[kernel][vm] first stab at a virtual memory manager

Add kernel/vm code to handle memory management in large page-aligned
regions of virtual space. This is composed via a pmm (physical
memory manager) and vmm (virtual memory manager) and the architecturally
specific code to manage the mmu.

Add ARMv7 paging code.

kernel/vm/vm.c

@@ -0,0 +1,162 @@
+/*
+ * Copyright (c) 2014 Travis Geiselbrecht
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include <kernel/vm.h>
+#include "vm_priv.h"
+
+#include <trace.h>
+#include <err.h>
+#include <string.h>
+#include <lk/init.h>
+#include <lib/console.h>
+#include <arch/mmu.h>
+
+#define LOCAL_TRACE 1
+
+extern int _start;
+extern int _end;
+
+/* mark the physical pages backing a range of virtual as in use.
+ * allocate the physical pages and throw them away */
+static void mark_pages_in_use(vaddr_t va, size_t len)
+{
+    LTRACEF("va 0x%lx, len 0x%zx\n", va, len);
+    for (size_t offset = 0; offset < len; offset += PAGE_SIZE) {
+        uint flags;
+        paddr_t pa;
+
+        status_t err = arch_mmu_query(va + offset, &pa, &flags);
+        if (err >= 0) {
+            //LTRACEF("va 0x%x, pa 0x%x, flags 0x%x, err %d\n", va + offset, pa, flags, err);
+
+            /* alloate the range, throw the results away */
+            struct list_node list;
+            pmm_alloc_range(pa, 1, &list);
+        }
+    }
+}
+
+static void vm_init_preheap(uint level)
+{
+    LTRACE_ENTRY;
+
+    /* mark all of the kernel pages in use */
+    LTRACEF("marking all kernel pages as used\n");
+    mark_pages_in_use((vaddr_t)&_start, ((uintptr_t)&_end - (uintptr_t)&_start));
+
+    /* mark the physical pages used by the boot time allocator */
+    if (boot_alloc_end != boot_alloc_start) {
+        LTRACEF("marking boot alloc used from 0x%lx to 0x%lx\n", boot_alloc_start, boot_alloc_end);
+
+        // XXX handle last partial page?
+        mark_pages_in_use(boot_alloc_start, boot_alloc_end - boot_alloc_start);
+    }
+}
+
+static void vm_init_postheap(uint level)
+{
+    LTRACE_ENTRY;
+
+    vmm_init();
+
+    /* create vmm regions to cover what is already there from the initial mapping table */
+    struct mmu_initial_mapping *map = mmu_initial_mappings;
+    while (map->size > 0) {
+        if (!(map->flags & MMU_INITIAL_MAPPING_TEMPORARY)) {
+            vmm_reserve_space(vmm_get_kernel_aspace(), map->name, map->size, map->virt);
+        }
+
+        map++;
+    }
+}
+
+void *paddr_to_kvaddr(paddr_t pa)
+{
+    /* slow path to do reverse lookup */
+    struct mmu_initial_mapping *map = mmu_initial_mappings;
+    while (map->size > 0) {
+        if (!(map->flags & MMU_INITIAL_MAPPING_TEMPORARY) &&
+            pa >= map->phys &&
+            pa <= map->phys + map->size) {
+            return (void *)(map->virt + (pa - map->phys));
+        }
+        map++;
+    }
+    return NULL;
+}
+
+static int cmd_vm(int argc, const cmd_args *argv)
+{
+    if (argc < 2) {
+notenoughargs:
+        printf("not enough arguments\n");
+usage:
+        printf("usage:\n");
+        printf("%s phys2virt <address>\n", argv[0].str);
+        printf("%s virt2phys <address>\n", argv[0].str);
+        printf("%s map <phys> <virt> <count> <flags>\n", argv[0].str);
+        printf("%s unmap <virt> <count>\n", argv[0].str);
+        return ERR_GENERIC;
+    }
+
+    if (!strcmp(argv[1].str, "phys2virt")) {
+        if (argc < 3) goto notenoughargs;
+
+        void *ptr = paddr_to_kvaddr(argv[2].u);
+        printf("paddr_to_kvaddr returns %p\n", ptr);
+    } else if (!strcmp(argv[1].str, "virt2phys")) {
+        if (argc < 3) goto notenoughargs;
+
+        paddr_t pa;
+        uint flags;
+        status_t err = arch_mmu_query(argv[2].u, &pa, &flags);
+        printf("arch_mmu_query returns %d\n", err);
+        if (err >= 0) {
+            printf("\tpa 0x%lx, flags 0x%x\n", pa, flags);
+        }
+    } else if (!strcmp(argv[1].str, "map")) {
+        if (argc < 6) goto notenoughargs;
+
+        int err = arch_mmu_map(argv[3].u, argv[2].u, argv[4].u, argv[5].u);
+        printf("arch_mmu_map returns %d\n", err);
+    } else if (!strcmp(argv[1].str, "unmap")) {
+        if (argc < 4) goto notenoughargs;
+
+        int err = arch_mmu_unmap(argv[2].u, argv[3].u);
+        printf("arch_mmu_unmap returns %d\n", err);
+    } else {
+        printf("unknown command\n");
+        goto usage;
+    }
+
+    return NO_ERROR;
+}
+
+STATIC_COMMAND_START
+#if LK_DEBUGLEVEL > 0
+{ "vm", "vm commands", &cmd_vm },
+#endif
+STATIC_COMMAND_END(vm);
+
+LK_INIT_HOOK(vm_preheap, &vm_init_preheap, LK_INIT_LEVEL_HEAP - 1);
+LK_INIT_HOOK(vm, &vm_init_postheap, LK_INIT_LEVEL_VM);
+