kernel: vm: Add initial mmap() impl

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

2 files changed, 96 insertions, 0 deletions

diff --git a/sys/include/sys/mman.h b/sys/include/sys/mman.h
new file mode 100644
index 0000000..98ff8fe
--- /dev/null
+++ b/sys/include/sys/mman.h
@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2023-2025 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.
+ */
+
+#ifndef _SYS_MMAN_H_
+#define _SYS_MMAN_H_
+
+#include <sys/types.h>
+#include <sys/syscall.h>
+#if defined(_KERNEL)
+#include <sys/tree.h>
+#include <vm/vm_obj.h>
+#endif  /* _KERNEL */
+
+/*
+ * If we are in kernel space, all defines we want are
+ * in vm/pmap.h
+ */
+#if !defined(_KERNEL)
+#define PROT_WRITE 0x00000001
+#define PROT_EXEC  0x00000002
+#define PROT_NONE  0x00000004
+#define PROT_READ  PROT_NONE
+#endif  /* !_KERNEL */
+
+/* mmap() flags */
+#define MAP_SHARED  0x0001
+#define MAP_PRIVATE 0x0002
+#define MAP_FIXED   0x0004
+#define MAP_ANON    0x0008
+
+#if defined(_KERNEL)
+/*
+ * The mmap ledger entry
+ *
+ * @va_start: Starting virtual address.
+ * @obj: VM object representing this entry.
+ */
+struct mmap_entry {
+    vaddr_t va_start;
+    struct vm_object *obj;
+    size_t size;
+    RBT_ENTRY(mmap_entry) hd;
+};
+
+/*
+ * The mmap ledger is a per-process structure that
+ * describes memory mappings made using mmap()
+ *
+ * @hd: Red-black tree of mmap_entry structures
+ * @nbytes: Total bytes mapped.
+ */
+struct mmap_lgdr {
+    RBT_HEAD(lgdr_entries, mmap_entry) hd;
+    size_t nbytes;
+};
+
+/* Kernel mmap() routine */
+void *mmap_at(void *addr, size_t len, int prot, int flags,
+              int fildes, off_t off);
+
+int mmap_entrycmp(const struct mmap_entry *a, const struct mmap_entry *b);
+RBT_PROTOTYPE(lgdr_entries, mmap_entry, hd, mmap_entrycmp)
+#endif  /* _KERNEL */
+
+/* Syscall layer */
+scret_t mmap(struct syscall_args *scargs);
+
+#endif  /* !_SYS_MMAN_H_ */
diff --git a/sys/include/sys/proc.h b/sys/include/sys/proc.h
index 5e0e927..c561e91 100644
--- a/sys/include/sys/proc.h
+++ b/sys/include/sys/proc.h
@@ -34,6 +34,7 @@
 #include <sys/spinlock.h>
 #include <sys/queue.h>
 #include <sys/param.h>
+#include <sys/mman.h>
 #include <sys/cdefs.h>
 #include <sys/syscall.h>
 #include <sys/exec.h>
@@ -57,6 +58,7 @@ struct proc {
     struct exec_prog exec;
     struct ksiginfo *ksig_list[PROC_SIGMAX];
     struct filedesc *fds[PROC_MAX_FILEDES];
+    struct mmap_lgdr *mlgdr;
     struct vcache *vcache;
     struct spinlock vcache_lock;
     struct trapframe tf;