Debugging showed that the timeout can be made to happen much more frequently by optimizing the DMM driver, so that there's almost no code between writing the last DMM descriptors to RAM, and writing to DMM register which starts the DMM transaction. The current theory is that a wmb() does not properly ensure that the data written to RAM is observable by all the components in the system. This DMM timeout has caused interesting (and rare) bugs as the error handling was not functioning properly (the error handling has been fixed in previous commits): * If a DMM timeout happened when a GEM buffer was being pinned for display on the screen, a timeout error would be shown, but the driver would continue programming DSS HW with broken buffer, leading to SYNCLOST floods and possible crashes. * If a DMM timeout happened when other user (say, video decoder) was pinning a GEM buffer, a timeout would be shown but if the user handled the error properly, no other issues followed. * If a DMM timeout happened when a GEM buffer was being released, the driver does not even notice the error, leading to crashes or hang later. This patch adds wmb() and readl() calls after the last bit is written to RAM, which should ensure that the execution proceeds only after the data is actually in RAM, and thus observable by DMM. The read-back should not be needed. Further study is required to understand if DMM is somehow special case and read-back is ok, or if DRA7's memory barriers do not work correctly. Signed-off-by: Tomi Valkeinen Signed-off-by: Peter Ujfalusi Signed-off-by: Sasha Levin --- drivers/gpu/drm/omapdrm/omap_dmm_tiler.c | 11 +++++++++++ 1 file changed, 11 insertions(+) -- 2.17.1 diff --git a/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c b/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c index df05fe53c399..32901c6fe3df 100644 --- a/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c +++ b/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c @@ -273,6 +273,17 @@ static int dmm_txn_commit(struct dmm_txn *txn, bool wait) } txn->last_pat->next_pa = 0; + /* ensure that the written descriptors are visible to DMM */ + wmb(); + + /* + * NOTE: the wmb() above should be enough, but there seems to be a bug + * in OMAP's memory barrier implementation, which in some rare cases may + * cause the writes not to be observable after wmb(). + */ + + /* read back to ensure the data is in RAM */ + readl(&txn->last_pat->next_pa); /* write to PAT_DESCR to clear out any pending transaction */ dmm_write(dmm, 0x0, reg[PAT_DESCR][engine->id]); From patchwork Sun Nov 4 13:53:12 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sasha Levin X-Patchwork-Id: 150119 Delivered-To: patch@linaro.org Received: by 2002:a2e:299d:0:0:0:0:0 with SMTP id p29-v6csp1543138ljp; Sun, 4 Nov 2018 06:00:01 -0800 (PST) X-Google-Smtp-Source: AJdET5eIhBnvHHNFB/l++nhj5pHTMFv14x0U/OIRy3BbA2NhR9led3C7uYmJjItZgwWCzpCDyFDB X-Received: by 2002:a17:902:7445:: with SMTP id e5-v6mr8497349plt.325.1541340001118; Sun, 04 Nov 2018 06:00:01 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1541340001; cv=none; d=google.com; s=arc-20160816; b=H1BHRX7DwuuqvTqEr3FqmdbQg3Edib/PQpLMvrlu55yio9l+g42m2fwOWaPTEANNST PWooI45l/9BElD/LxqyK/ZIuL6deOCfUFqZSvOiuDmdKIfkrxzXa154/bFmiCwN6UgsJ rKh1k7JtoS844HCkTm13mPVWh8ATcpdJeMa54n0GcDZqZTJPsPtVbjrANCYkQRFv+61H