diff options
| -rw-r--r-- | arch/x86_64/kernel/kprobes.c | 76 |
1 files changed, 62 insertions, 14 deletions
diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c index 324bf57925a9..4e680f87a75f 100644 --- a/arch/x86_64/kernel/kprobes.c +++ b/arch/x86_64/kernel/kprobes.c @@ -45,12 +45,10 @@ static DECLARE_MUTEX(kprobe_mutex); -/* kprobe_status settings */ -#define KPROBE_HIT_ACTIVE 0x00000001 -#define KPROBE_HIT_SS 0x00000002 - static struct kprobe *current_kprobe; static unsigned long kprobe_status, kprobe_old_rflags, kprobe_saved_rflags; +static struct kprobe *kprobe_prev; +static unsigned long kprobe_status_prev, kprobe_old_rflags_prev, kprobe_saved_rflags_prev; static struct pt_regs jprobe_saved_regs; static long *jprobe_saved_rsp; static kprobe_opcode_t *get_insn_slot(void); @@ -240,6 +238,31 @@ void arch_remove_kprobe(struct kprobe *p) down(&kprobe_mutex); } +static inline void save_previous_kprobe(void) +{ + kprobe_prev = current_kprobe; + kprobe_status_prev = kprobe_status; + kprobe_old_rflags_prev = kprobe_old_rflags; + kprobe_saved_rflags_prev = kprobe_saved_rflags; +} + +static inline void restore_previous_kprobe(void) +{ + current_kprobe = kprobe_prev; + kprobe_status = kprobe_status_prev; + kprobe_old_rflags = kprobe_old_rflags_prev; + kprobe_saved_rflags = kprobe_saved_rflags_prev; +} + +static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs) +{ + current_kprobe = p; + kprobe_saved_rflags = kprobe_old_rflags + = (regs->eflags & (TF_MASK | IF_MASK)); + if (is_IF_modifier(p->ainsn.insn)) + kprobe_saved_rflags &= ~IF_MASK; +} + static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) { regs->eflags |= TF_MASK; @@ -319,10 +342,30 @@ int kprobe_handler(struct pt_regs *regs) regs->eflags |= kprobe_saved_rflags; unlock_kprobes(); goto no_kprobe; + } else if (kprobe_status == KPROBE_HIT_SSDONE) { + /* TODO: Provide re-entrancy from + * post_kprobes_handler() and avoid exception + * stack corruption while single-stepping on + * the instruction of the new probe. + */ + arch_disarm_kprobe(p); + regs->rip = (unsigned long)p->addr; + ret = 1; + } else { + /* We have reentered the kprobe_handler(), since + * another probe was hit while within the + * handler. We here save the original kprobe + * variables and just single step on instruction + * of the new probe without calling any user + * handlers. + */ + save_previous_kprobe(); + set_current_kprobe(p, regs); + p->nmissed++; + prepare_singlestep(p, regs); + kprobe_status = KPROBE_REENTER; + return 1; } - arch_disarm_kprobe(p); - regs->rip = (unsigned long)p->addr; - ret = 1; } else { p = current_kprobe; if (p->break_handler && p->break_handler(p, regs)) { @@ -352,11 +395,7 @@ int kprobe_handler(struct pt_regs *regs) } kprobe_status = KPROBE_HIT_ACTIVE; - current_kprobe = p; - kprobe_saved_rflags = kprobe_old_rflags - = (regs->eflags & (TF_MASK | IF_MASK)); - if (is_IF_modifier(p->ainsn.insn)) - kprobe_saved_rflags &= ~IF_MASK; + set_current_kprobe(p, regs); if (p->pre_handler && p->pre_handler(p, regs)) /* handler has already set things up, so skip ss setup */ @@ -506,14 +545,23 @@ int post_kprobe_handler(struct pt_regs *regs) if (!kprobe_running()) return 0; - if (current_kprobe->post_handler) + if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) { + kprobe_status = KPROBE_HIT_SSDONE; current_kprobe->post_handler(current_kprobe, regs, 0); + } if (current_kprobe->post_handler != trampoline_post_handler) resume_execution(current_kprobe, regs); regs->eflags |= kprobe_saved_rflags; - unlock_kprobes(); + /* Restore the original saved kprobes variables and continue. */ + if (kprobe_status == KPROBE_REENTER) { + restore_previous_kprobe(); + goto out; + } else { + unlock_kprobes(); + } +out: preempt_enable_no_resched(); /* |
