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Subject[PATCH v11 0/2] Checkpoint Support for Syscall User Dispatch
v11: backout complex compat code, change struct to more generic typing
(padding to ensure struct size is the same in 32 compat)
update selftest
tested selftest on 64 machine and in 32-bit compat mode

v10: move refactor code into patch ahead of change
add compat support
documentation change

v9: tglx feedback
documentation of ptrace struct
shorten struct name
helper function for set_syscall_user_dispatch
use task variant of set/clear_syscall_work
use task variant of test_syscall_work in getter

v8: fix include issue Reported-by: kernel test robot <>
+++ b/kernel/entry/syscall_user_dispatch.c
+ include <linux/ptrace.h>

v7: drop ptrace suspend flag, not required
hanging unreferenced variable

v6: drop fs/proc/array update, it's not needed
drop on_dispatch field exposure in config structure, it's not
checkpoint relevant.
(Thank you for the reviews Oleg and Andrei)

v5: automated test for !defined(GENERIC_ENTRY) failed, fix fs/proc
note: syscall user dispatch is not presently supported for
non-generic entry, but could be implemented. question is
whether the TIF_ define should be carved out now or then

v4: Whitespace
check test_syscall_work(SYSCALL_USER_DISPATCH) to determine if it's
turned on or not in fs/proc/array and getter interface

v3: Kernel test robot static function fix
Whitespace nitpicks

v2: Implements the getter/setter interface in ptrace rather than prctl

Syscall user dispatch makes it possible to cleanly intercept system
calls from user-land. However, most transparent checkpoint software
presently leverages some combination of ptrace and system call
injection to place software in a ready-to-checkpoint state.

If Syscall User Dispatch is enabled at the time of being quiesced,
injected system calls will subsequently be interposed upon and
dispatched to the task's signal handler.

Patch summary:
- Refactor configuration setting interface to operate on a task
rather than current, so the set and error paths can be consolidated

- Implement a getter interface for Syscall User Dispatch config info.
To resume successfully, the checkpoint/resume software has to
save and restore this information. Presently this configuration
is write-only, with no way for C/R software to save it.

This was done in ptrace because syscall user dispatch is not part of
uapi. The syscall_user_dispatch_config structure was added to the
ptrace exports.

Gregory Price (2):
syscall_user_dispatch: helper function to operate on given task
ptrace,syscall_user_dispatch: checkpoint/restore support for SUD

.../admin-guide/syscall-user-dispatch.rst | 4 +
include/linux/syscall_user_dispatch.h | 18 +++++
include/uapi/linux/ptrace.h | 30 ++++++++
kernel/entry/syscall_user_dispatch.c | 63 +++++++++++++--
kernel/ptrace.c | 9 +++
tools/testing/selftests/ptrace/.gitignore | 1 +
tools/testing/selftests/ptrace/Makefile | 2 +-
tools/testing/selftests/ptrace/get_set_sud.c | 77 +++++++++++++++++++
8 files changed, 195 insertions(+), 9 deletions(-)
create mode 100644 tools/testing/selftests/ptrace/get_set_sud.c


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