Problem with Memory Management

danipiresk · Post by **danipiresk** » Mon Nov 30, 2009 12:21 pm

Hi,
I am have a problem with memory management...

Well,
Code Test:
[cide]
typedef struct {
int dia, mes, ano;
} calendario;

-----------------------

calendar * d;
d = malloc (sizeof(calendar));
d->day = 30;
d->moth = 11;
d->year = 2009;

printf("test malloc.: %d/%d/%d\n", d->day, d->moth, d->year);

free(d);
[/code]

The result:
test malloc.: -1/-1/2009
FREE: Address of memory is isconrrect (FFFFFFFF FFFD2537).

Assembly code (start)

Code: Select all

[BITS 32]
global start
start:
    mov esp, _sys_stack     ; Aponta a pilha para sua nova área de pilha
    jmp stublet

; Está parte DEVE ser 4Byte alinhada, assim resolvemos a questão usando 'ALIGN 4'
ALIGN 4
mboot:
    ; Macros multiboot para fazer umas poucas linhas mais tarde serem mais legíveis
    MULTIBOOT_PAGE_ALIGN	equ 1<<0
    MULTIBOOT_MEMORY_INFO	equ 1<<1
    MULTIBOOT_AOUT_KLUDGE	equ 1<<16
    MULTIBOOT_HEADER_MAGIC	equ 0x1BADB002
    MULTIBOOT_HEADER_FLAGS	equ MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO | MULTIBOOT_AOUT_KLUDGE
    MULTIBOOT_CHECKSUM	equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
    EXTERN code, bss, end

    ; Este é o cabeçalho do Multiboot GRUB. Uma assinatura de boot
    dd MULTIBOOT_HEADER_MAGIC
    dd MULTIBOOT_HEADER_FLAGS
    dd MULTIBOOT_CHECKSUM
    
    ; AOUT kludge - precisa ser endereços físicos. Faça uma nota disto:
    ; O script de linker preenche os dados para uns destes!
    dd mboot
    dd code
    dd bss
    dd end
    dd start

; Este é um laço sem fim.
stublet:
    extern _kernel_main
    call _kernel_main
    jmp $

; Este vai atribuir nossos novos registradores de segmento.
; Aqui temos um salto longo. Um salto que inclui um segmento assim como um offset.
; Este é declarado em C como 'extern void gdt_flush();'
global _gdt_flush
extern _gp
_gdt_flush:
    lgdt [_gp]
    mov ax, 0x10
    mov ds, ax
    mov es, ax
    mov fs, ax
    mov gs, ax
    jmp 0x08:flush2
flush2:
    ret

; Carrega a IDT definida como '_idtp' dentro do processador.
; Este é declarado em C como 'extern void idt_load();'
global _idt_load
extern _idtp
_idt_load:
    lidt [_idtp]
    ret

; Rotinas para Serviço de Interrupção (ISRs) diretamente aqui!
global _isr0
global _isr1
global _isr2
global _isr3
global _isr4
global _isr5
global _isr6
global _isr7
global _isr8
global _isr9
global _isr10
global _isr11
global _isr12
global _isr13
global _isr14
global _isr15
global _isr16
global _isr17
global _isr18
global _isr19
global _isr20
global _isr21
global _isr22
global _isr23
global _isr24
global _isr25
global _isr26
global _isr27
global _isr28
global _isr29
global _isr30
global _isr31

;  0: Divide By Zero Exception
_isr0:
    cli
    push byte 0
    push byte 0
    jmp isr_common_stub

;  1: Debug Exception
_isr1:
    cli
    push byte 0
    push byte 1
    jmp isr_common_stub

;  2: Non Maskable Interrupt Exception
_isr2:
    cli
    push byte 0
    push byte 2
    jmp isr_common_stub

;  3: Int 3 Exception
_isr3:
    cli
    push byte 0
    push byte 3
    jmp isr_common_stub

;  4: INTO Exception
_isr4:
    cli
    push byte 0
    push byte 4
    jmp isr_common_stub

;  5: Out of Bounds Exception
_isr5:
    cli
    push byte 0
    push byte 5
    jmp isr_common_stub

;  6: Invalid Opcode Exception
_isr6:
    cli
    push byte 0
    push byte 6
    jmp isr_common_stub

;  7: Coprocessor Not Available Exception
_isr7:
    cli
    push byte 0
    push byte 7
    jmp isr_common_stub

