Re: clean up and streamline probe_kernel_* and friends v4

[Andrew Morton]

On Thu, 21 May 2020 17:22:38 +0200 Christoph Hellwig <hch@xxxxxx> wrote:

> this series start cleaning up the safe kernel and user memory probing
> helpers in mm/maccess.c, and then allows architectures to implement
> the kernel probing without overriding the address space limit and
> temporarily allowing access to user memory.  It then switches x86
> over to this new mechanism by reusing the unsafe_* uaccess logic.
> 
> This version also switches to the saner copy_{from,to}_kernel_nofault
> naming suggested by Linus.
> 
> I kept the x86 helpers as-is without calling unsage_{get,put}_user as
> that avoids a number of hard to trace casts, and it will still work
> with the asm-goto based version easily.

hm.  Applying linux-next to this series generates a lot of rejects against
powerpc:

-rw-rw-r-- 1 akpm akpm  493 May 25 15:06 arch/powerpc/kernel/kgdb.c.rej
-rw-rw-r-- 1 akpm akpm 6461 May 25 15:06 arch/powerpc/kernel/trace/ftrace.c.rej
-rw-rw-r-- 1 akpm akpm  447 May 25 15:06 arch/powerpc/mm/fault.c.rej
-rw-rw-r-- 1 akpm akpm  623 May 25 15:06 arch/powerpc/perf/core-book3s.c.rej
-rw-rw-r-- 1 akpm akpm 1408 May 25 15:06 arch/riscv/kernel/patch.c.rej

the arch/powerpc/kernel/trace/ftrace.c ones aren't very trivial.

It's -rc7.  Perhaps we should park all this until 5.8-rc1?