kernel/arch/powerpc/kexec/file_load_64.c, branch linux-rolling-stable

powerpc/crash: adjust the elfcorehdr size

2026-03-19T15:14:45Z

[ Upstream commit 04e707cb77c272cb0bb2e2e3c5c7f844d804a089 ] With crash hotplug support enabled, additional memory is allocated to the elfcorehdr kexec segment to accommodate resources added during memory hotplug events. However, the kdump FDT is not updated with the same size, which can result in elfcorehdr corruption in the kdump kernel. Update elf_headers_sz (the kimage member representing the size of the elfcorehdr kexec segment) to reflect the total memory allocated for the elfcorehdr segment instead of the elfcorehdr buffer size at the time of kdump load. This allows of_kexec_alloc_and_setup_fdt() to reserve the full elfcorehdr memory in the kdump FDT and prevents elfcorehdr corruption. Fixes: 849599b702ef8 ("powerpc/crash: add crash memory hotplug support") Reviewed-by: Hari Bathini Signed-off-by: Sourabh Jain Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260227171801.2238847-1-sourabhjain@linux.ibm.com Signed-off-by: Sasha Levin

powerpc/crash: use generic APIs to locate memory hole for kdump

2025-03-17T05:30:48Z

On PowerPC, the memory reserved for the crashkernel can contain components like RTAS, TCE, OPAL, etc., which should be avoided when loading kexec segments into crashkernel memory. Due to these special components, PowerPC has its own set of APIs to locate holes in the crashkernel memory for loading kexec segments for kdump. However, for loading kexec segments in the kexec case, PowerPC already uses generic APIs to locate holes. The previous patch in this series, titled "crash: Let arch decide usable memory range in reserved area," introduced arch-specific hook to handle such special regions in the crashkernel area. So, switch PowerPC to use the generic APIs to locate memory holes for kdump and remove the redundant PowerPC-specific APIs. Link: https://lkml.kernel.org/r/20250131113830.925179-5-sourabhjain@linux.ibm.com Signed-off-by: Sourabh Jain Cc: Baoquan he Cc: Hari Bathini Cc: Madhavan Srinivasan Cc: Mahesh Salgaonkar Cc: Michael Ellerman Signed-off-by: Andrew Morton

powerpc/kexec: Fix return of uninitialized variable

2024-11-14T13:29:46Z

of_property_read_u64() can fail and leave the variable uninitialized, which will then be used. Return error if reading the property failed. Fixes: 2e6bd221d96f ("powerpc/kexec_file: Enable early kernel OPAL calls") Signed-off-by: Zhang Zekun Signed-off-by: Michael Ellerman Link: https://patch.msgid.link/20240930075628.125138-1-zhangzekun11@huawei.com

powerpc/kexec: Use of_property_read_reg()

2024-07-04T11:55:18Z

Replace open-coded parsing of "reg" property with of_property_read_reg(). Signed-off-by: Rob Herring (Arm) [mpe: Rename end to size, add comment to the bail out case] Signed-off-by: Michael Ellerman Link: https://msgid.link/20240702210344.722364-1-robh@kernel.org

powerpc/kexec_file: fix extra size calculation for kexec FDT

2024-06-17T12:48:45Z

While setting up the FDT for kexec, CPU nodes that are added after the system boots and reserved memory ranges are incorporated into the initial_boot_params (base FDT). However, they are not taken into account when determining the additional size needed for the kexec FDT. As a result, kexec fails to load, generating the following error: [1116.774451] Error updating memory reserve map: FDT_ERR_NOSPACE kexec_file_load failed: No such process Therefore, consider the extra size for CPU nodes added post-system boot and reserved memory ranges while preparing the kexec FDT. While adding a new parameter to the setup_new_fdt_ppc64 function, it was noticed that there were a couple of unused parameters, so they were removed. Signed-off-by: Sourabh Jain Signed-off-by: Michael Ellerman Link: https://msgid.link/20240510102235.2269496-2-sourabhjain@linux.ibm.com

