The first highmem implementation.
Signed-off-by: Michal Simek <monstr@monstr.eu>
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"
#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))
*/
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
};
--- /dev/null
+/*
+ * 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 */
obj-y := consistent.o init.o
obj-$(CONFIG_MMU) += pgtable.o mmu_context.o fault.o
+obj-$(CONFIG_HIGHMEM) += highmem.o
--- /dev/null
+/*
+ * 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);
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.
*/
/* 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);
}
}
+#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;
#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",
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 */
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();
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