microblaze: Highmem support

The first highmem implementation.

Signed-off-by: Michal Simek <monstr@monstr.eu>

6 files changed, 272 insertions, 13 deletions

diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 3267cc5065d..86ae27871f4 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -159,20 +159,18 @@ config XILINX_UNCACHED_SHADOW
           The feature requires the design to define the RAM memory controller
           window to be twice as large as the actual physical memory.
 
-config HIGHMEM_START_BOOL
-        bool "Set high memory pool address"
-        depends on ADVANCED_OPTIONS && HIGHMEM
-        help
-          This option allows you to set the base address of the kernel virtual
-          area used to map high memory pages.  This can be useful in
-          optimizing the layout of kernel virtual memory.
-
-          Say N here unless you know what you are doing.
-
-config HIGHMEM_START
-        hex "Virtual start address of high memory pool" if HIGHMEM_START_BOOL
+config HIGHMEM
+        bool "High memory support"
         depends on MMU
-        default "0xfe000000"
+        help
+          The address space of Microblaze processors is only 4 Gigabytes large
+          and it has to accommodate user address space, kernel address
+          space as well as some memory mapped IO. That means that, if you
+          have a large amount of physical memory and/or IO, not all of the
+          memory can be "permanently mapped" by the kernel. The physical
+          memory that is not permanently mapped is called "high memory".
+
+          If unsure, say n.
 
 config LOWMEM_SIZE_BOOL
         bool "Set maximum low memory"
diff --git a/arch/microblaze/include/asm/fixmap.h b/arch/microblaze/include/asm/fixmap.h
index dd89754f0a8..f2b312e10b1 100644
--- a/arch/microblaze/include/asm/fixmap.h
+++ b/arch/microblaze/include/asm/fixmap.h
@@ -21,6 +21,10 @@
 #ifndef __ASSEMBLY__
 #include <linux/kernel.h>
 #include <asm/page.h>
+#ifdef CONFIG_HIGHMEM
+#include <linux/threads.h>
+#include <asm/kmap_types.h>
+#endif
 
 #define FIXADDR_TOP     ((unsigned long)(-PAGE_SIZE))
 
@@ -44,6 +48,10 @@
  */
 enum fixed_addresses {
         FIX_HOLE,
+#ifdef CONFIG_HIGHMEM
+        FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
+        FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * num_possible_cpus()) - 1,
+#endif
         __end_of_fixed_addresses
 };
 
diff --git a/arch/microblaze/include/asm/highmem.h b/arch/microblaze/include/asm/highmem.h
new file mode 100644
index 00000000000..2446a73140a
--- /dev/null
+++ b/arch/microblaze/include/asm/highmem.h
@@ -0,0 +1,96 @@
+/*
+ * highmem.h: virtual kernel memory mappings for high memory
+ *
+ * Used in CONFIG_HIGHMEM systems for memory pages which
+ * are not addressable by direct kernel virtual addresses.
+ *
+ * Copyright (C) 1999 Gerhard Wichert, Siemens AG
+ *                    Gerhard.Wichert@pdb.siemens.de
+ *
+ *
+ * Redesigned the x86 32-bit VM architecture to deal with
+ * up to 16 Terabyte physical memory. With current x86 CPUs
+ * we now support up to 64 Gigabytes physical RAM.
+ *
+ * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
+ */
+#ifndef _ASM_HIGHMEM_H
+#define _ASM_HIGHMEM_H
+
+#ifdef __KERNEL__
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/uaccess.h>
+#include <asm/fixmap.h>
+
+extern pte_t *kmap_pte;
+extern pgprot_t kmap_prot;
+extern pte_t *pkmap_page_table;
+
+/*
+ * Right now we initialize only a single pte table. It can be extended
+ * easily, subsequent pte tables have to be allocated in one physical
+ * chunk of RAM.
+ */
+/*
+ * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
+ * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
+ * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
+ * in case of 16K/64K/256K page sizes.
+ */
+
+#define PKMAP_ORDER     PTE_SHIFT
+#define LAST_PKMAP      (1 << PKMAP_ORDER)
+
+#define PKMAP_BASE      ((FIXADDR_START - PAGE_SIZE * (LAST_PKMAP + 1)) \
+                                                                & PMD_MASK)
+
+#define LAST_PKMAP_MASK (LAST_PKMAP - 1)
+#define PKMAP_NR(virt)  ((virt - PKMAP_BASE) >> PAGE_SHIFT)
+#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
+
+extern void *kmap_high(struct page *page);
+extern void kunmap_high(struct page *page);
+extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
+extern void __kunmap_atomic(void *kvaddr);
+
+static inline void *kmap(struct page *page)
+{
+        might_sleep();
+        if (!PageHighMem(page))
+                return page_address(page);
+        return kmap_high(page);
+}
+
+static inline void kunmap(struct page *page)
+{
+        BUG_ON(in_interrupt());
+        if (!PageHighMem(page))
+                return;
+        kunmap_high(page);
+}
+
+static inline void *__kmap_atomic(struct page *page)
+{
+        return kmap_atomic_prot(page, kmap_prot);
+}
+
+static inline struct page *kmap_atomic_to_page(void *ptr)
+{
+        unsigned long idx, vaddr = (unsigned long) ptr;
+        pte_t *pte;
+
+        if (vaddr < FIXADDR_START)
+                return virt_to_page(ptr);
+
+        idx = virt_to_fix(vaddr);
+        pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
+        return pte_page(*pte);
+}
+
+#define flush_cache_kmaps()     { flush_icache(); flush_dcache(); }
+
+#endif /* __KERNEL__ */
+
+#endif /* _ASM_HIGHMEM_H */
diff --git a/arch/microblaze/mm/Makefile b/arch/microblaze/mm/Makefile
index 09c49ed8723..7313bd8acbb 100644
--- a/arch/microblaze/mm/Makefile
+++ b/arch/microblaze/mm/Makefile
@@ -5,3 +5,4 @@
 obj-y := consistent.o init.o
 
