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authorChris Wilson <chris@chris-wilson.co.uk>2021-02-05 22:00:12 +0000
committerDaniel Vetter <daniel.vetter@ffwll.ch>2021-02-16 09:59:41 +0100
commitbfe3911a91047557eb0e620f95a370aee6a248c7 (patch)
tree6c6ebd4ca25f09ece5d55ce0c186a026b0d37509 /kernel/Makefile
parentf40ddce88593482919761f74910f42f4b84c004b (diff)
downloadlinux-bfe3911a91047557eb0e620f95a370aee6a248c7.tar.gz
kcmp: Support selection of SYS_kcmp without CHECKPOINT_RESTORE
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.

Rasmus Villemoes also pointed out that systemd uses SYS_kcmp to
deduplicate the per-service file descriptor store.

Note that some distributions such as Ubuntu are already enabling
CHECKPOINT_RESTORE in their configs and so, by extension, SYS_kcmp.

References: https://gitlab.freedesktop.org/drm/intel/-/issues/3046
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>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: stable@vger.kernel.org
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> # DRM depends on kcmp
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> # systemd uses kcmp
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210205220012.1983-1-chris@chris-wilson.co.uk
Diffstat (limited to 'kernel/Makefile')
-rw-r--r--kernel/Makefile2
1 files changed, 1 insertions, 1 deletions
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