1 files changed, 102 insertions, 0 deletions
diff --git a/sys/arch/amd64/os/os_process.c b/sys/arch/amd64/os/os_process.c
new file mode 100644
index 0000000..2a1d09a
--- /dev/null
+++ b/sys/arch/amd64/os/os_process.c
@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 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.
+ */
+
+#include <sys/errno.h>
+#include <mu/process.h>
+#include <mu/mmu.h>
+#include <vm/phys.h>
+#include <lib/string.h>
+
+#define STACK_TOP 0xBFFFFFFF
+#define GDT_KERNCODE 0x08
+#define GDT_KERNDATA 0x10
+#define GDT_USERCODE 0x18
+#define GDT_USERDATA 0x20
+
+int
+mu_process_init(struct process *process, uintptr_t ip, int flags)
+{
+    struct trapframe *tf;
+    struct pcb *pcb;
+    uintptr_t stack_base;
+    uint8_t cs, ds;
+    int error;
+
+    if (process == NULL) {
+        return -EINVAL;
+    }
+
+    pcb = &process->pcb;
+    tf = &pcb->tf;
+
+    error = mu_pmap_forkvas(&pcb->vas);
+    if (error < 0) {
+        return error;
+    }
+
+    /* Allocate a new stack */
+    stack_base = vm_phys_alloc(1);
+    if (stack_base == 0) {
+        vm_phys_free(pcb->vas.cr3, 1);
+        return -ENOMEM;
+    }
+
+    /* Get the segment selectors based on mode */
+    if (ISSET(flags, PROC_KERN)) {
+        cs = GDT_KERNCODE;
+        ds = GDT_KERNDATA;
+    } else {
+        cs = GDT_USERCODE | 3;
+        ds = GDT_USERDATA | 3;
+    }
+
+    memset(tf, 0, sizeof(*tf));
+    tf->rip = ip;
+    tf->rflags = 0x202;
+    tf->cs = cs;
+    tf->ss = ds;
+
+    /* Map out the stack */
+    error = mu_pmap_map(
+        &pcb->vas,
+        stack_base,
+        STACK_TOP,
+        PROT_READ | PROT_WRITE,
+        PAGESIZE_4K
+    );
+
+    if (error < 0) {
+        vm_phys_free(stack_base, 1);
+        vm_phys_free(pcb->vas.cr3, 1);
+        return error;
+    }
+
+    tf->rsp = ALIGN_DOWN(STACK_TOP + (PAGESIZE - 1), 16);
+    return 0;
+}