From a3670076897821660f24815c1e3c655593a4cd5f Mon Sep 17 00:00:00 2001
From: Geoffrey Challen <challen@buffalo.edu>
Date: Sat, 5 Mar 2016 09:55:44 -0500
Subject: [PATCH] Add function to track free bytes in the coremap.

---
 kern/arch/mips/vm/dumbvm.c | 9 +++++++++
 kern/include/vm.h          | 8 ++++++++
 kern/vm/kmalloc.c          | 6 +++---
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/kern/arch/mips/vm/dumbvm.c b/kern/arch/mips/vm/dumbvm.c
index 93606d1..5a7d619 100644
--- a/kern/arch/mips/vm/dumbvm.c
+++ b/kern/arch/mips/vm/dumbvm.c
@@ -126,6 +126,15 @@ free_kpages(vaddr_t addr)
 	(void)addr;
 }
 
+unsigned
+int
+coremap_free_bytes() {
+
+	/* dumbvm doesn't track page allocations. Return 0 so that khu works. */
+
+	return 0;
+}
+
 void
 vm_tlbshootdown_all(void)
 {
diff --git a/kern/include/vm.h b/kern/include/vm.h
index fd1b299..96b6ffe 100644
--- a/kern/include/vm.h
+++ b/kern/include/vm.h
@@ -55,6 +55,14 @@ int vm_fault(int faulttype, vaddr_t faultaddress);
 vaddr_t alloc_kpages(unsigned npages);
 void free_kpages(vaddr_t addr);
 
+/*
+ * Return amount of free memory (in bytes) available in unallocated coremap pages.
+ * If there are ongoing allocations, this value could change after it is
+ * returned to the caller. But it should have been correct at some point in
+ * time.
+ */
+unsigned int coremap_free_bytes(void);
+
 /* TLB shootdown handling called from interprocessor_interrupt */
 void vm_tlbshootdown_all(void);
 void vm_tlbshootdown(const struct tlbshootdown *);
diff --git a/kern/vm/kmalloc.c b/kern/vm/kmalloc.c
index 5537c28..bc2771a 100644
--- a/kern/vm/kmalloc.c
+++ b/kern/vm/kmalloc.c
@@ -827,16 +827,16 @@ kheap_printused(void)
 {
 	struct pageref *pr;
 	unsigned long total = 0;
+	char total_string[32];
+
 	/* print the whole thing with interrupts off */
 	spinlock_acquire(&kmalloc_spinlock);
-
 	for (pr = allbase; pr != NULL; pr = pr->next_all) {
 		total += subpage_stats(pr, true);
 	}
-
+	total += coremap_free_bytes();
 	spinlock_release(&kmalloc_spinlock);
 
-	char total_string[32];
 	snprintf(total_string, sizeof(total_string), "%lu", total);
 	secprintf(SECRET, total_string, "khu");
 }