trace: trace_kprobe.c always shows interrupts off

From: Mathieu Desnoyers
Date: Tue Nov 17 2015 - 11:35:46 EST


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.

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.

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 ?



Mathieu Desnoyers
EfficiOS Inc.
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