linux-kernel - Re: [PATCH 3/5] efi arm64: do not enter virtual mode in case booting with efi=noruntime or noefi

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Date:	Wed, 13 Aug 2014 09:29:41 +0800
From:	Dave Young <dyoung@...hat.com>
To:	Will Deacon <will.deacon@....com>
Cc:	Matt Fleming <matt.fleming@...el.com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"hpa@...or.com" <hpa@...or.com>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Leif Lindholm <leif.lindholm@...aro.org>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	"msalter@...hat.com" <msalter@...hat.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>
Subject: Re: [PATCH 3/5] efi arm64: do not enter virtual mode in case booting
 with efi=noruntime or noefi

On 08/12/14 at 11:46am, Will Deacon wrote:
> On Tue, Aug 12, 2014 at 07:10:20AM +0100, Dave Young wrote:
> > In case efi runtime disabled via noefi kernel cmdline arm64_enter_virtual_mode
> > should error out.
> > 
> > At the same time move early_memunmap(memmap.map, mapsize) to the beginning of
> > the function or it will leak early mem.
> > 
> > Signed-off-by: Dave Young <dyoung@...hat.com>
> > ---
> >  arch/arm64/kernel/efi.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
> > index e72f310..324cdd1 100644
> > --- a/arch/arm64/kernel/efi.c
> > +++ b/arch/arm64/kernel/efi.c
> > @@ -386,7 +386,10 @@ static int __init arm64_enter_virtual_mode(void)
> >  	int count = 0;
> >  	unsigned long flags;
> >  
> > -	if (!efi_enabled(EFI_BOOT)) {
> > +	mapsize = memmap.map_end - memmap.map;
> > +	early_memunmap(memmap.map, mapsize);
> > +
> > +	if (!efi_enabled(EFI_BOOT) || efi_runtime_disabled()) {
> 
> Hmm, is this right? We only set EFI_BOOT if we find EFI parameters in the
> DT (see efi_init -> uefi_init), so you run the risk of unmapping something
> we never mapped here.

Good catch, I missed the case. will fix it in next update

> 
> Furthermore, there seems to be a leak in uefi_init anyway, as we return
> -EINVAL if the signature of the EFI table doesn't match without unmapping it
> first.

Yes, will add a new patch to fix the error handling in uefi_init.

BTW, Matt, I forgot to cc Xen/SGI people, will send an update soon and cc them.

Thanks
Dave
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