6 files changed, 453 insertions, 204 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index a08e9100e7e4..f12ca8fba71b 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -235,6 +235,9 @@ config WARN_STACK_SIZE
 
 source "mm/Kconfig"
 
+config HOLES_IN_ZONE
+        def_bool y
+
 comment "I/O subsystem configuration"
 
 config MACHCHK_WARNING
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index b928fecdc743..b8a1ce215142 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -64,7 +64,7 @@ unsigned int console_devno = -1;
 unsigned int console_irq = -1;
 unsigned long machine_flags = 0;
 
-struct mem_chunk memory_chunk[MEMORY_CHUNKS];
+struct mem_chunk __initdata memory_chunk[MEMORY_CHUNKS];
 volatile int __cpu_logical_map[NR_CPUS]; /* logical cpu to cpu address */
 unsigned long __initdata zholes_size[MAX_NR_ZONES];
 static unsigned long __initdata memory_end;
diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile
index aa9a42b6e62d..8e09db1edbb9 100644
--- a/arch/s390/mm/Makefile
+++ b/arch/s390/mm/Makefile
@@ -2,6 +2,6 @@
 # Makefile for the linux s390-specific parts of the memory manager.
 #
 
-obj-y    := init.o fault.o ioremap.o extmem.o mmap.o
+obj-y    := init.o fault.o ioremap.o extmem.o mmap.o vmem.o
 obj-$(CONFIG_CMM) += cmm.o
 
diff --git a/arch/s390/mm/extmem.c b/arch/s390/mm/extmem.c
index 9e9bc48463a5..775bf19e742b 100644
--- a/arch/s390/mm/extmem.c
+++ b/arch/s390/mm/extmem.c
@@ -16,6 +16,7 @@
 #include <linux/bootmem.h>
 #include <linux/ctype.h>
 #include <asm/page.h>
+#include <asm/pgtable.h>
 #include <asm/ebcdic.h>
 #include <asm/errno.h>
 #include <asm/extmem.h>
@@ -238,65 +239,6 @@ query_segment_type (struct dcss_segment *seg)
 }
 
