On Thu, Jul 16, 2020 at 08:22:10PM +0200, Thomas Gleixner wrote: > From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > Like syscall entry all architectures have similar and pointlessly different > code to handle pending work before returning from a syscall to user space. > > 1) One-time syscall exit work: > - rseq syscall exit > - audit > - syscall tracing > - tracehook (single stepping) > > 2) Preparatory work > - Exit to user mode loop (common TIF handling). > - Architecture specific one time work arch_exit_to_user_mode_prepare() > - Address limit and lockdep checks > > 3) Final transition (lockdep, tracing, context tracking, RCU). Invokes > arch_exit_to_user_mode() to handle e.g. speculation mitigations > > Provide a generic version based on the x86 code which has all the RCU and > instrumentation protections right. > > Provide a variant for interrupt return to user mode as well which shares > the above #2 and #3 work items. > > After syscall_exit_to_user_mode() and irqentry_exit_to_user_mode() the > architecture code just has to return to user space. The code after > returning from these functions must not be instrumented. > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> This looks correct to me. Did you happen to run the seccomp selftests under this series? Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> -- Kees Cook
