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SubjectRe: remove the last set_fs() in common code, and remove it for x86 and powerpc v3
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Le 04/09/2020 à 23:01, David Laight a écrit :
> From: Alexey Dobriyan
>> Sent: 04 September 2020 18:58
>>
>> On Fri, Sep 04, 2020 at 08:00:24AM +0200, Ingo Molnar wrote:
>>> * Christoph Hellwig <hch@lst.de> wrote:
>>>> this series removes the last set_fs() used to force a kernel address
>>>> space for the uaccess code in the kernel read/write/splice code, and then
>>>> stops implementing the address space overrides entirely for x86 and
>>>> powerpc.
>>>
>>> Cool! For the x86 bits:
>>>
>>> Acked-by: Ingo Molnar <mingo@kernel.org>
>>
>> set_fs() is older than some kernel hackers!
>>
>> $ cd linux-0.11/
>> $ find . -type f -name '*.h' | xargs grep -e set_fs -w -n -A3
>> ./include/asm/segment.h:61:extern inline void set_fs(unsigned long val)
>> ./include/asm/segment.h-62-{
>> ./include/asm/segment.h-63- __asm__("mov %0,%%fs"::"a" ((unsigned short) val));
>> ./include/asm/segment.h-64-}
>
> What is this strange %fs register you are talking about.
> Figure 2-4 only has CS, DS, SS and ES.
>

Intel added registers FS and GS in the i386

Christophe

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