[PATCH] Documentation: kprobes: Document jprobes stack copying limitations
mhiramat at kernel.org
Fri Aug 12 16:46:26 PDT 2016
On Fri, 12 Aug 2016 16:24:44 -0400
David Long <dave.long at linaro.org> wrote:
> From: "David A. Long" <dave.long at linaro.org>
> Some architectures (i.e.: sparc64 and arm64) make reasonable partial stack
> duplication for jprobes problematic. Document this.
> Signed-off-by: David A. Long <dave.long at linaro.org>
Looks good to me.
Acked-by: Masami Hiramatsu <mhiramat at kernel.org>
> Documentation/kprobes.txt | 10 ++++++++++
> 1 file changed, 10 insertions(+)
> diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
> index 1f9b3e2..1f6d45a 100644
> --- a/Documentation/kprobes.txt
> +++ b/Documentation/kprobes.txt
> @@ -103,6 +103,16 @@ Note that the probed function's args may be passed on the stack
> or in registers. The jprobe will work in either case, so long as the
> handler's prototype matches that of the probed function.
> +Note that in some architectures (e.g.: arm64 and sparc64) the stack
> +copy is not done, as the actual location of stacked parameters may be
> +outside of a reasonable MAX_STACK_SIZE value and because that location
> +cannot be determined by the jprobes code. In this case the jprobes
> +user must be careful to make certain the calling signature of the
> +function does not cause parameters to be passed on the stack (e.g.:
> +more than eight function arguments, an argument of more than sixteen
> +bytes, or more than 64 bytes of argument data, depending on
> 1.3 Return Probes
> 1.3.1 How Does a Return Probe Work?
Masami Hiramatsu <mhiramat at kernel.org>
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