From 562b710877a533b4b8cd441c12c45b067fc94e04 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Wed, 3 Oct 2007 20:42:43 -0700 Subject: [PATCH] vcompound: Add vmalloc_address() Sometimes we need to figure out which vmalloc address is in use for a certain page struct. There is no easy way to figure out the vmalloc address from the page struct. Simply search through the kernel page tables to find the address. Use sparingly. Signed-off-by: Christoph Lameter --- include/linux/mm.h | 2 + mm/vmalloc.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 81 insertions(+) Index: linux-2.6/include/linux/mm.h =================================================================== --- linux-2.6.orig/include/linux/mm.h 2008-02-16 18:30:55.000000000 -0800 +++ linux-2.6/include/linux/mm.h 2008-02-16 18:36:53.000000000 -0800 @@ -243,6 +243,8 @@ static inline int is_vmalloc_addr(const return addr >= VMALLOC_START && addr < VMALLOC_END; } +void *vmalloc_address(struct page *); + static inline struct page *compound_head(struct page *page) { if (unlikely(PageTail(page))) Index: linux-2.6/mm/vmalloc.c =================================================================== --- linux-2.6.orig/mm/vmalloc.c 2008-02-16 18:36:26.000000000 -0800 +++ linux-2.6/mm/vmalloc.c 2008-02-16 18:36:53.000000000 -0800 @@ -883,3 +883,82 @@ void free_vm_area(struct vm_struct *area kfree(area); } EXPORT_SYMBOL_GPL(free_vm_area); + + +/* + * Determine vmalloc address from a page struct. + * + * Linear search through all ptes of the vmalloc area. + */ +static unsigned long vaddr_pte_range(pmd_t *pmd, unsigned long addr, + unsigned long end, unsigned long pfn) +{ + pte_t *pte; + + pte = pte_offset_kernel(pmd, addr); + do { + pte_t ptent = *pte; + if (pte_present(ptent) && pte_pfn(ptent) == pfn) + return addr; + } while (pte++, addr += PAGE_SIZE, addr != end); + return 0; +} + +static inline unsigned long vaddr_pmd_range(pud_t *pud, unsigned long addr, + unsigned long end, unsigned long pfn) +{ + pmd_t *pmd; + unsigned long next; + unsigned long n; + + pmd = pmd_offset(pud, addr); + do { + next = pmd_addr_end(addr, end); + if (pmd_none_or_clear_bad(pmd)) + continue; + n = vaddr_pte_range(pmd, addr, next, pfn); + if (n) + return n; + } while (pmd++, addr = next, addr != end); + return 0; +} + +static inline unsigned long vaddr_pud_range(pgd_t *pgd, unsigned long addr, + unsigned long end, unsigned long pfn) +{ + pud_t *pud; + unsigned long next; + unsigned long n; + + pud = pud_offset(pgd, addr); + do { + next = pud_addr_end(addr, end); + if (pud_none_or_clear_bad(pud)) + continue; + n = vaddr_pmd_range(pud, addr, next, pfn); + if (n) + return n; + } while (pud++, addr = next, addr != end); + return 0; +} + +void *vmalloc_address(struct page *page) +{ + pgd_t *pgd; + unsigned long next, n; + unsigned long addr = VMALLOC_START; + unsigned long pfn = page_to_pfn(page); + + pgd = pgd_offset_k(VMALLOC_START); + do { + next = pgd_addr_end(addr, VMALLOC_END); + if (pgd_none_or_clear_bad(pgd)) + continue; + n = vaddr_pud_range(pgd, addr, next, pfn); + if (n) + return (void *)n; + } while (pgd++, addr = next, addr < VMALLOC_END); + return NULL; +} +EXPORT_SYMBOL(vmalloc_address); +