{"id":3559,"date":"2011-11-22T12:16:47","date_gmt":"2011-11-22T04:16:47","guid":{"rendered":"http:\/\/edsionte.com\/techblog\/?p=3559"},"modified":"2011-11-22T12:16:47","modified_gmt":"2011-11-22T04:16:47","slug":"vmalloc%e7%9a%84%e5%ae%9e%e7%8e%b0-%e5%88%86%e6%95%a3%e7%9a%84%e7%89%a9%e7%90%86%e9%a1%b5%e6%a1%86%e4%b8%8e%e8%bf%9e%e7%bb%advmalloc%e5%8c%ba%e7%9a%84%e6%98%a0%e5%b0%84","status":"publish","type":"post","link":"http:\/\/edsionte.com\/techblog\/archives\/3559","title":{"rendered":"vmalloc()\u7684\u5b9e\u73b0-\u5206\u6563\u7684\u7269\u7406\u9875\u6846\u4e0e\u8fde\u7eedvmalloc\u533a\u7684\u6620\u5c04"},"content":{"rendered":"

\u5728vmalloc()\u7684\u5b9e\u73b0\u8fc7\u7a0b\u4e2d\uff0c\u9996\u5148\u904d\u5386vmlist\u94fe\u8868\u627e\u5230\u4e00\u4e2a\u6240\u9700\u5927\u5c0f\u7684vmalloc\u533a\uff0c\u63a5\u7740\u4e3a\u8fd9\u4e2a\u5b50\u5185\u5b58\u533a\u4f9d\u6b21\u5206\u914d\u7269\u7406\u9875\u6846\u3002\u4ece\u8fd9\u4e24\u90e8\u5206\u7684\u5b9e\u73b0\u8fc7\u7a0b\u53ef\u4ee5\u770b\u5230\uff0c\u865a\u62df\u7684\u5b50\u5185\u5b58\u533a\u662f\u5728\u6574\u4e2avmalloc\u533a\u4e2d\u67e5\u627e\u4e00\u5757\u5408\u9002\u5927\u5c0f\u7684\u5b50\u533a\u57df\uff0c\u800c\u7269\u7406\u5185\u5b58\u5219\u662f\u5206\u6563\u7684\u4f9d\u6b21\u5206\u914d\u3002\u56e0\u6b64\uff0cvmalloc()\u7684\u5b9e\u73b0\u5c31\u843d\u5728\u4e86\u5982\u4f55\u5c06\u8fd9\u4e9b\u5206\u6563\u7684\u7269\u7406\u9875\u6846\u6620\u5c04\u5230\u8fde\u7eed\u7684vmalloc\u533a\u4e0a\u3002\u6574\u4e2a\u6620\u5c04\u8fc7\u7a0b\u53ef\u4ee5\u7b80\u5355\u7684\u770b\u4f5c\u662f\u4e0d\u65ad\u4fee\u6539\u5185\u6838\u9875\u8868\u7684\u8fc7\u7a0b\u3002<\/p>\n

map_vm_area()\u7684\u5b9e\u73b0<\/h3>\n

vmalloc()\u901a\u8fc7map_vm_area()\u5b8c\u6210\u7269\u7406\u9875\u6846\u4e0e\u865a\u62df\u5b50\u5185\u5b58\u533a\u7684\u6620\u5c04\u3002map_vm_area()\u9996\u5148\u8ba1\u7b97\u865a\u62df\u5185\u5b58\u5b50\u533a\u57df\u7684\u8d77\u59cb\u5730\u5740addr\u548c\u7ec8\u6b62\u5730\u5740end\u3002\u7531\u4e8evm_struct\u4e2d\u7684size\u662f\u5b9e\u9645\u5b50\u533a\u95f4\u957f\u5ea6\u52a0\u4e0a\u4e00\u4e2a\u9875\u5927\u5c0f\uff0c\u56e0\u6b64\u7ec8\u6b62\u5730\u5740\u5fc5\u987b\u51cf\u53bbPAGE_SIZE\u3002\u63a5\u7740\u5b83\u8c03\u7528\u4e86vmap_page_range()\u3002\u4e0b\u9762\u7684\u4ee3\u7801\u8868\u660e\u4e86map_vm_area()\u7684\u5b9e\u9645\u8c03\u7528\u8fc7\u7a0b(\u672c\u6587\u6240\u6709\u5185\u6838\u6e90\u7801\u5747\u53d6\u81eav2.6.34)\u3002<\/p>\n

int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages)\r\n{\r\n        unsigned long addr = (unsigned long)area->addr;\r\n        unsigned long end = addr + area->size - PAGE_SIZE;\r\n        int err;\r\n\r\n        err = vmap_page_range(addr, end, prot, *pages);\r\n        if (err > 0) {\r\n                *pages += err;\r\n                err = 0;\r\n        }\r\n\r\n        return err;\r\n}<\/pre>\n
vmap_page_range()\u53c8\u518d\u6b21\u5c01\u88c5\u4e86\u771f\u6b63\u7528\u4e8e\u6620\u5c04\u7684\u51fd\u6570vmap_page_range_noflush()\u3002\u5f53\u6620\u5c04\u5b8c\u6bd5\u540e\uff0c\u5b83\u8c03\u7528flush_cache_vmap()\uff0c\u5373\u5c06\u521a\u521a\u4fee\u6539\u7684\u5185\u6838\u9875\u8868\u9879\u5237\u65b0\u5230CPU\u9ad8\u901f\u7f13\u5b58\u3002<\/p>\n
static int vmap_page_range(unsigned long start, unsigned long end,\r\n                           pgprot_t prot, struct page **pages)\r\n{\r\n        int ret;\r\n\r\n        ret = vmap_page_range_noflush(start, end, prot, pages);\r\n        flush_cache_vmap(start, end);\r\n        return ret;\r\n}<\/pre>\n
