On 11/04/2022, 10:43:57, Sourabh Jain wrote:
> The kernel changes needed for crash hotplug support for kexec_load system
> calls are similar to kexec_file_load (which has already been implemented
> in earlier patches) except for finding the index of the FDT segment in the
> kexec segment array. Since the kexec segment array is prepared by the
> kexec tool in the userspace, the kernel is not aware of at which index FDT
> segment is present.
>
> Now to enable crash hotplug support for the kexec_load case, the crash
> hotplug handler is updated to identify the index at which the FDT segment
> is present in the kexec segment array by comparing the first 32 bits of
> every kexec segment with the FDT magic number.
>
> Signed-off-by: Sourabh Jain <sourabhjain@xxxxxxxxxxxxx>
> ---
> arch/powerpc/kexec/core_64.c | 22 +++++++++++++++++++++-
> 1 file changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kexec/core_64.c b/arch/powerpc/kexec/core_64.c
> index 62f77cc86407..e3f224f8eb3a 100644
> --- a/arch/powerpc/kexec/core_64.c
> +++ b/arch/powerpc/kexec/core_64.c
> @@ -480,7 +480,9 @@ int update_cpus_node(void *fdt)
> void arch_crash_hotplug_handler(struct kimage *image, unsigned int hp_action,
> unsigned long a, unsigned long b)
> {
> - void *fdt;
> + void *fdt, *ptr;
> + unsigned int n;
> + unsigned long mem, memsz;
>
> /* No action needed for CPU hot-unplug */
> if (hp_action == KEXEC_CRASH_HP_REMOVE_CPU)
> @@ -492,6 +494,24 @@ void arch_crash_hotplug_handler(struct kimage *image, unsigned int hp_action,
> return;
> }
>
> + /* Sine kexec segments for kexec_load system call is prepred by
Since
FWIW,
Reviewed-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
> + * kexec tool in userspace we need loop through all the segments
> + * to find out segment index corresponds FDT segment. In case of
> + * kexec_file_load it is discovered during the load itself.
> + */
> + if (!image->arch.fdt_index_valid) {
> + for (n = 0; n < image->nr_segments; n++) {
> + mem = image->segment[n].mem;
> + memsz = image->segment[n].memsz;
> + ptr = __va(mem);
> + if (ptr && fdt_magic(ptr) == FDT_MAGIC) {
> + image->arch.fdt_index = n;
> + image->arch.fdt_index_valid = true;
> + break;
> + }
> + }
> + }
> +
> /* Must have valid FDT index */
> if (!image->arch.fdt_index_valid) {
> pr_err("crash hp: unable to locate FDT segment");
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