 obj-$(CONFIG_MMU) += pgtable.o mmu_context.o fault.o
+obj-$(CONFIG_HIGHMEM) += highmem.o
diff --git a/arch/microblaze/mm/highmem.c b/arch/microblaze/mm/highmem.c
new file mode 100644
index 00000000000..7d78838e8bf
--- /dev/null
+++ b/arch/microblaze/mm/highmem.c
@@ -0,0 +1,88 @@
+/*
+ * highmem.c: virtual kernel memory mappings for high memory
+ *
+ * PowerPC version, stolen from the i386 version.
+ *
+ * Used in CONFIG_HIGHMEM systems for memory pages which
+ * are not addressable by direct kernel virtual addresses.
+ *
+ * Copyright (C) 1999 Gerhard Wichert, Siemens AG
+ *                    Gerhard.Wichert@pdb.siemens.de
+ *
+ *
+ * Redesigned the x86 32-bit VM architecture to deal with
+ * up to 16 Terrabyte physical memory. With current x86 CPUs
+ * we now support up to 64 Gigabytes physical RAM.
+ *
+ * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
+ *
+ * Reworked for PowerPC by various contributors. Moved from
+ * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
+ */
+
+#include <linux/highmem.h>
+#include <linux/module.h>
+
+/*
+ * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
+ * gives a more generic (and caching) interface. But kmap_atomic can
+ * be used in IRQ contexts, so in some (very limited) cases we need
+ * it.
+ */
+#include <asm/tlbflush.h>
+
+void *kmap_atomic_prot(struct page *page, pgprot_t prot)
+{
+
+        unsigned long vaddr;
+        int idx, type;
+
+        /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+        pagefault_disable();
+        if (!PageHighMem(page))
+                return page_address(page);
+
+
+        type = kmap_atomic_idx_push();
+        idx = type + KM_TYPE_NR*smp_processor_id();
+        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+#ifdef CONFIG_DEBUG_HIGHMEM
+        BUG_ON(!pte_none(*(kmap_pte-idx)));
+#endif
+        set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
+        local_flush_tlb_page(NULL, vaddr);
+
+        return (void *) vaddr;
+}
+EXPORT_SYMBOL(kmap_atomic_prot);
+
+void __kunmap_atomic(void *kvaddr)
+{
+        unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
+        int type;
+
+        if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
+                pagefault_enable();
+                return;
+        }
+
+        type = kmap_atomic_idx();
+#ifdef CONFIG_DEBUG_HIGHMEM
+        {
+                unsigned int idx;
+
+                idx = type + KM_TYPE_NR * smp_processor_id();
+                BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
+
+                /*
+                 * force other mappings to Oops if they'll try to access
+                 * this pte without first remap it
+                 */
+                pte_clear(&init_mm, vaddr, kmap_pte-idx);
+                local_flush_tlb_page(NULL, vaddr);
+        }
+#endif
+        kmap_atomic_idx_pop();
+        pagefault_enable();
+}
+EXPORT_SYMBOL(__kunmap_atomic);
diff --git a/arch/microblaze/mm/init.c b/arch/microblaze/mm/init.c
index 43b3f604baf..95297b13dd9 100644
--- a/arch/microblaze/mm/init.c
+++ b/arch/microblaze/mm/init.c
@@ -49,6 +49,53 @@ unsigned long memory_size;
 EXPORT_SYMBOL(memory_size);
 unsigned long lowmem_size;
 