powerpc/crash: add crash memory hotplug support

2024-04-23T05:00:04Z

Extend the arch crash hotplug handler, as introduced by the patch title ("powerpc: add crash CPU hotplug support"), to also support memory add/remove events. Elfcorehdr describes the memory of the crash kernel to capture the kernel; hence, it needs to be updated if memory resources change due to memory add/remove events. Therefore, arch_crash_handle_hotplug_event() is updated to recreate the elfcorehdr and replace it with the previous one on memory add/remove events. The memblock list is used to prepare the elfcorehdr. In the case of memory hot remove, the memblock list is updated after the arch crash hotplug handler is triggered, as depicted in Figure 1. Thus, the hot-removed memory is explicitly removed from the crash memory ranges to ensure that the memory ranges added to elfcorehdr do not include the hot-removed memory. Memory remove | v Offline pages | v Initiate memory notify call <----> crash hotplug handler chain for MEM_OFFLINE event | v Update memblock list Figure 1 There are two system calls, `kexec_file_load` and `kexec_load`, used to load the kdump image. A few changes have been made to ensure that the kernel can safely update the elfcorehdr component of the kdump image for both system calls. For the kexec_file_load syscall, kdump image is prepared in the kernel. To support an increasing number of memory regions, the elfcorehdr is built with extra buffer space to ensure that it can accommodate additional memory ranges in future. For the kexec_load syscall, the elfcorehdr is updated only if the KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag is passed to the kernel by the kexec tool. Passing this flag to the kernel indicates that the elfcorehdr is built to accommodate additional memory ranges and the elfcorehdr segment is not considered for SHA calculation, making it safe to update. The changes related to this feature are kept under the CRASH_HOTPLUG config, and it is enabled by default. Signed-off-by: Sourabh Jain Acked-by: Hari Bathini Signed-off-by: Michael Ellerman Link: https://msgid.link/20240326055413.186534-7-sourabhjain@linux.ibm.com

powerpc/crash: add crash CPU hotplug support

2024-04-23T05:00:04Z

Due to CPU/Memory hotplug or online/offline events, the elfcorehdr (which describes the CPUs and memory of the crashed kernel) and FDT (Flattened Device Tree) of kdump image becomes outdated. Consequently, attempting dump collection with an outdated elfcorehdr or FDT can lead to failed or inaccurate dump collection. Going forward, CPU hotplug or online/offline events are referred as CPU/Memory add/remove events. The current solution to address the above issue involves monitoring the CPU/Memory add/remove events in userspace using udev rules and whenever there are changes in CPU and memory resources, the entire kdump image is loaded again. The kdump image includes kernel, initrd, elfcorehdr, FDT, purgatory. Given that only elfcorehdr and FDT get outdated due to CPU/Memory add/remove events, reloading the entire kdump image is inefficient. More importantly, kdump remains inactive for a substantial amount of time until the kdump reload completes. To address the aforementioned issue, commit 247262756121 ("crash: add generic infrastructure for crash hotplug support") added a generic infrastructure that allows architectures to selectively update the kdump image component during CPU or memory add/remove events within the kernel itself. In the event of a CPU or memory add/remove events, the generic crash hotplug event handler, `crash_handle_hotplug_event()`, is triggered. It then acquires the necessary locks to update the kdump image and invokes the architecture-specific crash hotplug handler, `arch_crash_handle_hotplug_event()`, to update the required kdump image components. This patch adds crash hotplug handler for PowerPC and enable support to update the kdump image on CPU add/remove events. Support for memory add/remove events is added in a subsequent patch with the title "powerpc: add crash memory hotplug support" As mentioned earlier, only the elfcorehdr and FDT kdump image components need to be updated in the event of CPU or memory add/remove events. However, on PowerPC architecture crash hotplug handler only updates the FDT to enable crash hotplug support for CPU add/remove events. Here's why. The elfcorehdr on PowerPC is built with possible CPUs, and thus, it does not need an update on CPU add/remove events. On the other hand, the FDT needs to be updated on CPU add events to include the newly added CPU. If the FDT is not updated and the kernel crashes on a newly added CPU, the kdump kernel will fail to boot due to the unavailability of the crashing CPU in the FDT. During the early boot, it is expected that the boot CPU must be a part of the FDT; otherwise, the kernel will raise a BUG and fail to boot. For more information, refer to commit 36ae37e3436b0 ("powerpc: Make boot_cpuid common between 32 and 64-bit"). Since it is okay to have an offline CPU in the kdump FDT, no action is taken in case of CPU removal. There are two system calls, `kexec_file_load` and `kexec_load`, used to load the kdump image. Few changes have been made to ensure kernel can safely update the FDT of kdump image loaded using both system calls. For kexec_file_load syscall the kdump image is prepared in kernel. So to support an increasing number of CPUs, the FDT is constructed with extra buffer space to ensure it can accommodate a possible number of CPU nodes. Additionally, a call to fdt_pack (which trims the unused space once the FDT is prepared) is avoided if this feature is enabled. For the kexec_load syscall, the FDT is updated only if the KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag is passed to the kernel by userspace (kexec tools). When userspace passes this flag to the kernel, it indicates that the FDT is built to accommodate possible CPUs, and the FDT segment is excluded from SHA calculation, making it safe to update. The changes related to this feature are kept under the CRASH_HOTPLUG config, and it is enabled by default. Signed-off-by: Sourabh Jain Acked-by: Hari Bathini Signed-off-by: Michael Ellerman Link: https://msgid.link/20240326055413.186534-6-sourabhjain@linux.ibm.com

