Commit 7a9011db authored by David A. Long's avatar David A. Long Committed by Jonathan Corbet

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: default avatarDavid A. Long <dave.long@linaro.org>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent a78a136f
...@@ -103,6 +103,16 @@ Note that the probed function's args may be passed on the stack ...@@ -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 or in registers. The jprobe will work in either case, so long as the
handler's prototype matches that of the probed function. 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 Return Probes
1.3.1 How Does a Return Probe Work? 1.3.1 How Does a Return Probe Work?
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