uprobes: Introduce MMF_RECALC_UPROBES
Add the new MMF_RECALC_UPROBES flag, it means that MMF_HAS_UPROBES
can be false positive after remove_breakpoint() or uprobe_munmap().
It is also set by uprobe_dup_mmap(), this is not optimal but simple.
We could add the new hook, uprobe_dup_vma(), to set MMF_HAS_UPROBES
only if the new mm actually has uprobes, but I don't think this
makes sense.
The next patch will use this flag to clear MMF_HAS_UPROBES.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index ba9f1e7..9a7f08b 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -684,7 +684,9 @@
set_bit(MMF_HAS_UPROBES, &mm->flags);
ret = set_swbp(&uprobe->arch, mm, vaddr);
- if (ret && first_uprobe)
+ if (!ret)
+ clear_bit(MMF_RECALC_UPROBES, &mm->flags);
+ else if (first_uprobe)
clear_bit(MMF_HAS_UPROBES, &mm->flags);
return ret;
@@ -693,6 +695,11 @@
static void
remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr)
{
+ /* can happen if uprobe_register() fails */
+ if (!test_bit(MMF_HAS_UPROBES, &mm->flags))
+ return;
+
+ set_bit(MMF_RECALC_UPROBES, &mm->flags);
set_orig_insn(&uprobe->arch, mm, vaddr);
}
@@ -1026,6 +1033,25 @@
return 0;
}
+static bool
+vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end)
+{
+ loff_t min, max;
+ struct inode *inode;
+ struct rb_node *n;
+
+ inode = vma->vm_file->f_mapping->host;
+
+ min = vaddr_to_offset(vma, start);
+ max = min + (end - start) - 1;
+
+ spin_lock(&uprobes_treelock);
+ n = find_node_in_range(inode, min, max);
+ spin_unlock(&uprobes_treelock);
+
+ return !!n;
+}
+
/*
* Called in context of a munmap of a vma.
*/
@@ -1037,10 +1063,12 @@
if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */
return;
- if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags))
+ if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) ||
+ test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags))
return;
- /* TODO: unmapping uprobe(s) will need more work */
+ if (vma_has_uprobes(vma, start, end))
+ set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags);
}
/* Slot allocation for XOL */
@@ -1146,8 +1174,11 @@
{
newmm->uprobes_state.xol_area = NULL;
- if (test_bit(MMF_HAS_UPROBES, &oldmm->flags))
+ if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) {
set_bit(MMF_HAS_UPROBES, &newmm->flags);
+ /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */
+ set_bit(MMF_RECALC_UPROBES, &newmm->flags);
+ }
}
/*
