linux-kernel - Re: [PATCH v3 1/4] kexec: simplify compat_sys_kexec

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Date:   Wed, 19 May 2021 11:55:05 +0200
From:   Arnd Bergmann <arnd@...nel.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     linux-arch <linux-arch@...r.kernel.org>,
        Christoph Hellwig <hch@...radead.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Borislav Petkov <bp@...en8.de>,
        Brian Gerst <brgerst@...il.com>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>, kexec@...ts.infradead.org
Subject: Re: [PATCH v3 1/4] kexec: simplify compat_sys_kexec_load

On Wed, May 19, 2021 at 12:45 AM Eric W. Biederman
<ebiederm@...ssion.com> wrote:
> Arnd Bergmann <arnd@...nel.org> writes:
> > On Tue, May 18, 2021 at 4:05 PM Arnd Bergmann <arnd@...nel.org> wrote:
> >> On Tue, May 18, 2021 at 3:41 PM Eric W. Biederman <ebiederm@...ssion.com> wrote:
>
> I think something like the untested diff below is enough to get rid of
> compat_alloc_user cleanly.
>
> Certainly it should be enough to give any idea what I am thinking.

Yes, that looks sufficient to me. I had started a slightly different
approach by trying
to move the kimage_alloc_init() into the top-level entry points to
avoid the extra
kmalloc, but that got rather complicated, and your patch is simpler overall.

The allocation could still be combined with kexec_load_check() into a new
function to reduce the number of duplicate lines, but if you think the current
version is ok, then I'll leave this part as it is.

I've fixed a duplicate kfree() and some whitespace damage, and rebased the
rest of my series on top of this to give it a spin on the build test boxes.
I'll send a v4 series once I have made sure there are no build-time regressions.

Can I add your Signed-off-by for the patch?
Is there a set of tests I should run on it?

      Arnd