On 12/03/2023 19:11:51, Sourabh Jain wrote:
> A new member "fdt_index" is added to the kimage_arch struct to hold
> the index of the FDT (Flattened Device Tree) segment from the kexec
> the segment array.
>
> fdt_index will provide direct access to the FDT segment in the kexec
> segment array after the kdump kernel is loaded.
>
> The new attribute will be used in the arch crash hotplug handler
> (added in upcoming patches) on every CPU and memory hotplug event.
>
> The fdt_index is populated for both kexec_load and kexec_file_load
> case.
>
> Signed-off-by: Sourabh Jain <sourabhj...@linux.ibm.com>
> ---
> arch/powerpc/include/asm/kexec.h | 5 +++++
> arch/powerpc/kexec/core_64.c | 31 +++++++++++++++++++++++++++++++
> 2 files changed, 36 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/kexec.h
> b/arch/powerpc/include/asm/kexec.h
> index 8090ad7d97d9d..348eb96e8ca67 100644
> --- a/arch/powerpc/include/asm/kexec.h
> +++ b/arch/powerpc/include/asm/kexec.h
> @@ -103,6 +103,8 @@ void kexec_copy_flush(struct kimage *image);
> struct crash_mem;
> int update_cpus_node(void *fdt);
> int get_crash_memory_ranges(struct crash_mem **mem_ranges);
> +int machine_kexec_post_load(struct kimage *image);
> +#define machine_kexec_post_load machine_kexec_post_load
Minor comment, when CONFIG_CRASH_HOTPLUG is not set the function is simply
returning 0, why not defining it has an inline in that case?
> #endif
>
> #if defined(CONFIG_CRASH_DUMP) && defined(CONFIG_PPC_RTAS)
> @@ -118,6 +120,9 @@ extern const struct kexec_file_ops kexec_elf64_ops;
> struct kimage_arch {
> struct crash_mem *exclude_ranges;
>
> +#if defined(CONFIG_CRASH_HOTPLUG)
> + int fdt_index;
> +#endif
> unsigned long backup_start;
> void *backup_buf;
> void *fdt;
> diff --git a/arch/powerpc/kexec/core_64.c b/arch/powerpc/kexec/core_64.c
> index 0b292f93a74cc..531486c973988 100644
> --- a/arch/powerpc/kexec/core_64.c
> +++ b/arch/powerpc/kexec/core_64.c
> @@ -77,6 +77,37 @@ int machine_kexec_prepare(struct kimage *image)
> return 0;
> }
>
> +int machine_kexec_post_load(struct kimage *kimage)
> +{
> +#if defined(CONFIG_CRASH_HOTPLUG)
> + int i;
> + void *ptr;
> + unsigned long mem;
> +
> + /* Mark fdt_index invalid */
> + kimage->arch.fdt_index = -1;
Why is that not done in the series introducing the generic
crash hotplug update, in do_kimage_alloc_init() ?
This way there is a guarantee that the field will not be used while set by
default to 0.
> +
> + /* fdt_index remains invalid if it is not a crash kernel load */
> + if (kimage->type != KEXEC_TYPE_CRASH)
> + return 0;
> + /*
> + * Find the FDT segment index in kexec segment array and
> + * assign it to kimage's member fdt_index to enable direct
> + * access to FDT segment later on.
> + */
> + for (i = 0; i < kimage->nr_segments; i++) {
> + mem = kimage->segment[i].mem;
> + ptr = __va(mem);
> +
> + if (ptr && fdt_magic(ptr) == FDT_MAGIC) {
> + kimage->arch.fdt_index = i;
> + break;
> + }
> + }
> +#endif
> + return 0;
> +}
> +
> /* Called during kexec sequence with MMU off */
> static notrace void copy_segments(unsigned long ind)
> {
