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From: "Raslan, KarimAllah" <karahmed@amazon.de>
To: "will@kernel.org" <will@kernel.org>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
	"anders.roxell@linaro.org" <anders.roxell@linaro.org>,
	"yuzhao@google.com" <yuzhao@google.com>,
	"ard.biesheuvel@linaro.org" <ard.biesheuvel@linaro.org>,
	"info@metux.net" <info@metux.net>,
	"anshuman.khandual@arm.com" <anshuman.khandual@arm.com>,
	"linux@armlinux.org.uk" <linux@armlinux.org.uk>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"yaojun8558363@gmail.com" <yaojun8558363@gmail.com>,
	"james.morse@arm.com" <james.morse@arm.com>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"rppt@linux.ibm.com" <rppt@linux.ibm.com>,
	"robin.murphy@arm.com" <robin.murphy@arm.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] arm: Extend the check for RAM in /dev/mem
Date: Fri, 12 Jul 2019 15:13:38 +0000	[thread overview]
Message-ID: <1562944417.1345.17.camel@amazon.de> (raw)
In-Reply-To: <20190712145711.mxmnuyn6kpv2dr7u@willie-the-truck>

On Fri, 2019-07-12 at 15:57 +0100, Will Deacon wrote:
> On Fri, Jul 12, 2019 at 12:21:21AM +0200, KarimAllah Ahmed wrote:
> > 
> > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> > index 3645f29..cdc3e8e 100644
> > --- a/arch/arm64/mm/mmu.c
> > +++ b/arch/arm64/mm/mmu.c
> > @@ -78,7 +78,7 @@ void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
> >  pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
> >  			      unsigned long size, pgprot_t vma_prot)
> >  {
> > -	if (!pfn_valid(pfn))
> > +	if (!memblock_is_memory(__pfn_to_phys(pfn)))
> 
> This looks broken to me, since it will end up returning 'true' for nomap
> memory and we really don't want to map that using writeback attributes.

True, I will fix this by using memblock_is_map_memory instead. That said, do
you have any concerns about this approach in general?

> 
> Will



Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879


_______________________________________________
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: "Raslan, KarimAllah" <karahmed@amazon.de>
To: "will@kernel.org" <will@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"yaojun8558363@gmail.com" <yaojun8558363@gmail.com>,
	"ard.biesheuvel@linaro.org" <ard.biesheuvel@linaro.org>,
	"linux@armlinux.org.uk" <linux@armlinux.org.uk>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"james.morse@arm.com" <james.morse@arm.com>,
	"robin.murphy@arm.com" <robin.murphy@arm.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"info@metux.net" <info@metux.net>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"yuzhao@google.com" <yuzhao@google.com>,
	"rppt@linux.ibm.com" <rppt@linux.ibm.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"anders.roxell@linaro.org" <anders.roxell@linaro.org>,
	"anshuman.khandual@arm.com" <anshuman.khandual@arm.com>
Subject: Re: [PATCH] arm: Extend the check for RAM in /dev/mem
Date: Fri, 12 Jul 2019 15:13:38 +0000	[thread overview]
Message-ID: <1562944417.1345.17.camel@amazon.de> (raw)
In-Reply-To: <20190712145711.mxmnuyn6kpv2dr7u@willie-the-truck>

On Fri, 2019-07-12 at 15:57 +0100, Will Deacon wrote:
> On Fri, Jul 12, 2019 at 12:21:21AM +0200, KarimAllah Ahmed wrote:
> > 
> > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> > index 3645f29..cdc3e8e 100644
> > --- a/arch/arm64/mm/mmu.c
> > +++ b/arch/arm64/mm/mmu.c
> > @@ -78,7 +78,7 @@ void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
> >  pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
> >  			      unsigned long size, pgprot_t vma_prot)
> >  {
> > -	if (!pfn_valid(pfn))
> > +	if (!memblock_is_memory(__pfn_to_phys(pfn)))
> 
> This looks broken to me, since it will end up returning 'true' for nomap
> memory and we really don't want to map that using writeback attributes.

True, I will fix this by using memblock_is_map_memory instead. That said, do
you have any concerns about this approach in general?

> 
> Will



Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879



  reply	other threads:[~2019-07-12 15:13 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-11 22:21 [PATCH] arm: Extend the check for RAM in /dev/mem KarimAllah Ahmed
2019-07-11 22:21 ` KarimAllah Ahmed
2019-07-12  2:36 ` Anshuman Khandual
2019-07-12  2:36   ` Anshuman Khandual
2019-07-12  2:58   ` Raslan, KarimAllah
2019-07-12  2:58     ` Raslan, KarimAllah
2019-07-12  8:56     ` Russell King - ARM Linux admin
2019-07-12  8:56       ` Russell King - ARM Linux admin
2019-07-12  8:59       ` Raslan, KarimAllah
2019-07-12  8:59         ` Raslan, KarimAllah
2019-07-12 14:57 ` Will Deacon
2019-07-12 14:57   ` Will Deacon
2019-07-12 15:13   ` Raslan, KarimAllah [this message]
2019-07-12 15:13     ` Raslan, KarimAllah
2019-07-12 15:34     ` Will Deacon
2019-07-12 15:34       ` Will Deacon
2019-07-12 15:46       ` Raslan, KarimAllah
2019-07-12 15:46         ` Raslan, KarimAllah

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