Messages in this thread |  | | | Date | Wed, 27 Jun 2007 11:53:46 -0700 (PDT) | | From | Casey Leedom <> | | Subject | Re: ZERO_PAGE() vs. loadable modules in Redhat 4.4 i386 kernels ... |
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--- Arjan van de Ven <arjan@infradead.org> wrote: > you forgot to attach your source code or provide a URL to it.....
Sorry, my bad. I'm just diving into Linux for the first time and wasn't aware of the protocols. Here's the code fragment I'm currently using:
address = skb_vaddr(skb) & PAGE_MASK; end = PAGE_ALIGN(skb_vaddr(skb) + len);
down_read(¤t->mm->mmap_sem); vma = find_vma(current->mm, skb_vaddr(skb));
spin_lock(¤t->mm->page_table_lock); for (i = 0; i < skb_shinfo(skb)->nr_frags; i++, address += PAGE_SIZE) { pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t *ptep; skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; /* * If we're looking at the ZERO_PAGE() then we don't have to * do anything. It's never going to be modified. See also * where we avoid the ZERO_PAGE() in skb_dma_complete(). */ if (frag->page == ZERO_PAGE(address)) continue; atomic_inc(&frag->page->_mapcount);
/* * If we're not dealing with the ZERO_PAGE() then it should * not be possible to end up without a mapping to the page. * But just in case we check here and issue a BUG() if the * mapping is missing ... */ if (unlikely((pgd = pgd_offset(current->mm, address), pgd_none(*pgd)) || (pud = pud_offset(pgd, address), pud_none(*pud)) || (pmd = pmd_offset(pud, address), pmd_none(*pmd)) || (ptep = pte_offset_map(pmd, address), pte_none(*ptep)))) { printk("skb_dma_pending: missing %s page mapping" " for vaddr=%#lx, page=%p\n", pgd_none(*pgd) ? "pgd" : pud_none(*pud) ? "pud" : pmd_none(*pmd) ? "pmd" : "pte", address, frag->page); BUG(); } ptep_set_wrprotect(current->mm, address, ptep); pte_unmap(ptep); } spin_unlock(¤t->mm->page_table_lock); flush_tlb_range(vma, address, end); I hope that isn't too large but I wanted to provide sufficient context.
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