Modify syscalls to fit Linux, add second heap, 'Pheap'.

Author: levex

apps/hw/hw

@@ -1,12 +1,10 @@
+static char *text = "Hello, world! LevOS and Linux cross-compatibility!\n";
 void main()
 {
-	char *text = "Hello, world!\n";
-	int file = -1;
-	/* syscall 1: open() eax=1 ebx=stdout(1) RET: eax=file*/
-	asm volatile("int $0x80":"=a"(file):"a"(1), "b"(1));
-	/* syscall 2: write() eax=2 ebx=buffer ecx=file RET: none*/
-	asm volatile("int $0x80": :"a"(2), "b"(text), "c"(file));
-	/* syscall 0: exit() eax=0 RET: none */
-	asm volatile("int $0x80": :"a"(0));
-	return;
+	/* syscall 4: write()      eax=4  ebx=file ecx=buffer edx=size RET: ecx=size*/
+	asm volatile("int $0x80": :"a"(4), "b"(0), "c"(text), "d"(52));
+	/* syscall 1: exit()       eax=1 ebx=err */
+	asm volatile("xor %eax, %eax\n");
+	asm volatile("int $0x80": :"a"(1), "b"(0));
+	while(1);
 }

apps/hw/hw.c

@@ -1,3 +1,5 @@
 apps:
 	i586-elf-gcc -c hw.c -o hw.o -std=gnu99 -ffreestanding -O2 -Wall -Wextra
 	i586-elf-gcc -T link.ld -o hw -ffreestanding -O2 -nostdlib hw.o  -lgcc
+	cp hw /mnt/floppy/bin/hw
+	sync

apps/hw/makefile

@@ -42,6 +42,7 @@ uint8_t elf_start(uint8_t *buf, elf_priv_data *priv UNUSED)
 	}
 	/* Map the virtual space */
 	uint32_t phys_loc = loader_get_unused_load_location();
+	uint32_t cr3 = pmalloc(4096);
 	/* Find first program header and loop through them */
 	elf_program_header_t *ph = (elf_program_header_t *)(buf + header->e_phoff);
 	for(int i = 0; i < header->e_phnum; i++, ph++)

exec/elfloader.c

@@ -24,20 +24,27 @@ void syscall()
 	//kprintf("SYSCALL! a: 0x%x b: 0x%x c:0x%x\n", eax, ebx, ecx);
 	switch(eax)
 	{
-		case 0: /* syscall 0: exit() eax=0 RET: none */
+		case 0: /* syscall 0: restart() */
+			break;
+		case 1: /* syscall 1: exit() eax=1 ebx=err */
 			_kill();
+			for(;;);
 			break;
-		case 1: /* syscall 1: open() eax=1 ebx=stdout(1) RET: eax=file*/
-			asm volatile("movl $1, %eax");
+		case 2: /* syscall 2: fork() eax = 2 ebx=pt_regs (?) */
+			break;
+		case 3: /* syscall 3: read() eax=3 ebx=file ecx=buf edx=size */
 			break;
-		case 2: /* syscall 2: write() eax=2 ebx=buffer ecx=file RET: none*/
-			switch(ecx)
+		case 4: /* syscall 4: write() eax=4 ebx=file ecx=buffer edx=size RET: ecx=size*/
+			switch(ebx)
 			{
 				case 0:
-					kprintf("%s\n", ebx);
+					kprintf("%s", ecx);
 					break;
 			}
 			break;
+		case 5: /* syscall 5: open() eax=5 ebx=file ecx=flags  edx=mode RET: eax=file */
+			asm volatile("movl $1, %eax");
+			break;
 		default:
 			break;
 	}

exec/syscalls.c

@@ -15,6 +15,7 @@ extern void mm_print_out();
 extern void paging_init();
 extern void paging_map_virtual_to_phys(uint32_t virt, uint32_t phys);
 
