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.
---
kernel/events/uprobes.c | 31 +++++++++++++++++++------------
1 files changed, 19 insertions(+), 12 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 29e881b..3d0a4d6 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1474,21 +1474,12 @@ 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);
@@ -1506,6 +1497,22 @@ static void handle_swbp(struct pt_regs *regs)
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);
--
1.5.5.1
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