Re: [PATCH 0/6] generic relative extable support

["H. Peter Anvin" <hpa@zytor.com>]

On 01/04/2016 03:20 AM, Heiko Carstens wrote:
> On Sun, Jan 03, 2016 at 05:05:51PM +0100, Ard Biesheuvel wrote:
>> There are currently four architectures (x86, ia64, alpha and s390) whose
>> user-access exception tables are relative to the table entry address rather
>> than absolute. Each of these architectures has its own search_extable() and
>> sort_extable() implementation, which are not only mostly identical to each
>> other, but also deviate very little from the generic absolute implementations
>> in lib/extable.c that they override.
>>
>> So before making arm64 the fifth architecture that reimplements this, let's
>> refactor the existing code so that all of these architectures use common code
>> for searching and sorting the relative extables. Archs may set
>> ARCH_HAS_RELATIVE_EXTABLE to indicate that the table consists of a pair of
>> relative ints, and may define swap_ex_entry_fixup() if the fixup member needs
>> special treatment in the swapping step of the sorting routine (such as alpha).
>>
>> Note that the s390 patch applies on top of the following patch:
>>
>>   http://article.gmane.org/gmane.linux.kernel/2117036
>>
>> which fixes a bug I spotted while working on this code. Since that probably
>> needs to go to -stable, I broke it out and posted it separately.
>>
>> Ard Biesheuvel (6):
>>   extable: add support for relative extables to search and sort routines
>>   alpha/extable: use generic search and sort routines
>>   s390/extable: use generic search and sort routines
>>   x86/extable: use generic search and sort routines
>>   ia64/extable: use generic search and sort routines
>>   arm64: switch to relative exception tables
> 
> For the s390 bits:
> 
> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
> 

For the x86 bits:

Acked-by: H. Peter Anvin <hpa@linux.intel.com>

*However*, please see my comment about generalizing _ASM_EXTABLE() for
the non-x86 architectures.

	-hpa