access_process_vm device memory infrastructure
In order to be able to debug things like the X server and programs using the PPC Cell SPUs, the debugger needs to be able to access device memory through ptrace and /proc/pid/mem. This patch: Add the generic_access_phys access function and put the hooks in place to allow access_process_vm to access device or PPC Cell SPU memory. [riel@redhat.com: Add documentation for the vm_ops->access function] Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Benjamin Herrensmidt <benh@kernel.crashing.org> Cc: Dave Airlie <airlied@linux.ie> Cc: Hugh Dickins <hugh@veritas.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnd Bergmann <arnd@arndb.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rik van Riel
committed by
Linus Torvalds
Linus Torvalds
parent
0d71d10a42
commit
28b2ee20c7
131
mm/memory.c
131
mm/memory.c
@@ -2751,6 +2751,86 @@ int in_gate_area_no_task(unsigned long addr)
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#endif /* __HAVE_ARCH_GATE_AREA */
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#ifdef CONFIG_HAVE_IOREMAP_PROT
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static resource_size_t follow_phys(struct vm_area_struct *vma,
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unsigned long address, unsigned int flags,
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unsigned long *prot)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *ptep, pte;
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spinlock_t *ptl;
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resource_size_t phys_addr = 0;
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struct mm_struct *mm = vma->vm_mm;
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VM_BUG_ON(!(vma->vm_flags & (VM_IO | VM_PFNMAP)));
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pgd = pgd_offset(mm, address);
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if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
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goto no_page_table;
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pud = pud_offset(pgd, address);
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if (pud_none(*pud) || unlikely(pud_bad(*pud)))
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goto no_page_table;
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pmd = pmd_offset(pud, address);
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if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
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goto no_page_table;
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/* We cannot handle huge page PFN maps. Luckily they don't exist. */
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if (pmd_huge(*pmd))
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goto no_page_table;
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ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
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if (!ptep)
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goto out;
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pte = *ptep;
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if (!pte_present(pte))
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goto unlock;
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if ((flags & FOLL_WRITE) && !pte_write(pte))
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goto unlock;
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phys_addr = pte_pfn(pte);
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phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */
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*prot = pgprot_val(pte_pgprot(pte));
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unlock:
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pte_unmap_unlock(ptep, ptl);
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out:
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return phys_addr;
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no_page_table:
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return 0;
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}
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int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
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void *buf, int len, int write)
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{
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resource_size_t phys_addr;
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unsigned long prot = 0;
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void *maddr;
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int offset = addr & (PAGE_SIZE-1);
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if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
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return -EINVAL;
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phys_addr = follow_phys(vma, addr, write, &prot);
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if (!phys_addr)
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return -EINVAL;
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maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
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if (write)
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memcpy_toio(maddr + offset, buf, len);
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else
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memcpy_fromio(buf, maddr + offset, len);
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iounmap(maddr);
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return len;
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}
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#endif
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/*
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* Access another process' address space.
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* Source/target buffer must be kernel space,
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@@ -2760,7 +2840,6 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
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{
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struct mm_struct *mm;
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struct vm_area_struct *vma;
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struct page *page;
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void *old_buf = buf;
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mm = get_task_mm(tsk);
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@@ -2772,28 +2851,44 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
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while (len) {
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int bytes, ret, offset;
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void *maddr;
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struct page *page = NULL;
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ret = get_user_pages(tsk, mm, addr, 1,
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write, 1, &page, &vma);
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if (ret <= 0)
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break;
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bytes = len;
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offset = addr & (PAGE_SIZE-1);
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if (bytes > PAGE_SIZE-offset)
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bytes = PAGE_SIZE-offset;
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maddr = kmap(page);
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if (write) {
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copy_to_user_page(vma, page, addr,
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maddr + offset, buf, bytes);
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set_page_dirty_lock(page);
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if (ret <= 0) {
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/*
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* Check if this is a VM_IO | VM_PFNMAP VMA, which
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* we can access using slightly different code.
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*/
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#ifdef CONFIG_HAVE_IOREMAP_PROT
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vma = find_vma(mm, addr);
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if (!vma)
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break;
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if (vma->vm_ops && vma->vm_ops->access)
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ret = vma->vm_ops->access(vma, addr, buf,
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len, write);
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if (ret <= 0)
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#endif
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break;
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bytes = ret;
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} else {
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copy_from_user_page(vma, page, addr,
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buf, maddr + offset, bytes);
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bytes = len;
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offset = addr & (PAGE_SIZE-1);
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if (bytes > PAGE_SIZE-offset)
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bytes = PAGE_SIZE-offset;
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maddr = kmap(page);
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if (write) {
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copy_to_user_page(vma, page, addr,
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maddr + offset, buf, bytes);
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set_page_dirty_lock(page);
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} else {
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copy_from_user_page(vma, page, addr,
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buf, maddr + offset, bytes);
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}
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kunmap(page);
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page_cache_release(page);
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}
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kunmap(page);
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page_cache_release(page);
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len -= bytes;
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buf += bytes;
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addr += bytes;
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