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 <sourabhjain@linux.ibm.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240326055413.186534-7-sourabhjain@linux.ibm.com
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 <sourabhjain@linux.ibm.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240326055413.186534-4-sourabhjain@linux.ibm.com
The following build failure occurs when CONFIG_PPC_64S_HASH_MMU is not
set:
arch/powerpc/kernel/setup_64.c: In function ‘setup_per_cpu_areas’:
arch/powerpc/kernel/setup_64.c:811:21: error: ‘mmu_linear_psize’ undeclared (first use in this function); did you mean ‘mmu_virtual_psize’?
811 | if (mmu_linear_psize == MMU_PAGE_4K)
| ^~~~~~~~~~~~~~~~
| mmu_virtual_psize
arch/powerpc/kernel/setup_64.c:811:21: note: each undeclared identifier is reported only once for each function it appears in
Move the declaration of mmu_linear_psize outside of
CONFIG_PPC_64S_HASH_MMU ifdef.
After the above is fixed, it fails later with the following error:
ld: arch/powerpc/kexec/file_load_64.o: in function `.arch_kexec_kernel_image_probe':
file_load_64.c:(.text+0x1c1c): undefined reference to `.add_htab_mem_range'
Fix that, too, by conditioning add_htab_mem_range() symbol to
CONFIG_PPC_64S_HASH_MMU.
Fixes: 387e220a2e ("powerpc/64s: Move hash MMU support code under CONFIG_PPC_64S_HASH_MMU")
Reported-by: Erhard F. <erhard_f@mailbox.org>
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=215567
Link: https://lore.kernel.org/r/20220301204743.45133-1-muriloo@linux.ibm.com
crashkernel region could have an overlap with special memory regions
like OPAL, RTAS, TCE table & such. These regions are referred to as
excluded memory ranges. Setup these ranges during image probe in order
to avoid them while finding the buffer for different kdump segments.
Override arch_kexec_locate_mem_hole() to locate a memory hole taking
these ranges into account.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/159602281047.575379.6636807148335160795.stgit@hbathini
In kexec case, the kernel to be loaded uses the same memory layout as
the running kernel. So, passing on the DT of the running kernel would
be good enough.
But in case of kdump, different memory ranges are needed to manage
loading the kdump kernel, booting into it and exporting the elfcore of
the crashing kernel. The ranges are exclude memory ranges, usable
memory ranges, reserved memory ranges and crash memory ranges.
Exclude memory ranges specify the list of memory ranges to avoid while
loading kdump segments. Usable memory ranges list the memory ranges
that could be used for booting kdump kernel. Reserved memory ranges
list the memory regions for the loading kernel's reserve map. Crash
memory ranges list the memory ranges to be exported as the crashing
kernel's elfcore.
Add helper functions for setting up the above mentioned memory ranges.
This helpers facilitate in understanding the subsequent changes better
and make it easy to setup the different memory ranges listed above, as
and when appropriate.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Pingfan Liu <piliu@redhat.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/159602279194.575379.8526552316948643550.stgit@hbathini
