[PATCH 1/2] arm: use generic fixmap.h

[Leif Lindholm]

From: Mark Salter <msalter at redhat.com>

ARM is different from other architectures in that fixmap pages are
indexed with a positive offset from FIXADDR_START. Other architectures
index with a negative offset from FIXADDR_TOP. In order to use the
generic fixmap.h definitions, this patch redefines FIXADDR_TOP to be
inclusive of the useable range. That is, FIXADDR_TOP is the virtual
address of the topmost fixed page. The newly defined FIXADDR_END is
the first virtual address past the fixed mappings.

The patch also introduces local helper macros in highmem.c to reverse
the iteration order of fixmap pages.

Signed-off-by: Mark Salter <msalter at redhat.com>
[Rebased to 3.16-rc4, reverse kmap fixmap traversal]
Signed-off-by: Leif Lindholm <leif.lindholm at linaro.org>
---
 arch/arm/include/asm/fixmap.h |   45 ++++++++++++++++++++++++++---------------
 arch/arm/mm/highmem.c         |   13 +++++++-----
 arch/arm/mm/init.c            |    2 +-
 3 files changed, 38 insertions(+), 22 deletions(-)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index 74124b0..8992431 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -1,28 +1,41 @@
 #ifndef _ASM_FIXMAP_H
 #define _ASM_FIXMAP_H
 
+#include <asm/pgtable.h>
+
 #define FIXADDR_START		0xffc00000UL
-#define FIXADDR_TOP		0xffe00000UL
-#define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
+#define FIXADDR_END		0xffe00000UL
+#define FIXADDR_SIZE		(FIXADDR_END - FIXADDR_START)
+#define FIXADDR_TOP		(FIXADDR_END - PAGE_SIZE)
 
 #define FIX_KMAP_NR_PTES	(FIXADDR_SIZE >> PAGE_SHIFT)
 
-#define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
-#define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
+enum fixed_addresses {
+	FIX_KMAP_BEGIN,
+	FIX_KMAP_END = FIX_KMAP_NR_PTES - 1,
+	__end_of_fixed_addresses
+};
+
+/*
+ * Temporary boot-time mappings, used by early_ioremap(),
+ * before ioremap() is functional.
+ *
+ * (P)re-using the last pmd of the FIXADDR region, which is used for
+ * highmem later on, and statically aligned to 1MB.
+ * Growing down from FIXADDR_TOP
+ */
+#define NR_FIX_BTMAPS		32
+#define FIX_BTMAPS_SLOTS	(PTRS_PER_PTE / NR_FIX_BTMAPS)
+#define TOTAL_FIX_BTMAPS	(NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
+#define FIX_BTMAP_END		FIX_KMAP_BEGIN
+#define FIX_BTMAP_BEGIN		(FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1)
 
-extern void __this_fixmap_does_not_exist(void);
+#define FIXMAP_PAGE_NORMAL (L_PTE_MT_WRITEBACK | L_PTE_YOUNG | L_PTE_PRESENT)
+#define FIXMAP_PAGE_IO (L_PTE_MT_DEV_NONSHARED | L_PTE_YOUNG | L_PTE_PRESENT)
 
-static inline unsigned long fix_to_virt(const unsigned int idx)
-{
-	if (idx >= FIX_KMAP_NR_PTES)
-		__this_fixmap_does_not_exist();
-	return __fix_to_virt(idx);
-}
+extern void __early_set_fixmap(enum fixed_addresses idx,
+			       phys_addr_t phys, pgprot_t flags);
 
-static inline unsigned int virt_to_fix(const unsigned long vaddr)
-{
-	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
-	return __virt_to_fix(vaddr);
-}
+#include <asm-generic/fixmap.h>
 
 #endif
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index 45aeaac..3c59cdf 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -20,16 +20,19 @@
 
 pte_t *fixmap_page_table;
 
+#define __kmap_fix_to_virt(x)	(__fix_to_virt(FIX_KMAP_NR_PTES - 1 - (x)))
+#define __kmap_virt_to_fix(x)	(FIX_KMAP_NR_PTES - 1 - __fix_to_virt(x))
+
 static inline void set_fixmap_pte(int idx, pte_t pte)
 {
-	unsigned long vaddr = __fix_to_virt(idx);
+	unsigned long vaddr = __kmap_fix_to_virt(idx);
 	set_pte_ext(fixmap_page_table + idx, 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);
+	unsigned long idx = __kmap_virt_to_fix(vaddr);
 	return *(fixmap_page_table + idx);
 }
 
@@ -78,7 +81,7 @@ void *kmap_atomic(struct page *page)
 	type = kmap_atomic_idx_push();
 
 	idx = type + KM_TYPE_NR * smp_processor_id();
-	vaddr = __fix_to_virt(idx);
+	vaddr = __kmap_fix_to_virt(idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
 	/*
 	 * With debugging enabled, kunmap_atomic forces that entry to 0.
@@ -109,7 +112,7 @@ void __kunmap_atomic(void *kvaddr)
 		if (cache_is_vivt())
 			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 #ifdef CONFIG_DEBUG_HIGHMEM
-		BUG_ON(vaddr != __fix_to_virt(idx));
+		BUG_ON(vaddr != __kmap_fix_to_virt(idx));
 		set_fixmap_pte(idx, __pte(0));
 #else
 		(void) idx;  /* to kill a warning */
@@ -132,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
 
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR * smp_processor_id();
-	vaddr = __fix_to_virt(idx);
+	vaddr = __kmap_fix_to_virt(idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
 	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
 #endif
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 659c75d..ad82c05 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -570,7 +570,7 @@ void __init mem_init(void)
 			MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
 			MLK(ITCM_OFFSET, (unsigned long) itcm_end),
 #endif
-			MLK(FIXADDR_START, FIXADDR_TOP),
+			MLK(FIXADDR_START, FIXADDR_END),
 			MLM(VMALLOC_START, VMALLOC_END),
 			MLM(PAGE_OFFSET, (unsigned long)high_memory),
 #ifdef CONFIG_HIGHMEM
-- 
1.7.10.4