|| ||Mathieu Desnoyers <email@example.com>|
|| ||Ingo Molnar <firstname.lastname@example.org>, email@example.com,
Frederic Weisbecker <firstname.lastname@example.org>,
Steven Rostedt <email@example.com>,
|| ||[RFC patch 00/21] TIF_KERNEL_TRACE thread flags|
|| ||Sun, 15 Mar 2009 15:03:40 -0400|
|| ||Article, Thread
This is the implementatino of TIF_KERNEL_TRACE thread flags I did in the LTTng
tree. Basically, it offers :
- Setting a per-thread flag for _all_ threads to enable system-wide syscall
- No performance impact when disabled, no need to stop threads upon
activation/deactivation (does not add latency to userspace threads upon
The most tricky bits are in the x86_64 architecture, because its entry_64.S
code does not expect the thread flags to be changed concurrently while the
thread is running. I modified entry_64.S so that the architecture does not
suffer of any performance impact when syscall audit or secure computing is
enabled, but tests for the TIF_KERNEL_TRACE flag upon return to userspace too.
Given this looks very much like what Frederic is currently doing, I think it's
good to post it for comments.
utrace tracehooks could potentially make this patchset obsolete, but I an not
yet convinced that utrace offers the same low-latency guarantees as this code.
It applies on top of kernel 2.6.29-rc7.
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