On Mon, 21 Dec 2020 06:18:03 +0000 (UTC), Christophe Leroy wrote: > We need r1 to be properly set before activating MMU, otherwise any new > exception taken while saving registers into the stack in syscall > prologs will use the user stack, which is wrong and will even lockup > or crash when KUAP is selected. > > Do that by switching the meaning of r11 and r1 until we have saved r1 > to the stack: copy r1 into r11 and setup the new stack pointer in r1. > To avoid complicating and impacting all generic and specific prolog > code (and more), copy back r1 into r11 once r11 is save onto > the stack. > > [...]
Applied to powerpc/fixes. [1/1] powerpc/32: Fix vmap stack - Properly set r1 before activating MMU on syscall too https://git.kernel.org/powerpc/c/d5c243989fb0cb03c74d7340daca3b819f706ee7 cheers