 /*
- * check if the given segment collides with guest storage.
- * returns 1 if this is the case, 0 if no collision was found
- */
-static int
-segment_overlaps_storage(struct dcss_segment *seg)
-{
-        int i;
-
-        for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++) {
-                if (memory_chunk[i].type != CHUNK_READ_WRITE)
-                        continue;
-                if ((memory_chunk[i].addr >> 20) > (seg->end >> 20))
-                        continue;
-                if (((memory_chunk[i].addr + memory_chunk[i].size - 1) >> 20)
-                                < (seg->start_addr >> 20))
-                        continue;
-                return 1;
-        }
-        return 0;
-}
-
-/*
- * check if segment collides with other segments that are currently loaded
- * returns 1 if this is the case, 0 if no collision was found
- */
-static int
-segment_overlaps_others (struct dcss_segment *seg)
-{
-        struct list_head *l;
-        struct dcss_segment *tmp;
-
-        BUG_ON(!mutex_is_locked(&dcss_lock));
-        list_for_each(l, &dcss_list) {
-                tmp = list_entry(l, struct dcss_segment, list);
-                if ((tmp->start_addr >> 20) > (seg->end >> 20))
-                        continue;
-                if ((tmp->end >> 20) < (seg->start_addr >> 20))
-                        continue;
-                if (seg == tmp)
-                        continue;
-                return 1;
-        }
-        return 0;
-}
-
-/*
- * check if segment exceeds the kernel mapping range (detected or set via mem=)
- * returns 1 if this is the case, 0 if segment fits into the range
- */
-static inline int
-segment_exceeds_range (struct dcss_segment *seg)
-{
-        int seg_last_pfn = (seg->end) >> PAGE_SHIFT;
-        if (seg_last_pfn > max_pfn)
-                return 1;
-        return 0;
-}
-
-/*
  * get info about a segment
  * possible return values:
  * -ENOSYS  : we are not running on VM
@@ -341,24 +283,26 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long
         rc = query_segment_type (seg);
         if (rc < 0)
                 goto out_free;
-        if (segment_exceeds_range(seg)) {
-                PRINT_WARN ("segment_load: not loading segment %s - exceeds"
-                                " kernel mapping range\n",name);
-                rc = -ERANGE;
+
+        rc = add_shared_memory(seg->start_addr, seg->end - seg->start_addr + 1);
+
+        switch (rc) {
+        case 0:
+                break;
+        case -ENOSPC:
+                PRINT_WARN("segment_load: not loading segment %s - overlaps "
+                           "storage/segment\n", name);
                 goto out_free;
-        }
-        if (segment_overlaps_storage(seg)) {
-                PRINT_WARN ("segment_load: not loading segment %s - overlaps"
-                                " storage\n",name);
-                rc = -ENOSPC;
+        case -ERANGE:
+                PRINT_WARN("segment_load: not loading segment %s - exceeds "
+                           "kernel mapping range\n", name);
                 goto out_free;
-        }
-        if (segment_overlaps_others(seg)) {
-                PRINT_WARN ("segment_load: not loading segment %s - overlaps"
-                                " other segments\n",name);
-                rc = -EBUSY;
+        default:
+                PRINT_WARN("segment_load: not loading segment %s (rc: %d)\n",
+                           name, rc);
                 goto out_free;
         }
+
         if (do_nonshared)
                 dcss_command = DCSS_LOADNSR;
         else
@@ -372,7 +316,7 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long
                 rc = dcss_diag_translate_rc (seg->end);
                 dcss_diag(DCSS_PURGESEG, seg->dcss_name,
                                 &seg->start_addr, &seg->end);
-                goto out_free;
+                goto out_shared;
         }
         seg->do_nonshared = do_nonshared;
         atomic_set(&seg->ref_count, 1);
@@ -391,6 +335,8 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long
                                 (void*)seg->start_addr, (void*)seg->end,
                                 segtype_string[seg->vm_segtype]);
         goto out;
+ out_shared:
+        remove_shared_memory(seg->start_addr, seg->end - seg->start_addr + 1);
  out_free:
         kfree(seg);
  out:
@@ -530,12 +476,12 @@ segment_unload(char *name)
                                 "please report to linux390@de.ibm.com\n",name);
                 goto out_unlock;
         }
-        if (atomic_dec_return(&seg->ref_count) == 0) {
-                list_del(&seg->list);
-                dcss_diag(DCSS_PURGESEG, seg->dcss_name,
-                          &dummy, &dummy);
-                kfree(seg);
-        }
+        if (atomic_dec_return(&seg->ref_count) != 0)
+                goto out_unlock;
+        remove_shared_memory(seg->start_addr, seg->end - seg->start_addr + 1);
+        list_del(&seg->list);
+        dcss_diag(DCSS_PURGESEG, seg->dcss_name, &dummy, &dummy);
+        kfree(seg);
 out_unlock:
         mutex_unlock(&dcss_lock);
 }
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index e1881c31b1cb..5ea12a573cad 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -69,6 +69,8 @@ void show_mem(void)
         printk("Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
         i = max_mapnr;
         while (i-- > 0) {
+                if (!pfn_valid(i))
+                        continue;
                 page = pfn_to_page(i);
                 total++;
                 if (PageReserved(page))
@@ -84,67 +86,53 @@ void show_mem(void)
         printk("%d pages swap cached\n",cached);
 }
 
