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Subject[PATCH 4.3 044/125] x86/setup: Fix low identity map for >= 2GB kernel range
Date
4.3-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Krzysztof Mazur <krzysiek@podlesie.net>

commit 68accac392d859d24adcf1be3a90e41f978bd54c upstream.

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@podlesie.net>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Link: http://lkml.kernel.org/r/1446815916-22105-1-git-send-email-krzysiek@podlesie.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/setup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1180,7 +1180,7 @@ 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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