From 3a9ea0520f38def4a3915b91f82455b749f07d88 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 29 May 2012 21:28:57 +0200 Subject: 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 Acked-by: Srikar Dronamraju Cc: Ananth N Mavinakayanahalli Cc: Anton Arapov Cc: Linus Torvalds Cc: Masami Hiramatsu Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20120529192857.GC8057@redhat.com Signed-off-by: Ingo Molnar --- kernel/events/uprobes.c | 47 ++++++++++++++++++++++++++++------------------- 1 file changed, 28 insertions(+), 19 deletions(-) (limited to 'kernel/events') 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); -- cgit v1.2.2