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Date: Mon, 04 Dec 2017 15:07:14 +0100
From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirsky <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
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        Will Deacon <will.deacon@arm.com>, daniel.gruss@iaik.tugraz.at,
        Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@suse.de>,
        Dave Hansen <dave.hansen@linux.intel.com>
Subject: [patch 08/60] x86/entry/gdt: Put per-CPU GDT remaps in ascending order
References: <20171204140706.296109558@linutronix.de>
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From: Andy Lutomirski <luto@kernel.org>

We currently have CPU 0's GDT at the top of the GDT range and
higher-numbered CPUs at lower addresses.  This happens because the
fixmap is upside down (index 0 is the top of the fixmap).

Flip it so that GDTs are in ascending order by virtual address.
This will simplify a future patch that will generalize the GDT
remap to contain multiple pages.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/3966a6edf6fd45deca4cf52a9b9276402499dda9.1511497875.git.luto@kernel.org

---
 arch/x86/include/asm/desc.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -63,7 +63,7 @@ static inline struct desc_struct *get_cu
 /* Get the fixmap index for a specific processor */
 static inline unsigned int get_cpu_gdt_ro_index(int cpu)
 {
-	return FIX_GDT_REMAP_BEGIN + cpu;
+	return FIX_GDT_REMAP_END - cpu;
 }
 
 /* Provide the fixmap address of the remapped GDT */