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authorOleg Nesterov <oleg@redhat.com>2012-08-19 16:15:09 +0200
committerAnton Arapov <anton@redhat.com>2012-10-29 11:42:38 +0100
commitfb24db0d43cfd7d1b6f5fb3332707a4de9e90efd (patch)
treeae5afd1af6c19bb03f746b5e88747b3619773bd9
parent5ce4a327695a4c08001a98c29f931fe4d04be75c (diff)
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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>
-rw-r--r--include/linux/sched.h3
-rw-r--r--kernel/events/uprobes.c39
2 files changed, 37 insertions, 5 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index adae87f..ba300be 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -446,7 +446,8 @@ extern int get_dumpable(struct mm_struct *mm);
#define MMF_VM_HUGEPAGE 17 /* set when VM_HUGEPAGE is set on vma */
#define MMF_EXE_FILE_CHANGED 18 /* see prctl_set_mm_exe_file() */
-#define MMF_HAS_UPROBES 19 /* might have uprobes */
+#define MMF_HAS_UPROBES 19 /* has uprobes */
+#define MMF_RECALC_UPROBES 20 /* MMF_HAS_UPROBES can be wrong */
#define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
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 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
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 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
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 @@ int uprobe_mmap(struct vm_area_struct *vma)
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 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
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 @@ void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
{
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);
+ }
}
/*