linux-kernel - Re: [PATCH V3 2/3] arm64: support initrd outside kernel linear map

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Message-ID: <1439818347.3153.95.camel@redhat.com>
Date:	Mon, 17 Aug 2015 09:32:27 -0400
From:	Mark Salter <msalter@...hat.com>
To:	Will Deacon <will.deacon@....com>
Cc:	Catalin Marinas <Catalin.Marinas@....com>,
	"x86@...nel.org" <x86@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Mark Rutland <Mark.Rutland@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
Subject: Re: [PATCH V3 2/3] arm64: support initrd outside kernel linear map

On Mon, 2015-08-17 at 12:22 +0100, Will Deacon wrote:
> Hi Mark,
> 
> On Sun, Aug 16, 2015 at 09:49:27PM +0100, Mark Salter wrote:
> > The use of mem= could leave part or all of the initrd outside of
> > the kernel linear map. This will lead to an error when unpacking
> > the initrd and a probable failure to boot. This patch catches that
> > situation and relocates the initrd to be fully within the linear
> > map.
> > 
> > Signed-off-by: Mark Salter <msalter@...hat.com>
> > ---
> >  arch/arm64/kernel/setup.c | 59 
> > +++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 59 insertions(+)
> > 
> > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> > index f3067d4..5f45fd9 100644
> > --- a/arch/arm64/kernel/setup.c
> > +++ b/arch/arm64/kernel/setup.c
> > @@ -359,6 +359,64 @@ static void __init 
> > request_standard_resources(void)
> >  	}
> >  }
> >  
> > +#ifdef CONFIG_BLK_DEV_INITRD
> > +/*
> > + * Relocate initrd if it is not completely within the linear mapping.
> > + * This would be the case if mem= cuts out all or part of it.
> > + */
> > +static void __init relocate_initrd(void)
> > +{
> > +	phys_addr_t orig_start = __virt_to_phys(initrd_start);
> > +	phys_addr_t orig_end = __virt_to_phys(initrd_end);
> 
> Any particular reason to use the __* variants here?

To avoid need to cast initrd_{start,end} to pointer.

> 
> > +	phys_addr_t ram_end = memblock_end_of_DRAM();
> > +	phys_addr_t new_start;
> > +	unsigned long size, to_free = 0;
> > +	void *dest;
> > +
> > +	if (orig_end <= ram_end)
> > +		return;
> > +
> > +	/* Note if any of original initrd will freeing below */
> 
> The comment doesn't make sense.

No it doesn't.

> 
> > +	if (orig_start < ram_end)
> > +		to_free = ram_end - orig_start;
> > +
> > +	size = orig_end - orig_start;
> > +
> > +	/* initrd needs to be relocated completely inside linear 
> > mapping */
> > +	new_start = memblock_find_in_range(0, PFN_PHYS(max_pfn),
> > +					   size, PAGE_SIZE);
> > +	if (!new_start)
> > +		panic("Cannot relocate initrd of size %ld\n", size);
> > +	memblock_reserve(new_start, size);
> > +
> > +	initrd_start = __phys_to_virt(new_start);
> > +	initrd_end   = initrd_start + size;
> > +
> > +	pr_info("Moving initrd from [%llx-%llx] to [%llx-%llx]\n",
> > +		orig_start, orig_start + size - 1,
> > +		new_start, new_start + size - 1);
> > +
> > +	dest = (void *)initrd_start;
> > +
> > +	if (to_free) {
> > +		memcpy(dest, (void *)__phys_to_virt(orig_start), 
> > to_free);
> > +		dest += to_free;
> > +	}
> > +
> > +	copy_from_early_mem(dest, orig_start + to_free, size - 
> > to_free);
> > +
> > +	if (to_free) {
> > +		pr_info("Freeing original RAMDISK from [%llx-%llx]\n",
> > +			orig_start, orig_start + to_free - 1);
> > +		memblock_free(orig_start, to_free);
> > +	}
> > +}
> > +#else
> > +static inline void __init reserve_initrd(void)
> 
> relocate_initrd ?

Yes

Thanks, will fix that and the comment.


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