-----Original Message-----
> > > > > @@ -1185,8 +1234,20 @@ arm64_VTOP(ulong addr)
> > > > > return addr - machdep->machspec->kimage_voffset;
> > > > > }
> > > > >
> > > > > - if (addr >= machdep->machspec->page_offset)
> > > > > - return addr + machdep->machspec->physvirt_offset;
>
> I had thought it worked for all versions before commit 5383cc6efed1 (arm64: mm: Introduce vabits_actual).
> So !(machdep->flags & FLIPPED_VM) branch should use the formula.
>
> But it turns out to be wrong. PLS see the comment followed.
>
> > > > > + if (addr >= machdep->machspec->page_offset) {
> > > > > + ulong paddr;
> > > > > +
> > > > > + if (!(machdep->flags & FLIPPED_VM) || (machdep->flags & HAS_PHYSVIRT_OFFSET))
> {
> > > > > + paddr = addr;
> > > > > + } else {
> > > > > + /*
> > > > > + * #define __lm_to_phys(addr) (((addr) & ~PAGE_OFFSET) +
> PHYS_OFFSET)
> > > > > + */
> > > > > + paddr = addr & ~
> _PAGE_OFFSET(machdep->machspec->CONFIG_ARM64_VA_BITS);
> > > > > + }
> > > > > + paddr += machdep->machspec->physvirt_offset;
> > > > > + return paddr;
> > > >
> > > > Hmm, complex. It should be symmetric to PTOV, why differences?
> > >
> [...]
> >
> > Yes, it's one of them, and this looks better, but...
> >
> > Hmm ok, I summarized these and my question why they're asymmetric emerged:
> >
> Thank you for the patient.
>
> > if physvirt_offset exists // HAS_PHYSVIRT_OFFSET
> > ms->physvirt_offset = read physvirt_offset;
> > else if (machdep->flags & FLIPPED_VM)
> > ms->physvirt_offset = ms->phys_offset_nominal;
> > else // !FLIPPED_VM
> > ms->physvirt_offset = ms->phys_offset - ms->page_offset;
> >
> > PTOV:
> > if (machdep->flags & HAS_PHYSVIRT_OFFSET)
> > v = paddr - ms->physvirt_offset; // looks ok
> > else
> > v = (paddr - ms->physvirt_offset) | PAGE_OFFSET; // Is this ok when !FLIPPED_VM ?
> >
> It works for !FLIPPED_VM. But I did make a mistake on VTOP()
>
> Flipped mm is introduced by 14c127c957c1 ("arm64: mm: Flip kernel VA space")
>
> $ git show 14c127c957c1c6070647c171e72f06e0db275ebf:arch/arm64/include/asm/memory.h | grep "#define
> __phys_to_virt"
> #define __phys_to_virt(x) ((unsigned long)((x) - PHYS_OFFSET) | PAGE_OFFSET)
> $ git show 14c127c957c1c6070647c171e72f06e0db275ebf~1:arch/arm64/include/asm/memory.h | grep "#define
> __phys_to_virt"
> #define __phys_to_virt(x) ((unsigned long)((x) - PHYS_OFFSET) | PAGE_OFFSET)
>
> So the formula keeps unchange across filpped-mm. The same case for VTOP.
> And what matters is physvirt_offset introduced by 5383cc6efed1 ("arm64: mm: Introduce vabits_actual")
>
> > VTOP:
> > if (machdep->flags & HAS_PHYSVIRT_OFFSET || !(machdep->flags & FLIPPED_VM))
> > p = vaddr + ms->physvirt_offset; // looks ok
> > else
> > p = (vaddr & ~PAGE_OFFSET) + ms->physvirt_offset; // looks ok
> >
>
> Similar,
> $git show 14c127c957c1c6070647c171e72f06e0db275ebf:arch/arm64/include/asm/memory.h | grep __lm_to_phys
> #define __lm_to_phys(addr) (((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
> __is_lm_address(__x) ? __lm_to_phys(__x) : \
> $ git show 14c127c957c1c6070647c171e72f06e0db275ebf~1:arch/arm64/include/asm/memory.h | grep __lm_to_phys
> #define __lm_to_phys(addr) (((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
> __is_lm_address(__x) ? __lm_to_phys(__x) : \
>
> >
> > When !FLIPPED_VM, PTOV calculates:
> > v = (paddr - ms->physvirt_offset) | PAGE_OFFSET
> > = (paddr - ms->physoffset + ms->page_offset) | PAGE_OFFSET
> >
> > This might be not wrong in the result value because of the or operation,
> > but looks wrong formula. So PTOV also needs the !(machdep->flags & FLIPPED_VM)
> > condition? or I'm missing something?
> >
>
> So I need to drop the !(machdep->flags & FLIPPED_VM) in VTOP(), instead of adding in PTOV().
> Sorry for the confusion and hope I make it clear.
If you do so, you mean that you will change
ms->physvirt_offset = ms->phys_offset - ms->page_offset
to
ms->physvirt_offset = ms->phys_offset
if !FLIPPED_VM ?
For me, it's readable and understandable to match the formulas with kernel's
one. In this case, use the physvirt_offset only if physvirt_offset exists.
We can do it now because we are introducing a switchable PTOV/VTOP.
For example:
ms->phys_offset_nominal = read phys_offset;
if (ms->phys_offset_nominal < 0)
ms->phys_offset = ms->phys_offset_nominal + MEMSTART_ADDR_OFFSET;
else
ms->phys_offset = ms->phys_offset_nominal
PTOV:
if (machdep->flags & HAS_PHYSVIRT_OFFSET)
v = paddr - ms->physvirt_offset;
else
v = (paddr - ms->phys_offset_nominal) | PAGE_OFFSET
VTOP:
if (machdep->flags & HAS_PHYSVIRT_OFFSET)
p = vaddr + ms->physvirt_offset;
else
p = (vaddr & ~PAGE_OFFSET) + ms->phys_offset_nominal;
btw, just to clarify, where is the phys_offset used except for
PTOV and VTOP? I cannot find it..
> while getting PFN offset in a dumpfile, phys_offset is
> required.
Thanks,
Kazu
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