+static void __init setup_ro_region(void)
+{
+        pgd_t *pgd;
+        pmd_t *pmd;
+        pte_t *pte;
+        pte_t new_pte;
+        unsigned long address, end;
+
+        address = ((unsigned long)&__start_rodata) & PAGE_MASK;
+        end = PFN_ALIGN((unsigned long)&__end_rodata);
+
+        for (; address < end; address += PAGE_SIZE) {
+                pgd = pgd_offset_k(address);
+                pmd = pmd_offset(pgd, address);
+                pte = pte_offset_kernel(pmd, address);
+                new_pte = mk_pte_phys(address, __pgprot(_PAGE_RO));
+                set_pte(pte, new_pte);
+        }
+}
+
 extern unsigned long __initdata zholes_size[];
+extern void vmem_map_init(void);
 /*
  * paging_init() sets up the page tables
  */
-
-#ifndef CONFIG_64BIT
 void __init paging_init(void)
 {
-        pgd_t * pg_dir;
-        pte_t * pg_table;
-        pte_t   pte;
-        int     i;
-        unsigned long tmp;
-        unsigned long pfn = 0;
-        unsigned long pgdir_k = (__pa(swapper_pg_dir) & PAGE_MASK) | _KERNSEG_TABLE;
-        static const int ssm_mask = 0x04000000L;
-        unsigned long ro_start_pfn, ro_end_pfn;
+        pgd_t *pg_dir;
+        int i;
+        unsigned long pgdir_k;
+        static const int ssm_mask = 0x04000000L;
         unsigned long zones_size[MAX_NR_ZONES];
+        unsigned long dma_pfn, high_pfn;
 
-        ro_start_pfn = PFN_DOWN((unsigned long)&__start_rodata);
-        ro_end_pfn = PFN_UP((unsigned long)&__end_rodata);
-
-        memset(zones_size, 0, sizeof(zones_size));
-        zones_size[ZONE_DMA] = max_low_pfn;
-        free_area_init_node(0, &contig_page_data, zones_size,
-                            __pa(PAGE_OFFSET) >> PAGE_SHIFT,
-                            zholes_size);
-
-        /* unmap whole virtual address space */
+        pg_dir = swapper_pg_dir;
         
-        pg_dir = swapper_pg_dir;
-
+#ifdef CONFIG_64BIT
+        pgdir_k = (__pa(swapper_pg_dir) & PAGE_MASK) | _KERN_REGION_TABLE;
         for (i = 0; i < PTRS_PER_PGD; i++)
-                pmd_clear((pmd_t *) pg_dir++);
-                
-        /*
-         * map whole physical memory to virtual memory (identity mapping) 
-         */
-
-        pg_dir = swapper_pg_dir;
-
-        while (pfn < max_low_pfn) {
-                /*
-                 * pg_table is physical at this point
-                 */
-                pg_table = (pte_t *) alloc_bootmem_pages(PAGE_SIZE);
-
-                pmd_populate_kernel(&init_mm, (pmd_t *) pg_dir, pg_table);
-                pg_dir++;
-
-                for (tmp = 0 ; tmp < PTRS_PER_PTE ; tmp++,pg_table++) {
-                        if (pfn >= ro_start_pfn && pfn < ro_end_pfn)
-                                pte = pfn_pte(pfn, __pgprot(_PAGE_RO));
-                        else
-                                pte = pfn_pte(pfn, PAGE_KERNEL);
-                        if (pfn >= max_low_pfn)
-                                pte_val(pte) = _PAGE_TYPE_EMPTY;
-                        set_pte(pg_table, pte);
-                        pfn++;
-                }
-        }
+                pgd_clear(pg_dir + i);
+#else
+        pgdir_k = (__pa(swapper_pg_dir) & PAGE_MASK) | _KERNSEG_TABLE;
+        for (i = 0; i < PTRS_PER_PGD; i++)
+                pmd_clear((pmd_t *)(pg_dir + i));
+#endif
+        vmem_map_init();
+        setup_ro_region();
 
         S390_lowcore.kernel_asce = pgdir_k;
 
@@ -154,31 +142,9 @@ void __init paging_init(void)
         __ctl_load(pgdir_k, 13, 13);
         __raw_local_irq_ssm(ssm_mask);
 