;  8: Double Fault Exception (With Error Code!)
_isr8:
    cli
    push byte 8
    jmp isr_common_stub

;  9: Coprocessor Segment Overrun Exception
_isr9:
    cli
    push byte 0
    push byte 9
    jmp isr_common_stub

; 10: Bad TSS Exception (With Error Code!)
_isr10:
    cli
    push byte 10
    jmp isr_common_stub

; 11: Segment Not Present Exception (With Error Code!)
_isr11:
    cli
    push byte 11
    jmp isr_common_stub

; 12: Stack Fault Exception (With Error Code!)
_isr12:
    cli
    push byte 12
    jmp isr_common_stub

; 13: General Protection Fault Exception (With Error Code!)
_isr13:
    cli
    push byte 13
    jmp isr_common_stub

; 14: Page Fault Exception (With Error Code!)
_isr14:
    cli
    push byte 14
    jmp isr_common_stub

; 15: Reserved Exception
_isr15:
    cli
    push byte 0
    push byte 15
    jmp isr_common_stub

; 16: Floating Point Exception
_isr16:
    cli
    push byte 0
    push byte 16
    jmp isr_common_stub

; 17: Alignment Check Exception
_isr17:
    cli
    push byte 0
    push byte 17
    jmp isr_common_stub

; 18: Machine Check Exception
_isr18:
    cli
    push byte 0
    push byte 18
    jmp isr_common_stub

; 19: Reserved
_isr19:
    cli
    push byte 0
    push byte 19
    jmp isr_common_stub

; 20: Reserved
_isr20:
    cli
    push byte 0
    push byte 20
    jmp isr_common_stub

; 21: Reserved
_isr21:
    cli
    push byte 0
    push byte 21
    jmp isr_common_stub

; 22: Reserved
_isr22:
    cli
    push byte 0
    push byte 22
    jmp isr_common_stub

; 23: Reserved
_isr23:
    cli
    push byte 0
    push byte 23
    jmp isr_common_stub

; 24: Reserved
_isr24:
    cli
    push byte 0
    push byte 24
    jmp isr_common_stub

; 25: Reserved
_isr25:
    cli
    push byte 0
    push byte 25
    jmp isr_common_stub

; 26: Reserved
_isr26:
    cli
    push byte 0
    push byte 26
    jmp isr_common_stub

; 27: Reserved
_isr27:
    cli
    push byte 0
    push byte 27
    jmp isr_common_stub

; 28: Reserved
_isr28:
    cli
    push byte 0
    push byte 28
    jmp isr_common_stub

; 29: Reserved
_isr29:
    cli
    push byte 0
    push byte 29
    jmp isr_common_stub

; 30: Reserved
_isr30:
    cli
    push byte 0
    push byte 30
    jmp isr_common_stub

; 31: Reserved
_isr31:
    cli
    push byte 0
    push byte 31
    jmp isr_common_stub

extern _fault_handler

; Partes comuns de ISR. Este salva o estado do processador, atribui
; os segmentos para modo kernel, chama o tratamento nível-C de faltas,
; e finalmente restaura a moldura da pilha.
isr_common_stub:
    pusha
    push ds
    push es
    push fs
    push gs
    mov ax, 0x10
    mov ds, ax
    mov es, ax
    mov fs, ax
    mov gs, ax
    mov eax, esp
    push eax
    mov eax, _fault_handler
    call eax
    pop eax
    pop gs
    pop fs
    pop es
    pop ds
    popa
    add esp, 8
    iret

global _irq0
global _irq1
global _irq2
global _irq3
global _irq4
global _irq5
global _irq6
global _irq7
global _irq8
global _irq9
global _irq10
global _irq11
global _irq12
global _irq13
global _irq14
global _irq15

; 32: IRQ0
_irq0:
    cli
    push byte 0
    push byte 32
    jmp irq_common_stub

; 33: IRQ1
_irq1:
    cli
    push byte 0
    push byte 33
    jmp irq_common_stub

; 34: IRQ2
_irq2:
    cli
    push byte 0
    push byte 34
    jmp irq_common_stub

; 35: IRQ3
_irq3:
    cli
    push byte 0
    push byte 35
    jmp irq_common_stub

; 36: IRQ4
_irq4:
    cli
    push byte 0
    push byte 36
    jmp irq_common_stub

; 37: IRQ5
_irq5:
    cli
    push byte 0
    push byte 37
    jmp irq_common_stub

