From e0b34937b1bd674c05d609331501f81740fbb87f Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Thu, 23 May 2024 01:31:02 -0400
Subject: kernel: vm: Add memory stats

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/include/vm/physseg.h |  7 +++++++
 sys/include/vm/vm.h      |  6 ++++++
 sys/vm/vm_physseg.c      | 41 +++++++++++++++++++++++++++++++++++++++++
 sys/vm/vm_stat.c         | 40 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 94 insertions(+)
 create mode 100644 sys/vm/vm_stat.c

diff --git a/sys/include/vm/physseg.h b/sys/include/vm/physseg.h
index aced4cb..af8cae8 100644
--- a/sys/include/vm/physseg.h
+++ b/sys/include/vm/physseg.h
@@ -32,8 +32,15 @@
 
 #include <sys/types.h>
 
+struct physmem_stat {
+    size_t reserved_kib;     /* Reserved memory */
+    size_t total_kib;        /* Total memory */
+};
+
 void vm_physseg_init(void);
 uintptr_t vm_alloc_pageframe(size_t count);
+
 void vm_free_pageframe(uintptr_t base, size_t count);
+struct physmem_stat vm_phys_memstat(void);
 
 #endif      /* !_VM_VM_PHYSSEG_H_ */
diff --git a/sys/include/vm/vm.h b/sys/include/vm/vm.h
index 975eff0..f6fba66 100644
--- a/sys/include/vm/vm.h
+++ b/sys/include/vm/vm.h
@@ -39,6 +39,7 @@
 #include <sys/cdefs.h>
 #include <vm/page.h>
 #include <vm/pmap.h>
+#include <vm/physseg.h>
 
 extern volatile struct limine_hhdm_request g_hhdm_request;
 
@@ -52,6 +53,10 @@ struct vm_range {
     uintptr_t end;
 };
 
+struct vm_memstat {
+    struct physmem_stat pmem_stat;
+};
+
 /*
  * Returns the machine's pagesize:
  *
@@ -67,5 +72,6 @@ vm_get_page_size(void)
 void vm_init(void);
 struct vm_ctx *vm_get_ctx(void);
 struct vas vm_get_kvas(void);
+struct vm_memstat vm_memstat(void);
 
 #endif      /* !_VM_H_ */
diff --git a/sys/vm/vm_physseg.c b/sys/vm/vm_physseg.c
index ee7f06e..6b803c2 100644
--- a/sys/vm/vm_physseg.c
+++ b/sys/vm/vm_physseg.c
@@ -67,11 +67,40 @@ static const int MAX_SEGMENTS = __ARRAY_COUNT(segment_name);
 
 
 static bitmap_t bitmap = NULL;
+static size_t pages_total = 0;
+static size_t pages_reserved = 0;
 static size_t last_used_idx = 0;
 static size_t bitmap_size = 0;
 static size_t highest_frame_idx;
 static size_t bitmap_free_start;    /* Beginning bit of free region */
 
+static void
+vm_physseg_getstat(void)
+{
+    struct limine_memmap_entry *entry;
+    size_t entry_pages = 0;
+
+    pages_total = 0;
+    pages_reserved = 0;
+
+    for (size_t i = 0; i < resp->entry_count; ++i) {
+        entry = resp->entries[i];
+        entry_pages = entry->length / vm_get_page_size();
+
+        /* Drop invalid entries */
+        if (entry->type >= MAX_SEGMENTS) {
+            continue;
+        }
+
+        pages_total += entry_pages;
+
+        if (entry->type != LIMINE_MEMMAP_USABLE) {
+            pages_reserved += entry_pages;
+            continue;
+        }
+    }
+}
+
 static void
 vm_physseg_bitmap_alloc(void)
 {
@@ -223,3 +252,15 @@ vm_physseg_init(void)
 
     vm_physseg_bitmap_init();
 }
+
+struct physmem_stat
+vm_phys_memstat(void)
+{
+    size_t pagesize = vm_get_page_size();
+    struct physmem_stat stat;
+
+    vm_physseg_getstat();
+    stat.total_kib = (pages_total * pagesize) / 1024;
+    stat.reserved_kib = (pages_reserved * pagesize) / 1024;
+    return stat;
+}
diff --git a/sys/vm/vm_stat.c b/sys/vm/vm_stat.c
new file mode 100644
index 0000000..99ee9a9
--- /dev/null
+++ b/sys/vm/vm_stat.c
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2023-2024 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 <vm/physseg.h>
+#include <vm/vm.h>
+
+struct vm_memstat
+vm_memstat(void)
+{
+    struct vm_memstat stat;
+
+    stat.pmem_stat = vm_phys_memstat();
+    return stat;
+}
-- 
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