[PATCH v7 0/7] Syscall User Dispatch

Gabriel Krisman Bertazi
2020-11-18T03:29:00Z

Hi,

This is the v7 of syscall user dispatch. This version is a bit
different from v6 on the following points, after the modifications
requested on that submission.

* The interface no longer receives <start>,<end> end parameters, but
<start>,<length> as suggested by PeterZ.

* Syscall User Dispatch is now done before ptrace, and this means there
is some SYSCALL_WORK_EXIT work that needs to be done. No challenges
there, but I'd like to draw attention to that region of the code that
is new in this submission.

* The previous TIF_SYSCALL_USER_DISPATCH is now handled through
SYSCALL_WORK flags.

* Introduced a new test as patch 6, which benchmarks the fast submission
path and test the return in blocked selector state.

* Nothing is architecture dependent anymore. No config switches. It
only depends on CONFIG_GENERIC_ENTRY.

Other smaller changes are documented one each commit.

This was tested using the kselftests tests in patch 5 and 6 and compiled
tested with !CONFIG_GENERIC_ENTRY.

This patchset is based on the core/entry branch of the TIP tree.

A working tree with this patchset is available at:

https://gitlab.collabora.com/krisman/linux -b syscall-user-dispatch-v7

Previous submissions are archived at:

RFC/v1: https://lkml.org/lkml/2020/7/8/96
v2: https://lkml.org/lkml/2020/7/9/17
v3: https://lkml.org/lkml/2020/7/12/4
v4: https://www.spinics.net/lists/linux-kselftest/msg16377.html
v5: https://lkml.org/lkml/2020/8/10/1320
v6: https://lkml.org/lkml/2020/9/4/1122

Gabriel Krisman Bertazi (7):
x86: vdso: Expose sigreturn address on vdso to the kernel
signal: Expose SYS_USER_DISPATCH si_code type
kernel: Implement selective syscall userspace redirection
entry: Support Syscall User Dispatch on common syscall entry
selftests: Add kselftest for syscall user dispatch
selftests: Add benchmark for syscall user dispatch
docs: Document Syscall User Dispatch

.../admin-guide/syscall-user-dispatch.rst | 87 +++++
arch/x86/entry/vdso/vdso2c.c | 2 +
arch/x86/entry/vdso/vdso32/sigreturn.S | 2 +
arch/x86/entry/vdso/vma.c | 15 +
arch/x86/include/asm/elf.h | 2 +
arch/x86/include/asm/vdso.h | 2 +
arch/x86/kernel/signal_compat.c | 2 +-
fs/exec.c | 3 +
include/linux/entry-common.h | 2 +
include/linux/sched.h | 2 +
include/linux/syscall_user_dispatch.h | 40 +++
include/linux/thread_info.h | 2 +
include/uapi/asm-generic/siginfo.h | 3 +-
include/uapi/linux/prctl.h | 5 +
kernel/entry/Makefile | 2 +-
kernel/entry/common.c | 17 +
kernel/entry/common.h | 16 +
kernel/entry/syscall_user_dispatch.c | 102 ++++++
kernel/fork.c | 1 +
kernel/sys.c | 5 +
tools/testing/selftests/Makefile | 1 +
.../syscall_user_dispatch/.gitignore | 3 +
.../selftests/syscall_user_dispatch/Makefile | 9 +
.../selftests/syscall_user_dispatch/config | 1 +
.../syscall_user_dispatch/sud_benchmark.c | 200 +++++++++++
.../syscall_user_dispatch/sud_test.c | 310 ++++++++++++++++++
26 files changed, 833 insertions(+), 3 deletions(-)
create mode 100644 Documentation/admin-guide/syscall-user-dispatch.rst
create mode 100644 include/linux/syscall_user_dispatch.h
create mode 100644 kernel/entry/common.h
create mode 100644 kernel/entry/syscall_user_dispatch.c
create mode 100644 tools/testing/selftests/syscall_user_dispatch/.gitignore
create mode 100644 tools/testing/selftests/syscall_user_dispatch/Makefile
create mode 100644 tools/testing/selftests/syscall_user_dispatch/config
create mode 100644 tools/testing/selftests/syscall_user_dispatch/sud_benchmark.c
create mode 100644 tools/testing/selftests/syscall_user_dispatch/sud_test.c

--
2.29.2