-        local_flush_tlb();
-}
-
-#else /* CONFIG_64BIT */
-
-void __init paging_init(void)
-{
-        pgd_t * pg_dir;
-        pmd_t * pm_dir;
-        pte_t * pt_dir;
-        pte_t   pte;
-        int     i,j,k;
-        unsigned long pfn = 0;
-        unsigned long pgdir_k = (__pa(swapper_pg_dir) & PAGE_MASK) |
-          _KERN_REGION_TABLE;
-        static const int ssm_mask = 0x04000000L;
-        unsigned long zones_size[MAX_NR_ZONES];
-        unsigned long dma_pfn, high_pfn;
-        unsigned long ro_start_pfn, ro_end_pfn;
-
         memset(zones_size, 0, sizeof(zones_size));
         dma_pfn = MAX_DMA_ADDRESS >> PAGE_SHIFT;
         high_pfn = max_low_pfn;
-        ro_start_pfn = PFN_DOWN((unsigned long)&__start_rodata);
-        ro_end_pfn = PFN_UP((unsigned long)&__end_rodata);
 
         if (dma_pfn > high_pfn)
                 zones_size[ZONE_DMA] = high_pfn;
@@ -190,56 +156,7 @@ void __init paging_init(void)
         /* Initialize mem_map[].  */
         free_area_init_node(0, &contig_page_data, zones_size,
                             __pa(PAGE_OFFSET) >> PAGE_SHIFT, zholes_size);
-
-        /*
-         * map whole physical memory to virtual memory (identity mapping) 
-         */
-
-        pg_dir = swapper_pg_dir;
-        
-        for (i = 0 ; i < PTRS_PER_PGD ; i++,pg_dir++) {
-        
-                if (pfn >= max_low_pfn) {
-                        pgd_clear(pg_dir);
-                        continue;
-                }          
-        
-                pm_dir = (pmd_t *) alloc_bootmem_pages(PAGE_SIZE * 4);
-                pgd_populate(&init_mm, pg_dir, pm_dir);
-
-                for (j = 0 ; j < PTRS_PER_PMD ; j++,pm_dir++) {
-                        if (pfn >= max_low_pfn) {
-                                pmd_clear(pm_dir);
-                                continue; 
-                        }          
-                        
-                        pt_dir = (pte_t *) alloc_bootmem_pages(PAGE_SIZE);
-                        pmd_populate_kernel(&init_mm, pm_dir, pt_dir);
-        
-                        for (k = 0 ; k < PTRS_PER_PTE ; k++,pt_dir++) {
-                                if (pfn >= ro_start_pfn && pfn < ro_end_pfn)
-                                        pte = pfn_pte(pfn, __pgprot(_PAGE_RO));
-                                else
-                                        pte = pfn_pte(pfn, PAGE_KERNEL);
-                                if (pfn >= max_low_pfn)
-                                        pte_val(pte) = _PAGE_TYPE_EMPTY;
-                                set_pte(pt_dir, pte);
-                                pfn++;
-                        }
-                }
-        }
-
-        S390_lowcore.kernel_asce = pgdir_k;
-
-        /* enable virtual mapping in kernel mode */
-        __ctl_load(pgdir_k, 1, 1);
-        __ctl_load(pgdir_k, 7, 7);
-        __ctl_load(pgdir_k, 13, 13);
-        __raw_local_irq_ssm(ssm_mask);
-
-        local_flush_tlb();
 }
-#endif /* CONFIG_64BIT */
 
 void __init mem_init(void)
 {
@@ -269,6 +186,8 @@ void __init mem_init(void)
         printk("Write protected kernel read-only data: %#lx - %#lx\n",
                (unsigned long)&__start_rodata,
                PFN_ALIGN((unsigned long)&__end_rodata) - 1);
+        printk("Virtual memmap size: %ldk\n",
+               (max_pfn * sizeof(struct page)) >> 10);
 }
 
