Am Freitag, dem 05.02.2021 um 16:37 +0000 schrieb Chris Wilson:
Userspace has discovered the functionality offered by SYS_kcmp and has started to depend upon it. In particular, Mesa uses SYS_kcmp for os_same_file_description() in order to identify when two fd (e.g. device or dmabuf) point to the same struct file. Since they depend on it for core functionality, lift SYS_kcmp out of the non-default CONFIG_CHECKPOINT_RESTORE into the selectable syscall category.
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Kees Cook keescook@chromium.org Cc: Andy Lutomirski luto@amacapital.net Cc: Will Drewry wad@chromium.org Cc: Andrew Morton akpm@linux-foundation.org Cc: Dave Airlie airlied@gmail.com Cc: Daniel Vetter daniel@ffwll.ch Cc: Lucas Stach l.stach@pengutronix.de
init/Kconfig | 11 +++++++++++ kernel/Makefile | 2 +- tools/testing/selftests/seccomp/seccomp_bpf.c | 2 +- 3 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig index b77c60f8b963..f62fca13ac5b 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1194,6 +1194,7 @@ endif # NAMESPACES config CHECKPOINT_RESTORE bool "Checkpoint/restore support" select PROC_CHILDREN
- select KCMP
default n help Enables additional kernel features in a sake of checkpoint/restore. @@ -1737,6 +1738,16 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS config ARCH_HAS_MEMBARRIER_SYNC_CORE bool
+config KCMP
- bool "Enable kcmp() system call" if EXPERT
- default y
- help
Enable the file descriptor comparison system call. It providesuser-space with the ability to compare two fd to see if theypoint to the same file, and check other attributes.
This description undersells the abilities of kcmp, while fd compare is the only thing used by the graphics stack, kcmp can compare a handful of other system resources, see man 2 kcmp. I think the helptext should at least try to cover this fact somewhat.
Regards, Lucas
If unsure, say Y.config RSEQ bool "Enable rseq() system call" if EXPERT default y diff --git a/kernel/Makefile b/kernel/Makefile index aa7368c7eabf..320f1f3941b7 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -51,7 +51,7 @@ obj-y += livepatch/ obj-y += dma/ obj-y += entry/
-obj-$(CONFIG_CHECKPOINT_RESTORE) += kcmp.o +obj-$(CONFIG_KCMP) += kcmp.o obj-$(CONFIG_FREEZER) += freezer.o obj-$(CONFIG_PROFILING) += profile.o obj-$(CONFIG_STACKTRACE) += stacktrace.o diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index 26c72f2b61b1..1b6c7d33c4ff 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -315,7 +315,7 @@ TEST(kcmp) ret = __filecmp(getpid(), getpid(), 1, 1); EXPECT_EQ(ret, 0); if (ret != 0 && errno == ENOSYS)
SKIP(return, "Kernel does not support kcmp() (missing CONFIG_CHECKPOINT_RESTORE?)");
SKIP(return, "Kernel does not support kcmp() (missing CONFIG_KCMP?)");}
TEST(mode_strict_support)