From: Dave Young <dyoung@redhat.com>
To: WANG Chao <chaowang@redhat.com>
Cc: kexec@lists.infradead.org, ebiederm@xmission.com, vgoyal@redhat.com
Subject: Re: [kexec-tools PATCH] x86: extend kernel text size up to 1GB
Date: Fri, 14 Mar 2014 15:08:52 +0800 [thread overview]
Message-ID: <20140314070852.GC8248@dhcp-16-126.nay.redhat.com> (raw)
In-Reply-To: <20140314070357.GA22782@dhcp-17-89.nay.redhat.com>
On 03/14/14 at 03:03pm, WANG Chao wrote:
> On 03/14/14 at 02:47pm, Dave Young wrote:
> > On 03/14/14 at 02:12pm, Dave Young wrote:
> > > On 03/12/14 at 11:13am, WANG Chao wrote:
> > > > Currently kexec hard code X86_64_KERNEL_TEXT_SIZE to 512M. With kASLR
> > > > enabled (CONFIG_RANDOMIZED_BASE=y), kernel image base offset could be
> > > > randomized from 0 to 1GB and kexec-tools fails to get kernel virtual
> > > > address from /proc/kcore when the offset is >512M.
> > > >
> > > > Now extend X86_64_KERNEL_TEXT_SIZE to 1GB to adapt kASLR.
> > > >
> > > > Signed-off-by: WANG Chao <chaowang@redhat.com>
> > > > ---
> > > > kexec/arch/i386/crashdump-x86.h | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/kexec/arch/i386/crashdump-x86.h b/kexec/arch/i386/crashdump-x86.h
> > > > index e68b626..a5b2dfd 100644
> > > > --- a/kexec/arch/i386/crashdump-x86.h
> > > > +++ b/kexec/arch/i386/crashdump-x86.h
> > > > @@ -18,7 +18,7 @@ int load_crashdump_segments(struct kexec_info *info, char *mod_cmdline,
> > > > #define X86_64_MAXMEM 0x3fffffffffffUL
> > > >
> > > > /* Kernel text size */
> > > > -#define X86_64_KERNEL_TEXT_SIZE (512UL*1024*1024)
> > > > +#define X86_64_KERNEL_TEXT_SIZE (1UL*1024*1024*1024)
> > >
> > > Should define a new macro such as: X86_KERNEL_TEXT_START_LIMIT (1UL*1024*1024*1024)
> > > and then check end addr with X86_64_KERNEL_TEXT_SIZE + X86_64_KERNEL_TEXT_SIZE
> >
> > I means check ktext with range <1G - 1.5G>
>
> You're right.
>
> I think it's fine adding new macro X86_64_RANDOMIZE_BASE_MAX_OFFSET
> as 0x40000000 (1G) and doing the following check:
>
> (start >= X86_64__START_KERNEL_map) &&
> (start <= X86_64__START_KERNEL_map + X86_64_RANDOMIZE_MAX_BASE_OFFSET) &&
> (end - start <= X86_64_KERNEL_TEXT_SIZE)
end - start < X86_64_KERNEL_TEXT_SIZE should be right, other wise I'm fine.
Thanks
Dave
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next prev parent reply other threads:[~2014-03-14 7:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-12 3:13 [kexec-tools PATCH] x86: extend kernel text size up to 1GB WANG Chao
2014-03-14 6:12 ` Dave Young
2014-03-14 6:47 ` Dave Young
2014-03-14 7:03 ` WANG Chao
2014-03-14 7:08 ` Dave Young [this message]
2014-03-14 7:29 ` WANG Chao
2014-03-20 3:44 ` Simon Horman
2014-03-20 4:53 ` WANG Chao
2014-03-20 5:49 ` Simon Horman
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