+extern char* pmalloc(size_t size); /* page aligned alloc */
 extern char* malloc(size_t size);
 extern void free(void *mem);
 

fda.img

@@ -17,6 +17,7 @@ typedef struct _process {
 	uint32_t esp;
 	uint32_t stacktop;
 	uint32_t eip;
+	uint32_t cr3;
 	uint32_t state;
 	void (*notify)(int);
 	struct _process* next;

include/memory.h

@@ -83,6 +83,7 @@ void _kill()
 	set_task(0);
 	free((void *)c->stacktop);
 	free(c);
+	pfree(c->cr3);
 	c->prev->next = c->next;
 	c->next->prev = c->prev;
 	set_task(1);
@@ -179,6 +180,7 @@ PROCESS* createProcess(char* name, uint32_t addr)
 	p->state = PROCESS_STATE_ALIVE;
 	p->notify = __notified;
 	p->esp = (uint32_t)malloc(4096);
+	asm volatile("mov %%cr3, %%eax":"=a"(p->cr3));
 	uint32_t* stack = (uint32_t *)(p->esp + 4096);
 	p->stacktop = p->esp;
 	*--stack = 0x00000202; // eflags
@@ -242,7 +244,6 @@ void schedule_noirq()
 	asm volatile("int $0x2e");
 	return;
 }
-
 void schedule()
 {
 	//asm volatile("add $0xc, %esp");
@@ -259,6 +260,7 @@ void schedule()
 	asm volatile("push %gs");
 	asm volatile("mov %%esp, %%eax":"=a"(c->esp));
 	c = c->next;
+	asm volatile("mov %%eax, %%cr3": :"a"(c->cr3));
 	asm volatile("mov %%eax, %%esp": :"a"(c->esp));
 	asm volatile("pop %gs");
 	asm volatile("pop %fs");

include/tasking.h

@@ -6,19 +6,25 @@
 #include "../include/pit.h"
 
 MODULE("MMU");
+#define MAX_PAGE_ALIGNED_ALLOCS 32
 
 uint32_t last_alloc = 0;
 uint32_t heap_end = 0;
 uint32_t heap_begin = 0;
-
+uint32_t pheap_begin = 0;
+uint32_t pheap_end = 0;
+uint8_t *pheap_desc = 0;
 uint32_t memory_used = 0;
 
 void mm_init(uint32_t kernel_end)
 {
 	last_alloc = kernel_end + 0x1000;
 	heap_begin = last_alloc;
-	heap_end = 0x400000;
+	pheap_end = 0x400000;
+	pheap_begin = pheap_end - (MAX_PAGE_ALIGNED_ALLOCS * 4096);
+	heap_end = pheap_begin;
 	memset((char *)heap_begin, 0, heap_end - heap_begin);
+	pheap_desc = (uint8_t *)malloc(MAX_PAGE_ALIGNED_ALLOCS);
 	mprint("Kernel heap starts at 0x%x\n", last_alloc);
 }
 
@@ -28,6 +34,8 @@ void mm_print_out()
 	kprintf("Memory free: %d bytes\n", heap_end - heap_begin - memory_used);
 	kprintf("Heap size: %d bytes\n", heap_end - heap_begin);
 	kprintf("Heap start: 0x%x\n", heap_begin);
+	kprintf("Heap end: 0x%x\n", heap_end);
+	kprintf("PHeap start: 0x%x\nPHeap end: 0x%x\n", pheap_begin, pheap_end);
 }
 
 void free(void *mem)
@@ -37,6 +45,32 @@ void free(void *mem)
 	alloc->status = 0;
 }
 
+void pfree(void *mem)
+{
+	if(mem < pheap_begin || mem > pheap_end) return;
+	/* Determine which page is it */
+	uint32_t ad = (uint32_t)mem;
+	ad -= pheap_begin;
+	ad /= 4096;
+	/* Now, ad has the id of the page */
+	pheap_desc[ad] = 0;
+	return;
+}
+
+char* pmalloc(size_t size)
+{
+	/* Loop through the avail_list */
+	for(int i = 0; i < MAX_PAGE_ALIGNED_ALLOCS; i++)
+	{
+		if(pheap_desc[i]) continue;
+		pheap_desc[i] = 1;
+		mprint("PAllocated from 0x%x to 0x%x\n", pheap_begin + i*4096, pheap_begin + (i+1)*4096);
+		return (char *)(pheap_begin + i*4096);
+	}
+	mprint("pmalloc: FATAL: failure!\n");
+	return 0;
+}
+
 char* malloc(size_t size)
 {
 	if(!size) return 0;