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-rw-r--r--Documentation/trace/kprobetrace.rst8
1 files changed, 6 insertions, 2 deletions
diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst
index 8a2dfee381..bf9cecb69f 100644
--- a/Documentation/trace/kprobetrace.rst
+++ b/Documentation/trace/kprobetrace.rst
@@ -61,8 +61,12 @@ Synopsis of kprobe_events
(x8/x16/x32/x64), "char", "string", "ustring", "symbol", "symstr"
and bitfield are supported.
- (\*1) only for the probe on function entry (offs == 0).
- (\*2) only for return probe.
+ (\*1) only for the probe on function entry (offs == 0). Note, this argument access
+ is best effort, because depending on the argument type, it may be passed on
+ the stack. But this only support the arguments via registers.
+ (\*2) only for return probe. Note that this is also best effort. Depending on the
+ return value type, it might be passed via a pair of registers. But this only
+ accesses one register.
(\*3) this is useful for fetching a field of data structures.
(\*4) "u" means user-space dereference. See :ref:`user_mem_access`.