From 19916128eeb882338f39c756945ad978eab13a49 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Mon, 10 Jun 2024 23:51:40 -0400
Subject: kernel: vm: Add initial code for MI layer

Add initial code for the machine independent virtual memory layer

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/vm/vm_map.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 sys/vm/vm_map.c

(limited to 'sys/vm/vm_map.c')

diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
new file mode 100644
index 0000000..d89cff5
--- /dev/null
+++ b/sys/vm/vm_map.c
@@ -0,0 +1,132 @@
+/*
+ * 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 <sys/param.h>
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <vm/pmap.h>
+#include <vm/map.h>
+#include <vm/vm.h>
+
+/*
+ * Create/destroy virtual memory mappings in a specific
+ * address space.
+ *
+ * @vas: Address space.
+ * @va: Virtual address.
+ * @pa: Physical address (zero if `unmap` is true)
+ * @prot: Protection flags (zero if `unmap` is true)
+ * @unmap: True to unmap.
+ * @count: Count of bytes to be mapped which is aligned to the
+ *         machine's page granularity.
+ *
+ * Returns 0 on success. On failure, this routine
+ * returns a less than zero value or greater than zero
+ * value that contains the offset into the memory where the
+ * mapping failed.
+ */
+static int
+vm_map_modify(struct vas vas, vaddr_t va, paddr_t pa, vm_prot_t prot, bool unmap,
+              size_t count)
+{
+    size_t misalign = va & (DEFAULT_PAGESIZE - 1);
+    int s;
+
+    if (count == 0) {
+        return -EINVAL;
+    }
+
+    /* Ensure we fully span pages */
+    count = ALIGN_UP(count + misalign, DEFAULT_PAGESIZE);
+    va = ALIGN_DOWN(va, DEFAULT_PAGESIZE);
+    pa = ALIGN_DOWN(pa, DEFAULT_PAGESIZE);
+
+    for (uintptr_t i = 0; i < count; i += DEFAULT_PAGESIZE) {
+        /* See if we should map or unmap the range */
+        if (unmap) {
+            s = pmap_unmap(vas, va + i);
+        } else {
+            s = pmap_map(vas, va + i, pa + i, prot);
+        }
+
+        if (s != 0) {
+            /* Something went wrong, return the offset */
+            return i;
+        }
+    }
+
+    return 0;
+}
+
+/*
+ * Create a virtual memory mapping in a specific
+ * address space.
+ *
+ * @vas: Address space.
+ * @va: Virtual address.
+ * @pa: Physical address.
+ * @prot: Protection flags.
+ * @count: Count of bytes to be mapped (aligned to page granularity).
+ *
+ *  Returns 0 on success, and a less than zero errno
+ *  on failure.
+ */
+int
+vm_map(struct vas vas, vaddr_t va, paddr_t pa, vm_prot_t prot, size_t count)
+{
+    int retval;
+
+    va = ALIGN_UP(va, DEFAULT_PAGESIZE);
+    retval = vm_map_modify(vas, va, pa, prot, false, count);
+
+    /* Return on success */
+    if (retval == 0)
+        return 0;
+
+    /* Failure, clean up */
+    for (int i = 0; i < retval; i += DEFAULT_PAGESIZE) {
+        pmap_unmap(vas, va + i);
+    }
+
+    return -1;
+}
+
+/*
+ * Unmap a virtual memory mapping in a specific
+ * address space.
+ *
+ * @vas: Address space.
+ * @va: Virtual address to start unmapping at.
+ * @count: Bytes to unmap (aligned to page granularity)
+ */
+int
+vm_unmap(struct vas vas, vaddr_t va, size_t count)
+{
+    return vm_map_modify(vas, va, 0, 0, true, count);
+}
-- 
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