uprobes: Don't recheck vma/f_mapping in write_opcode()
write_opcode() rechecks valid_vma() and ->f_mapping, this is pointless. The caller, register_for_each_vma() or uprobe_mmap(), has already done these checks under mmap_sem. To clarify, uprobe_mmap() checks valid_vma() only, but we can rely on build_probe_list(vm_file->f_mapping->host). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar.vnet.ibm.com> Cc: Anton Arapov <anton@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20120729182212.GA20304@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -206,33 +206,16 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
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unsigned long vaddr, uprobe_opcode_t opcode)
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{
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struct page *old_page, *new_page;
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struct address_space *mapping;
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void *vaddr_old, *vaddr_new;
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struct vm_area_struct *vma;
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struct uprobe *uprobe;
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int ret;
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retry:
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/* Read the page with vaddr into memory */
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ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma);
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if (ret <= 0)
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return ret;
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ret = -EINVAL;
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/*
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* We are interested in text pages only. Our pages of interest
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* should be mapped for read and execute only. We desist from
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* adding probes in write mapped pages since the breakpoints
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* might end up in the file copy.
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*/
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if (!valid_vma(vma, is_swbp_insn(&opcode)))
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goto put_out;
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uprobe = container_of(auprobe, struct uprobe, arch);
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mapping = uprobe->inode->i_mapping;
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if (mapping != vma->vm_file->f_mapping)
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goto put_out;
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ret = -ENOMEM;
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new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
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if (!new_page)
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