Re: [PATCH v4 1/5] powerpc: Refactor kexec functions to move arch independent code to IMA

Thiago Jung Bauermann
2020-08-27T23:36:53Z

Lakshmi Ramasubramanian <nramas@linux.microsoft.com> writes:

> The functions ima_get_kexec_buffer() and ima_free_kexec_buffer() that
> handle carrying forward the IMA measurement logs on kexec for powerpc
> do not have architecture specific code, but they are currently defined
> for powerpc only.
>
> Move these functions to IMA subsystem so that it can be used for other
> architectures as well. A later patch in this series will use these
> functions for carrying forward the IMA measurement log for ARM64.
>
> Define FDT_PROP_IMA_KEXEC_BUFFER for the chosen node, namely
> "linux,ima-kexec-buffer", that is added to the DTB to hold
> the address and the size of the memory reserved to carry
> the IMA measurement log.
>
> Co-developed-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
> Signed-off-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
> Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>

This patch removes two functions from arch/powerpc/kexec/ima.c, but adds
four to security/integrity/ima/ima_kexec.c. The extra ones are
get_addr_size_cells() and do_get_kexec_buffer(), which are being copied
from the powerpc code but can't be removed yet because they're still
used there by remove_ima_buffer() and setup_ima_buffer().

On the next patch you remove the need for these functions in powerpc
code and therefore delete them. This confused me at first, so I think it
would be cleared if you put patch 2 first in the series and then on this
patch you can simply move the four functions and delete them from
arch/powerpc/kexec/ima.c.

If you prefer to keep the current order, it's worth mentioning on the
commit log where get_addr_size_cells() and do_get_kexec_buffer() are
coming from.

Regardless:

Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>

--
Thiago Jung Bauermann
IBM Linux Technology Center