powerpc/kexec: make the update_cpus_node() function public

2024-04-23T04:59:51Z

Move the update_cpus_node() from kexec/{file_load_64.c => core_64.c} to allow other kexec components to use it. Later in the series, this function is used for in-kernel updates to the kdump image during CPU/memory hotplug or online/offline events for both kexec_load and kexec_file_load syscalls. No functional changes are intended. Signed-off-by: Sourabh Jain Acked-by: Hari Bathini Signed-off-by: Michael Ellerman Link: https://msgid.link/20240326055413.186534-5-sourabhjain@linux.ibm.com

powerpc/kexec: move *_memory_ranges functions to ranges.c

2024-04-23T04:59:01Z

Move the following functions form kexec/{file_load_64.c => ranges.c} and make them public so that components other than KEXEC_FILE can also use these functions. 1. get_exclude_memory_ranges 2. get_reserved_memory_ranges 3. get_crash_memory_ranges 4. get_usable_memory_ranges Later in the series get_crash_memory_ranges function is utilized for in-kernel updates to kdump image during CPU/Memory hotplug or online/offline events for both kexec_load and kexec_file_load syscalls. Since the above functions are moved to ranges.c, some of the helper functions in ranges.c are no longer required to be public. Mark them as static and removed them from kexec_ranges.h header file. Finally, remove the CONFIG_KEXEC_FILE build dependency for range.c because it is required for other config, such as CONFIG_CRASH_DUMP. No functional changes are intended. Signed-off-by: Sourabh Jain Acked-by: Hari Bathini Signed-off-by: Michael Ellerman Link: https://msgid.link/20240326055413.186534-4-sourabhjain@linux.ibm.com

powerpc/kexec: split CONFIG_KEXEC_FILE and CONFIG_CRASH_DUMP

2024-03-17T02:34:00Z

CONFIG_KEXEC_FILE does not have to select CONFIG_CRASH_DUMP. Move some code under CONFIG_CRASH_DUMP to support CONFIG_KEXEC_FILE and !CONFIG_CRASH_DUMP case. Signed-off-by: Hari Bathini Signed-off-by: Michael Ellerman Link: https://msgid.link/20240226103010.589537-3-hbathini@linux.ibm.com