Documentation: kprobes: Document jprobes stack copying limitations

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@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
David A. Long 2016-08-12 16:24:44 -04:00 committed by Jonathan Corbet
parent a78a136fa9
commit 7a9011db32
1 changed files with 10 additions and 0 deletions

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@ -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
architecture).
1.3 Return Probes
1.3.1 How Does a Return Probe Work?