 void free_initmem(void)
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
new file mode 100644
index 000000000000..7f2944d3ec2a
--- /dev/null
+++ b/arch/s390/mm/vmem.c
@@ -0,0 +1,381 @@
+/*
+ *  arch/s390/mm/vmem.c
+ *
+ *    Copyright IBM Corp. 2006
+ *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
+ */
+
+#include <linux/bootmem.h>
+#include <linux/pfn.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/setup.h>
+#include <asm/tlbflush.h>
+
+unsigned long vmalloc_end;
+EXPORT_SYMBOL(vmalloc_end);
+
+static struct page *vmem_map;
+static DEFINE_MUTEX(vmem_mutex);
+
+struct memory_segment {
+        struct list_head list;
+        unsigned long start;
+        unsigned long size;
+};
+
+static LIST_HEAD(mem_segs);
+
+void memmap_init(unsigned long size, int nid, unsigned long zone,
+                 unsigned long start_pfn)
+{
+        struct page *start, *end;
+        struct page *map_start, *map_end;
+        int i;
+
+        start = pfn_to_page(start_pfn);
+        end = start + size;
+
+        for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++) {
+                unsigned long cstart, cend;
+
+                cstart = PFN_DOWN(memory_chunk[i].addr);
+                cend = cstart + PFN_DOWN(memory_chunk[i].size);
+
+                map_start = mem_map + cstart;
+                map_end = mem_map + cend;
+
+                if (map_start < start)
+                        map_start = start;
+                if (map_end > end)
+                        map_end = end;
+
+                map_start -= ((unsigned long) map_start & (PAGE_SIZE - 1))
+                        / sizeof(struct page);
+                map_end += ((PFN_ALIGN((unsigned long) map_end)
+                             - (unsigned long) map_end)
+                            / sizeof(struct page));
+
+                if (map_start < map_end)
+                        memmap_init_zone((unsigned long)(map_end - map_start),
+                                         nid, zone, page_to_pfn(map_start));
+        }
+}
+
+static inline void *vmem_alloc_pages(unsigned int order)
+{
+        if (slab_is_available())
+                return (void *)__get_free_pages(GFP_KERNEL, order);
+        return alloc_bootmem_pages((1 << order) * PAGE_SIZE);
+}
+
+static inline pmd_t *vmem_pmd_alloc(void)
+{
+        pmd_t *pmd;
+        int i;
+
+        pmd = vmem_alloc_pages(PMD_ALLOC_ORDER);
+        if (!pmd)
+                return NULL;
+        for (i = 0; i < PTRS_PER_PMD; i++)
+                pmd_clear(pmd + i);
+        return pmd;
+}
+
+static inline pte_t *vmem_pte_alloc(void)
+{
+        pte_t *pte;
+        pte_t empty_pte;
+        int i;
+
+        pte = vmem_alloc_pages(PTE_ALLOC_ORDER);
+        if (!pte)
+                return NULL;
+        pte_val(empty_pte) = _PAGE_TYPE_EMPTY;
+        for (i = 0; i < PTRS_PER_PTE; i++)
+                set_pte(pte + i, empty_pte);
+        return pte;
+}
+
+/*
+ * Add a physical memory range to the 1:1 mapping.
+ */
+static int vmem_add_range(unsigned long start, unsigned long size)
+{
+        unsigned long address;
+        pgd_t *pg_dir;
+        pmd_t *pm_dir;
+        pte_t *pt_dir;
+        pte_t  pte;
+        int ret = -ENOMEM;
+
+        for (address = start; address < start + size; address += PAGE_SIZE) {
+                pg_dir = pgd_offset_k(address);
+                if (pgd_none(*pg_dir)) {
+                        pm_dir = vmem_pmd_alloc();
+                        if (!pm_dir)
+                                goto out;
+                        pgd_populate(&init_mm, pg_dir, pm_dir);
+                }
+
+                pm_dir = pmd_offset(pg_dir, address);
+                if (pmd_none(*pm_dir)) {
+                        pt_dir = vmem_pte_alloc();
+                        if (!pt_dir)
