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Subject[PATCH 04/43] x86/gdt: Put per-cpu GDT remaps in ascending order
Date
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: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/3966a6edf6fd45deca4cf52a9b9276402499dda9.1511497875.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/desc.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index 4011cb03ef08..95cd95eb7285 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -63,7 +63,7 @@ static inline struct desc_struct *get_current_gdt_rw(void)
/* 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 */
--
2.14.1
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