[RFC PATCH 24/27] powerpc/64s: interrupt return in C

[Michal Suchánek]

On Sun, Sep 15, 2019 at 11:28:10AM +1000, Nicholas Piggin wrote:
> Implement the bulk of interrupt return logic in C. The asm return code
> must handle a few cases: restoring full GPRs, and emulating stack store.
> 
> The asm return code is moved into 64e for now. The new logic has made
> allowance for 64e, but I don't have a full environment that works well
> to test it, and even booting in emulated qemu is not great for stress
> testing. 64e shouldn't be too far off working with this, given a bit
> more testing and auditing of the logic.
> 
> This is slightly faster on a POWER9 (page fault speed increases about
> 1.1%), probably due to reduced mtmsrd.
> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
...
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 24621e7e5033..45c1524b6c9e 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -524,6 +524,7 @@ void giveup_all(struct task_struct *tsk)
>  }
>  EXPORT_SYMBOL(giveup_all);
>  
> +#ifdef CONFIG_PPC_BOOK3S_64
This fails build on !BOOK3S_64 because restore_fpu and restore_altivec
are used exclusively from restore_math which is now BOOK3S_64 only.
>  /*
>   * The exception exit path calls restore_math() with interrupts hard disabled
>   * but the soft irq state not "reconciled". ftrace code that calls
> @@ -564,6 +565,7 @@ void notrace restore_math(struct pt_regs *regs)
>  
>  	regs->msr = msr;
>  }
> +#endif
>  
>  static void save_all(struct task_struct *tsk)
>  {

Thanks

Michal