From cca78b269dd889233268bf47080c3fd2a655c25c Mon Sep 17 00:00:00 2001
From: Mathieu Maret <mathieu.maret@gmail.com>
Date: Thu, 8 Feb 2024 00:07:12 +0100
Subject: [PATCH] init: use zero driver for stack alloc

---
 core/elf.c  |  4 +---
 core/main.c | 37 +++++++++++++++++++------------------
 2 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/core/elf.c b/core/elf.c
index f87572d..7837143 100644
--- a/core/elf.c
+++ b/core/elf.c
@@ -13,13 +13,11 @@
  * @return 0 when the program is not a valid ELF
  */
 
-uaddr_t loadElfProg(const char *prog, struct process * proc)
+uaddr_t loadElfProg(const char *prog, struct process *proc)
 {
     int i;
     uaddr_t lastUserAddr = 0;
 
-
-
 /* e_ident value */
 #define ELFMAG0 0x7f
 #define ELFMAG1 'E'
diff --git a/core/main.c b/core/main.c
index 8bed568..2db8bec 100644
--- a/core/main.c
+++ b/core/main.c
@@ -84,27 +84,28 @@ void loadUserSpace()
         return;
     }
 
-    struct process *proc = processCreate("init");
+    {
+        struct process *proc = processCreate("init");
+        struct uAddrSpace *as = processGetAddrSpace(proc);
 
-    threadChangeCurrentContext(processGetMMUContext(proc));
-    uaddr_t prog = loadElfProg(buf + FILE_HEADER_SIZE, proc);
-    if (prog == (uaddr_t)NULL) {
-        free(buf);
-        return;
+        threadChangeCurrentContext(processGetMMUContext(proc));
+        uaddr_t prog = loadElfProg(buf + FILE_HEADER_SIZE, proc);
+        if (prog == (uaddr_t)NULL) {
+            free(buf);
+            return;
+        }
+
+        // Alloc user stack
+        size_t stackSize = PAGE_SIZE * 2;
+        uaddr_t stack    = PAGING_TOP_USER_ADDRESS - stackSize + 1;
+        zeroMmap(as, &stack, stackSize, PAGING_MEM_USER | PAGING_MEM_WRITE | PAGING_MEM_READ,
+                 0);
+
+        threadCreateUser("init", proc, prog, 0, 0, stack + stackSize - 4);
+        processUnref(proc);
+        threadChangeCurrentContext(NULL);
     }
 
-    // Alloc user stack
-    uaddr_t stackTop    = 0xfffffffc;
-    uaddr_t stackBottom = ALIGN_DOWN(stackTop, PAGE_SIZE);
-    paddr_t stackPhy    = allocPhyPage(1);
-    assert(pageMap(stackBottom, stackPhy,
-                   PAGING_MEM_USER | PAGING_MEM_WRITE | PAGING_MEM_READ) == 0);
-    unrefPhyPage(stackPhy);
-
-    threadCreateUser("init", proc, prog, 0, 0, stackTop);
-    processUnref(proc);
-    threadChangeCurrentContext(NULL);
-
     free(buf);
 }