KDJPGNbKs9VLvlOvaSedjVop1STrCm3mrZrfVk/trlsHd67gQJ3xbvOO+1n9b80YzViT cwNHQIHt1oKM4ik9LblGydq7hh/WS7FOkk6qpd6thE49VWld+JrYYW/cDCEAdGJp1LBp KmJw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature; bh=M9YJTHASomuPid1YBC4H5TP0ehf3Jb/H6oWwX9qj8t4=; b=rulsIRtk39PvoT9j7cb6BVdKoLs+FfcYldF6sho4Mhx3GOtWu56ePbFFTpvMseAAWq HfToVMc/tbCzcS9fmTDMau8QwtjIxT/AQGmqeGk1BqgsToNw3xjL42YjXX7EGXR7Uy2z zxtPJAsWZ3fZWDKz5rg5Dg1lOUw7c39uf3LYt8SPiD3A+d0euw3bwyXkcjvhgDsvvsLZ IRY4545MnFIdwRI92k3ZJTQSkDfeUIPZO0nrEcm7sXqg+SxlnIqV/US3iJHqP2sH/kuX WpFYhFWgtxCEZbielIc67bDK8lxvCXat/1AnGLcFCq6HnXqz9/5Q/74ePxY3oI+PrNKy qZTg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=OvRx0zqJ; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id u18-v6si16843737pfm.288.2018.11.04.06.00.00; Sun, 04 Nov 2018 06:00:01 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=OvRx0zqJ; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731830AbeKDXPF (ORCPT + 32 others); Sun, 4 Nov 2018 18:15:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:47858 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731292AbeKDXIr (ORCPT ); Sun, 4 Nov 2018 18:08:47 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 936CA20862; Sun, 4 Nov 2018 13:53:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541339623; bh=xZXo0NyrnN9ENqHCMkPUPa3ZpIa13R7fzVlMeDCtsmY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OvRx0zqJqzJ7ZPwDeeHNHK2MVKfBYYBuL7HLuI0iH1miQJR/XHofRunu+XURtOE8P kav9PhSVlo4Ewt9anl9U8iKQBe4rSpRIUvWbcmqa7hYWacBpHgOtRa940VaTgMKTz/ MKy414TnVKzATQY2hLndHStQRyr6G54E2BIvMADU= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: John Garry , Xinliang Liu , Sasha Levin Subject: [PATCH AUTOSEL 4.14 17/30] drm/hisilicon: hibmc: Do not carry error code in HiBMC framebuffer pointer Date: Sun, 4 Nov 2018 08:53:12 -0500 Message-Id: <20181104135325.88524-17-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181104135325.88524-1-sashal@kernel.org> References: <20181104135325.88524-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: John Garry [ Upstream commit 331d880b35a76b5de0eec8cbcecbf615d758a5f9 ] In hibmc_drm_fb_create(), when the call to hibmc_framebuffer_init() fails with error, do not store the error code in the HiBMC device frame-buffer pointer, as this will be later checked for non-zero value in hibmc_fbdev_destroy() when our intention is to check for a valid function pointer. This fixes the following crash: [ 9.699791] Unable to handle kernel NULL pointer dereference at virtual address 000000000000001a [ 9.708672] Mem abort info: [ 9.711489] ESR = 0x96000004 [ 9.714570] Exception class = DABT (current EL), IL = 32 bits [ 9.720551] SET = 0, FnV = 0 [ 9.723631] EA = 0, S1PTW = 0 [ 9.726799] Data abort info: [ 9.729702] ISV = 0, ISS = 0x00000004 [ 9.733573] CM = 0, WnR = 0 [ 9.736566] [000000000000001a] user address but active_mm is swapper [ 9.742987] Internal error: Oops: 96000004 [#1] PREEMPT SMP [ 9.748614] Modules linked in: [ 9.751694] CPU: 16 PID: 293 Comm: kworker/16:1 Tainted: G W 4.19.0-rc4-next-20180920-00001-g9b0012c #322 [ 9.762681] Hardware name: Huawei Taishan 2280 /D05, BIOS Hisilicon D05 IT21 Nemo 2.0 RC0 04/18/2018 [ 9.771915] Workqueue: events work_for_cpu_fn [ 9.776312] pstate: 60000005 (nZCv daif -PAN -UAO) [ 9.781150] pc : drm_mode_object_put+0x0/0x20 [ 9.785547] lr : hibmc_fbdev_fini+0x40/0x58 [ 9.789767] sp : ffff00000af1bcf0 [ 9.793108] x29: ffff00000af1bcf0 x28: 0000000000000000 [ 9.798473] x27: 0000000000000000 x26: ffff000008f66630 [ 9.803838] x25: 0000000000000000 x24: ffff0000095abb98 [ 9.809203] x23: ffff8017db92fe00 x22: ffff8017d2b13000 [ 9.814568] x21: ffffffffffffffea x20: ffff8017d2f80018 [ 9.819933] x19: ffff8017d28a0018 x18: ffffffffffffffff [ 9.825297] x17: 0000000000000000 x16: 0000000000000000 [ 9.830662] x15: ffff0000092296c8 x14: ffff00008939970f [ 9.836026] x13: ffff00000939971d x12: ffff000009229940 [ 9.841391] x11: ffff0000085f8fc0 x10: ffff00000af1b9a0 [ 9.846756] x9 : 000000000000000d x8 : 6620657a696c6169 [ 9.852121] x7 : ffff8017d3340580 x6 : ffff8017d4168000 [ 9.857486] x5 : 0000000000000000 x4 : ffff8017db92fb20 [ 9.862850] x3 : 0000000000002690 x2 : ffff8017d3340480 [ 9.868214] x1 : 0000000000000028 x0 : 0000000000000002 [ 9.873580] Process kworker/16:1 (pid: 293, stack limit = 0x(____ptrval____)) [ 9.880788] Call trace: [ 9.883252] drm_mode_object_put+0x0/0x20 [ 9.887297] hibmc_unload+0x1c/0x80 [ 9.890815] hibmc_pci_probe+0x170/0x3c8 [ 9.894773] local_pci_probe+0x3c/0xb0 [ 9.898555] work_for_cpu_fn+0x18/0x28 [ 9.902337] process_one_work+0x1e0/0x318 [ 9.906382] worker_thread+0x228/0x450 [ 9.910164] kthread+0x128/0x130 [ 9.913418] ret_from_fork+0x10/0x18 [ 9.917024] Code: a94153f3 a8c27bfd d65f03c0 d503201f (f9400c01) [ 9.923180] ---[ end trace 2695ffa0af5be375 ]--- Fixes: d1667b86795a ("drm/hisilicon/hibmc: Add support for frame buffer") Signed-off-by: John Garry Reviewed-by: Xinliang Liu Signed-off-by: Xinliang Liu Signed-off-by: Sasha Levin --- drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_fbdev.c | 1 + 1 file changed, 1 insertion(+) -- 2.17.1 diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_fbdev.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_fbdev.c index b92595c477ef..8bd29075ae4e 100644 --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_fbdev.c +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_fbdev.c @@ -122,6 +122,7 @@ static int hibmc_drm_fb_create(struct drm_fb_helper *helper, hi_fbdev->fb = hibmc_framebuffer_init(priv->dev, &mode_cmd, gobj); if (IS_ERR(hi_fbdev->fb)) { ret = PTR_ERR(hi_fbdev->fb); + hi_fbdev->fb = NULL; DRM_ERROR("failed to initialize framebuffer: %d\n", ret); goto out_release_fbi; } From patchwork Sun Nov 4 13:53:17 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sasha Levin X-Patchwork-Id: 150118 Delivered-To: patch@linaro.org Received: by 2002:a2e:299d:0:0:0:0:0 with SMTP id p29-v6csp1542765ljp; Sun, 4 Nov 2018 05:59:33 -0800 (PST) X-Google-Smtp-Source: AJdET5cl14JGEt0fs0vwOjri17FCr5B7IeG42sINVZeuMBeL+UCEpwl9b/dgKoeN/Ab2N1Moc6t/ X-Received: by 2002:a63:e348:: with SMTP id o8mr16800389pgj.158.1541339973166; Sun, 04 Nov 2018 05:59:33 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1541339973; cv=none; d=google.com; s=arc-20160816; b=EP0mvQsCo0deZGkJviJJvFh998wplqz5oCH96AklFlTRE2r07Utny4o/KFH8SZZces QtdZY1qOl5ZLQoqCnYx/O3ethEPXuV6D8XyWTAppFTj9U9owJReODCez+CBjyzA3bIBb ZjtMZXj5Bf/AebrCedYcXTIdmxn7yKm+lDUvQJ37w8+UHbKNKddZRMLSk/85KTAXc7sL 5bQvoFGDCyXZMKq2OEB02x8sN+oEBuXjUZIsMf2q1KDakWwRsUFjMpPgM5N8byDI6CxA 9e2pILWcwmgnu/lsDDuqMQ5Knj+loHL0QPnifVJioSyIo+oklIMFHiFl/Tp9phTWPSvT a70w== ARC-Message-Signature: