linux-kernel - [tip:x86/urgent] x86/setup: Fix low identity map for >= 2GB kernel range

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Date:	Sat, 7 Nov 2015 01:44:15 -0800
From:	tip-bot for Krzysztof Mazur <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	lersek@...hat.com, luto@...capital.net, matt.fleming@...el.com,
	bp@...en8.de, krzysiek@...lesie.net, tglx@...utronix.de,
	pbonzini@...hat.com, mingo@...nel.org, hpa@...or.com,
	linux-kernel@...r.kernel.org
Subject: [tip:x86/urgent] x86/setup: Fix low identity map for >=
  2GB kernel range

Commit-ID:  68accac392d859d24adcf1be3a90e41f978bd54c
Gitweb:     http://git.kernel.org/tip/68accac392d859d24adcf1be3a90e41f978bd54c
Author:     Krzysztof Mazur <krzysiek@...lesie.net>
AuthorDate: Fri, 6 Nov 2015 14:18:36 +0100
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Sat, 7 Nov 2015 10:39:40 +0100

x86/setup: Fix low identity map for >= 2GB kernel range

The commit f5f3497cad8c extended the low identity mapping. However, if
the kernel uses more than 2 GB (VMSPLIT_2G_OPT or VMSPLIT_1G memory
split), the normal memory mapping is overwritten by the low identity
mapping causing a crash. To avoid overwritting, limit the low identity
map to cover only memory before kernel range (PAGE_OFFSET).

Fixes: f5f3497cad8c "x86/setup: Extend low identity map to cover whole kernel range
Signed-off-by: Krzysztof Mazur <krzysiek@...lesie.net>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Laszlo Ersek <lersek@...hat.com>
Cc: Matt Fleming <matt.fleming@...el.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: stable@...r.kernel.org
Link: http://lkml.kernel.org/r/1446815916-22105-1-git-send-email-krzysiek@podlesie.net
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index a1e4da9..29db25f 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1188,7 +1188,7 @@ void __init setup_arch(char **cmdline_p)
 	 */
 	clone_pgd_range(initial_page_table,
 			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
-			KERNEL_PGD_PTRS);
+			min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
 #endif
 
 	tboot_probe();
--
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