[PATCH v5 2/8] ARM: expand fixmap region to 3MB

Kees Cook
2014-09-03T21:59:55Z

From: Rob Herring <robh@kernel.org>

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>
---
Documentation/arm/memory.txt | 2 +-
arch/arm/include/asm/fixmap.h | 2 +-
arch/arm/mm/highmem.c | 15 ++++++++-------
arch/arm/mm/mmu.c | 6 +++---
4 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt
index 38dc06d0a791..4178ebda6e66 100644
--- 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 a7add6f9315d..d984ca69ce19 100644
--- 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 45aeaaca9052..81061987ac45 100644
--- 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 8348ed6b2efe..7fa0966cd15f 100644
--- 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)
--
1.9.1