On Fri, Oct 18, 2019 at 10:23 AM Mark Rutland <[email protected]> wrote: > I think scs_save() would better live in assembly in cpu_switch_to(), > where we switch the stack and current. It shouldn't matter whether > scs_load() is inlined or not, since the x18 value _should_ be invariant > from the PoV of the task.
Note that there's also a call to scs_save in cpu_die, because the current task's shadow stack pointer is only stored in x18 and we don't want to lose it. > We just need to add a TSK_TI_SCS to asm-offsets.c, and then insert a > single LDR at the end: > > mov sp, x9 > msr sp_el0, x1 > #ifdef CONFIG_SHADOW_CALL_STACK > ldr x18, [x1, TSK_TI_SCS] > #endif > ret TSK_TI_SCS is already defined, so yes, we could move this to cpu_switch_to. I would still prefer to have the overflow check that's in scs_thread_switch though. Sami
