uprobes: Teach find_active_uprobe() to provide the "is_swbp" info
A separate patch to simplify the review, and for the documentation. The patch adds another "int *is_swbp" argument to find_active_uprobe(), so far its only caller doesn't use this info. With this patch find_active_uprobe() additionally does: - if find_vma() + ->vm_start check fails, *is_swbp = -EFAULT - otherwise, if valid_vma() + find_uprobe() fails, it holds the result of is_swbp_at_addr(), can be negative too. The latter is only possible if we raced with another thread which did munmap/etc after we hit this bp. IOW. If find_active_uprobe(&is_swbp) returns NULL, the caller can look at is_swbp to figure out whether the current insn is bp or not, or detect the race with another thread if it is negative. Note: I think that performance-wise this change is fine. This adds is_swbp_at_addr(), but only if we raced with uprobe_unregister() or if we hit the "normal" int3 but this mm has uprobes as well. And even in this case the slow read_opcode() path is very unlikely, this insn recently triggered do_int3(), __copy_from_user_inatomic() shouldn't fail in the likely case. 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/20120529192914.GD8057@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
3a9ea0520f
commit
d790d34653
|
@ -1489,7 +1489,7 @@ static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
|
|||
return false;
|
||||
}
|
||||
|
||||
static struct uprobe *find_active_uprobe(unsigned long bp_vaddr)
|
||||
static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
|
||||
{
|
||||
struct mm_struct *mm = current->mm;
|
||||
struct uprobe *uprobe = NULL;
|
||||
|
@ -1497,7 +1497,6 @@ static struct uprobe *find_active_uprobe(unsigned long bp_vaddr)
|
|||
|
||||
down_read(&mm->mmap_sem);
|
||||
vma = find_vma(mm, bp_vaddr);
|
||||
|
||||
if (vma && vma->vm_start <= bp_vaddr) {
|
||||
if (valid_vma(vma, false)) {
|
||||
struct inode *inode;
|
||||
|
@ -1508,6 +1507,11 @@ static struct uprobe *find_active_uprobe(unsigned long bp_vaddr)
|
|||
offset += (vma->vm_pgoff << PAGE_SHIFT);
|
||||
uprobe = find_uprobe(inode, offset);
|
||||
}
|
||||
|
||||
if (!uprobe)
|
||||
*is_swbp = is_swbp_at_addr(mm, bp_vaddr);
|
||||
} else {
|
||||
*is_swbp = -EFAULT;
|
||||
}
|
||||
|
||||
srcu_read_unlock_raw(&uprobes_srcu, current->uprobe_srcu_id);
|
||||
|
@ -1526,9 +1530,10 @@ static void handle_swbp(struct pt_regs *regs)
|
|||
struct uprobe_task *utask;
|
||||
struct uprobe *uprobe;
|
||||
unsigned long bp_vaddr;
|
||||
int is_swbp;
|
||||
|
||||
bp_vaddr = uprobe_get_swbp_addr(regs);
|
||||
uprobe = find_active_uprobe(bp_vaddr);
|
||||
uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
|
||||
|
||||
if (!uprobe) {
|
||||
/* No matching uprobe; signal SIGTRAP. */
|
||||
|
|
Loading…
Reference in New Issue