Hello, This patch series implements a mechanism which allows the kernel to pass on a buffer to the kernel that will be kexec'd. This buffer is passed as a segment which is added to the kimage when it is being prepared by kexec_file_load. How the second kernel is informed of this buffer is architecture-specific. On PowerPC, this is done via the device tree, by checking the properties /chosen/linux,kexec-handover-buffer-start and /chosen/linux,kexec-handover-buffer-end, which is analogous to how the kernel finds the initrd. This feature was implemented because the Integrity Measurement Architecture subsystem needs to preserve its measurement list accross the kexec reboot. This is so that IMA can implement trusted boot support on the OpenPower platform, because on such systems an intermediary Linux instance running as part of the firmware is used to boot the target operating system via kexec. Using this mechanism, IMA on this intermediary instance can hand over to the target OS the measurements of the components that were used to boot it. Because there could be additional measurement events between the kexec_file_load call and the actual reboot, IMA needs a way to update the buffer with those additional events before rebooting. One can minimize the interval between the kexec_file_load and the reboot syscalls, but as small as it can be, there is always the possibility that the measurement list will be out of date at the time of reboot. To address this issue, this patch series also introduces kexec_update_segment, which allows a reboot notifier to change the contents of the image segment during the reboot process. There's one patch which makes kimage_load_normal_segment and kexec_update_segment share code. It's not much code that they can share though, so I'm not sure if it's worth including this patch. The last patch is not intended to be merged, it just demonstrates how this feature can be used. This series applies on top of v2 of the "kexec_file_load implementation for PowerPC" patch series at: http://lists.infradead.org/pipermail/kexec/2016-June/016078.html Thiago Jung Bauermann (6): kexec_file: Add buffer hand-over support for the next kernel powerpc: kexec_file: Add buffer hand-over support for the next kernel kexec_file: Allow skipping checksum calculation for some segments. kexec_file: Add mechanism to update kexec segments. kexec: Share logic to copy segment page contents. IMA: Demonstration code for kexec buffer passing. arch/powerpc/include/asm/kexec.h | 9 ++ arch/powerpc/kernel/kexec_elf_64.c | 50 +++++++- arch/powerpc/kernel/machine_kexec_64.c | 64 ++++++++++ arch/x86/kernel/crash.c | 4 +- arch/x86/kernel/kexec-bzimage64.c | 6 +- include/linux/ima.h | 11 ++ include/linux/kexec.h | 47 +++++++- kernel/kexec_core.c | 205 ++++++++++++++++++++++++++------- kernel/kexec_file.c | 102 ++++++++++++++-- security/integrity/ima/ima.h | 5 + security/integrity/ima/ima_init.c | 26 +++++ security/integrity/ima/ima_template.c | 79 +++++++++++++ 12 files changed, 547 insertions(+), 61 deletions(-) -- 1.9.1
