Re: [PATCH 1/2] kprobes: Update document about irq disabled statein kprobe handler

From: Ananth N Mavinakayanahalli
Date: Thu Aug 05 2010 - 08:56:08 EST


On Thu, Aug 05, 2010 at 09:35:05PM +0900, Masami Hiramatsu wrote:
> Update kprobes.txt about interrupts disabled state inside
> kprobes handlers, because optimized probe/boosted kretprobe
> run without disabling interrrupts on x86.
>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>

Acked-by: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>

> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-doc@xxxxxxxxxxxxxxx
> ---
>
> Documentation/kprobes.txt | 8 +++++---
> 1 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
> index 6653017..4189f01 100644
> --- a/Documentation/kprobes.txt
> +++ b/Documentation/kprobes.txt
> @@ -541,9 +541,11 @@ Kprobes does not use mutexes or allocate memory except during
> registration and unregistration.
>
> Probe handlers are run with preemption disabled. Depending on the
> -architecture, handlers may also run with interrupts disabled. In any
> -case, your handler should not yield the CPU (e.g., by attempting to
> -acquire a semaphore).
> +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).
>
> Since a return probe is implemented by replacing the return
> address with the trampoline's address, stack backtraces and calls
>
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