Re: [PATCH 3/9] x86: vdso: Introduce asm/vdso/page.h

Arnd Bergmann
2024-09-10T15:05:44Z

On Tue, Sep 10, 2024, at 12:28, Christophe Leroy wrote:
> Le 08/09/2024 à 22:48, Arnd Bergmann a écrit :
>> On Fri, Sep 6, 2024, at 18:40, Christophe Leroy wrote:
>
> uiomem->addr is a phys_addr_t
> r->start is a ressource_size_t hence a phys_addr_t
>
> And phys_addr_t is defined as:
>
> #ifdef CONFIG_PHYS_ADDR_T_64BIT
> typedef u64 phys_addr_t;
> #else
> typedef u32 phys_addr_t;
> #endif
>
> On a 32 bits platform, UL is unsigned 32 bits, so the r->start &
> PAGE_MASK will and r->start with 0x00000000fffff000
>
> That is wrong.

Right, I see. So out of the five 32-bit architectures with a
64-bit phys_addr_t, arc seems to ignore this problem, x86 has
a separate PHYSICAL_PAGE_MASK for its internal uses and
the other three have the definition you mention as

> (~((1 << PAGE_SHIFT) - 1))

And this is only documented properly on powerpc.

How about making the common definition this?

#ifdef CONFIG_PHYS_ADDR_T_64BIT
#define PAGE_MASK (~((1 << PAGE_SHIFT) - 1))
#else
#define PAGE_MASK (~(PAGE_SIZE-1))
#endif

That keeps it unchanged for everything other than arc
and x86-32, and hopefully fixes the currently behavior
on those two.

Arnd