kern: proc: Add initial proc init + PCB code

This commit introduces the initial logic for putting process descriptors
in an initialized state. This commit also introduces the process control
block definition.

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

4 files changed, 178 insertions, 0 deletions

diff --git a/src/sys/arch/amd64/os/os_proc.c b/src/sys/arch/amd64/os/os_proc.c
new file mode 100644
index 0000000..8fad7b6
--- /dev/null
+++ b/src/sys/arch/amd64/os/os_proc.c
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * 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 the project 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 <sys/proc.h>
+#include <sys/syslog.h>
+#include <vm/mmu.h>
+#include <machine/pcb.h>
+
+/*
+ * MD proc init code
+ */
+int
+md_proc_init(struct proc *procp, int flags)
+{
+    struct md_pcb *pcbp;
+    int error;
+
+    if (procp == NULL) {
+        return -EINVAL;
+    }
+
+    pcbp = &procp->pcb;
+    if ((error = mmu_new_vas(&pcbp->vas)) < 0) {
+        printf("md_proc_init: could not create new vas\n");
+        return error;
+    }
+    return 0;
+}
diff --git a/src/sys/include/arch/amd64/pcb.h b/src/sys/include/arch/amd64/pcb.h
new file mode 100644
index 0000000..852e28d
--- /dev/null
+++ b/src/sys/include/arch/amd64/pcb.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * 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 the project 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 _MACHINE_PCB_H_
+#define _MACHINE_PCB_H_ 1
+
+#include <machine/vas.h>
+
+/*
+ * Represents MD specific process data
+ *
+ * @vas: Current virtual address space
+ */
+struct md_pcb {
+    struct vm_vas vas;
+};
+
+#endif  /* _MACHINE_PCB_H_ */
diff --git a/src/sys/include/sys/proc.h b/src/sys/include/sys/proc.h
index ab112cc..deed09b 100644
--- a/src/sys/include/sys/proc.h
+++ b/src/sys/include/sys/proc.h
@@ -32,6 +32,7 @@
 
 #include <sys/types.h>
 #include <sys/queue.h>
+#include <machine/pcb.h>    /* standard */
 
 /*
  * A process describes a running program image
@@ -41,7 +42,31 @@
  */
 struct proc {
     pid_t pid;
+    struct md_pcb pcb;
     TAILQ_ENTRY(proc) link;
 };
 
+/*
+ * Initialize a process into a basic minimal
+ * state
+ *
+ * @procp: New process data is written here
+ * @flags: Optional flags
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value to indicate failure.
+ */
+int proc_init(struct proc *procp, int flags);
+
+/*
+ * Initialize machine dependent state of a process
+ *
+ * @procp: New process data is written here
+ * @flags: Optional flags
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value to indicate failure.
+ */
+int md_proc_init(struct proc *procp, int flags);
+
 #endif  /* !_SYS_PROC_H_ */
diff --git a/src/sys/os/os_proc.c b/src/sys/os/os_proc.c
new file mode 100644
index 0000000..5348eaf
--- /dev/null
+++ b/src/sys/os/os_proc.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * 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 the project 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/types.h>
+#include <sys/atomic.h>
+#include <sys/errno.h>
+#include <sys/proc.h>
+#include <string.h>
+
+static pid_t next_pid = 0;
+
+/*
+ * MI proc init code
+ */
+int
+proc_init(struct proc *procp, int flags)
+{
+    int error;
+
+    if (procp == NULL) {
+        return -EINVAL;
+    }
+
+    memset(procp, 0, sizeof(*procp));
+    procp->pid = atomic_inc_int(&next_pid);
+    error = md_proc_init(procp, flags);
+    return error;
+}