[PATCH v2] arm: fix clang build warning in include/asm/memory.h

[Linus Walleij]

On Thu, Mar 21, 2024 at 2:36 AM Yipeng Zou <zouyipeng at huawei.com> wrote:

> There is a build error has been founded with build in clang-15.0.4:
>
> ./arch/arm/include/asm/memory.h:358:12: error: result of comparison "phys addr_t’ (aka 'unsigned int’) > 4294967295 is always false [-Werror, -Wtautological-type-limit-compare]
>                              if (addr > (u32)~0)
>                                  ~~~~ ^ ~~~~~~~
>
> It will be always goes fail without CONFIG_PHYS_ADDR_T_64BIT.
>
> Directly silence it by Use CONFIG_PHYS_ADDR_T_64BIT.
>
> Fixes: 981b6714dbd2 ("ARM: provide improved virt_to_idmap() functionality")
> Signed-off-by: Yipeng Zou <zouyipeng at huawei.com>
> ---
> V2: IDMAP_INVALID_ADDR was used in other place, keep it defined.
>  arch/arm/include/asm/memory.h | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> index ef2aa79ece5a..07c7e759d04c 100644
> --- a/arch/arm/include/asm/memory.h
> +++ b/arch/arm/include/asm/memory.h
> @@ -353,8 +353,10 @@ static inline unsigned long phys_to_idmap(phys_addr_t addr)
>  {
>         if (IS_ENABLED(CONFIG_MMU) && arch_phys_to_idmap_offset) {
>                 addr += arch_phys_to_idmap_offset;
> +#ifdef CONFIG_PHYS_ADDR_T_64BIT
>                 if (addr > (u32)~0)

What about my suggestion:

#include <linux/limits.h>

if (addr > U32_MAX)

?

Yours,
Linus Walleij