On Wed, 15 Apr 2020 10:06:09 +0000 (UTC), Christophe Leroy wrote:
> To enable/disable kernel access to user space, the 8xx has to
> modify the properties of access group 1. This is done by writing
> predefined values into SPRN_Mx_AP registers.
>
> As of today, a __put_user() gives:
>
> 00000d64 <my_test>:
> d64: 3d 20 4f ff lis r9,20479
> d68: 61 29 ff ff ori r9,r9,65535
> d6c: 7d 3a c3 a6 mtspr 794,r9
> d70: 39 20 00 00 li r9,0
> d74: 90 83 00 00 stw r4,0(r3)
> d78: 3d 20 6f ff lis r9,28671
> d7c: 61 29 ff ff ori r9,r9,65535
> d80: 7d 3a c3 a6 mtspr 794,r9
> d84: 4e 80 00 20 blr
>
> [...]
Applied to powerpc/next.
[1/1] powerpc/8xx: Reduce time spent in allow_user_access() and friends
https://git.kernel.org/powerpc/c/332ce969b763553e9c4d55069e1e15aba4ea560f
cheers
