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Commit f1a45d02 authored by Oleg Nesterov's avatar Oleg Nesterov
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uprobes: Kill dup_mmap()->uprobe_mmap(), simplify uprobe_mmap/munmap 



1. Kill dup_mmap()->uprobe_mmap(), it was only needed to calculate
   new_mm->uprobes_state.count removed by the previous patch.

   If the forking process has a pending uprobe (int3) in vma, it will
   be copied by copy_page_range(), note that it checks vma->anon_vma
   so "Don't copy ptes" is not possible after install_breakpoint()
   which does anon_vma_prepare().

2. Remove is_swbp_at_addr() and "int count" in uprobe_mmap(). Again,
   this was needed for uprobes_state.count.

   As a side effect this fixes the bug pointed out by Srikar,
   this code lacked the necessary put_uprobe().

3. uprobe_munmap() becomes a nop after the previous patch. Remove the
   meaningless code but do not remove the helper, we will need it.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent 647c42df

kernel/events/uprobes.c

+3 −27
Original line number Diff line number Diff line
@@ -1010,7 +1010,7 @@ int uprobe_mmap(struct vm_area_struct *vma) 
	struct list_head tmp_list;

	struct uprobe *uprobe, *u;

	struct inode *inode;

	int ret, count;

	int ret;



	if (!atomic_read(&uprobe_events) || !valid_vma(vma, true))

		return 0;
@@ -1023,8 +1023,6 @@ int uprobe_mmap(struct vm_area_struct *vma) 
	build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list);



	ret = 0;

	count = 0;



	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {

		if (!ret) {

			unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);
@@ -1034,19 +1032,11 @@ int uprobe_mmap(struct vm_area_struct *vma) 
			 * We can race against uprobe_register(), see the

			 * comment near uprobe_hash().

			 */

			if (ret == -EEXIST) {

			if (ret == -EEXIST)

				ret = 0;



				if (!is_swbp_at_addr(vma->vm_mm, vaddr))

					continue;

			}



			if (!ret)

				count++;

		}

		put_uprobe(uprobe);

	}



	mutex_unlock(uprobes_mmap_hash(inode));



	return ret;
@@ -1057,27 +1047,13 @@ int uprobe_mmap(struct vm_area_struct *vma) 
 */

void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)

{

	struct list_head tmp_list;

	struct uprobe *uprobe, *u;

	struct inode *inode;



	if (!atomic_read(&uprobe_events) || !valid_vma(vma, false))

		return;



	if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */

		return;



	inode = vma->vm_file->f_mapping->host;

	if (!inode)

		return;



	mutex_lock(uprobes_mmap_hash(inode));

	build_probe_list(inode, vma, start, end, &tmp_list);



	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {

		put_uprobe(uprobe);

	}

	mutex_unlock(uprobes_mmap_hash(inode));

	/* TODO: unmapping uprobe(s) will need more work */

}



/* Slot allocation for XOL */

kernel/fork.c

+0 −3
Original line number Diff line number Diff line
@@ -454,9 +454,6 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 


		if (retval)

			goto out;



		if (file)

			uprobe_mmap(tmp);

	}

	/* a new mm has just been created */

	arch_dup_mmap(oldmm, mm);