Currently the error from arch_uprobe_post_xol() is silently ignored.
This doesn't look good and this can lead to the hard-to-debug problems.
1. Change handle_singlestep() to loudly complain and send SIGILL.
Note: this only affects x86, ppc/arm can't fail.
2. Change arch_uprobe_post_xol() to call arch_uprobe_abort_xol() and
avoid TF games if it is going to return an error.
This can help to to analyze the problem, if nothing else we should
not report ->ip = xol_slot in the core-file.
Note: this means that handle_riprel_post_xol() can be called twice,
but this is fine because it is idempotent.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
struct uprobe_task *utask = current->utask;
WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
struct uprobe_task *utask = current->utask;
WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
+
+ if (auprobe->ops->post_xol) {
+ int err = auprobe->ops->post_xol(auprobe, regs);
+ if (err) {
+ arch_uprobe_abort_xol(auprobe, regs);
+ return err;
+ }
+ }
+
current->thread.trap_nr = utask->autask.saved_trap_nr;
/*
* arch_uprobe_pre_xol() doesn't save the state of TIF_BLOCKSTEP
current->thread.trap_nr = utask->autask.saved_trap_nr;
/*
* arch_uprobe_pre_xol() doesn't save the state of TIF_BLOCKSTEP
else if (!(auprobe->fixups & UPROBE_FIX_SETF))
regs->flags &= ~X86_EFLAGS_TF;
else if (!(auprobe->fixups & UPROBE_FIX_SETF))
regs->flags &= ~X86_EFLAGS_TF;
- if (auprobe->ops->post_xol)
- return auprobe->ops->post_xol(auprobe, regs);
/*
* This function gets called when XOL instruction either gets trapped or
/*
* This function gets called when XOL instruction either gets trapped or
- * the thread has a fatal signal, so reset the instruction pointer to its
- * probed address.
+ * the thread has a fatal signal, or if arch_uprobe_post_xol() failed.
+ * Reset the instruction pointer to its probed address for the potential
+ * restart or for post mortem analysis.
*/
void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
*/
void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
{
struct uprobe *uprobe;
static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
{
struct uprobe *uprobe;
uprobe = utask->active_uprobe;
if (utask->state == UTASK_SSTEP_ACK)
uprobe = utask->active_uprobe;
if (utask->state == UTASK_SSTEP_ACK)
- arch_uprobe_post_xol(&uprobe->arch, regs);
+ err = arch_uprobe_post_xol(&uprobe->arch, regs);
else if (utask->state == UTASK_SSTEP_TRAPPED)
arch_uprobe_abort_xol(&uprobe->arch, regs);
else
else if (utask->state == UTASK_SSTEP_TRAPPED)
arch_uprobe_abort_xol(&uprobe->arch, regs);
else
spin_lock_irq(¤t->sighand->siglock);
recalc_sigpending(); /* see uprobe_deny_signal() */
spin_unlock_irq(¤t->sighand->siglock);
spin_lock_irq(¤t->sighand->siglock);
recalc_sigpending(); /* see uprobe_deny_signal() */
spin_unlock_irq(¤t->sighand->siglock);
+
+ if (unlikely(err)) {
+ uprobe_warn(current, "execute the probed insn, sending SIGILL.");
+ force_sig_info(SIGILL, SEND_SIG_FORCED, current);
+ }