[PATCH v2 1/1] ARM: LPAE: Fix mapping in alloc_init_pte for unaligned addresses.

Hi,
On Fri, Aug 17, 2012 at 4:32 PM, R, Sricharan [off-list ref] wrote:

Hi,

quoted

With LPAE, When either the start address or end address
or physical address to be mapped is unaligned,
alloc_init_section creates page granularity mappings.
alloc_init_section calls alloc_init_pte which populates
one pmd entry and sets up the ptes. But if the size is
greater than what can be mapped by one pmd entry,
then the rest remains unmapped.

The issue becomes visible when LPAE is enabled, where we have
the 3 levels with seperate pgd and pmd's.
When a static mapping for 3MB is requested, only 2MB is mapped
and the remaining 1MB is unmapped. Fixing this here, by looping
in to map the entire unaligned address range.

Boot tested on OMAP5 evm with both LPAE enabled/disabled
and verified that static mappings with unaligned addresses
are properly mapped.

Signed-off-by: R Sricharan <redacted>
Reviewed-by: Santosh Shilimkar <redacted>
Cc: Catalin Marinas <catalin.marinas@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.

 arch/arm/mm/mmu.c |   22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index cf4528d..0ed8808 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c

@@ -585,11 +585,25 @@ static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
                                  unsigned long end, unsigned long pfn,
                                  const struct mem_type *type)
 {
-       pte_t *pte = early_pte_alloc(pmd, addr, type->prot_l1);
+       unsigned long next;
+       pte_t *pte;
+       phys_addr_t phys;
+
        do {
-               set_pte_ext(pte, pfn_pte(pfn, __pgprot(type->prot_pte)), 0);
-               pfn++;
-       } while (pte++, addr += PAGE_SIZE, addr != end);
+               if ((end-addr) & PMD_MASK)
+                       next = (addr + PMD_SIZE) & PMD_MASK;
+               else
+                       next = end;
+
+               pte = early_pte_alloc(pmd, addr, type->prot_l1);
+               do {
+                       set_pte_ext(pte, pfn_pte(pfn,
+                                       __pgprot(type->prot_pte)), 0);
+                       pfn++;
+               } while (pte++, addr += PAGE_SIZE, addr != next);
+
+               phys += next - addr;
+       } while (pmd++, addr = next, addr != end);
 }

  ping..

  Ping again.
  The issue is reproducible in mainline with CMA + LPAE enabled.
  CMA tries to reserve/map 16 MB with 2 level table entries and
   crashes in alloc_init_pte.

  This patch fixes that. Just posted a V3 of the same patch.

         https://patchwork.kernel.org/patch/1472031/


Thanks,
 Sricharan