kprobes: Disable booster when CONFIG_PREEMPT=y
Disable kprobe booster when CONFIG_PREEMPT=y at this time, because it can't ensure that all kernel threads preempted on kprobe's boosted slot run out from the slot even using freeze_processes(). The booster on preemptive kernel will be resumed if synchronize_tasks() or something like that is introduced. Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> Cc: systemtap <systemtap@sources.redhat.com> Cc: DLE <dle-develop@lists.sourceforge.net> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <20100202214904.4694.24330.stgit@dhcp-100-2-132.bos.redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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57d818895f
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615d0ebbc7
3 changed files with 4 additions and 29 deletions
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@ -870,7 +870,7 @@ static int __kprobes pre_kprobes_handler(struct die_args *args)
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return 1;
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ss_probe:
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#if !defined(CONFIG_PREEMPT) || defined(CONFIG_FREEZER)
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#if !defined(CONFIG_PREEMPT)
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if (p->ainsn.inst_flag == INST_FLAG_BOOSTABLE && !p->post_handler) {
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/* Boost up -- we can execute copied instructions directly */
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ia64_psr(regs)->ri = p->ainsn.slot;
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@ -429,7 +429,7 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
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static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs,
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struct kprobe_ctlblk *kcb)
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{
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#if !defined(CONFIG_PREEMPT) || defined(CONFIG_FREEZER)
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#if !defined(CONFIG_PREEMPT)
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if (p->ainsn.boostable == 1 && !p->post_handler) {
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/* Boost up -- we can execute copied instructions directly */
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reset_current_kprobe();
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@ -124,30 +124,6 @@ static LIST_HEAD(kprobe_insn_pages);
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static int kprobe_garbage_slots;
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static int collect_garbage_slots(void);
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static int __kprobes check_safety(void)
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{
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int ret = 0;
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#if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER)
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ret = freeze_processes();
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if (ret == 0) {
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struct task_struct *p, *q;
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do_each_thread(p, q) {
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if (p != current && p->state == TASK_RUNNING &&
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p->pid != 0) {
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printk("Check failed: %s is running\n",p->comm);
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ret = -1;
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goto loop_end;
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}
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} while_each_thread(p, q);
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}
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loop_end:
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thaw_processes();
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#else
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synchronize_sched();
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#endif
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return ret;
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}
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/**
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* __get_insn_slot() - Find a slot on an executable page for an instruction.
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* We allocate an executable page if there's no room on existing ones.
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@ -235,9 +211,8 @@ static int __kprobes collect_garbage_slots(void)
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{
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struct kprobe_insn_page *kip, *next;
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/* Ensure no-one is preepmted on the garbages */
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if (check_safety())
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return -EAGAIN;
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/* Ensure no-one is interrupted on the garbages */
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synchronize_sched();
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list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) {
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int i;
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