Commit Graph

3 Commits

Author SHA1 Message Date
Gabriel Krisman Bertazi
36a6c843fd entry: Use different define for selector variable in SUD
Michael Kerrisk suggested that, from an API perspective, it is a bad
idea to share the PR_SYS_DISPATCH_ defines between the prctl operation
and the selector variable.

Therefore, define two new constants to be used by SUD's selector variable
and update the corresponding documentation and test cases.

While this changes the API syscall user dispatch has never been part of a
Linux release, it will show up for the first time in 5.11.

Suggested-by: Michael Kerrisk (man-pages) <mtk.manpages@gmail.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210205184321.2062251-1-krisman@collabora.com
2021-02-06 00:21:42 +01:00
Gabriel Krisman Bertazi
d87ae0fa21 selftests: Add benchmark for syscall user dispatch
This is the patch I'm using to evaluate the impact syscall user dispatch
has on native syscall (syscalls not redirected to userspace) when
enabled for the process and submiting syscalls though the unblocked
dispatch selector. It works by running a step to define a baseline of
the cost of executing sysinfo, then enabling SUD, and rerunning that
step.

On my test machine, an AMD Ryzen 5 1500X, I have the following results
with the latest version of syscall user dispatch patches.

root@olga:~# syscall_user_dispatch/sud_benchmark
  Calibrating test set to last ~5 seconds...
  test iterations = 37500000
  Avg syscall time 134ns.
  Caught sys_ff00
  trapped_call_count 1, native_call_count 0.
  Avg syscall time 147ns.
  Interception overhead: 9.7% (+13ns).

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20201127193238.821364-7-krisman@collabora.com
2020-12-02 15:07:57 +01:00
Gabriel Krisman Bertazi
179ef03599 selftests: Add kselftest for syscall user dispatch
Implement functionality tests for syscall user dispatch.  In order to
make the test portable, refrain from open coding syscall dispatchers and
calculating glibc memory ranges.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20201127193238.821364-6-krisman@collabora.com
2020-12-02 15:07:56 +01:00