1 files changed, 257 insertions, 0 deletions
diff --git a/kernel.soso/alloc.c b/kernel.soso/alloc.c
new file mode 100644
index 00000000..eceb3aa5
--- /dev/null
+++ b/kernel.soso/alloc.c
@@ -0,0 +1,257 @@
+#include "common.h"
+#include "screen.h"
+#include "alloc.h"
+#include "vmm.h"
+#include "process.h"
+#include "debugprint.h"
+
+#define KMALLOC_MINSIZE		16
+
+extern uint32 *gKernelPageDirectory;
+
+static char *gKernelHeap = NULL;
+static uint32 gKernelHeapUsed = 0;
+
+
+void initializeKernelHeap()
+{
+    gKernelHeap = (char *) KERN_HEAP_BEGIN;
+
+    ksbrkPage(1);
+}
+
+void *ksbrkPage(int n)
+{
+    struct MallocHeader *chunk;
+    char *p_addr;
+    int i;
+
+    if ((gKernelHeap + (n * PAGESIZE_4M)) > (char *) KERN_HEAP_END) {
+        //Screen_PrintF("ERROR: ksbrk(): no virtual memory left for kernel heap !\n");
+        return (char *) -1;
+    }
+
+    chunk = (struct MallocHeader *) gKernelHeap;
+
+    for (i = 0; i < n; i++)
+    {
+        p_addr = getPageFrame4M();
+
+        //Screen_PrintF("DEBUG: ksbrkPage(): got 4M on physical %x\n", p_addr);
+
+        if ((int)(p_addr) < 0)
+        {
+            PANIC("PANIC: ksbrkPage(): no free page frame available !");
+            return (char *) -1;
+        }
+
+        addPageToPd(gKernelPageDirectory, gKernelHeap, p_addr, 0); //add PG_USER to allow user programs to read kernel heap
+
+        gKernelHeap += PAGESIZE_4M;
+    }
+
+    chunk->size = PAGESIZE_4M * n;
+    chunk->used = 0;
+
+    return chunk;
+}
+
+void *kmalloc(uint32 size)
+{
+    if (size==0)
+        return 0;
+
+    unsigned long realsize;
+    struct MallocHeader *chunk, *other;
+
+    if ((realsize = sizeof(struct MallocHeader) + size) < KMALLOC_MINSIZE)
+    {
+        realsize = KMALLOC_MINSIZE;
+    }
+
+    chunk = (struct MallocHeader *) KERN_HEAP_BEGIN;
+    while (chunk->used || chunk->size < realsize)
+    {
+        if (chunk->size == 0)
+        {
+            printkf("\nPANIC: kmalloc(): corrupted chunk on %x with null size (heap %x) !\nSystem halted\n", chunk, gKernelHeap);
+
+            PANIC("kmalloc()");
+
+            return 0;
+        }
+
+        chunk = (struct MallocHeader *)((char *)chunk + chunk->size);
+
+        if (chunk == (struct MallocHeader *) gKernelHeap)
+        {
+            if ((int)(ksbrkPage((realsize / PAGESIZE_4M) + 1)) < 0)
+            {
+                PANIC("kmalloc(): no memory left for kernel !\nSystem halted\n");
+
+                return 0;
+            }
+        }
+        else if (chunk > (struct MallocHeader *) gKernelHeap)
+        {
+            printkf("\nPANIC: kmalloc(): chunk on %x while heap limit is on %x !\nSystem halted\n", chunk, gKernelHeap);
+
+            PANIC("kmalloc()");
+
+            return 0;
+        }
+    }
+
+
+    if (chunk->size - realsize < KMALLOC_MINSIZE)
+    {
+        chunk->used = 1;
+    }
+    else
+    {
+        other = (struct MallocHeader *)((char *) chunk + realsize);
+        other->size = chunk->size - realsize;
+        other->used = 0;
+
+        chunk->size = realsize;
+        chunk->used = 1;
+    }
+
+    gKernelHeapUsed += realsize;
+
+    return (char *) chunk + sizeof(struct MallocHeader);
+}
+
+void kfree(void *v_addr)
+{
+    if (v_addr==(void*)0)
+        return;
+
+    struct MallocHeader *chunk, *other;
+
+    chunk = (struct MallocHeader *)((uint32)v_addr - sizeof(struct MallocHeader));
+    chunk->used = 0;
+
+    gKernelHeapUsed -= chunk->size;
+
+    //Merge free block with next free block
+    while ((other = (struct MallocHeader *)((char *)chunk + chunk->size))
