linux-kernel - Re: [PATCH 2/6] arm64: Add function to create identity mappings

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Message-ID: <20140122173927.GE8065@arm.com>
Date:	Wed, 22 Jan 2014 17:39:28 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	Mark Salter <msalter@...hat.com>
Cc:	"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>,
	Will Deacon <Will.Deacon@....com>,
	"matt.fleming@...el.com" <matt.fleming@...el.com>,
	Leif Lindholm <leif.lindholm@...aro.org>,
	"roy.franz@...aro.org" <roy.franz@...aro.org>,
	"patches@...aro.org" <patches@...aro.org>,
	Grant Likely <grant.likely@...retlab.ca>
Subject: Re: [PATCH 2/6] arm64: Add function to create identity mappings

On Fri, Jan 10, 2014 at 10:29:06PM +0000, Mark Salter wrote:
> +void __init create_id_mapping(phys_addr_t addr, phys_addr_t size)
> +{
> +	pgd_t *pgd = &idmap_pg_dir[pgd_index(addr)];
> +
> +	if (pgd >= &idmap_pg_dir[ARRAY_SIZE(idmap_pg_dir)]) {
> +		pr_warn("BUG: not creating id mapping for 0x%016llx\n", addr);
> +		return;
> +	}

The condition above is always false since pgd_index() already ands the
index with (PTRS_PER_PGD - 1). Better check addr against something like
(PTRS_PER_PGD * PGDIR_SIZE) (for clarity, you could do other shifts,
doesn't really matter).

-- 
Catalin
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