[PATCH 0/5] Guarded Userspace Access Prevention on Radix

[Benjamin Herrenschmidt]

On Thu, 2018-11-08 at 18:52 +0100, Christophe LEROY wrote:
> 
> In signal_32.c and signal_64.c, save_user_regs() calls __put_user() to 
> modify code, then calls flush_icache_range() on user addresses.
> 
> Shouldn't flush_icache_range() be performed with userspace access 
> protection unlocked ?

Thankfully this code is pretty much never used these days...

Russell: To trigger that, you need to disable the VDSO.

This brings back the idea however of having a way to "bulk" open the
gate during the whole signal sequence...

Cheers,
Ben.