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authorOleg Nesterov <oleg@redhat.com>2012-05-29 21:28:57 +0200
committerIngo Molnar <mingo@kernel.org>2012-06-06 17:15:17 +0200
commit3a9ea0520f38def4a3915b91f82455b749f07d88 (patch)
tree810a4d5bb6f075497ad3b2cd94c120ae235e026f /kernel/events
parenta3d7bb47937b3a40b9f0c75655e97b3bb6407cbe (diff)
downloadlinux-3a9ea0520f38def4a3915b91f82455b749f07d88.tar.bz2
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@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anton Arapov <anton@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20120529192857.GC8057@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/uprobes.c47
1 files changed, 28 insertions, 19 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index a0dbc87a2ec6..eaf4d55fd424 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);