+                                goto out;
+                        pmd_populate_kernel(&init_mm, pm_dir, pt_dir);
+                }
+
+                pt_dir = pte_offset_kernel(pm_dir, address);
+                pte = pfn_pte(address >> PAGE_SHIFT, PAGE_KERNEL);
+                set_pte(pt_dir, pte);
+        }
+        ret = 0;
+out:
+        flush_tlb_kernel_range(start, start + size);
+        return ret;
+}
+
+/*
+ * Remove a physical memory range from the 1:1 mapping.
+ * Currently only invalidates page table entries.
+ */
+static void vmem_remove_range(unsigned long start, unsigned long size)
+{
+        unsigned long address;
+        pgd_t *pg_dir;
+        pmd_t *pm_dir;
+        pte_t *pt_dir;
+        pte_t  pte;
+
+        pte_val(pte) = _PAGE_TYPE_EMPTY;
+        for (address = start; address < start + size; address += PAGE_SIZE) {
+                pg_dir = pgd_offset_k(address);
+                if (pgd_none(*pg_dir))
+                        continue;
+                pm_dir = pmd_offset(pg_dir, address);
+                if (pmd_none(*pm_dir))
+                        continue;
+                pt_dir = pte_offset_kernel(pm_dir, address);
+                set_pte(pt_dir, pte);
+        }
+        flush_tlb_kernel_range(start, start + size);
+}
+
+/*
+ * Add a backed mem_map array to the virtual mem_map array.
+ */
+static int vmem_add_mem_map(unsigned long start, unsigned long size)
+{
+        unsigned long address, start_addr, end_addr;
+        struct page *map_start, *map_end;
+        pgd_t *pg_dir;
+        pmd_t *pm_dir;
+        pte_t *pt_dir;
+        pte_t  pte;
+        int ret = -ENOMEM;
+
+        map_start = vmem_map + PFN_DOWN(start);
+        map_end = vmem_map + PFN_DOWN(start + size);
+
+        start_addr = (unsigned long) map_start & PAGE_MASK;
+        end_addr = PFN_ALIGN((unsigned long) map_end);
+
+        for (address = start_addr; address < end_addr; address += PAGE_SIZE) {
+                pg_dir = pgd_offset_k(address);
+                if (pgd_none(*pg_dir)) {
+                        pm_dir = vmem_pmd_alloc();
+                        if (!pm_dir)
+                                goto out;
+                        pgd_populate(&init_mm, pg_dir, pm_dir);
+                }
+
+                pm_dir = pmd_offset(pg_dir, address);
+                if (pmd_none(*pm_dir)) {
+                        pt_dir = vmem_pte_alloc();
+                        if (!pt_dir)
+                                goto out;
+                        pmd_populate_kernel(&init_mm, pm_dir, pt_dir);
+                }
+
+                pt_dir = pte_offset_kernel(pm_dir, address);
+                if (pte_none(*pt_dir)) {
+                        unsigned long new_page;
+
+                        new_page =__pa(vmem_alloc_pages(0));
+                        if (!new_page)
+                                goto out;
+                        pte = pfn_pte(new_page >> PAGE_SHIFT, PAGE_KERNEL);
+                        set_pte(pt_dir, pte);
+                }
+        }
+        ret = 0;
+out:
+        flush_tlb_kernel_range(start_addr, end_addr);
+        return ret;
+}
+
+static int vmem_add_mem(unsigned long start, unsigned long size)
+{
+        int ret;
+
+        ret = vmem_add_range(start, size);
+        if (ret)
+                return ret;
+        return vmem_add_mem_map(start, size);
+}
+
+/*
+ * Add memory segment to the segment list if it doesn't overlap with
+ * an already present segment.
+ */
+static int insert_memory_segment(struct memory_segment *seg)
+{
+        struct memory_segment *tmp;
+
+        if (PFN_DOWN(seg->start + seg->size) > max_pfn ||
+            seg->start + seg->size < seg->start)
+                return -ERANGE;
+
+        list_for_each_entry(tmp, &mem_segs, list) {
+                if (seg->start >= tmp->start + tmp->size)