i=1; 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[209.132.180.67]) by mx.google.com with ESMTP id t20si9297230pgl.211.2018.11.04.05.59.32; Sun, 04 Nov 2018 05:59:33 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=lgKQXVCT; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731722AbeKDXOg (ORCPT + 32 others); Sun, 4 Nov 2018 18:14:36 -0500 Received: from mail.kernel.org ([198.145.29.99]:48046 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731341AbeKDXIw (ORCPT ); Sun, 4 Nov 2018 18:08:52 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7B9102085B; Sun, 4 Nov 2018 13:53:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541339628; bh=M+nlvSSWJ6LODF+My80H6Ek0nsvcQgbQobsSHZ3QULs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lgKQXVCTjMeBx2Lw1T/9/PSYwSYOV1mH8nSJPSw2XMx4HOHPcJAMJjsy6MCKdADrn huEhMYY8R7wVxzZ8I+wJ0z/LFF1L4hzqctciXCZ8YgKJsvVOmKFFQO1nl+PHpNiLKw nqDtwUPjyKusavh1TKNHqOtnRJVKM1WqdWNBOt7o= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Joel Stanley , Michael Ellerman , Sasha Levin Subject: [PATCH AUTOSEL 4.14 22/30] powerpc/boot: Ensure _zimage_start is a weak symbol Date: Sun, 4 Nov 2018 08:53:17 -0500 Message-Id: <20181104135325.88524-22-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181104135325.88524-1-sashal@kernel.org> References: <20181104135325.88524-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joel Stanley [ Upstream commit ee9d21b3b3583712029a0db65a4b7c081d08d3b3 ] When building with clang crt0's _zimage_start is not marked weak, which breaks the build when linking the kernel image: $ objdump -t arch/powerpc/boot/crt0.o |grep _zimage_start$ 0000000000000058 g .text 0000000000000000 _zimage_start ld: arch/powerpc/boot/wrapper.a(crt0.o): in function '_zimage_start': (.text+0x58): multiple definition of '_zimage_start'; arch/powerpc/boot/pseries-head.o:(.text+0x0): first defined here Clang requires the .weak directive to appear after the symbol is declared. The binutils manual says: This directive sets the weak attribute on the comma separated list of symbol names. If the symbols do not already exist, they will be created. So it appears this is different with clang. The only reference I could see for this was an OpenBSD mailing list post[1]. Changing it to be after the declaration fixes building with Clang, and still works with GCC. $ objdump -t arch/powerpc/boot/crt0.o |grep _zimage_start$ 0000000000000058 w .text 0000000000000000 _zimage_start Reported to clang as https://bugs.llvm.org/show_bug.cgi?id=38921 [1] https://groups.google.com/forum/#!topic/fa.openbsd.tech/PAgKKen2YCY Signed-off-by: Joel Stanley Reviewed-by: Nick Desaulniers Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin --- arch/powerpc/boot/crt0.S | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) -- 2.17.1 diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S index dcf2f15e6797..32dfe6d083f3 100644 --- a/arch/powerpc/boot/crt0.S +++ b/arch/powerpc/boot/crt0.S @@ -47,8 +47,10 @@ p_end: .long _end p_pstack: .long _platform_stack_top #endif - .weak _zimage_start .globl _zimage_start + /* Clang appears to require the .weak directive to be after the symbol + * is defined. See https://bugs.llvm.org/show_bug.cgi?id=38921 */ + .weak _zimage_start _zimage_start: .globl _zimage_start_lib _zimage_start_lib: