Hi Liam,
On Wed, Aug 19, 2020 at 5:07 AM Liam Beguin <[email protected]> wrote:
> The kernel test bot reported[1] that using set_mask_bits on a u8 causes
> the following issue on SuperH:
>
> >> ERROR: modpost: "__cmpxchg_called_with_bad_pointer"
> [drivers/phy/ti/phy-tusb1210.ko] undefined!
>
> Add support for cmpxchg on u8 and u16 pointers.
>
> [1] https://lore.kernel.org/patchwork/patch/1288894/#1485536
>
> Reported-by: kernel test robot <[email protected]>
> Signed-off-by: Liam Beguin <[email protected]>
> ---
>
> Hi,
>
> This was reported by the kernel test bot on an architecture I can't
> really test on. I was only able to make sure the build succeeds, but
> nothing more.
> This patch is based on the __cmpxchg_u32 impletmentation and seems
> incomplete based on the different cmpxchg headers I can find.
Indeed. This version is suitable for non-SMP machines only.
BTW, it looks like this version can be replaced by the one in asm-generic?
>
> Do these function need to be impletmented in each header
> simulataneously?
Yes, we need them for all variants.
> arch/sh/include/asm/cmpxchg-irq.h | 27 +++++++++++++++++++++++++++
> arch/sh/include/asm/cmpxchg.h | 5 +++--
> 2 files changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/arch/sh/include/asm/cmpxchg-irq.h
> b/arch/sh/include/asm/cmpxchg-irq.h
> index 07d3e7f08389..918c4153a930 100644
> --- a/arch/sh/include/asm/cmpxchg-irq.h
> +++ b/arch/sh/include/asm/cmpxchg-irq.h
> @@ -51,4 +51,31 @@ static inline unsigned long __cmpxchg_u32(volatile int *m,
> unsigned long old,
> return retval;
> }
>
> +static inline unsigned long __cmpxchg_u16(volatile u16 *m, unsigned long old,
> + unsigned long new)
> +{
> + u16 retval;
> + unsigned long flags;
> +
> + local_irq_save(flags);
> + retval = *m;
> + if (retval == old)
> + *m = new;
> + local_irq_restore(flags);
> + return (unsigned long)retval;
> +}
> +
> +static inline unsigned long __cmpxchg_u8(volatile u8 *m, unsigned long old,
> + unsigned long new)
> +{
> + u8 retval;
> + unsigned long flags;
> +
> + local_irq_save(flags);
> + retval = *m;
> + if (retval == old)
> + *m = new;
> + local_irq_restore(flags);
> + return (unsigned long)retval;
> +}
> #endif /* __ASM_SH_CMPXCHG_IRQ_H */
> diff --git a/arch/sh/include/asm/cmpxchg.h b/arch/sh/include/asm/cmpxchg.h
> index e9501d85c278..7d65d0fd1665 100644
> --- a/arch/sh/include/asm/cmpxchg.h
> +++ b/arch/sh/include/asm/cmpxchg.h
> @@ -56,8 +56,9 @@ static inline unsigned long __cmpxchg(volatile void * ptr,
> unsigned long old,
> unsigned long new, int size)
> {
> switch (size) {
> - case 4:
> - return __cmpxchg_u32(ptr, old, new);
> + case 4: return __cmpxchg_u32((int *)ptr, old, new);
> + case 2: return __cmpxchg_u16((u16 *)ptr, old, new);
> + case 1: return __cmpxchg_u8((u8 *)ptr, old, new);
> }
> __cmpxchg_called_with_bad_pointer();
> return old;
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
