linux-kernel - Re: [PATCH v5 05/22] powerpc/irq: Add helper to set regs->softe

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Message-Id: <1612832745.vhjk6358hf.astroid@bobo.none>
Date:   Tue, 09 Feb 2021 11:11:00 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Michael Ellerman <mpe@...erman.id.au>, msuchanek@...e.de,
        Paul Mackerras <paulus@...ba.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v5 05/22] powerpc/irq: Add helper to set regs->softe

Excerpts from Christophe Leroy's message of February 9, 2021 1:10 am:
> regs->softe doesn't exist on PPC32.
> 
> Add irq_soft_mask_regs_set_state() helper to set regs->softe.
> This helper will void on PPC32.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> ---
>  arch/powerpc/include/asm/hw_irq.h | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h
> index 614957f74cee..ed0c3b049dfd 100644
> --- a/arch/powerpc/include/asm/hw_irq.h
> +++ b/arch/powerpc/include/asm/hw_irq.h
> @@ -38,6 +38,8 @@
>  #define PACA_IRQ_MUST_HARD_MASK	(PACA_IRQ_EE)
>  #endif
>  
> +#endif /* CONFIG_PPC64 */
> +
>  /*
>   * flags for paca->irq_soft_mask
>   */
> @@ -46,8 +48,6 @@
>  #define IRQS_PMI_DISABLED	2
>  #define IRQS_ALL_DISABLED	(IRQS_DISABLED | IRQS_PMI_DISABLED)
>  
> -#endif /* CONFIG_PPC64 */
> -
>  #ifndef __ASSEMBLY__
>  
>  #ifdef CONFIG_PPC64
> @@ -287,6 +287,10 @@ extern void irq_set_pending_from_srr1(unsigned long srr1);
>  
>  extern void force_external_irq_replay(void);
>  
> +static inline void irq_soft_mask_regs_set_state(struct pt_regs *regs, unsigned long val)
> +{
> +	regs->softe = val;
> +}
>  #else /* CONFIG_PPC64 */
>  
>  static inline unsigned long arch_local_save_flags(void)
> @@ -355,6 +359,9 @@ static inline bool arch_irq_disabled_regs(struct pt_regs *regs)
>  
>  static inline void may_hard_irq_enable(void) { }
>  
> +static inline void irq_soft_mask_regs_set_state(struct pt_regs *regs, unsigned long val)
> +{
> +}
>  #endif /* CONFIG_PPC64 */
>  
>  #define ARCH_IRQ_INIT_FLAGS	IRQ_NOREQUEST

What I don't like about this where you use it is it kind of pollutes
the ppc32 path with this function which is not valid to use.

I would prefer if you had this purely so it could compile with:

  if (IS_ENABLED(CONFIG_PPC64)))
      irq_soft_mask_regs_set_state(regs, blah);

And then you could make the ppc32 cause a link error if it did not
get eliminated at compile time (e.g., call an undefined function).

You could do the same with the kuap_ functions to change some ifdefs
to IS_ENABLED.

That's just my preference but if you prefer this way I guess that's
okay.

Thanks,
Nick