remove the last set_fs() in common code, and remove it for x86 and powerpc v3

[Alexey Dobriyan]

On Fri, Sep 04, 2020 at 08:00:24AM +0200, Ingo Molnar wrote:
> * Christoph Hellwig <hch at 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 at 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-}