kernel: vm: Add PMAP abstraction

Signed-off-by: sigsegv7 <ian@vegaa.systems>

1 files changed, 50 insertions, 0 deletions

diff --git a/sys/arch/amd64/pmap.c b/sys/arch/amd64/pmap.c
new file mode 100644
index 0000000..0da80d9
--- /dev/null
+++ b/sys/arch/amd64/pmap.c
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2023 Ian Marco Moffett and the VegaOS 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 VegaOS 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/pmap.h>
+#include <sys/cdefs.h>
+
+#define PTE_ADDR_MASK 0x000FFFFFFFFFF000
+
+struct vas
+pmap_read_vas(void)
+{
+    struct vas vas;
+    uintptr_t cr3_raw;
+
+    __ASMV("mov %%cr3, %0"
+           : "=r" (cr3_raw)
+    );
+
+    vas.cr3_flags = cr3_raw & ~PTE_ADDR_MASK;
+    vas.top_level = cr3_raw & PTE_ADDR_MASK;
+    vas.use_l5_paging = false;      /* TODO: Check for support */
+    vas.lock.lock = 0;
+    return vas;
+}