Commit-ID: 2a1bca6ff0ef8fd9b943ce2e6a8826606dc58e3f
Gitweb: http://git.kernel.org/tip/2a1bca6ff0ef8fd9b943ce2e6a8826606dc58e3f
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate: Tue, 29 May 2012 21:28:57 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 6 Jun 2012 11:30:55 +0200
uprobes: Introduce find_active_uprobe() helper
No functional changes. Move the "find uprobe" code from
handle_swbp() to the new helper, find_active_uprobe().
Note: with or without this change, the find-active-uprobe logic
is not exactly right. We can race with another thread which
unmaps the memory with the valid uprobe before we take
mm->mmap_sem. We can't find this uprobe simply because
find_vma() fails. In this case we wrongly assume that this trap
was not caused by uprobe and send the erroneous SIGTRAP. See the
next changes.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Cc: Anton Arapov <anton@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20120529192857.GC8057@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/events/uprobes.c | 47 ++++++++++++++++++++++++++++-------------------
1 files changed, 28 insertions(+), 19 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index a0dbc87..eaf4d55 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1489,38 +1489,47 @@ static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
return false;
}
-/*
- * Run handler and ask thread to singlestep.
- * Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
- */
-static void handle_swbp(struct pt_regs *regs)
+static struct uprobe *find_active_uprobe(unsigned long bp_vaddr)
{
+ struct mm_struct *mm = current->mm;
+ struct uprobe *uprobe = NULL;
struct vm_area_struct *vma;
- struct uprobe_task *utask;
- struct uprobe *uprobe;
- struct mm_struct *mm;
- unsigned long bp_vaddr;
- uprobe = NULL;
- bp_vaddr = uprobe_get_swbp_addr(regs);
- mm = current->mm;
down_read(&mm->mmap_sem);
vma = find_vma(mm, bp_vaddr);
- if (vma && vma->vm_start <= bp_vaddr && valid_vma(vma, false)) {
- struct inode *inode;
- loff_t offset;
+ if (vma && vma->vm_start <= bp_vaddr) {
+ if (valid_vma(vma, false)) {
+ struct inode *inode;
+ loff_t offset;
- inode = vma->vm_file->f_mapping->host;
- offset = bp_vaddr - vma->vm_start;
- offset += (vma->vm_pgoff << PAGE_SHIFT);
- uprobe = find_uprobe(inode, offset);
+ inode = vma->vm_file->f_mapping->host;
+ offset = bp_vaddr - vma->vm_start;
+ offset += (vma->vm_pgoff << PAGE_SHIFT);
+ uprobe = find_uprobe(inode, offset);
+ }
}
srcu_read_unlock_raw(&uprobes_srcu, current->uprobe_srcu_id);
current->uprobe_srcu_id = -1;
up_read(&mm->mmap_sem);
+ return uprobe;
+}
+
+/*
+ * Run handler and ask thread to singlestep.
+ * Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
+ */
+static void handle_swbp(struct pt_regs *regs)
+{
+ struct uprobe_task *utask;
+ struct uprobe *uprobe;
+ unsigned long bp_vaddr;
+
+ bp_vaddr = uprobe_get_swbp_addr(regs);
+ uprobe = find_active_uprobe(bp_vaddr);
+
if (!uprobe) {
/* No matching uprobe; signal SIGTRAP. */
send_sig(SIGTRAP, current, 0);
--
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