+#ifdef CONFIG_HIGHMEM
+pte_t *kmap_pte;
+EXPORT_SYMBOL(kmap_pte);
+pgprot_t kmap_prot;
+EXPORT_SYMBOL(kmap_prot);
+
+static inline pte_t *virt_to_kpte(unsigned long vaddr)
+{
+        return pte_offset_kernel(pmd_offset(pgd_offset_k(vaddr),
+                        vaddr), vaddr);
+}
+
+static void __init highmem_init(void)
+{
+        pr_debug("%x\n", (u32)PKMAP_BASE);
+        map_page(PKMAP_BASE, 0, 0);     /* XXX gross */
+        pkmap_page_table = virt_to_kpte(PKMAP_BASE);
+
+        kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));
+        kmap_prot = PAGE_KERNEL;
+}
+
+static unsigned long highmem_setup(void)
+{
+        unsigned long pfn;
+        unsigned long reservedpages = 0;
+
+        for (pfn = max_low_pfn; pfn < max_pfn; ++pfn) {
+                struct page *page = pfn_to_page(pfn);
+
+                /* FIXME not sure about */
+                if (memblock_is_reserved(pfn << PAGE_SHIFT))
+                        continue;
+                ClearPageReserved(page);
+                init_page_count(page);
+                __free_page(page);
+                totalhigh_pages++;
+                reservedpages++;
+        }
+        totalram_pages += totalhigh_pages;
+        printk(KERN_INFO "High memory: %luk\n",
+                                        totalhigh_pages << (PAGE_SHIFT-10));
+
+        return reservedpages;
+}
+#endif /* CONFIG_HIGHMEM */
+
 /*
  * paging_init() sets up the page tables - in fact we've already done this.
  */
@@ -66,7 +113,14 @@ static void __init paging_init(void)
         /* Clean every zones */
         memset(zones_size, 0, sizeof(zones_size));
 
+#ifdef CONFIG_HIGHMEM
+        highmem_init();
+
+        zones_size[ZONE_DMA] = max_low_pfn;
+        zones_size[ZONE_HIGHMEM] = max_pfn;
+#else
         zones_size[ZONE_DMA] = max_pfn;
+#endif
 
         /* We don't have holes in memory map */
         free_area_init_nodes(zones_size);
@@ -241,6 +295,10 @@ void __init mem_init(void)
                 }
         }
 
+#ifdef CONFIG_HIGHMEM
+        reservedpages -= highmem_setup();
+#endif
+
         codesize = (unsigned long)&_sdata - (unsigned long)&_stext;
         datasize = (unsigned long)&_edata - (unsigned long)&_sdata;
         initsize = (unsigned long)&__init_end - (unsigned long)&__init_begin;
@@ -259,6 +317,10 @@ void __init mem_init(void)
 #ifdef CONFIG_MMU
         pr_info("Kernel virtual memory layout:\n");
         pr_info("  * 0x%08lx..0x%08lx  : fixmap\n", FIXADDR_START, FIXADDR_TOP);
+#ifdef CONFIG_HIGHMEM
+        pr_info("  * 0x%08lx..0x%08lx  : highmem PTEs\n",
+                PKMAP_BASE, PKMAP_ADDR(LAST_PKMAP));
+#endif /* CONFIG_HIGHMEM */
         pr_info("  * 0x%08lx..0x%08lx  : early ioremap\n",
                 ioremap_bot, ioremap_base);
         pr_info("  * 0x%08lx..0x%08lx  : vmalloc & ioremap\n",
@@ -346,7 +408,9 @@ asmlinkage void __init mmu_init(void)
 
         if (lowmem_size > CONFIG_LOWMEM_SIZE) {
                 lowmem_size = CONFIG_LOWMEM_SIZE;
+#ifndef CONFIG_HIGHMEM
                 memory_size = lowmem_size;
+#endif
         }
 
         mm_cmdline_setup(); /* FIXME parse args from command line - not used */
@@ -375,7 +439,11 @@ asmlinkage void __init mmu_init(void)
         mapin_ram();
 
         /* Extend vmalloc and ioremap area as big as possible */
+#ifdef CONFIG_HIGHMEM
+        ioremap_base = ioremap_bot = PKMAP_BASE;
+#else
         ioremap_base = ioremap_bot = FIXADDR_START;
+#endif
 
         /* Initialize the context management stuff */
         mmu_context_init();