From 3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 2 Sep 2026 15:31:14 -0700 Subject: treewide: refresh kmalloc_obj() conversions This is another run of the Coccinelle script for converting kmalloc() family of allocations to kmalloc_obj() via the existing rules in scripts/coccinelle/api/kmalloc_objs.cocci This catches both the set of kmalloc() uses added since the first kmalloc_obj() conversions in v7.0 and adds a large group missed in the first pass due to Coccinelle not interacting well with the cleanup.h scoped_...() family of macros[1]. I worked around this with spatch's "--macro-file" argument to a file with all the scoped_...() macros mapped to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control flow indicator I could find. Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc, riscv, and s390 with no new warnings. Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1] Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2] Signed-off-by: Kees Cook --- Documentation/userspace-api/liveupdate.rst | 51 ++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 Documentation/userspace-api/liveupdate.rst (limited to 'Documentation/userspace-api/liveupdate.rst') diff --git a/Documentation/userspace-api/liveupdate.rst b/Documentation/userspace-api/liveupdate.rst new file mode 100644 index 000000000..cdd74627a --- /dev/null +++ b/Documentation/userspace-api/liveupdate.rst @@ -0,0 +1,51 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================ +Live Update uAPI +================ +:Author: Pasha Tatashin + +ioctl interface +=============== +.. kernel-doc:: kernel/liveupdate/luo_core.c + :doc: LUO ioctl Interface + +ioctl uAPI +=========== +.. kernel-doc:: include/uapi/linux/liveupdate.h + +Note on Compatibility +===================== + +Note that the Live Update feature is still under development and subject to +change, so compatibility is not guaranteed when kexec rebooting between +different kernel versions. This is expected to change and stabilize in a future +version. + +Userspace Integration +===================== + +systemd (since version v261) uses LUO to preserve its per-service file +descriptor store across a kexec-based live update. Services opt in by setting +``FileDescriptorStoreMax=`` and ``FileDescriptorStorePreserve=`` in their unit, +and push file descriptors with a name into the store via +``sd_pid_notify_with_fds(... "FDSTORE=1\nFDNAME=foo")``. + +Services may also create their own LUO sessions (via ``/dev/liveupdate``) and +push the resulting session fds into their file descriptor store like any other +fd. systemd detects such session fds and handles them accordingly, and +hands the re-retrieved session fd back to the service after kexec, using the +existing file descriptor store service interface. + +For details, see: + +- `File Descriptor Store `_ +- `systemd.service(5) FileDescriptorStorePreserve= + `_ +- `sd_pid_notify_with_fds(3) + `_ + +See Also +======== + +- :doc:`Live Update Orchestrator ` -- cgit v1.3.1