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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id DDD36C433F5 for ; Wed, 8 Dec 2021 10:33:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=5SERgStgERiEYQK8IIZ2wCXuTe5wS4ST2pgv0igD9iY=; b=F6YDtoMKprtl5o 7UQfOdxyVsOqZVd5GzNT3cjoLhXPYgEjFHmujy7iVIlR4rBNzz1xqxigGocNd2fWYpjb5QwuKKi5G 0RFQl0DcR/QYwGCmnjOtkv5U4V4k1+sCZAgFejZ52dTQTuXd6zOGK8CQg/lb0+8OKQHCpYEu260FA KB4HPyFU5e3o0MuKyTmLK6BCGI40+bEHECsj5GIHPjIcLuthICwERc1tMhZl/0S5fimhE4/vzlj6q 9I1MOw4G+5zHWet5uiQ+r47XfUTCAobSUdiN+u8X/iHTj6OT7VI2Y055mqvvhlr0M8S8ebbXWzON+ yWUqhXHkGz6vbjBX5+GQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1muuFu-00C7IY-F5; Wed, 08 Dec 2021 10:32:58 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1muuFg-00C7FR-Mz; Wed, 08 Dec 2021 10:32:47 +0000 X-UUID: 213b942366b44b6f9c295d352565c605-20211208 X-UUID: 213b942366b44b6f9c295d352565c605-20211208 Received: from mtkcas66.mediatek.inc [(172.29.193.44)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 1481719843; Wed, 08 Dec 2021 03:32:41 -0700 Received: from mtkmbs10n1.mediatek.inc (172.21.101.34) by MTKMBS62N2.mediatek.inc (172.29.193.42) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 8 Dec 2021 02:22:38 -0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs10n1.mediatek.inc (172.21.101.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.792.15; Wed, 8 Dec 2021 18:22:37 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Wed, 8 Dec 2021 18:22:36 +0800 From: Mark-PK Tsai To: CC: , , , , , , , , , , , Subject: Re: [PATCH] arm: remove [_text, _stext) from kernel code resource Date: Wed, 8 Dec 2021 18:22:37 +0800 Message-ID: <20211208102237.19706-1-mark-pk.tsai@mediatek.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: References: MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211208_023244_782424_0602D972 X-CRM114-Status: GOOD ( 24.97 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org > On Wed, Dec 08, 2021 at 10:26:23AM +0800, Mark-PK Tsai wrote: > > > On Fri, Dec 03, 2021 at 10:14:16PM +0800, Mark-PK Tsai wrote: > > > > Remove the [_text, _stext) from Kernel Code. > > > > Although there are some startup code in head.text, they > > > > are freed to the buddy system after kernel boot. > > > > > > Hmm, I don't see it is being freed anywhere. Can you elaborate when and how > > > the range [_text, _stext) is freed? > > > > arm_memblock_init() reserve [KERNEL_START, KERNEL_END) which are defined as following. > > > > #define KERNEL_START _stext > > #define KERNEL_END _end > > > > free_low_memory_core_early() free all the non-reserved range in lowmem, > > so the range [_text, _stext) is also freed here. > > Right, I've misread KERNEL_START as if it was _text... > > > > > > > > And we have memory protection mechanism use this > > > > which have false alarm when some other IPs doing dma > > > > if the dma page frame is in the [_text, _stext). > > > > > > > > Below are my iomem resource and reserved memory information: > > > > console:/ # grep Kernel /proc/iomem > > > > 20208000-219fffff : Kernel code > > > > 21b00000-21c2e76f : Kernel data > > > > > > > > console:/ # cat /sys/kernel/debug/memblock/reserved > > > > 0: 0x20201000..0x20207fff > > > > 1: 0x20300000..0x21c2e76f > > > > > > What are the addresses of _text and _stext in your configuration? > > > > va pa > > c0008000 20208000 _text > > c0100000 20300000 _stext > > > > > > > > What these dumps are supposed to show here? > > > > > > > Below is the dump info after applied this patch. > > > > console:/ # grep Kernel /proc/iomem > > 20300000-219fffff : Kernel code > > 21b00000-21c2e76f : Kernel data > > > > console:/ # cat /sys/kernel/debug/memblock/reserved > > 0: 0x20201000..0x20207fff > > 1: 0x20300000..0x21c2e76f > > > > The difference is that Kernel Code resource match the reserved memblock 1 > > which is reserved in arm_memblock_init(). > > For that I'd extend the reservation in arm_memblock_init() to include > [_text, _stext). > > Even if the code there is not needed after init, at least we'll keep this > consistent with other architectures. > Extending the reservation in arm_memblock_init() will consume up to SECTION_SIZE memory for SECTION_SIZE alignment when CONFIG_STRICT_KERNEL_RWX=y. So we really don't want to extend the reservation because it affect the low RAM devices. And arm64_memblock_init() also reserve [_stext, _end) in the recent kernel. _______________________________________________ Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek