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arm64: mm: only perform memstart_addr sanity check if DEBUG_VM 

Checking whether memstart_addr has been assigned every time it is
referenced adds a branch instruction that may hurt performance if
the reference in question occurs on a hot path. So only perform the
check if CONFIG_DEBUG_VM=y.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[catalin.marinas@arm.com: replaced #ifdef with VM_BUG_ON]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ard Biesheuvel 2016-02-22 18:46:03 +01:00 committed by Catalin Marinas
parent 70c8abc287
commit a92405f082
1 changed files with 3 additions and 1 deletions
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4
arch/arm64/include/asm/memory.h
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@ -132,9 +132,11 @@
#ifndef __ASSEMBLY__
#include <linux/mmdebug.h>
extern phys_addr_t memstart_addr;
/* PHYS_OFFSET - the physical address of the start of memory. */
#define PHYS_OFFSET ({ BUG_ON(memstart_addr & 1); memstart_addr; })
#define PHYS_OFFSET ({ VM_BUG_ON(memstart_addr & 1); memstart_addr; })
/* the offset between the kernel virtual and physical mappings */
extern u64 kimage_voffset;