From dea0eba83d22323f55e584fdba46b05d9fd5eff0 Mon Sep 17 00:00:00 2001
From: Mathieu Maret <mathieu.maret@gmail.com>
Date: Wed, 6 Mar 2024 22:00:09 +0100
Subject: [PATCH] zero: keep track of allocated pages

---
 drivers/zero.c | 53 +++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 5 deletions(-)

diff --git a/drivers/zero.c b/drivers/zero.c
index b55bec3..b93e446 100644
--- a/drivers/zero.c
+++ b/drivers/zero.c
@@ -1,14 +1,41 @@
 #include "zero.h"
 
 #include "alloc.h"
+#include "errno.h"
 #include "kernel.h"
 #include "klibc.h"
 #include "mem.h"
+#include "list.h"
+#include "paging.h"
+#include "types.h"
+
+struct zeroMappedPage {
+    uaddr_t mappedAddr;
+    paddr_t phyAddr;
+
+    struct zeroMappedPage *prev, *next;
+};
 
 struct zeroMappedEntry {
     int refCnt;
+
+    struct zeroMappedPage *listMapped;
 };
 
+static int insertMappedPage(struct zeroMappedEntry *entry, uaddr_t vAddr, paddr_t pAddr){
+    struct zeroMappedPage *info = (struct zeroMappedPage *)zalloc(sizeof(struct zeroMappedPage));
+
+    if(!info)
+        return -ENOMEM;
+
+    info->mappedAddr = vAddr;
+    info->phyAddr = pAddr;
+
+    list_add_tail(entry->listMapped, info);
+    return 0;
+}
+
+
 static int zeroOpen(struct uAddrVirtualReg *vreg)
 {
     struct zeroMappedEntry *ent = (struct zeroMappedEntry *)vreg->res->customData;
@@ -21,6 +48,11 @@ static int zeroClose(struct uAddrVirtualReg *vreg)
     struct zeroMappedEntry *ent = (struct zeroMappedEntry *)vreg->res->customData;
     ent->refCnt--;
     if (ent->refCnt == 0) {
+        struct zeroMappedPage *pageInfo;
+        list_collapse(ent->listMapped, pageInfo){
+            pageUnmap(pageInfo->mappedAddr);
+            free(pageInfo);
+        }
         free(vreg->res->customData);
         free(vreg->res);
     }
@@ -29,17 +61,26 @@ static int zeroClose(struct uAddrVirtualReg *vreg)
 
 static int zeroNoPage(struct uAddrVirtualReg *vreg, uaddr_t addr, int right)
 {
-    (void)vreg;
+    int ret            = 0;
+    paddr_t ppage      = allocPhyPage(1);
+    uaddr_t mappedAddr = ALIGN_DOWN(addr, PAGE_SIZE);
+    ret                = pageMap(mappedAddr, ppage, right | PAGING_MEM_USER);
 
-    int ret       = 0;
-    paddr_t ppage = allocPhyPage(1);
-    ret           = pageMap(ALIGN_DOWN(addr, PAGE_SIZE), ppage, right | PAGING_MEM_USER) ;
+    struct zeroMappedEntry *ent = (struct zeroMappedEntry *)vreg->res->customData;
 
     unrefPhyPage(ppage);
     if (ret) {
         return ret;
     }
-    memset((void *)ALIGN_DOWN(addr, PAGE_SIZE), 0, PAGE_SIZE);
+
+    ret = insertMappedPage(ent, mappedAddr, ppage);
+    if (ret) {
+        pageUnmap(mappedAddr);
+        return ret;
+    }
+
+    memset((void *)mappedAddr, 0, PAGE_SIZE);
+
     return ret;
 }
 
@@ -65,6 +106,8 @@ int zeroMmap(struct uAddrSpace *as, uaddr_t *uaddr, size_t size, uint32_t rights
     struct zeroMappedEntry *cust =
         (struct zeroMappedEntry *)zalloc(sizeof(struct zeroMappedEntry));
 
+    list_init(cust->listMapped);
+
     res->allowedRight = PAGING_MEM_READ | PAGING_MEM_WRITE | PAGING_MEM_EXEC | PAGING_MEM_USER;
     res->ops          = &zeroOps;
     res->customData   = cust;