diff options
| -rw-r--r-- | arch/i386/kernel/kprobes.c | 133 |
1 files changed, 70 insertions, 63 deletions
diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c index 3762f6b35ab..fc8b1752176 100644 --- a/arch/i386/kernel/kprobes.c +++ b/arch/i386/kernel/kprobes.c @@ -127,48 +127,23 @@ static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) regs->eip = (unsigned long)&p->ainsn.insn; } -struct task_struct *arch_get_kprobe_task(void *ptr) -{ - return ((struct thread_info *) (((unsigned long) ptr) & - (~(THREAD_SIZE -1))))->task; -} - void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs) { unsigned long *sara = (unsigned long *)®s->esp; - struct kretprobe_instance *ri; - static void *orig_ret_addr; + struct kretprobe_instance *ri; + + if ((ri = get_free_rp_inst(rp)) != NULL) { + ri->rp = rp; + ri->task = current; + ri->ret_addr = (kprobe_opcode_t *) *sara; - /* - * Save the return address when the return probe hits - * the first time, and use it to populate the (krprobe - * instance)->ret_addr for subsequent return probes at - * the same addrress since stack address would have - * the kretprobe_trampoline by then. - */ - if (((void*) *sara) != kretprobe_trampoline) - orig_ret_addr = (void*) *sara; - - if ((ri = get_free_rp_inst(rp)) != NULL) { - ri->rp = rp; - ri->stack_addr = sara; - ri->ret_addr = orig_ret_addr; - add_rp_inst(ri); /* Replace the return addr with trampoline addr */ *sara = (unsigned long) &kretprobe_trampoline; - } else { - rp->nmissed++; - } -} -void arch_kprobe_flush_task(struct task_struct *tk) -{ - struct kretprobe_instance *ri; - while ((ri = get_rp_inst_tsk(tk)) != NULL) { - *((unsigned long *)(ri->stack_addr)) = - (unsigned long) ri->ret_addr; - recycle_rp_inst(ri); - } + add_rp_inst(ri); + } else { + rp->nmissed++; + } } /* @@ -286,36 +261,59 @@ no_kprobe: */ int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) { - struct task_struct *tsk; - struct kretprobe_instance *ri; - struct hlist_head *head; - struct hlist_node *node; - unsigned long *sara = ((unsigned long *) ®s->esp) - 1; - - tsk = arch_get_kprobe_task(sara); - head = kretprobe_inst_table_head(tsk); - - hlist_for_each_entry(ri, node, head, hlist) { - if (ri->stack_addr == sara && ri->rp) { - if (ri->rp->handler) - ri->rp->handler(ri, regs); - } - } - return 0; -} + struct kretprobe_instance *ri = NULL; + struct hlist_head *head; + struct hlist_node *node, *tmp; + unsigned long orig_ret_address = 0; + unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; -void trampoline_post_handler(struct kprobe *p, struct pt_regs *regs, - unsigned long flags) -{ - struct kretprobe_instance *ri; - /* RA already popped */ - unsigned long *sara = ((unsigned long *)®s->esp) - 1; + head = kretprobe_inst_table_head(current); - while ((ri = get_rp_inst(sara))) { - regs->eip = (unsigned long)ri->ret_addr; + /* + * It is possible to have multiple instances associated with a given + * task either because an multiple functions in the call path + * have a return probe installed on them, and/or more then one return + * return probe was registered for a target function. + * + * We can handle this because: + * - instances are always inserted at the head of the list + * - when multiple return probes are registered for the same + * function, the first instance's ret_addr will point to the + * real return address, and all the rest will point to + * kretprobe_trampoline + */ + hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { + if (ri->task != current) + /* another task is sharing our hash bucket */ + continue; + + if (ri->rp && ri->rp->handler) + ri->rp->handler(ri, regs); + + orig_ret_address = (unsigned long)ri->ret_addr; recycle_rp_inst(ri); + + if (orig_ret_address != trampoline_address) + /* + * This is the real return address. Any other + * instances associated with this task are for + * other calls deeper on the call stack + */ + break; } - regs->eflags &= ~TF_MASK; + + BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address)); + regs->eip = orig_ret_address; + + unlock_kprobes(); + preempt_enable_no_resched(); + + /* + * By returning a non-zero value, we are telling + * kprobe_handler() that we have handled unlocking + * and re-enabling preemption. + */ + return 1; } /* @@ -403,8 +401,7 @@ static inline int post_kprobe_handler(struct pt_regs *regs) current_kprobe->post_handler(current_kprobe, regs, 0); } - if (current_kprobe->post_handler != trampoline_post_handler) - resume_execution(current_kprobe, regs); + resume_execution(current_kprobe, regs); regs->eflags |= kprobe_saved_eflags; /*Restore back the original saved kprobes variables and continue. */ @@ -534,3 +531,13 @@ int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) } return 0; } + +static struct kprobe trampoline_p = { + .addr = (kprobe_opcode_t *) &kretprobe_trampoline, + .pre_handler = trampoline_probe_handler +}; + +int __init arch_init(void) +{ + return register_kprobe(&trampoline_p); +} |