\u4fee\u6539\u5185\u6838\u9875\u8868<\/h3>\n
map_vm_area()\u7ecf\u8fc7\u91cd\u91cd\u8c03\u7528\uff0c\u7ec8\u4e8e\u6765\u5230\u4e86\u8fdb\u884c\u5b9e\u9645\u6620\u5c04\u5de5\u4f5c\u7684vmap_page_range_noflush()\u4e2d\u3002\u8fd9\u4e2a\u51fd\u6570\u4e2d\u9996\u5148\u901a\u8fc7pgd_offset_k()\u8ba1\u7b97\u51faaddr\u5728\u4e3b\u5185\u6838\u9875\u5168\u5c40\u76ee\u5f55\u4e2d\u5bf9\u5e94\u7684\u9875\u8868\u9879\u5730\u5740\u3002\u63a5\u7740\u901a\u8fc7\u4e00\u4e2a\u5faa\u73af\uff0c\u4e3astart\u5230end\u4e4b\u95f4\u7684\u5b50\u5185\u5b58\u533a\u4fee\u6539\u5185\u6838\u9875\u8868\u3002 \u5728\u6bcf\u6b21\u5faa\u73af\u7684\u8fc7\u7a0b\u4e2d\uff0cnext\u4e3a\u5f53\u524d\u9875\u8868\u9879\u6240\u6620\u5c04\u7684\u5185\u5b58\u533a\u7684\u7ec8\u6b62\u5730\u5740\u3002\u901a\u8fc7vmap_pud_range()\u7ee7\u7eed\u4fee\u6539start\u5230next\u4e4b\u95f4\u6240\u5bf9\u5e94\u7684\u9875\u4e0a\u7ea7\u76ee\u5f55\u3002<\/p>\n
static int vmap_page_range_noflush(unsigned long start, unsigned long end,\r\n                                   pgprot_t prot, struct page **pages)\r\n{\r\n        pgd_t *pgd;\r\n        unsigned long next;\r\n        unsigned long addr = start;\r\n        int err = 0;\r\n        int nr = 0;\r\n\r\n        BUG_ON(addr >= end);\r\n        pgd = pgd_offset_k(addr);\r\n        do {\r\n                next = pgd_addr_end(addr, end);\r\n                err = vmap_pud_range(pgd, addr, next, prot, pages, &nr);\r\n                if (err)\r\n                        return err;\r\n        } while (pgd++, addr = next, addr != end);\r\n\r\n        return nr;\r\n}<\/pre>\n
vmap_pud_range()\u6240\u505a\u7684\u5de5\u4f5c\u548cvmap_page_range_noflush()\u7c7b\u4f3c\uff0c\u53ea\u4e0d\u8fc7\u5b83\u662f\u9488\u5bf9\u9875\u4e0a\u7ea7\u76ee\u5f55\u7684\u9875\u8868\u9879\u505a\u51fa\u5bf9\u5e94\u7684\u4fee\u6539\u3002\u9996\u5148pud_alloc()\u4e3aaddr\u5206\u914d\u5bf9\u5e94\u7684\u9875\u4e0a\u7ea7\u76ee\u5f55\uff0c\u540c\u65f6\u4e5f\u5c06\u8be5\u9875\u4e0a\u7ea7\u76ee\u5f55\u5bf9\u5e94\u7684\u7269\u7406\u5730\u5740\u5199\u5165\u9875\u5168\u5c40\u76ee\u5f55\u5bf9\u5e94\u7684\u8868\u9879\u4e2d\u3002\u63a5\u7740\u518d\u6b21\u8fdb\u5165\u4e00\u4e2a\u5faa\u73af\u6765\u4f9d\u6b21\u4fee\u6539addr\u5bf9\u5e94\u7684\u9875\u4e2d\u95f4\u76ee\u5f55\uff0c\u6bcf\u6b21\u5faa\u73af\u65f6\u8ba1\u7b97\u51fa\u5f53\u524d\u9875\u4e0a\u7ea7\u76ee\u5f55\u6240\u6620\u5c04\u7684\u5185\u5b58\u533a\u95f4\u8303\u56f4addr\u548cnext\u3002<\/p>\n
static int vmap_pud_range(pgd_t *pgd, unsigned long addr,\r\n                unsigned long end, pgprot_t prot, struct page **pages, int *nr)\r\n{\r\n        pud_t *pud;\r\n        unsigned long next;\r\n\r\n        pud = pud_alloc(&init_mm, pgd, addr);\r\n        if (!pud)\r\n                return -ENOMEM;\r\n        do {\r\n                next = pud_addr_end(addr, end);\r\n                if (vmap_pmd_range(pud, addr, next, prot, pages, nr))\r\n                        return -ENOMEM;\r\n        } while (pud++, addr = next, addr != end);\r\n        return 0;\r\n}<\/pre>\n
vmap_pmd_range()\u4e3a\u9875\u4e2d\u4ef6\u76ee\u5f55\u6240\u6307\u5411\u7684\u6240\u6709\u9875\u8868\u6267\u884c\u548c\u4e0a\u8ff0\u7c7b\u4f3c\u7684\u5faa\u73af\u3002<\/p>\n