; 38: IRQ6
_irq6:
    cli
    push byte 0
    push byte 38
    jmp irq_common_stub

; 39: IRQ7
_irq7:
    cli
    push byte 0
    push byte 39
    jmp irq_common_stub

; 40: IRQ8
_irq8:
    cli
    push byte 0
    push byte 40
    jmp irq_common_stub

; 41: IRQ9
_irq9:
    cli
    push byte 0
    push byte 41
    jmp irq_common_stub

; 42: IRQ10
_irq10:
    cli
    push byte 0
    push byte 42
    jmp irq_common_stub

; 43: IRQ11
_irq11:
    cli
    push byte 0
    push byte 43
    jmp irq_common_stub

; 44: IRQ12
_irq12:
    cli
    push byte 0
    push byte 44
    jmp irq_common_stub

; 45: IRQ13
_irq13:
    cli
    push byte 0
    push byte 45
    jmp irq_common_stub

; 46: IRQ14
_irq14:
    cli
    push byte 0
    push byte 46
    jmp irq_common_stub

; 47: IRQ15
_irq15:
    cli
    push byte 0
    push byte 47
    jmp irq_common_stub

extern _irq_handler

irq_common_stub:
    pusha
    push ds
    push es
    push fs
    push gs

    mov ax, 0x10
    mov ds, ax
    mov es, ax
    mov fs, ax
    mov gs, ax
    mov eax, esp

    push eax
    mov eax, _irq_handler
    call eax
    pop eax

    pop gs
    pop fs
    pop es
    pop ds
    popa
    add esp, 8
    iret

SECTION .bss
    resb 8192               ; Este reserva 8KBytes da memória aqui
_sys_stack:

mm.c

Code: Select all

void iniciar_memoria() //init memory
{
    mboot_mod_t * mod;
    mboot_info_t * mboot_info;

	int startheap = 0;
	int i, keep, discard;

	printf("[Sistema] Iniciando a gerencia de memoria:\n");

	// Verifica se o kernel está sendo iniciado pelo GRUB.
	if ((mboot_info->flags & MBF_MEMORY) == 0)
		panico("[Sistema] O GRUB nao setou a estutura com as informacoes da memoria."); //panico!

	printf("[Sistema] Memoria: Convencional=%dKB, Estendida=%dMB,\n",
				mboot_info->conv_mem, (mboot_info->ext_mem / 1024));

	// Se tiver módulos procura o endereço final dos módulos.
	if (mboot_info->flags & MBF_MODS)
	{
		for (i = 0; i < mboot_info->num_mods; i++){
			mod = (mboot_mod_t *)(mboot_info->mods_adr - kvirt_to_phys) + i;
			if (mod->end_adr > startheap)
				startheap = mod->end_adr;
		}
	}

	// Converte o endereço final dos módulos para o endereço físico.
	startheap -= kvirt_to_phys;

	// Talvez o kernel foi lido depois, então o endereço final será o g_end.
	if ((unsigned)g_end > startheap)
		startheap = (uint32_t)g_end;

	// Setaremos agora o heap do kernel.
	g_heap = (char *)startheap;

	// Cálculo do tamanho do heap.
	g_max_heap_size = ((1024 + mboot_info->ext_mem) * 1024 - kvirt_to_phys) - startheap;

	printf("[Sistema] Kernel Heap: Tamanho=%dMB, Endereco virtual=%X\n", (g_max_heap_size / 1024) / 1024, g_heap);

	printf("[Sistema] Kernel: Endereco virtual=%X, Endereco fisico=%X\n",
			g_d_code, g_d_code + kvirt_to_phys);

	keep	= (g_d_data - g_code) + (g_d_bss - g_data) + (g_end - g_bss);
	discard	= (g_code - g_d_code) + (g_data - g_d_data) + (g_bss - g_d_bss);

	printf("[Sistema] Tamanho dos segmentos: Code=%dKB, Data=%dKB, Bss=%dKB, Total=%dKB\n",
		(unsigned)((g_d_data - g_d_code)/1024),(unsigned)((g_d_bss - g_d_data)/1024),
		(unsigned)((g_end - g_bss)/1024),    (unsigned)((keep + discard)/1024));

	mmpi = (mmblock_t*)(g_heap);
    mmpi->magic = NM_MEMORY;
    mmpi->size  = 1;
    mmpi->next  = NULL;

    g_curr_heap_size = 0;
}

void * malloc(uint32_t size)
{
    mmblock_t * pn, * pt;
    int total_size, n;

