Kprobes does not use mutexes or allocate memory except during
registration and unregistration.
-Probe handlers are run with preemption disabled. Depending on the
-architecture and optimization state, handlers may also run with
-interrupts disabled (e.g., kretprobe handlers and optimized kprobe
-handlers run without interrupt disabled on x86/x86-64). In any case,
-your handler should not yield the CPU (e.g., by attempting to acquire
-a semaphore).
+Probe handlers are run with preemption disabled or interrupt disabled,
+which depends on the architecture and optimization state. (e.g.,
+kretprobe handlers and optimized kprobe handlers run without interrupt
+disabled on x86/x86-64). In any case, your handler should not yield
+the CPU (e.g., by attempting to acquire a semaphore, or waiting I/O).
Since a return probe is implemented by replacing the return
address with the trampoline's address, stack backtraces and calls
* stepping.
*/
regs->ip = (unsigned long)p->ainsn.insn;
- preempt_enable_no_resched();
return;
}
#endif
addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t));
/*
- * We don't want to be preempted for the entire
- * duration of kprobe processing. We conditionally
- * re-enable preemption at the end of this function,
- * and also in reenter_kprobe() and setup_singlestep().
+ * We don't want to be preempted for the entire duration of kprobe
+ * processing. Since int3 and debug trap disables irqs and we clear
+ * IF while singlestepping, it must be no preemptible.
*/
- preempt_disable();
kcb = get_kprobe_ctlblk();
p = get_kprobe(addr);
*/
if (!p->pre_handler || !p->pre_handler(p, regs))
setup_singlestep(p, regs, kcb, 0);
- else {
+ else
reset_current_kprobe();
- preempt_enable_no_resched();
- }
return 1;
}
} else if (*addr != BREAKPOINT_INSTRUCTION) {
* the original instruction.
*/
regs->ip = (unsigned long)addr;
- preempt_enable_no_resched();
return 1;
} /* else: not a kprobe fault; let the kernel handle it */
- preempt_enable_no_resched();
return 0;
}
NOKPROBE_SYMBOL(kprobe_int3_handler);
}
reset_current_kprobe();
out:
- preempt_enable_no_resched();
-
/*
* if somebody else is singlestepping across a probe point, flags
* will have TF set, in which case, continue the remaining processing
restore_previous_kprobe(kcb);
else
reset_current_kprobe();
- preempt_enable_no_resched();
} else if (kcb->kprobe_status == KPROBE_HIT_ACTIVE ||
kcb->kprobe_status == KPROBE_HIT_SSDONE) {
/*