On Tue, 17 Nov 2015 16:35:35 +0000 (UTC) Mathieu Desnoyers <[email protected]> wrote:
> Hi, > > I notice that trace_kprobe.c does local_save_flags() within > __kprobe_trace_func(), which is called (at least on x86) with > interrupts always disabled. This is then used as interrupt on/off > state within the recorded event, which is misleading. Kinda. The kprobe itself has interrupts disabled, so it's only a white lie. > > I also don't understand why arch/x86/kernel/kprobes/ftrace.c > pre handler disables interrupts, considering the following > comment above arch/x86/kernel/kprobes/core.c: kprobe_int3_handler() > > * Interrupts are disabled on entry as trap3 is an interrupt gate and they > * remain disabled throughout this function. I think you answered your own question. The key piece you may be missing is that kprobe_ftrace_handler() is not called from a trap, but from a function traced callback, which does not disable interrupts. > > A struct pt_regs is received by this function, but I don't see > any way to get the state of irq enable/disable from struct pt_regs > across architectures. > > Any thoughts on how to fix this ? Create a cross arch: flags = regs_irq_save(regs) function. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