+                        continue;
+                if (seg->start + seg->size <= tmp->start)
+                        continue;
+                return -ENOSPC;
+        }
+        list_add(&seg->list, &mem_segs);
+        return 0;
+}
+
+/*
+ * Remove memory segment from the segment list.
+ */
+static void remove_memory_segment(struct memory_segment *seg)
+{
+        list_del(&seg->list);
+}
+
+static void __remove_shared_memory(struct memory_segment *seg)
+{
+        remove_memory_segment(seg);
+        vmem_remove_range(seg->start, seg->size);
+}
+
+int remove_shared_memory(unsigned long start, unsigned long size)
+{
+        struct memory_segment *seg;
+        int ret;
+
+        mutex_lock(&vmem_mutex);
+
+        ret = -ENOENT;
+        list_for_each_entry(seg, &mem_segs, list) {
+                if (seg->start == start && seg->size == size)
+                        break;
+        }
+
+        if (seg->start != start || seg->size != size)
+                goto out;
+
+        ret = 0;
+        __remove_shared_memory(seg);
+        kfree(seg);
+out:
+        mutex_unlock(&vmem_mutex);
+        return ret;
+}
+
+int add_shared_memory(unsigned long start, unsigned long size)
+{
+        struct memory_segment *seg;
+        struct page *page;
+        unsigned long pfn, num_pfn, end_pfn;
+        int ret;
+
+        mutex_lock(&vmem_mutex);
+        ret = -ENOMEM;
+        seg = kzalloc(sizeof(*seg), GFP_KERNEL);
+        if (!seg)
+                goto out;
+        seg->start = start;
+        seg->size = size;
+
+        ret = insert_memory_segment(seg);
+        if (ret)
+                goto out_free;
+
+        ret = vmem_add_mem(start, size);
+        if (ret)
+                goto out_remove;
+
+        pfn = PFN_DOWN(start);
+        num_pfn = PFN_DOWN(size);
+        end_pfn = pfn + num_pfn;
+
+        page = pfn_to_page(pfn);
+        memset(page, 0, num_pfn * sizeof(struct page));
+
+        for (; pfn < end_pfn; pfn++) {
+                page = pfn_to_page(pfn);
+                init_page_count(page);
+                reset_page_mapcount(page);
+                SetPageReserved(page);
+                INIT_LIST_HEAD(&page->lru);
+        }
+        goto out;
+
+out_remove:
+        __remove_shared_memory(seg);
+out_free:
+        kfree(seg);
+out:
+        mutex_unlock(&vmem_mutex);
+        return ret;
+}
+
+/*
+ * map whole physical memory to virtual memory (identity mapping)
+ */
+void __init vmem_map_init(void)
+{
+        unsigned long map_size;
+        int i;
+
+        map_size = ALIGN(max_low_pfn, MAX_ORDER_NR_PAGES) * sizeof(struct page);
+        vmalloc_end = PFN_ALIGN(VMALLOC_END_INIT) - PFN_ALIGN(map_size);
+        vmem_map = (struct page *) vmalloc_end;
+        NODE_DATA(0)->node_mem_map = vmem_map;
+
+        for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++)
+                vmem_add_mem(memory_chunk[i].addr, memory_chunk[i].size);
+}
+
+/*
+ * Convert memory chunk array to a memory segment list so there is a single
+ * list that contains both r/w memory and shared memory segments.
+ */
+static int __init vmem_convert_memory_chunk(void)
+{
+        struct memory_segment *seg;
+        int i;
+
+        mutex_lock(&vmem_mutex);
+        for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++) {
+                if (!memory_chunk[i].size)
+                        continue;
+                seg = kzalloc(sizeof(*seg), GFP_KERNEL);
+                if (!seg)
+                        panic("Out of memory...\n");
+                seg->start = memory_chunk[i].addr;
+                seg->size = memory_chunk[i].size;
+                insert_memory_segment(seg);
+        }
+        mutex_unlock(&vmem_mutex);
+        return 0;
+}
+
+core_initcall(vmem_convert_memory_chunk);