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kprobes: Update document about irq disabled state in kprobe handler
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Update kprobes.txt about interrupts disabled state inside
kprobes handlers, because optimized probe/boosted kretprobe
run without disabling interrrupts on x86.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: 2nddept-manager@sdl.hitachi.co.jp
LKML-Reference: <20101014031018.4100.64883.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Masami Hiramatsu authored and Ingo Molnar committed Oct 14, 2010
1 parent 1efeb08 commit 0f55a2f
Showing 1 changed file with 5 additions and 3 deletions.
8 changes: 5 additions & 3 deletions Documentation/kprobes.txt
Original file line number Diff line number Diff line change
Expand Up @@ -542,9 +542,11 @@ Kprobes does not use mutexes or allocate memory except during
registration and unregistration.

Probe handlers are run with preemption disabled. Depending on the
architecture, handlers may also run with interrupts disabled. In any
case, your handler should not yield the CPU (e.g., by attempting to
acquire a semaphore).
architecture and optimization state, handlers may also run with
interrupts disabled (e.g., kretprobe handlers and optimized kprobe
handlers run without interrupt disabled on x86/x86-64). In any case,
your handler should not yield the CPU (e.g., by attempting to acquire
a semaphore).

Since a return probe is implemented by replacing the return
address with the trampoline's address, stack backtraces and calls
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