From c46767abb634d600dc5cb1ef5922ec3459ae4cf8 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Wed, 17 Sep 2025 18:04:28 -0400
Subject: kern/amd64: proc: Add proc_kill() routine

Add a new function to kill processes and clean them up. They will then
be marked as EXITING and it is up to the parent to do the rest.

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 src/sys/arch/amd64/os/os_proc.c | 40 ++++++++++++++++++++++++++++++++++++++++
 src/sys/include/sys/proc.h      | 28 ++++++++++++++++++++++++++++
 src/sys/os/os_proc.c            | 14 ++++++++++++++
 3 files changed, 82 insertions(+)

diff --git a/src/sys/arch/amd64/os/os_proc.c b/src/sys/arch/amd64/os/os_proc.c
index 8c7b6f3..1064c10 100644
--- a/src/sys/arch/amd64/os/os_proc.c
+++ b/src/sys/arch/amd64/os/os_proc.c
@@ -39,6 +39,8 @@
 #include <machine/lapic.h>
 #include <string.h>
 
+extern struct proc g_rootproc;
+
 /*
  * Put the current process into userland for its first
  * run. The catch is that we have never been in userland
@@ -212,3 +214,41 @@ done:
     lapic_eoi();
     lapic_timer_oneshot_us(SCHED_QUANTUM);
 }
+
+/*
+ * Commit procedural murder
+ */
+int
+md_proc_kill(struct proc *procp, int flags)
+{
+    struct proc *self;
+    struct pcore *core = this_core();
+    struct md_pcb *pcbp;
+
+    if (core == NULL) {
+        return -ENXIO;
+    }
+
+    /* Default to ourself */
+    if (procp == NULL) {
+        procp = core->curproc;
+    }
+
+    /* Release the VAS */
+    pcbp = &procp->pcb;
+    mmu_free_vas(&pcbp->vas);
+
+    /* Sanity check */
+    if ((self = core->curproc) == NULL) {
+        printf("kill: could not get self, using rootproc\n");
+        self = &g_rootproc;
+    }
+
+    /* If this is us, spin time */
+    if (self->pid == procp->pid) {
+        core->curproc = NULL;
+        md_proc_yield();
+    }
+
+    return 0;
+}
diff --git a/src/sys/include/sys/proc.h b/src/sys/include/sys/proc.h
index 52afada..15b382d 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/cdefs.h>
+#include <sys/param.h>
 #include <sys/queue.h>
 #include <machine/pcb.h>    /* standard */
 
@@ -46,15 +47,19 @@
  * on the system.
  *
  * @pid: Process ID
+ * @flags: State flags (see PROC_*)
  * @pcb: Process control block
  * @link: TAILQ link
  */
 struct proc {
     pid_t pid;
+    uint32_t flags;
     struct md_pcb pcb;
     TAILQ_ENTRY(proc) link;
 };
 
+#define PROC_EXITING BIT(0)
+
 /*
  * Initialize a process into a basic minimal
  * state
@@ -67,6 +72,17 @@ struct proc {
  */
 int proc_init(struct proc *procp, int flags);
 
+/*
+ * Kill a process with a specific status code
+ *
+ * @procp: Process to kill
+ * @status: Status code to send
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value is returned on failure.
+ */
+int proc_kill(struct proc *procp, int status);
+
 /*
  * Initialize machine dependent state of a process
  *
@@ -78,6 +94,18 @@ int proc_init(struct proc *procp, int flags);
  */
 int md_proc_init(struct proc *procp, int flags);
 
+/*
+ * Machine dependent kill routine which cleans up
+ * things that exist within the process control block
+ *
+ * @procp: Process to kill
+ * @flags: Optional flags to use
+ *
+ * Returns zero on success, otherwise less than zero
+ * value on failure.
+ */
+int md_proc_kill(struct proc *procp, int flags);
+
 /*
  * Set the instruction pointer field of a specific
  * process
diff --git a/src/sys/os/os_proc.c b/src/sys/os/os_proc.c
index 5348eaf..6880dda 100644
--- a/src/sys/os/os_proc.c
+++ b/src/sys/os/os_proc.c
@@ -52,3 +52,17 @@ proc_init(struct proc *procp, int flags)
     error = md_proc_init(procp, flags);
     return error;
 }
+
+/*
+ * Kill a specific process
+ */
+int
+proc_kill(struct proc *procp, int status)
+{
+    if (procp == NULL) {
+        return -EINVAL;
+    }
+
+    procp->flags |= PROC_EXITING;
+    return md_proc_kill(procp, 0);
+}
-- 
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