root/include/asm-generic/memory_model.h

INCLUDED FROM

#ifndef __ASM_MEMORY_MODEL_H
#define __ASM_MEMORY_MODEL_H

#ifndef __ASSEMBLY__

#if defined(CONFIG_FLATMEM)

#ifndef ARCH_PFN_OFFSET
#define ARCH_PFN_OFFSET         (0UL)
#endif

#elif defined(CONFIG_DISCONTIGMEM)

#ifndef arch_pfn_to_nid
#define arch_pfn_to_nid(pfn)    pfn_to_nid(pfn)
#endif

#ifndef arch_local_page_offset
#define arch_local_page_offset(pfn, nid)        \
        ((pfn) - NODE_DATA(nid)->node_start_pfn)
#endif

#endif /* CONFIG_DISCONTIGMEM */

/*
 * supports 3 memory models.
 */
#if defined(CONFIG_FLATMEM)

#define __pfn_to_page(pfn)      (mem_map + ((pfn) - ARCH_PFN_OFFSET))
#define __page_to_pfn(page)     ((unsigned long)((page) - mem_map) + \
                                 ARCH_PFN_OFFSET)
#elif defined(CONFIG_DISCONTIGMEM)

#define __pfn_to_page(pfn)                      \
({      unsigned long __pfn = (pfn);            \
        unsigned long __nid = arch_pfn_to_nid(pfn);  \
        NODE_DATA(__nid)->node_mem_map + arch_local_page_offset(__pfn, __nid);\
})

#define __page_to_pfn(pg)                                               \
({      struct page *__pg = (pg);                                       \
        struct pglist_data *__pgdat = NODE_DATA(page_to_nid(__pg));     \
        (unsigned long)(__pg - __pgdat->node_mem_map) +                 \
         __pgdat->node_start_pfn;                                       \
})

#elif defined(CONFIG_SPARSEMEM_VMEMMAP)

/* memmap is virtually contigious.  */
#define __pfn_to_page(pfn)      (vmemmap + (pfn))
#define __page_to_pfn(page)     ((page) - vmemmap)

#elif defined(CONFIG_SPARSEMEM)
/*
 * Note: section's mem_map is encorded to reflect its start_pfn.
 * section[i].section_mem_map == mem_map's address - start_pfn;
 */
#define __page_to_pfn(pg)                                       \
({      struct page *__pg = (pg);                               \
        int __sec = page_to_section(__pg);                      \
        (unsigned long)(__pg - __section_mem_map_addr(__nr_to_section(__sec))); \
})

#define __pfn_to_page(pfn)                              \
({      unsigned long __pfn = (pfn);                    \
        struct mem_section *__sec = __pfn_to_section(__pfn);    \
        __section_mem_map_addr(__sec) + __pfn;          \
})
#endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */

#ifdef CONFIG_OUT_OF_LINE_PFN_TO_PAGE
struct page;
/* this is useful when inlined pfn_to_page is too big */
extern struct page *pfn_to_page(unsigned long pfn);
extern unsigned long page_to_pfn(struct page *page);
#else
#define page_to_pfn __page_to_pfn
#define pfn_to_page __pfn_to_page
#endif /* CONFIG_OUT_OF_LINE_PFN_TO_PAGE */

#endif /* __ASSEMBLY__ */

#endif