uprobes: Don't recheck vma/f_mapping in write_opcode() (f403072c) · Commits · 戴 / test

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>

kernel/events/uprobes.c

+1 −18

Original line number	Diff line number	Diff line
		@@ -206,33 +206,16 @@ static int write_opcode(struct arch_uprobe auprobe, struct mm_struct mm,
		unsigned long vaddr, uprobe_opcode_t opcode)
		{
		struct page old_page, new_page;
		struct address_space *mapping;
		void vaddr_old, vaddr_new;
		struct vm_area_struct *vma;
		struct uprobe *uprobe;
		int ret;

		retry:
		/* Read the page with vaddr into memory */
		ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma);
		if (ret <= 0)
		return ret;

		ret = -EINVAL;

		/*
		* We are interested in text pages only. Our pages of interest
		* should be mapped for read and execute only. We desist from
		* adding probes in write mapped pages since the breakpoints
		* might end up in the file copy.
		*/
		if (!valid_vma(vma, is_swbp_insn(&opcode)))
		goto put_out;

		uprobe = container_of(auprobe, struct uprobe, arch);
		mapping = uprobe->inode->i_mapping;
		if (mapping != vma->vm_file->f_mapping)
		goto put_out;

		ret = -ENOMEM;
		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
		if (!new_page)

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