diff options
Diffstat (limited to 'arch/arm64/kernel/probes/kprobes.c')
| -rw-r--r-- | arch/arm64/kernel/probes/kprobes.c | 45 |
1 files changed, 44 insertions, 1 deletions
diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index 43a0361a8bf0..4e0efad5caf2 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -174,12 +174,27 @@ static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) { kcb->prev_kprobe.kp = kprobe_running(); kcb->prev_kprobe.status = kcb->kprobe_status; + + /* + * Save the outer kprobe's original DAIF flags before the nested + * kprobe calls kprobes_save_local_irqflag() and overwrites + * kcb->saved_irqflag. Without this, the outer kprobe will restore + * the wrong DAIF state and leave interrupts permanently masked. + */ + kcb->prev_kprobe.saved_irqflag = kcb->saved_irqflag; } static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) { __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); kcb->kprobe_status = kcb->prev_kprobe.status; + + /* + * Restore the outer kprobe's saved_irqflag so that when its + * single-step completes, kprobes_restore_local_irqflag() uses + * the correct original DAIF value. + */ + kcb->saved_irqflag = kcb->prev_kprobe.saved_irqflag; } static void __kprobes set_current_kprobe(struct kprobe *p) @@ -240,10 +255,16 @@ static int __kprobes reenter_kprobe(struct kprobe *p, switch (kcb->kprobe_status) { case KPROBE_HIT_SSDONE: case KPROBE_HIT_ACTIVE: + case KPROBE_HIT_SS: + /* + * A probe can be hit while another kprobe is preparing or + * executing its XOL single-step instruction. This is still a + * recoverable one-level reentry, so handle it in the same way as + * reentry from KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE. + */ kprobes_inc_nmissed_count(p); setup_singlestep(p, regs, kcb, 1); break; - case KPROBE_HIT_SS: case KPROBE_REENTER: pr_warn("Failed to recover from reentered kprobes.\n"); dump_kprobe(p); @@ -282,10 +303,32 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) struct kprobe *cur = kprobe_running(); struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + /* + * Simulated kprobes execute in the debug trap context and have no + * XOL slot. Any page fault taken while a simulated kprobe is in + * progress cannot have been caused by kprobe single-stepping and + * must be left alone for the normal page fault handler, including + * fixup_exception. + */ + if (cur && !cur->ainsn.xol_insn) + return 0; + switch (kcb->kprobe_status) { case KPROBE_HIT_SS: case KPROBE_REENTER: /* + * A page fault taken while in KPROBE_HIT_SS or + * KPROBE_REENTER state is only attributable to kprobe + * single-stepping if the faulting PC points to the + * current kprobe's XOL instruction. If the fault occurred + * elsewhere (e.g. in perf or tracing code invoked from the + * debug exception path), leave it for the normal page fault + * handler to process. + */ + if (instruction_pointer(regs) != (unsigned long)cur->ainsn.xol_insn) + break; + + /* * We are here because the instruction being single * stepped caused a page fault. We reset the current * kprobe and the ip points back to the probe address |