Changing Execution Path
-----------------------
-Since the kprobes can probe into a running kernel code, it can change
-the register set, including instruction pointer. This operation
-requires maximum attention, such as keeping the stack frame, recovering
-execution path etc. Since it is operated on running kernel and need deep
-knowladge of the archtecture and concurrent computing, you can easily
-shot your foot.
+Since kprobes can probe into a running kernel code, it can change the
+register set, including instruction pointer. This operation requires
+maximum care, such as keeping the stack frame, recovering the execution
+path etc. Since it operates on a running kernel and needs deep knowledge
+of computer architecture and concurrent computing, you can easily shoot
+your foot.
If you change the instruction pointer (and set up other related
-registers) in pre_handler, you must return !0 so that the kprobes
-stops single stepping and just returns to given address.
+registers) in pre_handler, you must return !0 so that kprobes stops
+single stepping and just returns to the given address.
This also means post_handler should not be called anymore.
-Note that this operation may be harder on some architectures which
-use TOC (Table of Contents) for function call, since you have to
-setup new TOC for your function in your module, and recover old
-one after back from it.
+Note that this operation may be harder on some architectures which use
+TOC (Table of Contents) for function call, since you have to setup a new
+TOC for your function in your module, and recover the old one after
+returning from it.
Return Probes
-------------
projects / linux-2.6-block.git / blobdiff