    // Calcula o espaço de memória que será necessário para armazenar o bloco e os dados.
    total_size = sizeof(mmblock_t) + size;

    // Se o tamanho for zero retorna NULL.
    if (size == 0) return NULL;

    // Percorrer a lista até encontrar um espaço capaz de armazenar o bloco e os dados.
    pn = mmpi;
    while (pn->next != NULL)
    {
        n = ((int)pn->next) - ((int)pn + sizeof(mmblock_t) + pn->size);
        // Em caso de uma lacuna na memória.
        if (total_size <= n)
        {
            pt = (mmblock_t*)((int)pn + (pn->size) + sizeof(mmblock_t));
            pt->magic = NM_MEMORY;
            pt->size  = size;
            pt->next  = pn->next;
            pn->next  = pt;

            g_curr_heap_size += total_size;

            return (void*)((int)pt + sizeof(mmblock_t));
        }
        if (pn->magic != NM_MEMORY)
        {
            panico("O Heap do kernel está corrompido."); //panico!
            return NULL;
        }
        pn = pn->next;
    }

    // Armazena no fim da memória.
    pt = (mmblock_t*)((int)pn + (pn->size) + sizeof(mmblock_t));
    pt->magic = NM_MEMORY;
    pt->size  = size;
    pt->next  = NULL;
    pn->next  = pt;

    g_curr_heap_size += total_size;
    return (void*)((int)pt + sizeof(mmblock_t));
}


// Libera memória
void free(void * mm)
{
    mmblock_t * pt, * pn;

    // Pega o bloco referente aquele endereço de memória.
    pt = (mmblock_t*)((int)mm - sizeof(mmblock_t));

    // Verifica se realmente é um bloco de memória.
    if (pt->magic != NM_MEMORY)
    {
        printf("Endereco de memoria incorreto(kfree %X %X).", pt->magic, (int)mm); //panico..
        return;
    }

    g_curr_heap_size -= (pt->size + sizeof(mmblock_t));

    // Mantém a lista encadeada e consistente.
    pn = mmpi;
    while(pn->next != NULL)
    {
        if (pn->next == pt)
        {
            pn->next = pt->next;
            return;
        }
        pn = pn->next;
    }
}

mm.h (header of mm.c)

Code: Select all

#ifndef __GM_H
#define __GM_H

char g_code[],	g_d_code[],	g_data[];
char g_d_data[],	g_bss[], g_d_bss[], g_end[];

char * g_heap;
unsigned g_curr_heap_size, g_max_heap_size;

#define NM_MEMORY 0xBABA01

typedef struct{
        uint32_t  magic;
        uint32_t  size;
        void   *next;
} mmblock_t;

mmblock_t * mmpi = NULL;

void iniciar_memory();

//----


void * malloc(uint32_t size);
void free(void * blk_UNUSED);
void * realloc(void * blk, uint32_t size);
void * zmalloc(uint32_t size);
void mmdump();

#endif

Thank's.

OBS: Sorry, for my bad english, I am brazilliam...

Combuster · Post by **Combuster** » Mon Nov 30, 2009 1:48 pm

You might want to save everybody the excess amounts of reading by applying debugging basics - you have a printf, use it!. Put some printouts in strategic locations (i.e. malloc), then check where the wrong values come from. Posting 10 pages of (irrelevant) code is only a strong indication that you have not bothered to try to find a solution yourself.

pcmattman · Post by **pcmattman** » Mon Nov 30, 2009 6:25 pm

Combuster wrote:Posting 10 pages of (irrelevant) code is only a strong indication that you have not bothered to try to find a solution yourself.

Just to back this up... I am on holiday and my only Internet access method is my mobile phone. Trawling through all that code looking for a solution is not enjoyable

That said, what is the value of 'kvirt_to_phys'? When malloc is called, are you sure the MM state is how you expect it to be? Add some extra printfs to malloc and free. As messy as it'll be initially, you will find your bug faster and then you can remove all that extra debugging (if you want cleaner output or code).

danipiresk · Post by **danipiresk** » Tue Dec 01, 2009 7:18 am

Wow, I was seeing now and I really did not configure a value to kvirt_to_phys..

danipiresk · Post by **danipiresk** » Wed Dec 02, 2009 3:59 pm

Ok, fixed!

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