Re: [PATCH v8 2/7] kexec: define functions to map and unmap segments

[steven chen]

On 2/20/2025 9:22 AM, Mimi Zohar wrote:
> Hi Steven,
>
> On Tue, 2025-02-18 at 14:54 -0800, steven chen 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.
> Obviously up to now Kexec was mapping the segments. Missing from this patch description is
> the reason "why" these functions are needed now.  It's not enough to say "is needed when
> IMA is allocating the memory segments during kexec 'load' operation".  The question is why
> does "IMA" need to allocate the memory segments.  Don't make the kexec/kexec_dump
> maintainers guess.
>
> Refer to the section "Describe your changes" in
> https://www.kernel.org/doc/Documentation/process/submitting-patches.rst
>
> > 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().
> >
> > From: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
> > Author: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
> Again, no such thing as an "Author" tag.  Refer to the comments on 1/7.
>
> > Signed-off-by: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
> As previously requested, please add the Cc's inline here and in all the kexec/kdump
> related patches:
>
> Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
> Cc: Baoquan He <bhe@xxxxxxxxxx>
> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
> Cc: Dave Young <dyoung@xxxxxxxxxx>
>
> > Signed-off-by: steven chen <chenste@xxxxxxxxxxxxxxxxxxx>
> thanks,
>
> Mimi

Mimi, thanks. I will update in next version.

Steven