ARM Linux下的page和pfn之间转换的宏。

  ARM Linux下的page和pfn之间转换的宏如下：

  1）page_to_pfn

  2）pfn_to_page

  这两个宏依赖于内核编译时，选择的内存模型。在include/asm-generic/memory_model.h文件中定义了这两个宏。

 

include/asm-generic/memory_model.h

  1 #ifndef __ASM_MEMORY_MODEL_H
  2 #define __ASM_MEMORY_MODEL_H
  3
  4 #ifndef __ASSEMBLY__
  5
  6 #if defined(CONFIG_FLATMEM)
  7
  8 #ifndef ARCH_PFN_OFFSET
  9 #define ARCH_PFN_OFFSET         (0UL)
 10 #endif
 11
 12 #elif defined(CONFIG_DISCONTIGMEM)
 13
 14 #ifndef arch_pfn_to_nid
 15 #define arch_pfn_to_nid(pfn)    pfn_to_nid(pfn)
 16 #endif
 17
 18 #ifndef arch_local_page_offset
 19 #define arch_local_page_offset(pfn, nid)        \
 20         ((pfn) - NODE_DATA(nid)->node_start_pfn)
 21 #endif
 22
 23 #endif /* CONFIG_DISCONTIGMEM */
 24
 25 /*
 26  * supports 3 memory models.
 27  */
 28 #if defined(CONFIG_FLATMEM)
 29
 30 #define __pfn_to_page(pfn)      (mem_map + ((pfn) - ARCH_PFN_OFFSET))
 31 #define __page_to_pfn(page)     ((unsigned long)((page) - mem_map) + \
 32                                  ARCH_PFN_OFFSET)
 33 #elif defined(CONFIG_DISCONTIGMEM)
 34
 35 #define __pfn_to_page(pfn)                      \
 36 ({      unsigned long __pfn = (pfn);            \
 37         unsigned long __nid = arch_pfn_to_nid(__pfn);  \
 38         NODE_DATA(__nid)->node_mem_map + arch_local_page_offset(__pfn, __nid);\
 39 })
 40
 41 #define __page_to_pfn(pg)                                               \
 42 ({      struct page *__pg = (pg);                                       \
 43         struct pglist_data *__pgdat = NODE_DATA(page_to_nid(__pg));     \
 44         (unsigned long)(__pg - __pgdat->node_mem_map) +                 \
 45          __pgdat->node_start_pfn;                                       \
 46 })
 47
 48 #elif defined(CONFIG_SPARSEMEM_VMEMMAP)
 49
 50 /* memmap is virtually contiguous.  */
 51 #define __pfn_to_page(pfn)      (vmemmap + (pfn))
 52 #define __page_to_pfn(page)     (unsigned long)((page) - vmemmap)
 53
 54 #elif defined(CONFIG_SPARSEMEM)
 55 /*
 56  * Note: section's mem_map is encorded to reflect its start_pfn.
 57  * section[i].section_mem_map == mem_map's address - start_pfn;
 58  */
 59 #define __page_to_pfn(pg)                                       \
 60 ({      struct page *__pg = (pg);                               \
 61         int __sec = page_to_section(__pg);                      \
 62         (unsigned long)(__pg - __section_mem_map_addr(__nr_to_section(__sec))); \
 63 })
 64
 65 #define __pfn_to_page(pfn)                              \
 66 ({      unsigned long __pfn = (pfn);                    \
 67         struct mem_section *__sec = __pfn_to_section(__pfn);    \
 68         __section_mem_map_addr(__sec) + __pfn;          \
 69 })
 70 #endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */
 71
 72 #define page_to_pfn __page_to_pfn
 73 #define pfn_to_page __pfn_to_page
 74
 75 #endif /* __ASSEMBLY__ */
 76
 77 #endif