From 50e1b103669a334d31bb27d7d858400c7a12e29e Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Fri, 19 Sep 2025 23:29:18 -0400
Subject: kern: proc: Keep track of mapped areas with ranges

This commit adds a virtual memory range queue to the process descriptor
in order to keep track of mapped pages and free their respective frames
upon program exit.

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 src/sys/include/sys/proc.h | 18 ++++++++++++++++
 src/sys/include/vm/vm.h    | 16 ++++++++++++++
 src/sys/os/os_proc.c       | 54 ++++++++++++++++++++++++++++++++++++++++++++++
 src/sys/vm/vm_map.c        |  9 ++++++++
 4 files changed, 97 insertions(+)

(limited to 'src/sys')

diff --git a/src/sys/include/sys/proc.h b/src/sys/include/sys/proc.h
index 200d5ce..cf00850 100644
--- a/src/sys/include/sys/proc.h
+++ b/src/sys/include/sys/proc.h
@@ -35,6 +35,7 @@
 #include <sys/cdefs.h>
 #include <sys/param.h>
 #include <sys/queue.h>
+#include <vm/vm.h>
 #include <machine/pcb.h>    /* standard */
 
 /*
@@ -52,6 +53,7 @@
  * @flags: State flags (see PROC_*)
  * @pcb: Process control block
  * @scdom: Syscall domain
+ * @maplist: List of mapped regions
  * @link: TAILQ link
  */
 struct proc {
@@ -59,6 +61,7 @@ struct proc {
     uint32_t flags;
     struct md_pcb pcb;
     struct syscall_domain scdom;
+    TAILQ_HEAD(, vm_range) maplist;
     TAILQ_ENTRY(proc) link;
 };
 
@@ -82,6 +85,21 @@ int proc_init(struct proc *procp, int flags);
  */
 struct proc *proc_self(void);
 
+/*
+ * Allocate a range descriptor and add it to the
+ * process's range tracking list for cleanup upon
+ * exit.
+ *
+ * @procp: Process to initialize the range of
+ * @va: Virtual address to use
+ * @pa: Physical address to use
+ * @len: Length to use
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value upon error.
+ */
+int proc_add_range(struct proc *procp, vaddr_t va, paddr_t pa, size_t len);
+
 /*
  * Kill a process with a specific status code
  *
diff --git a/src/sys/include/vm/vm.h b/src/sys/include/vm/vm.h
index 790fe0b..f5f7b16 100644
--- a/src/sys/include/vm/vm.h
+++ b/src/sys/include/vm/vm.h
@@ -31,6 +31,7 @@
 #define _VM_H_ 1
 
 #include <sys/types.h>
+#include <sys/queue.h>
 #include <sys/bootvars.h>
 
 #define VM_HIGHER_HALF (get_kernel_base())
@@ -42,6 +43,21 @@
 typedef uintptr_t vaddr_t;
 typedef uintptr_t paddr_t;
 
+/*
+ * Describes a virtual memory range
+ *
+ * @pa_base: Physical memory base
+ * @va_base: Virtual memory base
+ * @len: Length of region
+ * @link: Queue link
+ */
+struct vm_range {
+    paddr_t pa_base;
+    vaddr_t va_base;
+    size_t len;
+    TAILQ_ENTRY(vm_range) link;
+};
+
 void vm_init(void);
 
 #endif  /* !_VM_H_ */
diff --git a/src/sys/os/os_proc.c b/src/sys/os/os_proc.c
index 329a3ea..3a42496 100644
--- a/src/sys/os/os_proc.c
+++ b/src/sys/os/os_proc.c
@@ -30,11 +30,38 @@
 #include <sys/types.h>
 #include <sys/atomic.h>
 #include <sys/errno.h>
+#include <sys/cdefs.h>
+#include <sys/queue.h>
 #include <sys/proc.h>
+#include <vm/vm.h>
+#include <vm/physseg.h>
+#include <os/kalloc.h>
 #include <string.h>
 
 static pid_t next_pid = 0;
 
+/*
+ * Deallocate saved memory ranges
+ *
+ * @proc: Process to target
+ */
+static void
+proc_clear_ranges(struct proc *proc)
+{
+    const size_t PSIZE = DEFAULT_PAGESIZE;
+    struct vm_range *range;
+    size_t n_pages;
+
+    TAILQ_FOREACH(range, &proc->maplist, link) {
+        if (range == NULL) {
+            continue;
+        }
+
+        n_pages = ALIGN_UP(range->len, PSIZE) / PSIZE;
+        vm_free_frame(range->pa_base, n_pages);
+    }
+}
+
 /*
  * MI proc init code
  */
@@ -52,6 +79,7 @@ proc_init(struct proc *procp, int flags)
     /* Put the process in a known state */
     scdp = &procp->scdom;
     memset(procp, 0, sizeof(*procp));
+    TAILQ_INIT(&procp->maplist);
 
     /*
      * Initialize each platform latch
@@ -72,6 +100,31 @@ proc_init(struct proc *procp, int flags)
     return error;
 }
 
+/*
+ * Add range to process
+ */
+int
+proc_add_range(struct proc *procp, vaddr_t va, paddr_t pa, size_t len)
+{
+    const size_t PSIZE = DEFAULT_PAGESIZE;
+    struct vm_range *range;
+
+    if (procp == NULL) {
+        return -EINVAL;
+    }
+
+    range = kalloc(sizeof(*range));
+    if (range == NULL) {
+        return -ENOMEM;
+    }
+
+    range->pa_base = pa;
+    range->va_base = va;
+    range->len = ALIGN_UP(len, PSIZE);
+    TAILQ_INSERT_TAIL(&procp->maplist, range, link);
+    return 0;
+}
+
 /*
  * Kill a specific process
  */
@@ -83,5 +136,6 @@ proc_kill(struct proc *procp, int status)
     }
 
     procp->flags |= PROC_EXITING;
+    proc_clear_ranges(procp);
     return md_proc_kill(procp, 0);
 }
diff --git a/src/sys/vm/vm_map.c b/src/sys/vm/vm_map.c
index d8cb4b7..27cdcce 100644
--- a/src/sys/vm/vm_map.c
+++ b/src/sys/vm/vm_map.c
@@ -103,15 +103,19 @@ __vm_map(struct vm_vas *vas, struct mmu_map *spec, size_t len, int prot)
 int
 vm_map(struct vm_vas *vas, struct mmu_map *spec, size_t len, int prot)
 {
+    const size_t PSIZE = DEFAULT_PAGESIZE;
     int retval;
     size_t unmap_len;
     struct mmu_map spec_cpy;
+    struct proc *self = proc_self();
 
     if (spec != NULL) {
         spec_cpy = *spec;
     }
 
+
     /* If this fails, unmap the partial region */
+    len = ALIGN_UP(len, PSIZE);
     retval = __vm_map(vas, spec, len, prot);
     if (retval != 0) {
         printf("vm_map: could not map <%p>\n", spec_cpy.va);
@@ -121,6 +125,11 @@ vm_map(struct vm_vas *vas, struct mmu_map *spec, size_t len, int prot)
         return -1;
     }
 
+    /* Add the range if we can */
+    if (self != NULL) {
+        proc_add_range(self, spec->va, spec->pa, len);
+    }
+
     /* Place a guard page at the end */
     spec->va = spec_cpy.va + len;
     __vm_map(vas, spec, DEFAULT_PAGESIZE, 0);
-- 
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