+           && other < (struct MallocHeader *)gKernelHeap
+           && other->used == 0)
+    {
+        chunk->size += other->size;
+    }
+}
+
+static void sbrkPage(Process* process, int pageCount)
+{
+    if (pageCount > 0)
+    {
+        for (int i = 0; i < pageCount; ++i)
+        {
+            if ((process->heapNextUnallocatedPageBegin + PAGESIZE_4M) > (char*)USER_OFFSET_END)
+            {
+                return;
+            }
+
+            char * p_addr = getPageFrame4M();
+
+            if ((int)(p_addr) < 0)
+            {
+                //PANIC("sbrkPage(): no free page frame available !");
+                return;
+            }
+
+            addPageToPd(process->pd, process->heapNextUnallocatedPageBegin, p_addr, PG_USER);
+
+            process->heapNextUnallocatedPageBegin += PAGESIZE_4M;
+        }
+    }
+    else if (pageCount < 0)
+    {
+        pageCount *= -1;
+
+        for (int i = 0; i < pageCount; ++i)
+        {
+            if (process->heapNextUnallocatedPageBegin - PAGESIZE_4M >= process->heapBegin)
+            {
+                process->heapNextUnallocatedPageBegin -= PAGESIZE_4M;
+
+                //This also releases the page frame
+                removePageFromPd(process->pd, process->heapNextUnallocatedPageBegin, TRUE);
+            }
+        }
+    }
+}
+
+void initializeProcessHeap(Process* process)
+{
+    process->heapBegin = (char*) USER_OFFSET;
+    process->heapEnd = process->heapBegin;
+    process->heapNextUnallocatedPageBegin = process->heapBegin;
+
+    //Userland programs (their code, data,..) start from USER_OFFSET
+    //So we should leave some space for them by moving heap pointer.
+    //As a result userspace malloc functions start from a forward point (+ USER_EXE_IMAGE).
+
+    sbrk(process, USER_EXE_IMAGE);
+}
+
+void *sbrk(Process* process, int nBytes)
+{
+    printkf("sbrk:1: pid:%d nBytes:%d\n", process->pid, nBytes);
+
+    char* previousBreak = process->heapEnd;
+    printkf("before: %x\n", previousBreak);
+
+    if (nBytes > 0)
+    {
+        int remainingInThePage = process->heapNextUnallocatedPageBegin - process->heapEnd;
+
+        //Screen_PrintF("sbrk:2: remainingInThePage:%d\n", remainingInThePage);
+
+        if (nBytes > remainingInThePage)
+        {
+            int bytesNeededInNewPages = nBytes - remainingInThePage;
+            int neededNewPageCount = (bytesNeededInNewPages / PAGESIZE_4M) + 1;
+
+            //Screen_PrintF("sbrk:3: neededNewPageCount:%d\n", neededNewPageCount);
+
+            uint32 freePages = getFreePageCount();
+            if ((uint32)neededNewPageCount + 1 > freePages)
+            {
+                return (void*)-1;
+            }
+
+            sbrkPage(process, neededNewPageCount);
+        }
+    }
+    else if (nBytes < 0)
+    {
+        char* currentPageBegin = process->heapNextUnallocatedPageBegin - PAGESIZE_4M;
+
+        int remainingInThePage = process->heapEnd - currentPageBegin;
+
+        //Screen_PrintF("sbrk:4: remainingInThePage:%d\n", remainingInThePage);
+
+        if (-nBytes > remainingInThePage)
+        {
+            int bytesInPreviousPages = -nBytes - remainingInThePage;
+            int neededNewPageCount = (bytesInPreviousPages / PAGESIZE_4M) + 1;
+
+            //Screen_PrintF("sbrk:5: neededNewPageCount:%d\n", neededNewPageCount);
+
+            sbrkPage(process, -neededNewPageCount);
+        }
+    }
+
+    process->heapEnd += nBytes;
+    printkf("after: %x\n", process->heapEnd);
+
+    return previousBreak;
+}
+
+uint32 getKernelHeapUsed()
+{
+    return gKernelHeapUsed;
+}