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From: Michael Ellerman <mpe@ellerman.id.au>
To: Hari Bathini <hbathini@linux.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: kernel test robot <lkp@intel.com>, Pingfan Liu <piliu@redhat.com>,
	Kexec-ml <kexec@lists.infradead.org>,
	Nayna Jain <nayna@linux.ibm.com>, Petr Tesarik <ptesarik@suse.cz>,
	Mahesh J Salgaonkar <mahesh@linux.ibm.com>,
	Mimi Zohar <zohar@linux.ibm.com>,
	lkml <linux-kernel@vger.kernel.org>,
	linuxppc-dev <linuxppc-dev@ozlabs.org>,
	Sourabh Jain <sourabhjain@linux.ibm.com>,
	Vivek Goyal <vgoyal@redhat.com>, Dave Young <dyoung@redhat.com>,
	Thiago Jung Bauermann <bauerman@linux.ibm.com>,
	Eric Biederman <ebiederm@xmission.com>
Subject: Re: [PATCH v4 07/12] ppc64/kexec_file: add support to relocate purgatory
Date: Wed, 22 Jul 2020 14:25:19 +1000	[thread overview]
Message-ID: <871rl4rxao.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <159524956457.20855.12480643681198700190.stgit@hbathini.in.ibm.com>

Hari Bathini <hbathini@linux.ibm.com> writes:
> Right now purgatory implementation is only minimal. But if purgatory
> code is to be enhanced to copy memory to the backup region and verify
> sha256 digest, relocations may have to be applied to the purgatory.
> So, add support to relocate purgatory in kexec_file_load system call
> by setting up TOC pointer and applying RELA relocations as needed.
>
> Reported-by: kernel test robot <lkp@intel.com>
> [lkp: In v1, 'struct mem_sym' was declared in parameter list]
> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
> ---
>
> * Michael, can you share your opinion on the below:
>     - https://lore.kernel.org/patchwork/patch/1272027/
>     - My intention in cover note.

It seems like a lot of complexity for little benefit.

AFAICS your final purgatory_64.c is only 36 lines, and all it does is a
single (open coded) memcpy().

It seems like we could write that in not many more lines of assembler
and avoid all this code.

What am I missing?

cheers

  reply	other threads:[~2020-07-22  4:29 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-20 12:49 [PATCH v4 00/12] ppc64: enable kdump support for kexec_file_load syscall Hari Bathini
2020-07-20 12:50 ` [PATCH v4 01/12] kexec_file: allow archs to handle special regions while locating memory hole Hari Bathini
2020-07-20 12:50 ` [PATCH v4 02/12] powerpc/kexec_file: mark PPC64 specific code Hari Bathini
2020-07-20 12:51 ` [PATCH v4 03/12] powerpc/kexec_file: add helper functions for getting memory ranges Hari Bathini
2020-07-20 12:59   ` Hari Bathini
2020-07-23 22:12   ` Thiago Jung Bauermann
2020-07-20 12:52 ` [PATCH v4 04/12] ppc64/kexec_file: avoid stomping memory used by special regions Hari Bathini
2020-07-23 22:19   ` Thiago Jung Bauermann
2020-07-20 12:52 ` [PATCH v4 05/12] powerpc/drmem: make lmb walk a bit more flexible Hari Bathini
2020-07-20 12:52 ` [PATCH v4 06/12] ppc64/kexec_file: restrict memory usage of kdump kernel Hari Bathini
2020-07-24  0:06   ` Thiago Jung Bauermann
2020-07-24 14:08     ` Hari Bathini
2020-07-25  0:32       ` Thiago Jung Bauermann
2020-07-20 12:53 ` [PATCH v4 07/12] ppc64/kexec_file: add support to relocate purgatory Hari Bathini
2020-07-22  4:25   ` Michael Ellerman [this message]
2020-07-22 17:33     ` Hari Bathini
2020-07-23  6:47       ` Michael Ellerman
2020-07-20 12:53 ` [PATCH v4 08/12] ppc64/kexec_file: setup the stack for purgatory Hari Bathini
2020-07-20 12:54 ` [PATCH v4 09/12] ppc64/kexec_file: setup backup region for kdump kernel Hari Bathini
2020-07-24  0:28   ` Thiago Jung Bauermann
2020-07-20 12:54 ` [PATCH v4 10/12] ppc64/kexec_file: prepare elfcore header for crashing kernel Hari Bathini
2020-07-24  0:33   ` Thiago Jung Bauermann
2020-07-20 12:54 ` [PATCH v4 11/12] ppc64/kexec_file: add appropriate regions for memory reserve map Hari Bathini
2020-07-20 12:55 ` [PATCH v4 12/12] ppc64/kexec_file: fix kexec load failure with lack of memory hole Hari Bathini

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