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kprobes: Disable booster when CONFIG_PREEMPT=y

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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 <[email protected]>
Cc: systemtap <[email protected]>
Cc: DLE <[email protected]>
Cc: Ananth N Mavinakayanahalli <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jim Keniston <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Steven Rostedt <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Masami Hiramatsu 2010-02-02 16:49:04 -05:00 • committed by Ingo Molnar
commit 615d0ebbc7
3 changed files with 4 additions and 29 deletions
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29
kernel/kprobes.c
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@ -124,30 +124,6 @@ static LIST_HEAD(kprobe_insn_pages);
static int kprobe_garbage_slots;
static int collect_garbage_slots(void);
static int __kprobes check_safety(void)
{
int ret = 0;
#if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER)
ret = freeze_processes();
if (ret == 0) {
struct task_struct *p, *q;
do_each_thread(p, q) {
if (p != current && p->state == TASK_RUNNING &&
p->pid != 0) {
printk("Check failed: %s is running\n",p->comm);
ret = -1;
goto loop_end;
}
} while_each_thread(p, q);
}
loop_end:
thaw_processes();
#else
synchronize_sched();
#endif
return ret;
}
/**
* __get_insn_slot() - Find a slot on an executable page for an instruction.
* We allocate an executable page if there's no room on existing ones.
@ -235,9 +211,8 @@ static int __kprobes collect_garbage_slots(void)
{
struct kprobe_insn_page *kip, *next;
/* Ensure no-one is preepmted on the garbages */
if (check_safety())
return -EAGAIN;
/* Ensure no-one is interrupted on the garbages */
synchronize_sched();
list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) {
int i;