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kernel/linux-rt-4.4.41/arch/xtensa/include/asm/fixmap.h 2.33 KB
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  /*
   * fixmap.h: compile-time virtual memory allocation
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 1998 Ingo Molnar
   *
   * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
   */
  
  #ifndef _ASM_FIXMAP_H
  #define _ASM_FIXMAP_H
  
  #include <asm/pgtable.h>
  #ifdef CONFIG_HIGHMEM
  #include <linux/threads.h>
  #include <asm/kmap_types.h>
  #endif
  
  /*
   * 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 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.
   *
   * these 'compile-time allocated' memory buffers are
   * fixed-size 4k pages. (or larger if used with an increment
   * higher than 1) use fixmap_set(idx,phys) to associate
   * physical memory with fixmap indices.
   */
  enum fixed_addresses {
  #ifdef CONFIG_HIGHMEM
  	/* reserved pte's for temporary kernel mappings */
  	FIX_KMAP_BEGIN,
  	FIX_KMAP_END = FIX_KMAP_BEGIN +
  		(KM_TYPE_NR * NR_CPUS * DCACHE_N_COLORS) - 1,
  #endif
  	__end_of_fixed_addresses
  };
  
  #define FIXADDR_TOP     (VMALLOC_START - PAGE_SIZE)
  #define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
  #define FIXADDR_START	((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK)
  
  #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( \
  		pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \
  		(vaddr) \
  	)
  
  #endif