Re: [PATCH v5 03/22] x86, ACPI, mm: Kill max_low_pfn_mapped

[Toshi Kani]

On Mon, 2013-06-17 at 16:36 -0700, Yinghai Lu wrote:
> On Mon, Jun 17, 2013 at 4:19 PM, Toshi Kani <toshi.kani@xxxxxx> wrote:
> > On Fri, 2013-06-14 at 17:56 -0700, Yinghai Lu wrote:
> >> Now we have arch_pfn_mapped array, and max_low_pfn_mapped should not
> >> be used anymore.
> >
> > Can you describe why max_low_pfn_mapped should not be used?  Is this to
> > allow moving the code of acpi_initrd_override() up before
> > init_mem_mapping() in a succeeding patch, or is there also another
> > reason behind it?  Also, I think arch_pfn_mapped should be pfn_mapped[].
> 
> ok, assumption that from [0, max_low_pfn_mapped) all mapped.
> 
> Now we only map the  RAM or KERNL_RESERVED, to prevent user from
> taking it granted that only check it is below max_low_pfn_mapped to assume
> it mapped.

Oh, I see.  So, it is not necessary any more.

> Yes, is should be pfn_mapped[]

OK.

Please update the change log per the info you described here.  With
that:

Acked-by: Toshi Kani <toshi.kani@xxxxxx>

Thanks,
-Toshi


> >
> > Thanks,
> > -Toshi
> >
> >
> >> User should use arch_pfn_mapped or just 1UL<<(32-PAGE_SHIFT) instead.
> >>
> >> Only user is ACPI_INITRD_TABLE_OVERRIDE, and it should not use that,
> >> as later accessing is using early_ioremap(). We could change to use
> >> 1U<<(32_PAGE_SHIFT) with it, aka under 4G.
> >>
> >> -v2: Leave alone max_low_pfn_mapped in i915 code according to tj.
> >>
> >> Suggested-by: H. Peter Anvin <hpa@xxxxxxxxx>
> >> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> >> Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
> >> Cc: Jacob Shin <jacob.shin@xxxxxxx>
> >> Cc: Pekka Enberg <penberg@xxxxxxxxxx>
> >> Cc: linux-acpi@xxxxxxxxxxxxxxx
> >> Tested-by: Thomas Renninger <trenn@xxxxxxx>
> >> Reviewed-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
> >> Tested-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
> >> ---
> >>  arch/x86/include/asm/page_types.h | 1 -
> >>  arch/x86/kernel/setup.c           | 4 +---
> >>  arch/x86/mm/init.c                | 4 ----
> >>  drivers/acpi/osl.c                | 6 +++---
> >>  4 files changed, 4 insertions(+), 11 deletions(-)
> >>
> >> diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h
> >> index 54c9787..b012b82 100644
> >> --- a/arch/x86/include/asm/page_types.h
> >> +++ b/arch/x86/include/asm/page_types.h
> >> @@ -43,7 +43,6 @@
> >>
> >>  extern int devmem_is_allowed(unsigned long pagenr);
> >>
> >> -extern unsigned long max_low_pfn_mapped;
> >>  extern unsigned long max_pfn_mapped;
> >>
> >>  static inline phys_addr_t get_max_mapped(void)
> >> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> >> index 66ab495..6ca5f2c 100644
> >> --- a/arch/x86/kernel/setup.c
> >> +++ b/arch/x86/kernel/setup.c
> >> @@ -112,13 +112,11 @@
> >>  #include <asm/prom.h>
> >>
> >>  /*
> >> - * max_low_pfn_mapped: highest direct mapped pfn under 4GB
> >> - * max_pfn_mapped:     highest direct mapped pfn over 4GB
> >> + * max_pfn_mapped:     highest direct mapped pfn
> >>   *
> >>   * The direct mapping only covers E820_RAM regions, so the ranges and gaps are
> >>   * represented by pfn_mapped
> >>   */
> >> -unsigned long max_low_pfn_mapped;
> >>  unsigned long max_pfn_mapped;
> >>
> >>  #ifdef CONFIG_DMI
> >> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> >> index eaac174..8554656 100644
> >> --- a/arch/x86/mm/init.c
> >> +++ b/arch/x86/mm/init.c
> >> @@ -313,10 +313,6 @@ static void add_pfn_range_mapped(unsigned long start_pfn, unsigned long end_pfn)
> >>       nr_pfn_mapped = clean_sort_range(pfn_mapped, E820_X_MAX);
> >>
> >>       max_pfn_mapped = max(max_pfn_mapped, end_pfn);
> >> -
> >> -     if (start_pfn < (1UL<<(32-PAGE_SHIFT)))
> >> -             max_low_pfn_mapped = max(max_low_pfn_mapped,
> >> -                                      min(end_pfn, 1UL<<(32-PAGE_SHIFT)));
> >>  }
> >>
> >>  bool pfn_range_is_mapped(unsigned long start_pfn, unsigned long end_pfn)
> >> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> >> index e721863..93e3194 100644
> >> --- a/drivers/acpi/osl.c
> >> +++ b/drivers/acpi/osl.c
> >> @@ -624,9 +624,9 @@ void __init acpi_initrd_override(void *data, size_t size)
> >>       if (table_nr == 0)
> >>               return;
> >>
> >> -     acpi_tables_addr =
> >> -             memblock_find_in_range(0, max_low_pfn_mapped << PAGE_SHIFT,
> >> -                                    all_tables_size, PAGE_SIZE);
> >> +     /* under 4G at first, then above 4G */
> >> +     acpi_tables_addr = memblock_find_in_range(0, (1ULL<<32) - 1,
> >> +                                     all_tables_size, PAGE_SIZE);
> >>       if (!acpi_tables_addr) {
> >>               WARN_ON(1);
> >>               return;
> >
> >
> > --
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