kernel: vm: Add vm_map interface

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 124 insertions, 0 deletions

diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
new file mode 100644
index 0000000..0002dde
--- /dev/null
+++ b/sys/vm/vm_map.c
@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <vm/map.h>
+#include <vm/vm.h>
+#include <vm/pmap.h>
+#include <sys/types.h>
+#include <sys/cdefs.h>
+#include <sys/panic.h>
+#include <lib/assert.h>
+
+/*
+ * Internal routine for cleaning up.
+ *
+ * @va: VA to start unmapping at.
+ * @bytes_aligned: Amount of bytes to unmap.
+ *
+ * XXX DANGER!!: `bytes_aligned' is expected to be aligned by the
+ *               machine's page granule. If this is not so,
+ *               undefined behaviour will occur. This will
+ *               be enforced via a panic.
+ */
+static void
+vm_map_cleanup(struct vm_ctx *ctx, vaddr_t va, size_t bytes_aligned,
+               size_t granule)
+{
+    __assert(bytes_aligned != 0);
+    __assert((bytes_aligned & (granule - 1)) == 0);
+
+    for (size_t i = 0; i < bytes_aligned; i += 0x1000) {
+        if (pmap_unmap(ctx, va + i) != 0) {
+            /*
+             * XXX: This shouldn't happen... If it somehow does,
+             *      then this should be handled.
+             */
+            panic("Could not cleanup!!!\n");
+        }
+    }
+}
+
+/*
+ * Create a virtual memory mappings in the current
+ * address space.
+ *
+ * @va: Virtual address.
+ * @pa: Physical address.
+ * @prot: Protection flags.
+ * @bytes: Amount of bytes to be mapped. This is aligned by the
+ *         machine's page granule, typically a 4k boundary.
+ */
+int
+vm_map_create(vaddr_t va, paddr_t pa, vm_prot_t prot, size_t bytes)
+{
+    size_t granule = vm_get_page_size();
+    int s;
+
+    /*
+     * TODO: This needs to be changed, once vm_get_bsp_ctx()
+     *       is no longer used, we'll need to fetch it from
+     *       the current process!
+     */
+    struct vm_ctx *ctx = vm_get_bsp_ctx();
+
+    /* We want bytes to be aligned by the granule */
+    bytes = __ALIGN_UP(bytes, granule);
+
+    /*
+     * The VA and PA must be aligned by the granule as well.
+     * However, it is a terrible idea to do this ourselves
+     * as that could introduce very hard to find bugs...
+     * If one of them aren't aligned, the caller most likely
+     * screwed something up and silently continuing would be
+     * a terrible thing! The offset of the addresses should be 0,
+     * i.e., we should be at the very beginning of the page.
+     */
+    if ((va & (granule - 1)) != 0) {
+        return -1;
+    }
+    if ((pa & (granule - 1)) != 0) {
+        return -1;
+    }
+
+    if (bytes == 0) {
+        /* You can't map 0 pages, silly! */
+        return -1;
+    }
+
+    for (uintptr_t i = 0; i < bytes; i += granule) {
+        s = pmap_map(ctx, va + i, pa + i, prot);
+        if (s != 0) {
+            /* Something went a bit wrong here, cleanup */
+            vm_map_cleanup(ctx, va, i, bytes);
+            return -1;
+        }
+    }
+
+    return 0;
+}