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xtensa: make fixmap region addressing grow with index

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It's much easier to reason about alignment and coloring of regions
located in the fixmap when fixmap index is just a PFN within the fixmap
region. Change fixmap addressing so that index 0 corresponds to
FIXADDR_START instead of the FIXADDR_TOP.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Max Filippov
2014-07-15 02:27:50 +04:00
parent 5224712374
commit 22def76811
2 changed files with 27 additions and 6 deletions
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27
arch/xtensa/include/asm/fixmap.h
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@@ -23,8 +23,8 @@
* Here we define all the compile-time 'special' virtual
* addresses. The point is to have a constant address at
* compile time, but to set the physical address only
* in the boot process. We allocate these special addresses
* from the end of the consistent memory region backwards.
* in the boot process. We allocate these special addresses
* from the start of the consistent memory region upwards.
* Also this lets us do fail-safe vmalloc(), we
* can guarantee that these special addresses and
* vmalloc()-ed addresses never overlap.
@@ -47,7 +47,28 @@ enum fixed_addresses {
#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_START ((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK)
#include <asm-generic/fixmap.h>
#define __fix_to_virt(x) (FIXADDR_START + ((x) << PAGE_SHIFT))
#define __virt_to_fix(x) (((x) - FIXADDR_START) >> PAGE_SHIFT)
#ifndef __ASSEMBLY__
/*
* 'index to address' translation. If anyone tries to use the idx
* directly without translation, we catch the bug with a NULL-deference
* kernel oops. Illegal ranges of incoming indices are caught too.
*/
static __always_inline unsigned long fix_to_virt(const unsigned int idx)
{
BUILD_BUG_ON(idx >= __end_of_fixed_addresses);
return __fix_to_virt(idx);
}
static inline unsigned long virt_to_fix(const unsigned long vaddr)
{
BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
return __virt_to_fix(vaddr);
}
#endif
#define kmap_get_fixmap_pte(vaddr) \
pte_offset_kernel( \