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xtensa: make fixmap region addressing grow with index 

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
View File

@ -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( \

6
arch/xtensa/mm/highmem.c
View File

@ -28,9 +28,9 @@ void *kmap_atomic(struct page *page)
idx = type + KM_TYPE_NR * smp_processor_id();
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
#ifdef CONFIG_DEBUG_HIGHMEM
BUG_ON(!pte_none(*(kmap_pte - idx)));
BUG_ON(!pte_none(*(kmap_pte + idx)));
#endif
set_pte(kmap_pte - idx, mk_pte(page, PAGE_KERNEL_EXEC));
set_pte(kmap_pte + idx, mk_pte(page, PAGE_KERNEL_EXEC));
return (void *)vaddr;
}
@ -51,7 +51,7 @@ void __kunmap_atomic(void *kvaddr)
* is a bad idea also, in case the page changes cacheability
* attributes or becomes a protected page in a hypervisor.
*/
pte_clear(&init_mm, kvaddr, kmap_pte - idx);
pte_clear(&init_mm, kvaddr, kmap_pte + idx);
local_flush_tlb_kernel_range((unsigned long)kvaddr,
(unsigned long)kvaddr + PAGE_SIZE);