On Sun, Sep 13, 2015 at 02:42:17PM +0000, Jungseok Lee wrote: > Currently, kernel context and interrupts are handled using a single > kernel stack navigated by sp_el1. This forces many systems to use > 16KB stack, not 8KB one. Low memory platforms naturally suffer from > memory pressure accompanied by performance degradation. > > This patch addresses the issue as introducing a separate percpu IRQ > stack to handle both hard and soft interrupts with two ground rules: > > - Utilize sp_el0 in EL1 context, which is not used currently > - Do not complicate current_thread_info calculation > > It is a core concept to trace struct thread_info using sp_el0 instead > of sp_el1. This approach helps arm64 align with other architectures > regarding object_is_on_stack() without additional complexity.
I'm still trying to understand how this patch works. I initially thought that we would set SPSel = 0 while in kernel thread mode to make use of SP_EL0 but I can't find any such code. Do you still use SP_EL1 all the time and SP_EL0 just for temporary saving the thread stack? -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