static int vmap_pmd_range(pud_t *pud, unsigned long addr,\r\n                unsigned long end, pgprot_t prot, struct page **pages, int *nr)\r\n{\r\n        pmd_t *pmd;\r\n        unsigned long next;\r\n\r\n        pmd = pmd_alloc(&init_mm, pud, addr);\r\n        if (!pmd)\r\n                return -ENOMEM;\r\n        do {\r\n                next = pmd_addr_end(addr, end);\r\n                if (vmap_pte_range(pmd, addr, next, prot, pages, nr))\r\n                        return -ENOMEM;\r\n        } while (pmd++, addr = next, addr != end);\r\n        return 0;\r\n}<\/pre>\n
\u73b0\u5728\u4e3aaddr\u66f4\u65b0\u6700\u540e\u4e00\u7ea7\u9875\u8868\uff0c\u9996\u5148\u7531pte_alloc_kernel()\u751f\u6210\u9875\u8868pte\uff0c\u518d\u901a\u8fc7\u5faa\u73af\u4f9d\u6b21\u66f4\u65b0\u6bcf\u4e2a\u9875\u8868\u9879\u3002\u5728\u6bcf\u6b21\u5faa\u73af\u8fc7\u7a0b\u4e2d\uff0c\u5148\u901a\u8fc7pages\u6570\u7ec4\u5f97\u5230\u7b2cnr\u4e2a\u9875\u6846\u7684\u9875\u63cf\u8ff0\u7b26page\uff0c\u518d\u5c06\u5176\u4f20\u5165mk_pte\u751f\u6210\u5bf9\u5e94\u9875\u8868\u9879\u3002\u6700\u540e\u7531set_pte_at()\u5c06\u6b64\u9875\u8868\u9879\u66f4\u65b0\u5230pte\u6240\u6307\u7684\u9875\u8868\u7684\u5bf9\u5e94\u9879\u4e2d\u3002\u9875\u8868\u9879\u7684\u589e\u52a0\u8fc7\u7a0b\u7531\u5f53\u524d\u7ebf\u6027\u5730\u5740addr\u52a0\u4e0aPAGE_SIZE\u5b8c\u6210\u3002<\/p>\n
static int vmap_pte_range(pmd_t *pmd, unsigned long addr,\r\n                unsigned long end, pgprot_t prot, struct page **pages, int *nr)\r\n{\r\n        pte_t *pte;\r\n\r\n        pte = pte_alloc_kernel(pmd, addr);\r\n        if (!pte)\r\n                return -ENOMEM;\r\n        do {\r\n                struct page *page = pages[*nr];\r\n\r\n                if (WARN_ON(!pte_none(*pte)))\r\n                        return -EBUSY;\r\n                if (WARN_ON(!page))\r\n                        return -ENOMEM;\r\n                set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));\r\n                (*nr)++;\r\n        } while (pte++, addr += PAGE_SIZE, addr != end);\r\n        return 0;\r\n}<\/pre>\n
\u7ecf\u8fc7\u5bf9\u6bcf\u7ea7\u9875\u8868\u7684\u5c42\u5c42\u4fee\u6539\uff0c\u6700\u7ec8start\u5230end\u4e4b\u95f4\u7684\u8fde\u7eedvmalloc\u533a\u90fd\u4e0e\u76f8\u5e94\u7684\u7269\u7406\u9875\u6846\u76f8\u6620\u5c04\u3002\u6574\u4e2avmalloc()\u5b8c\u6210\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u5728vmalloc()\u7684\u5b9e\u73b0\u8fc7\u7a0b\u4e2d\uff0c\u9996\u5148\u904d\u5386vmlist\u94fe\u8868\u627e\u5230\u4e00\u4e2a\u6240\u9700\u5927\u5c0f\u7684vmalloc\u533a\uff0c\u63a5\u7740\u4e3a\u8fd9\u4e2a\u5b50\u5185\u5b58 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[266],"tags":[289,290,291],"class_list":["post-3559","post","type-post","status-publish","format-standard","hentry","category-266","tag-vmalloc","tag-vm_struct","tag-291"],"views":10231,"_links":{"self":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/3559","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/comments?post=3559"}],"version-history":[{"count":0,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/3559\/revisions"}],"wp:attachment":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/media?parent=3559"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/categories?post=3559"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/tags?post=3559"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}