Re: [PATCH 08/16] mm/unicore32: use vm_flags_t for vma flags

[Guan Xuetao]

On 03/27/2012 01:58 PM, Konstantin Khlebnikov wrote:
> Guan Xuetao wrote:
> > On 03/21/2012 02:56 PM, Konstantin Khlebnikov wrote:
> > > The same magic like in arm: assembler code wants to test VM_EXEC,
> > > but for big-endian we should get upper word for this.
> > >
> > > Signed-off-by: Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>
> > > Cc: Guan Xuetao<gxt@xxxxxxxxxxxxxxx>
> > > ---
> > >    arch/unicore32/kernel/asm-offsets.c |    6 +++++-
> > >    arch/unicore32/mm/fault.c           |    2 +-
> > >    2 files changed, 6 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/arch/unicore32/kernel/asm-offsets.c 
> > > b/arch/unicore32/kernel/asm-offsets.c
> > > index ffcbe75..e3199b5 100644
> > > --- a/arch/unicore32/kernel/asm-offsets.c
> > > +++ b/arch/unicore32/kernel/asm-offsets.c
> > > @@ -87,9 +87,13 @@ int main(void)
> > >        DEFINE(S_FRAME_SIZE,    sizeof(struct pt_regs));
> > >        BLANK();
> > >        DEFINE(VMA_VM_MM,    offsetof(struct vm_area_struct, vm_mm));
> > > +#if defined(CONFIG_CPU_BIG_ENDIAN)&&   (NR_VMA_FLAGS>   32)
> > > +    DEFINE(VMA_VM_FLAGS,    offsetof(struct vm_area_struct, 
> > > vm_flags) + 4);
> > > +#else
> > CONFIG_CPU_BIG/LITTLE_ENDIAN is defined only in some archs, and not
> > supported by unicore32.
>
> Ok, I'll drop this in v2
>
> > >        DEFINE(VMA_VM_FLAGS,    offsetof(struct vm_area_struct, 
> > > vm_flags));
> > > +#endif
> > >        BLANK();
> > > -    DEFINE(VM_EXEC,        VM_EXEC);
> > > +    DEFINE(VM_EXEC,        (__force unsigned int)VM_EXEC);
>
> > Is this check useful for asm-offsets.h?
>
> this forced-typecast to make sparse happy, because  we use here only 
> (int) part of vma->vm_flags.
Perhaps,  vm_flags_t,  not unsigned int is more proper.

> > >        BLANK();
> > >        DEFINE(PAGE_SZ,        PAGE_SIZE);
> > >        BLANK();
> > > diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c
> > > index 283aa4b..9137996 100644
> > > --- a/arch/unicore32/mm/fault.c
> > > +++ b/arch/unicore32/mm/fault.c
> > > @@ -158,7 +158,7 @@ void do_bad_area(unsigned long addr, unsigned 
> > > int fsr, struct pt_regs *regs)
> > >     */
> > >    static inline bool access_error(unsigned int fsr, struct 
> > > vm_area_struct *vma)
> > >    {
> > > -    unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
> > > +    vm_flags_t mask = VM_READ | VM_WRITE | VM_EXEC;
> >
> > I am confused  for the type of vm_flags in vm_area_struct being
> > 'unsigned long',  not vm_flags_t.
>
> Second patch in this patchset changes it.
> vm_flags_t will be unsigned long or or unsigned long long depending on 
> vma flags count.
> But more likely it will be unsigned int, because I have another 
> patchset in work,
> which currently drop four bits in vm_flags, so we can postpone its 
> expansion.
I see. Thanks for your explanation.

Regards,
Guan Xuetao

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