[PATCH v5 2/8] kexec: define functions to map and unmap segments

[Mimi Zohar]

On Wed, 2024-02-14 at 07:38 -0800, Tushar Sugandhi wrote:
> Currently, the mechanism to map and unmap segments to the kimage
> structure is not available to the subsystems outside of kexec.  This
> functionality is needed when IMA is allocating the memory segments
> during kexec 'load' operation.  Implement functions to map and unmap
> segments to kimage.
> 
> Implement kimage_map_segment() to enable mapping of IMA buffer source
> pages to the kimage structure post kexec 'load'.  This function,
> accepting a kimage pointer, an address, and a size, will gather the
> source pages within the specified address range, create an array of page
> pointers, and map these to a contiguous virtual address range.  The
> function returns the start of this range if successful, or NULL if
> unsuccessful.
> 
> Implement kimage_unmap_segment() for unmapping segments
> using vunmap().  Relocate 'for_each_kimage_entry()' macro from
> kexec_core.c to kexec.h for broader accessibility.
> 
> Signed-off-by: Tushar Sugandhi <tusharsu at linux.microsoft.com>
> ---
>  include/linux/kexec.h | 13 ++++++++++
>  kernel/kexec_core.c   | 59 +++++++++++++++++++++++++++++++++++++++----
>  2 files changed, 67 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 400cb6c02176..3145447eb77a 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -486,6 +486,11 @@ static inline void arch_kexec_pre_free_pages(void *vaddr,
> unsigned int pages) {
>  static inline void arch_crash_handle_hotplug_event(struct kimage *image) { }
>  #endif
>  
> +#define for_each_kimage_entry(image, ptr, entry) \
> +	for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \
> +		ptr = (entry & IND_INDIRECTION) ? \
> +			boot_phys_to_virt((entry & PAGE_MASK)) : ptr + 1)
> +

I don't see a reason for moving this macro.

Mimi