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2021-02-06entry: Use different define for selector variable in SUDGabriel Krisman Bertazi1-3/+5
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
2020-12-02selftests: Add benchmark for syscall user dispatchGabriel Krisman Bertazi1-0/+200
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