linux-kernel - [PATCH 1/1] x86_64: fix KASan shadow region page tables

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Date:	Fri, 22 May 2015 19:03:01 +0300
From:	Alexander Popov <alpopov@...ecurity.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrey Ryabinin <a.ryabinin@...sung.com>,
	Andrey Konovalov <adech.fo@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Andy Lutomirski <luto@...capital.net>,
	Alexander Kuleshov <kuleshovmail@...il.com>,
	Alexander Popov <alpopov@...ecurity.com>,
	"Sergey Kovalev" <SKovalev@...ecurity.com>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH 1/1] x86_64: fix KASan shadow region page tables

Physical addresses in KASan shadow region page tables need fixup:
kernel halts without it if phys_base is not zero.

Signed-off-by: Alexander Popov <alpopov@...ecurity.com>
---
 arch/x86/kernel/head_64.S | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index ae6588b..f7711bb 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -95,6 +95,20 @@ startup_64:
 
 	addq	%rbp, level2_fixmap_pgt + (506*8)(%rip)
 
+#ifdef CONFIG_KASAN
+	xor	%rax, %rax
+	leaq	kasan_zero_pud(%rip), %rbx
+	leaq	kasan_zero_pmd(%rip), %rcx
+	leaq	kasan_zero_pte(%rip), %rdx
+1:
+	addq	%rbp, (%rbx,%rax,8)
+	addq	%rbp, (%rcx,%rax,8)
+	addq	%rbp, (%rdx,%rax,8)
+	inc	%rax
+	cmp	$512, %rax
+	jne	1b
+#endif
+
 	/*
 	 * Set up the identity mapping for the switchover.  These
 	 * entries should *NOT* have the global bit set!  This also
-- 
1.9.1

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