ARM: expand fixmap region to 3MB

With commit a05e54c103b0 ("ARM: 8031/2: change fixmap mapping region to
support 32 CPUs"), the fixmap region was expanded to 2MB, but it
precluded any other uses of the fixmap region. In order to support other
uses the fixmap region needs to be expanded beyond 2MB. Fortunately, the
adjacent 1MB range 0xffe00000-0xfff00000 is availabe.

Remove fixmap_page_table ptr and lookup the page table via the virtual
address so that the fixmap region can span more that one pmd. The 2nd
pmd is already created since it is shared with the vector page.

Signed-off-by: Rob Herring <robh@kernel.org>
[kees: fixed CONFIG_DEBUG_HIGHMEM get_fixmap() calls]
[kees: moved pte allocation outside of CONFIG_HIGHMEM]
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Nicolas Pitre <nico@linaro.org>

diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt
index 38dc06d..4178ebd 100644 (file)
--- a/Documentation/arm/memory.txt
+++ b/Documentation/arm/memory.txt
@@ -41,7 +41,7 @@ fffe8000      fffeffff        DTCM mapping area for platforms with
 fffe0000       fffe7fff        ITCM mapping area for platforms with
                                ITCM mounted inside the CPU.
 
-ffc00000       ffdfffff        Fixmap mapping region.  Addresses provided
+ffc00000       ffefffff        Fixmap mapping region.  Addresses provided
                                by fix_to_virt() will be located here.
 
 fee00000       feffffff        Mapping of PCI I/O space. This is a static

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index a7add6f..d984ca6 100644 (file)
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -2,7 +2,7 @@
 #define _ASM_FIXMAP_H
 
 #define FIXADDR_START          0xffc00000UL
-#define FIXADDR_END            0xffe00000UL
+#define FIXADDR_END            0xfff00000UL
 #define FIXADDR_TOP            (FIXADDR_END - PAGE_SIZE)
 
 #include <asm/kmap_types.h>

diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index 45aeaac..8106198 100644 (file)
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -18,19 +18,20 @@
 #include <asm/tlbflush.h>
 #include "mm.h"
 
-pte_t *fixmap_page_table;
-
 static inline void set_fixmap_pte(int idx, pte_t pte)
 {
        unsigned long vaddr = __fix_to_virt(idx);
-       set_pte_ext(fixmap_page_table + idx, pte, 0);
+       pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
+
+       set_pte_ext(ptep, pte, 0);
        local_flush_tlb_kernel_page(vaddr);
 }
 
 static inline pte_t get_fixmap_pte(unsigned long vaddr)
 {
-       unsigned long idx = __virt_to_fix(vaddr);
-       return *(fixmap_page_table + idx);
+       pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
+
+       return *ptep;
 }
 
 void *kmap(struct page *page)
@@ -84,7 +85,7 @@ void *kmap_atomic(struct page *page)
         * With debugging enabled, kunmap_atomic forces that entry to 0.
         * Make sure it was indeed properly unmapped.
         */
-       BUG_ON(!pte_none(*(fixmap_page_table + idx)));
+       BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
 #endif
        /*
         * When debugging is off, kunmap_atomic leaves the previous mapping
@@ -134,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
        idx = type + KM_TYPE_NR * smp_processor_id();
        vaddr = __fix_to_virt(idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
-       BUG_ON(!pte_none(*(fixmap_page_table + idx)));
+       BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
 #endif
        set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
 

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 8348ed6..7fa0966 100644 (file)
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1326,10 +1326,10 @@ static void __init kmap_init(void)
 #ifdef CONFIG_HIGHMEM
        pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
                PKMAP_BASE, _PAGE_KERNEL_TABLE);
-
-       fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START),
-               FIXADDR_START, _PAGE_KERNEL_TABLE);
 #endif
+
+       early_pte_alloc(pmd_off_k(FIXADDR_START), FIXADDR_START,
+                       _PAGE_KERNEL_TABLE);
 }
 
 static void __init map_lowmem(void)