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    SubjectRe: [PATCH 03/22] ARM: LPAE: use phys_addr_t on virt <--> phys conversion
    On 8/6/2012 7:14 AM, Russell King - ARM Linux wrote:
    > On Tue, Jul 31, 2012 at 07:04:39PM -0400, Cyril Chemparathy wrote:
    >> This patch fixes up the types used when converting back and forth between
    >> physical and virtual addresses.
    >>
    >> Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
    >> Signed-off-by: Cyril Chemparathy <cyril@ti.com>
    >> ---
    >> arch/arm/include/asm/memory.h | 17 +++++++++++------
    >> 1 file changed, 11 insertions(+), 6 deletions(-)
    >>
    >> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
    >> index 01c710d..4a0108f 100644
    >> --- a/arch/arm/include/asm/memory.h
    >> +++ b/arch/arm/include/asm/memory.h
    >> @@ -157,22 +157,27 @@ extern unsigned long __pv_phys_offset;
    >>
    >> extern unsigned long __pv_offset;
    >>
    >> -static inline unsigned long __virt_to_phys(unsigned long x)
    >> +static inline phys_addr_t __virt_to_phys(unsigned long x)
    >> {
    >> unsigned long t;
    >> early_patch_imm8(x, t, "add", __pv_offset);
    >> return t;
    >> }
    >>
    >> -static inline unsigned long __phys_to_virt(unsigned long x)
    >> +static inline unsigned long __phys_to_virt(phys_addr_t x)
    >> {
    >> unsigned long t;
    >> early_patch_imm8(x, t, "sub", __pv_offset);
    >> return t;
    >> }
    >> #else
    >> -#define __virt_to_phys(x) ((x) - PAGE_OFFSET + PHYS_OFFSET)
    >> -#define __phys_to_virt(x) ((x) - PHYS_OFFSET + PAGE_OFFSET)
    >> +
    >> +#define __virt_to_phys(x) \
    >> + ((phys_addr_t)(x) - PAGE_OFFSET + PHYS_OFFSET)
    >> +
    >> +#define __phys_to_virt(x) \
    >> + ((unsigned long)((phys_addr_t)(x) - PHYS_OFFSET + PAGE_OFFSET))
    >> +
    >> #endif
    >> #endif
    >>
    >> @@ -207,14 +212,14 @@ static inline phys_addr_t virt_to_phys(const volatile void *x)
    >>
    >> static inline void *phys_to_virt(phys_addr_t x)
    >> {
    >> - return (void *)(__phys_to_virt((unsigned long)(x)));
    >> + return (void *)__phys_to_virt(x);
    >> }
    >>
    >> /*
    >> * Drivers should NOT use these either.
    >> */
    >> #define __pa(x) __virt_to_phys((unsigned long)(x))
    >> -#define __va(x) ((void *)__phys_to_virt((unsigned long)(x)))
    >> +#define __va(x) ((void *)__phys_to_virt((phys_addr_t)(x)))
    >> #define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
    >
    > This as a whole does not fill me with a great amount of enthusiasm,
    > because it breaks some of the typechecking that we have here.
    >
    > The whole point of __phys_to_virt() and __virt_to_phys() is that they work
    > on integer types, and warn if you dare to use them with pointers. Adding
    > a cast into them breaks that.
    >

    Understood. Thanks. The casts were needed to upgrade to 64-bit before
    arithmetic. We should convert the non-patch __phys_to_virt and
    __virt_to_phys to inlines to keep the typechecking intact.

    > The whole point is that the typecasting is explicitly inside phys_to_virt()
    > and virt_to_phys() and not their macro counterparts.
    >
    > Secondly, are you sure that this patch is correct on its own? You're
    > passing a u64 into assembly only expecting a 32-bit register. Have you
    > checked it does the right thing with a 64-bit phys_addr_t on both LE
    > and BE?
    >

    We should explicitly pass in the lower order bits here, at least until
    the next patch in the series fixes things up for 64-bit. Thanks.

    We've tested with 64-bit and 32-bit phys_addr_t, but only on LE. Thanks
    for pointing this out, we'll figure out a way to run BE as well.

    --
    Thanks
    - Cyril


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