On Wed, Apr 21, 2021 at 04:29:48PM +0530, Anshuman Khandual wrote:
>
> On 4/21/21 12:21 PM, Mike Rapoport wrote:
> > From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> >
> > The intended semantics of pfn_valid() is to verify whether there is a
> > struct page for the pfn in question and nothing else.
> >
> > Yet, on arm64 it is used to distinguish memory areas that are mapped in the
> > linear map vs those that require ioremap() to access them.
> >
> > Introduce a dedicated pfn_is_map_memory() wrapper for
> > memblock_is_map_memory() to perform such check and use it where
> > appropriate.
> >
> > Using a wrapper allows to avoid cyclic include dependencies.
> >
> > Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> > ---
> > arch/arm64/include/asm/memory.h | 2 +-
> > arch/arm64/include/asm/page.h | 1 +
> > arch/arm64/kvm/mmu.c | 2 +-
> > arch/arm64/mm/init.c | 11 +++++++++++
> > arch/arm64/mm/ioremap.c | 4 ++--
> > arch/arm64/mm/mmu.c | 2 +-
> > 6 files changed, 17 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> > index 0aabc3be9a75..194f9f993d30 100644
> > --- a/arch/arm64/include/asm/memory.h
> > +++ b/arch/arm64/include/asm/memory.h
> > @@ -351,7 +351,7 @@ static inline void *phys_to_virt(phys_addr_t x)
> >
> > #define virt_addr_valid(addr) ({ \
> > __typeof__(addr) __addr = __tag_reset(addr); \
> > - __is_lm_address(__addr) && pfn_valid(virt_to_pfn(__addr)); \
> > + __is_lm_address(__addr) && pfn_is_map_memory(virt_to_pfn(__addr)); \
> > })
> >
> > void dump_mem_limit(void);
> > diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
> > index 012cffc574e8..99a6da91f870 100644
> > --- a/arch/arm64/include/asm/page.h
> > +++ b/arch/arm64/include/asm/page.h
> > @@ -38,6 +38,7 @@ void copy_highpage(struct page *to, struct page *from);
> > typedef struct page *pgtable_t;
> >
> > extern int pfn_valid(unsigned long);
> > +extern int pfn_is_map_memory(unsigned long);
>
> Check patch is complaining about this.
>
> WARNING: function definition argument 'unsigned long' should also have an identifier name
> #50: FILE: arch/arm64/include/asm/page.h:41:
> +extern int pfn_is_map_memory(unsigned long);
>
>
> >
> > #include <asm/memory.h>
> >
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index 8711894db8c2..23dd99e29b23 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -85,7 +85,7 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
> >
> > static bool kvm_is_device_pfn(unsigned long pfn)
> > {
> > - return !pfn_valid(pfn);
> > + return !pfn_is_map_memory(pfn);
> > }
> >
> > /*
> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> > index 3685e12aba9b..dc03bdc12c0f 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -258,6 +258,17 @@ int pfn_valid(unsigned long pfn)
> > }
> > EXPORT_SYMBOL(pfn_valid);
> >
> > +int pfn_is_map_memory(unsigned long pfn)
> > +{
> > + phys_addr_t addr = PFN_PHYS(pfn);
> > +
>
> Should also bring with it, the comment regarding upper bits in
> the pfn from arm64 pfn_valid().
I think a reference to the comment in pfn_valid() will suffice.
BTW, I wonder how is that other architectures do not need this check?
> > + if (PHYS_PFN(addr) != pfn)
> > + return 0;
> > +
>
> ^^^^^ trailing spaces here.
>
> ERROR: trailing whitespace
> #81: FILE: arch/arm64/mm/init.c:263:
> +^I$
Oops :)
> > + return memblock_is_map_memory(addr);
> > +}
> > +EXPORT_SYMBOL(pfn_is_map_memory);
> > +
>
> Is the EXPORT_SYMBOL() required to build drivers which will use
> pfn_is_map_memory() but currently use pfn_valid() ?
Yes, this is required for virt_addr_valid() that is used by modules.
--
Sincerely yours,
Mike.
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