linux-kernel - Re: [PATCH] x86: add phys addr validity check for /dev/mem mmap

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Date:	Thu, 04 Apr 2013 09:11:53 +0800
From:	Simon Jeons <simon.jeons@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Frantisek Hrbata <fhrbata@...hat.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	tglx@...utronix.de, mingo@...hat.com, x86@...nel.org,
	oleg@...hat.com, kamaleshb@...ibm.com, hechjie@...ibm.com
Subject: Re: [PATCH] x86: add phys addr validity check for /dev/mem mmap

Hi H.Peter,
On 04/03/2013 02:48 AM, H. Peter Anvin wrote:
> On 04/02/2013 05:28 AM, Frantisek Hrbata wrote:
>> diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
>> index d8e8eef..39607c6 100644
>> --- a/arch/x86/include/asm/io.h
>> +++ b/arch/x86/include/asm/io.h
>> @@ -242,6 +242,10 @@ static inline void flush_write_buffers(void)
>>   #endif
>>   }
>>   
>> +#define ARCH_HAS_VALID_PHYS_ADDR_RANGE
>> +extern int valid_phys_addr_range(phys_addr_t addr, size_t count);
>> +extern int valid_mmap_phys_addr_range(unsigned long pfn, size_t count);
>> +
>>   #endif /* __KERNEL__ */
>>   
>>   extern void native_io_delay(void);
>> diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
>> index 845df68..92ec31c 100644
>> --- a/arch/x86/mm/mmap.c
>> +++ b/arch/x86/mm/mmap.c
>> @@ -31,6 +31,8 @@
>>   #include <linux/sched.h>
>>   #include <asm/elf.h>
>>   
>> +#include "physaddr.h"
>> +
>>   struct __read_mostly va_alignment va_align = {
>>   	.flags = -1,
>>   };
>> @@ -122,3 +124,14 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
>>   		mm->unmap_area = arch_unmap_area_topdown;
>>   	}
>>   }
>> +
>> +int valid_phys_addr_range(phys_addr_t addr, size_t count)
>> +{
>> +	return addr + count <= __pa(high_memory);
>> +}
>> +
>> +int valid_mmap_phys_addr_range(unsigned long pfn, size_t count)
>> +{
>> +	resource_size_t addr = (pfn << PAGE_SHIFT) + count;
>> +	return phys_addr_valid(addr);
>> +}
>>

Why we consider boot_cpu_data.x86_phys_bits instead of e820 map here?

>
> 	-hpa
>

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