[PATCH V6] ARM: LPAE: Fix mapping in alloc_init_section for unaligned addresses

Russell King - ARM Linux linux at arm.linux.org.uk
Mon Mar 18 06:45:43 EDT 2013


On Mon, Mar 18, 2013 at 11:20:47AM +0530, Sricharan R wrote:
> Hi Russell,
> 
> On Monday 18 March 2013 01:22 AM, Christoffer Dall wrote:
> > On Sat, Mar 16, 2013 at 10:05 PM, Sricharan R <r.sricharan at ti.com> wrote:
> >> From: R Sricharan <r.sricharan at ti.com>
> >>
> >> With LPAE enabled, alloc_init_section() does not map the entire
> >> address space for unaligned addresses.
> >>
> >> The issue also reproduced with CMA + LPAE. CMA tries to map 16MB
> >> with page granularity mappings during boot. alloc_init_pte()
> >> is called and out of 16MB, only 2MB gets mapped and rest remains
> >> unaccessible.
> >>
> >> Because of this OMAP5 boot is broken with CMA + LPAE enabled.
> >> Fix the issue by ensuring that the entire addresses are
> >> mapped.
> >>
> >> Signed-off-by: R Sricharan <r.sricharan at ti.com>
> >> Cc: Catalin Marinas <catalin.marinas at arm.com>
> >> Cc: Christoffer Dall <chris at cloudcar.com>
> >> Cc: Russell King <linux at arm.linux.org.uk>
> >> Cc: Santosh Shilimkar <santosh.shilimkar at ti.com>
> >> Tested-by: Laura Abbott <lauraa at codeaurora.org>
> >> Acked-by: Catalin Marinas <catalin.marinas at arm.com>
> >> ---
> >>  [V2] Moved the loop to alloc_init_pte as per Russell's
> >>      feedback and changed the subject accordingly.
> >>      Using PMD_XXX instead of SECTION_XXX to avoid
> >>      different loop increments with/without LPAE.
> >>
> >>  [v3] Removed the dummy variable phys and updated
> >>       the commit log for CMA case.
> >>
> >>  [v4] Resending with updated change log and
> >>       updating the tags.
> >>
> >>  [v5] Renamed alloc_init_section to alloc_init_pmd
> >>       and moved the loop back there. Also introduced
> >>       map_init_section as per Catalin's comments.
> >>
> >>  [v6] Corrected tags and updated the comments for code.
> >>
> >>  arch/arm/mm/mmu.c |   73 ++++++++++++++++++++++++++++++++++-------------------
> >>  1 file changed, 47 insertions(+), 26 deletions(-)
> >>
> >> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> >> index e95a996..7897894 100644
> >> --- a/arch/arm/mm/mmu.c
> >> +++ b/arch/arm/mm/mmu.c
> >> @@ -598,39 +598,60 @@ static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
> >>         } while (pte++, addr += PAGE_SIZE, addr != end);
> >>  }
> >>
> >> -static void __init alloc_init_section(pud_t *pud, unsigned long addr,
> >> -                                     unsigned long end, phys_addr_t phys,
> >> -                                     const struct mem_type *type)
> >> +static void __init map_init_section(pmd_t *pmd, unsigned long addr,
> >> +                       unsigned long end, phys_addr_t phys,
> >> +                       const struct mem_type *type)
> >>  {
> >> -       pmd_t *pmd = pmd_offset(pud, addr);
> >> -
> >> +#ifndef CONFIG_ARM_LPAE
> >>         /*
> >> -        * Try a section mapping - end, addr and phys must all be aligned
> >> -        * to a section boundary.  Note that PMDs refer to the individual
> >> -        * L1 entries, whereas PGDs refer to a group of L1 entries making
> >> -        * up one logical pointer to an L2 table.
> >> +        * In classic MMU format, puds and pmds are folded in to
> >> +        * the pgds. pmd_offset gives the PGD entry. PGDs refer to a
> >> +        * group of L1 entries making up one logical pointer to
> >> +        * an L2 table (2MB), where as PMDs refer to the individual
> >> +        * L1 entries (1MB). Hence increment to get the correct
> >> +        * offset for odd 1MB sections.
> >> +        * (See arch/arm/include/asm/pgtable-2level.h)
> >>          */
> >> -       if (type->prot_sect && ((addr | end | phys) & ~SECTION_MASK) == 0) {
> >> -               pmd_t *p = pmd;
> >> -
> >> -#ifndef CONFIG_ARM_LPAE
> >> -               if (addr & SECTION_SIZE)
> >> -                       pmd++;
> >> +       if (addr & SECTION_SIZE)
> >> +               pmd++;
> >>  #endif
> >> +       do {
> >> +               *pmd = __pmd(phys | type->prot_sect);
> >> +               phys += SECTION_SIZE;
> >> +       } while (pmd++, addr += SECTION_SIZE, addr != end);
> >>
> >> -               do {
> >> -                       *pmd = __pmd(phys | type->prot_sect);
> >> -                       phys += SECTION_SIZE;
> >> -               } while (pmd++, addr += SECTION_SIZE, addr != end);
> >> +       flush_pmd_entry(pmd);
> >> +}
> >>
> >> -               flush_pmd_entry(p);
> >> -       } else {
> >> +static void __init alloc_init_pmd(pud_t *pud, unsigned long addr,
> >> +                                     unsigned long end, phys_addr_t phys,
> >> +                                     const struct mem_type *type)
> >> +{
> >> +       pmd_t *pmd = pmd_offset(pud, addr);
> >> +       unsigned long next;
> >> +
> >> +       do {
> >>                 /*
> >> -                * No need to loop; pte's aren't interested in the
> >> -                * individual L1 entries.
> >> +                * With LPAE, we must loop over to map
> >> +                * all the pmds for the given range.
> >>                  */
> >> -               alloc_init_pte(pmd, addr, end, __phys_to_pfn(phys), type);
> >> -       }
> >> +               next = pmd_addr_end(addr, end);
> >> +
> >> +               /*
> >> +                * Try a section mapping - addr, next and phys must all be
> >> +                * aligned to a section boundary.
> >> +                */
> >> +               if (type->prot_sect &&
> >> +                               ((addr | next | phys) & ~SECTION_MASK) == 0) {
> >> +                       map_init_section(pmd, addr, next, phys, type);
> >> +               } else {
> >> +                       alloc_init_pte(pmd, addr, next,
> >> +                                               __phys_to_pfn(phys), type);
> >> +               }
> >> +
> >> +               phys += next - addr;
> >> +
> >> +       } while (pmd++, addr = next, addr != end);
> >>  }
> >>
> >>  static void __init alloc_init_pud(pgd_t *pgd, unsigned long addr,
> >> @@ -641,7 +662,7 @@ static void __init alloc_init_pud(pgd_t *pgd, unsigned long addr,
> >>
> >>         do {
> >>                 next = pud_addr_end(addr, end);
> >> -               alloc_init_section(pud, addr, next, phys, type);
> >> +               alloc_init_pmd(pud, addr, next, phys, type);
> >>                 phys += next - addr;
> >>         } while (pud++, addr = next, addr != end);
> >>  }
> >> --
> >> 1.7.9.5
> >>
> > Acked-by: Christoffer Dall <chris at cloudcar.com>
> 
> I am not able to add this in to the patch system because my login fails.
> I was trying using the credentials registered with linux-arm-kernel
>  mailing list. Can you please help me here ?

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