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Date:   Tue, 09 Feb 2021 11:11:00 +1000
From:   Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH v5 05/22] powerpc/irq: Add helper to set regs->softe
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Michael Ellerman <mpe@ellerman.id.au>, msuchanek@suse.de,
        Paul Mackerras <paulus@samba.org>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
References: <cover.1612796617.git.christophe.leroy@csgroup.eu>
        <5f37d1177a751fdbca79df461d283850ca3a34a2.1612796617.git.christophe.leroy@csgroup.eu>
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Excerpts from Christophe Leroy's message of February 9, 2021 1:10 am:
> regs->softe doesn't exist on PPC32.
>=20
> Add irq_soft_mask_regs_set_state() helper to set regs->softe.
> This helper will void on PPC32.
>=20
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
>  arch/powerpc/include/asm/hw_irq.h | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>=20
> 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
> =20
> +#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)
> =20
> -#endif /* CONFIG_PPC64 */
> -
>  #ifndef __ASSEMBLY__
> =20
>  #ifdef CONFIG_PPC64
> @@ -287,6 +287,10 @@ extern void irq_set_pending_from_srr1(unsigned long =
srr1);
> =20
>  extern void force_external_irq_replay(void);
> =20
> +static inline void irq_soft_mask_regs_set_state(struct pt_regs *regs, un=
signed long val)
> +{
> +	regs->softe =3D val;
> +}
>  #else /* CONFIG_PPC64 */
> =20
>  static inline unsigned long arch_local_save_flags(void)
> @@ -355,6 +359,9 @@ static inline bool arch_irq_disabled_regs(struct pt_r=
egs *regs)
> =20
>  static inline void may_hard_irq_enable(void) { }
> =20
> +static inline void irq_soft_mask_regs_set_state(struct pt_regs *regs, un=
signed long val)
> +{
> +}
>  #endif /* CONFIG_PPC64 */
> =20
>  #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