9os

commit 9469372d1915f951022b6e83a77cfa02cd5d0419
parent a71b8e7bb7ede0884ff47116bdefc00a1700762d
Author: Roberto E. Vargas Caballero <roberto.vargas@midokura.com>
Date:   Sat, 19 Nov 2022 08:07:04 +0100

os9: Implement page pool

A page pool is needed if we want to be able to allocate and free
pages. A buffer pool is not enough because we need a container
to keep track of all the pages in a map.

Diffstat:
M
include/os9/os9.h
 | 
13
++++++++++++-
M
src/os9/alloc.c
 | 
100
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
M
src/os9/proc.c
 | 
33
++++++++++++++++++++++-----------

3 files changed, 128 insertions(+), 18 deletions(-)
diff --git a/include/os9/os9.h b/include/os9/os9.h
@@ -42,12 +42,12 @@
 typedef struct ptable Ptable;
 typedef struct context Context;
 typedef struct task Task;
-typedef struct win Win;
 typedef struct chan Chan;
 typedef struct qid Qid;
 typedef struct dir Dir;
 typedef struct mach Mach;
 typedef struct map Map;
+typedef struct page Page;
 typedef struct nspace Nspace;
 typedef struct fdset Fdset;
 typedef struct ref Ref;
@@ -104,6 +104,12 @@ struct ref {
 	int cnt;
 };
 
+struct page {
+	int allocated;
+	phyaddr_t pa;
+	struct page *next;
+};
+
 struct map {
 	Ref ref;
 	char *name;
@@ -112,6 +118,9 @@ struct map {
 	phyaddr_t pa;
 	uintptr_t va;
 	size_t siz;
+
+	Page *pages;
+
 	Map *next;
 };
 
@@ -256,7 +265,9 @@ extern void unlocktask(Task *);
 /* alloc.c */
 extern void *alloc(size_t);
 extern void *allocb(void);
+extern Page *allocp(phyaddr_t);
 extern void freeb(void *);
+extern void freep(Page *);
 extern void ialloc(void);
 
 /* sys.c */
diff --git a/src/os9/alloc.c b/src/os9/alloc.c
@@ -1,5 +1,7 @@
 #include <os9/os9.h>
 
+#include <libk.h>
+
 #include <errno.h>
 #include <string.h>
 
@@ -9,23 +11,29 @@ union bucket {
 	union bucket *next;
 };
 
-struct {
+struct bufpool {
 	union bucket *list;
 	mutex_t m;
-} bufpool;
+};
+
+struct pagepool {
+	Page *list;
+	mutex_t m;
+};
 
 static union bucket *heap;
+static struct bufpool bufpool;
+static struct pagepool pagepool;
 
 void
 freeb(void *bp)
 {
-	union bucket *p;
+	union bucket *p = bp;
 
-	if (!bp)
+	if (!p)
 		return;
 
 	lock(&bufpool.m);
-	p = bp;
 	p->next = bufpool.list;
 	bufpool.list = p;
 	unlock(&bufpool.m);
@@ -77,13 +85,90 @@ alloc(size_t size)
 	return bp;
 }
 
+/*
+ * This functions is always called with the page pool locked
+ */
+static int
+morepages(void)
+{
+	int i;
+	void *bp;
+	Page *p, *ptable;
+
+	if (pagepool.list)
+		return 1;
+
+	if ((bp = allocb()) == NULL)
+		return 0;
+
+	ptable = bp;
+	for (i = 0; i < PAGESIZE/sizeof(Page); i++) {
+		p = &ptable[i];
+		p->next = p+1;
+	}
+	p->next = NULL;
+
+	pagepool.list = bp;
+
+	return 1;
+}
+
+Page *
+allocp(phyaddr_t pa)
+{
+	int alloc = 0;
+	void *bp = NULL;
+	Page *p;
+
+	if (pa == -1) {
+		if ((bp = allocb()) == NULL)
+			return NULL;
+		pa = (phyaddr_t) PMEM(bp);
+		alloc = 1;
+	}
+
+	lock(&pagepool.m);
+
+	if (!morepages()) {
+		freeb(bp);
+		unlock(&pagepool.m);
+		return NULL;
+	}
+
+	p = pagepool.list;
+	pagepool.list = p->next;
+
+	unlock(&pagepool.m);
+
+	p->pa = pa;
+	p->allocated = alloc;
+	p->next = NULL;
+
+	return p;
+}
+
+void
+freep(Page *p)
+{
+	if (!p)
+		return;
+
+	if (p->allocated)
+		freeb(VMEM(p->pa));
+
+	lock(&pagepool.m);
+	p->next = pagepool.list;
+	pagepool.list = p;
+	unlock(&pagepool.m);
+}
+
 void
 ialloc(void)
 {
 	int i;
 	union bucket *bp, *prev;
 
-	heap = buffertab;
+	heap = (union bucket *) buffertab;
 
 	prev = NULL;
 	for (i = HEAPSIZ; i < NR_BUFFERS; i++) {
@@ -92,4 +177,7 @@ ialloc(void)
 		prev = bp;
 	}
 	bufpool.list = bp;
+
+	kprint("%d available buffers: %d heap, %d buffer pool\n",
+	       NR_BUFFERS, HEAPSIZ, NR_BUFFERS - HEAPSIZ);
 }
diff --git a/src/os9/proc.c b/src/os9/proc.c
@@ -108,12 +108,18 @@ gettask(int pid)
 }
 
 int
+unmapseg(Map *mp)
+{
+	return 0;
+}
+
+int
 mapseg(Map *mp)
 {
 	phyaddr_t pa;
 	uintptr_t va;
-	void *bp;
 	unsigned long i, n;
+	Page *p;
 
 	assert(mp->perm & MR);
 
@@ -126,26 +132,31 @@ mapseg(Map *mp)
 		(mp->perm & MX) ? 'x' : '-',
 		mp->siz);
 
-	bp = NULL;
 	n =  (mp->siz + PAGESIZE-1)/PAGESIZE;
 	va = mp->va;
 	pa = mp->pa;
+
 	for (i = 0; i < n; i++) {
-		if (mp->pa == -1) {
-			if ((bp = allocb()) == NULL)
-				return -1;
-			pa = (phyaddr_t) PMEM(bp);
-		}
+		if (mp->pa == -1)
+			pa = -1;
+
+		if ((p = allocp(pa)) == NULL)
+			goto err;
+		p->next = mp->pages;
+		mp->pages = p;
+
+		if (vmap(p->pa, va, mp->perm) < 0)
+			goto err;
 
-		if (vmap(pa, va, mp->perm) < 0) {
-			freeb(bp);
-			return -1;
-		}
 		pa += PAGESIZE;
 		va += PAGESIZE;
 	}
 
 	return 0;
+
+err:
+	unmapseg(mp);
+	return -1;
 }
 
 Map *