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#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) {
//printkf("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();
//printkf("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;
//printkf("sbrk:2: remainingInThePage:%d\n", remainingInThePage);
if (nBytes > remainingInThePage) {
int bytesNeededInNewPages = nBytes - remainingInThePage;
int neededNewPageCount = (bytesNeededInNewPages / PAGESIZE_4M) + 1;
//printkf("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;
//printkf("sbrk:4: remainingInThePage:%d\n", remainingInThePage);
if (-nBytes > remainingInThePage) {
int bytesInPreviousPages = -nBytes - remainingInThePage;
int neededNewPageCount = (bytesInPreviousPages / PAGESIZE_4M) + 1;
//printkf("sbrk:5: neededNewPageCount:%d\n", neededNewPageCount);
sbrkPage(process, -neededNewPageCount);
}
}
process->heapEnd += nBytes;
printkf("after: %x\n", process->heapEnd);
return previousBreak;
}
uint32 getKernelHeapUsed() {
return gKernelHeapUsed;
}
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