[PATCH v2 0/2] syscall_user_dispatch: add build/runtime configs

[Gregory Price]

Syscall User Dispatch is presently compiled in by default for all
architectures enabling CONFIG_GENERIC_SYSCALL, and some users may
not wish to have the feature functional at runtime.

Add CONFIG_SYSCALL_USER_DISPATCH and kernel.syscall_user_dispatch
to make it a configurable feature at both build and runtime.

CONFIG_SYSCALL_USER_DISPATCH depends on CONFIG_GENERIC_SYSCALL
but is separately configurable.

The sysctl is enabled by default, and disabling the feature while a
task has already enabled it does not cause it to become inactive in
that task's conetxt. Instead it remains active until the user attempts
to disable/re-enable via prctl or ptrace.  On the next attempt to
re-enable, the prctl/ptrace call fails gracefully.

Gregory Price (2):
  syscall_user_dispatch: Make it configurable in Kconfig
  syscall_user_dispatch: add kernel.syscall_user_dispatch sysctl

 Documentation/admin-guide/sysctl/kernel.rst | 16 ++++++++++++
 arch/Kconfig                                | 11 ++++++++
 include/linux/entry-common.h                |  6 ++---
 include/linux/syscall_user_dispatch.h       | 28 +++++++++++++++++++--
 include/linux/syscall_user_dispatch_types.h |  2 +-
 kernel/entry/Makefile                       |  3 ++-
 kernel/entry/syscall_user_dispatch.c        | 28 +++++++++++++++++++++
 7 files changed, 86 insertions(+), 8 deletions(-)

-- 
2.54.0