linux-kernel - [PATCH 5/5] x86: if kernel .text .data .bss are not marked as E820

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Date:	Fri, 24 Aug 2012 18:55:16 -0500
From:	Jacob Shin <jacob.shin@....com>
To:	X86-ML <x86@...nel.org>
CC:	LKML <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>, Yinghai Lu <yinghai@...nel.org>,
	Tejun Heo <tj@...nel.org>, Dave Young <dyoung@...hat.com>,
	Chao Wang <chaowang@...hat.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Borislav Petkov <borislav.petkov@....com>,
	Jacob Shin <jacob.shin@....com>
Subject: [PATCH 5/5] x86: if kernel .text .data .bss are not marked as E820_RAM, complain and fix

There could be cases where user supplied memmap=exactmap memory
mappings do not mark the region where the kernel .text .data and
.bss reside as E820_RAM as reported here:

https://lkml.org/lkml/2012/8/14/86

Handle it by complaining, and adding the range back into the e820.

Signed-off-by: Jacob Shin <jacob.shin@....com>
---
 arch/x86/kernel/setup.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 4217fb4..b84aceb5 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -926,6 +926,21 @@ void __init setup_arch(char **cmdline_p)
 	insert_resource(&iomem_resource, &data_resource);
 	insert_resource(&iomem_resource, &bss_resource);
 
+	/*
+	 * Complain if .text .data and .bss are not marked as E820_RAM and
+	 * attempt to fix it by adding the range. We may have a confused BIOS,
+	 * or the user may have incorrectly supplied it via memmap=exactmap. If
+	 * we really are running on top non-RAM, we will crash later anyways.
+	 */
+	if (!e820_all_mapped(code_resource.start, bss_resource.end, E820_RAM)) {
+		pr_warn(".text .data .bss are not marked as E820_RAM!\n");
+
+		e820_add_region(code_resource.start,
+				bss_resource.end - code_resource.start + 1,
+				E820_RAM);
+		sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
+	}
+
 	trim_bios_range();
 #ifdef CONFIG_X86_32
 	if (ppro_with_ram_bug()) {
-- 
1.7.9.5


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