Problems with asm code inside a c script (at linking with other asm script)


i will explain my problem...
I'm coding a kernel in c + assembly, and when I coded some asm in-line in the main c script with gcc as compiler I had this problem:
All looked fine, the script compiled as always, without errors or warnings, but when I tried to build the version of my program (the kernel I was building) had a linker problem, pointing to a script failure.
The installation is simple, it is like:
Step 1: nasm -f elf32 loader.asm -o kasm.o
Step 2: gcc -m32 -c kernel.c -o kc.o
Step 3: ld -m elf_i386 -T linker.ld -o kernel kasm.o kc.o
And you get a executable than can be run at qemu as kernel.
But when it came to the last step (the step 3) I had this problem:

kc.o: In function `enablePaging':
kernel.c:(.text+0x379): undefined reference to `__stack_chk_fail_local'
ld: kernel: hidden symbol `__stack_chk_fail_local' isn't defined
ld: final link failed: Bad value

I put here the 3 scripts involved in this process:
1: kernel.c, the main kernel file

 * kernel.c - version 0.0.1
 * This script is under the license of the distributed package, this license
 * can be found in the package itself
 * Script coded by Cristian Simón for the CKA Proyect
 * ----
 * License: GNU GPL v3
 * Coder: Cristian Simón
 * Proyect: CKA 

#define BLACK_BGROUND 0X07 /* black background */
#define WHITE_TXT 0x07 /* light gray on black text */
#define GREEN_TXT 0x02 /* light green on black text */
#define RED_TXT 0x04 /* light red on black text*/
#include <stddef.h>
#include <stdint.h>

void k_clear_screen();
void k_sleep_3sec();
unsigned int k_printf(char *message, unsigned int line, float color);

/* k_clear_screen : to clear the entire text screen */
void k_clear_screen()
    char *vidmem = (char *) 0xC00B8000;
    unsigned int i=0;
    while(i < (80*25*2))
        vidmem[i]=' ';

/* k_printf : the message and the line # */
unsigned int k_printf(char *message, unsigned int line, float color)
    char *vidmem = (char *) 0xC00B8000;
    unsigned int i=0;


        if(*message=='\n') // check for a new line
        } else {


/* k_sleep_10sec : to make a simple delay of aprox 10 sec */
void k_sleep_3sec()
    int c = 1, d = 1;
    for ( c = 1 ; c <= 20000 ; c++ )
    for ( d = 1 ; d <= 20000 ; d++ )
extern void loadPageDirectory(unsigned int*);
extern void enablePaging();
/*main function*/
void k_main() 
    k_printf(" Wellcome to", 0, WHITE_TXT);
    k_printf(" CKA!", 1, GREEN_TXT);
    k_printf("==============>", 2, WHITE_TXT);
    k_printf(" CKA stands for C Kernel with Assembly", 3, WHITE_TXT);
    k_printf(" Version 0.0.1, => based in the job of Debashis Barman", 4, WHITE_TXT);
    k_printf(" Contact => /", 5, WHITE_TXT);
    k_printf("           or in the github repository page", 6, WHITE_TXT);
    //here start the magic
    k_printf(" Starting Checkup", 0, RED_TXT);

    //paging setup
    k_printf(" [Proc1] Setting up paging", 1, WHITE_TXT);
    uint32_t page_directory[1024] __attribute__((aligned(4096)));
    //set each entry to not present
    int i;
    for(i = 0; i < 1024; i++)
        // This sets the following flags to the pages:
        //   Supervisor: Only kernel-mode can access them
        //   Write Enabled: It can be both read from and written to
        //   Not Present: The page table is not present
        page_directory[i] = 0x00000002;
    uint32_t first_page_table[1024] __attribute__((aligned(4096)));
    // holds the physical address where we want to start mapping these pages to.
    // in this case, we want to map these pages to the very beginning of memory.
    unsigned int w;

    //we will fill all 1024 entries in the table, mapping 4 megabytes
    for(w = 0; w < 1024; w++)
        // As the address is page aligned, it will always leave 12 bits zeroed.
        // Those bits are used by the attributes ;)
        first_page_table[w] = (w * 0x1000) | 3; // attributes: supervisor level, read/write, present.
    // attributes: supervisor level, read/write, present
    page_directory[0] = ((unsigned int)first_page_table) | 3;
    //paging asm
            ".globl loadPageDirectory\n\t" 
            "push %ebp\n\t"
            "mov %esp, %ebp\n\t"
            "mov 8(%esp), %eax\n\t"
            "mov %eax, %cr3\n\t"
            "mov %ebp, %esp\n\t"
            "pop %ebp\n\t"
            ".globl enablePaging\n\t"
            "push %ebp\n\t"
            "mov %esp, %ebp\n\t"
            "mov %cr0, %eax\n\t"
            "or $0x80000000, %eax\n\t"
            "mov %eax, %cr0\n\t"
            "mov %ebp, %esp\n\t"
            "pop %ebp\n\t"
    k_printf("[Proc1] Paging enabled!", 2, GREEN_TXT);

As you can see the asm code that is my suspect of cause the problem is at the end, in the second asm(...) block

Script 2: linker, to link loader and kernel


   /* The kernel will live at 3GB + 1MB in the virtual
      address space, which will be mapped to 1MB in the
      physical address space. */
   . = 0xC0100000;

   .text : AT(ADDR(.text) - 0xC0000000) {

   .data ALIGN (0x1000) : AT(ADDR(.data) - 0xC0000000) {

   .bss : AT(ADDR(.bss) - 0xC0000000) {
       _sbss = .;
       _ebss = .;

Script 3: Loader, in assembly.

global _loader                          ; Make entry point visible to linker.
extern k_main                           ; _main is defined elsewhere

; setting up the Multiboot header - see GRUB docs for details
MODULEALIGN equ  1<<0             ; align loaded modules on page boundaries
MEMINFO     equ  1<<1             ; provide memory map
FLAGS       equ  MODULEALIGN | MEMINFO  ; this is the Multiboot 'flag' field
MAGIC       equ    0x1BADB002     ; 'magic number' lets bootloader find the header
CHECKSUM    equ -(MAGIC + FLAGS)  ; checksum required

; This is the virtual base address of kernel space. It must be used to convert virtual
; addresses into physical addresses until paging is enabled. Note that this is not
; the virtual address where the kernel image itself is loaded -- just the amount that must
; be subtracted from a virtual address to get a physical address.
KERNEL_VIRTUAL_BASE equ 0xC0000000                  ; 3GB
KERNEL_PAGE_NUMBER equ (KERNEL_VIRTUAL_BASE >> 22)  ; Page directory index of kernel's 4MB PTE.

section .data
align 0x1000
    ; This page directory entry identity-maps the first 4MB of the 32-bit physical address space.
    ; All bits are clear except the following:
    ; bit 7: PS The kernel page is 4MB.
    ; bit 1: RW The kernel page is read/write.
    ; bit 0: P  The kernel page is present.
    ; This entry must be here -- otherwise the kernel will crash immediately after paging is
    ; enabled because it can't fetch the next instruction! It's ok to unmap this page later.
    dd 0x00000083
    times (KERNEL_PAGE_NUMBER - 1) dd 0                 ; Pages before kernel space.
    ; This page directory entry defines a 4MB page containing the kernel.
    dd 0x00000083
    times (1024 - KERNEL_PAGE_NUMBER - 1) dd 0  ; Pages after the kernel image.

section .text
align 4
    dd MAGIC
    dd FLAGS

; reserve initial kernel stack space -- that's 16k.
STACKSIZE equ 0x4000

; setting up entry point for linker
loader equ (_loader - 0xC0000000)
global loader

    ; NOTE: Until paging is set up, the code must be position-independent and use physical
    ; addresses, not virtual ones!
    mov ecx, (BootPageDirectory - KERNEL_VIRTUAL_BASE)
    mov cr3, ecx                                        ; Load Page Directory Base Register.

    mov ecx, cr4
    or ecx, 0x00000010                          ; Set PSE bit in CR4 to enable 4MB pages.
    mov cr4, ecx

    mov ecx, cr0
    or ecx, 0x80000000                          ; Set PG bit in CR0 to enable paging.
    mov cr0, ecx

    ; Start fetching instructions in kernel space.
    ; Since eip at this point holds the physical address of this command (approximately 0x00100000)
    ; we need to do a long jump to the correct virtual address of StartInHigherHalf which is
    ; approximately 0xC0100000.
    lea ecx, [StartInHigherHalf]
    jmp ecx                                                     ; NOTE: Must be absolute jump!

    ; Unmap the identity-mapped first 4MB of physical address space. It should not be needed
    ; anymore.
    mov dword [BootPageDirectory], 0
    invlpg [0]

    ; NOTE: From now on, paging should be enabled. The first 4MB of physical address space is
    ; mapped starting at KERNEL_VIRTUAL_BASE. Everything is linked to this address, so no more
    ; position-independent code or funny business with virtual-to-physical address translation
    ; should be necessary. We now have a higher-half kernel.
    mov esp, stack+STACKSIZE           ; set up the stack
    push eax                           ; pass Multiboot magic number

    ; pass Multiboot info structure -- WARNING: This is a physical address and may not be
    ; in the first 4MB!
    push ebx

    call  k_main                 ; call kernel proper
    hlt                          ; halt machine should kernel return

section .bss
align 32
    resb STACKSIZE      ; reserve 16k stack on a uint64_t boundary

Honestly I dont think the last one have nothing wrong, but is Freestanding coding with a language that I dont domine, so well, ensure is nothing bad at all.
Some specs of the kernel that could be helpfull:
The part that does error is related to paging.
It works in "Higher Half", but I dont thing this disturb anything.

asked on Stack Overflow Jul 22, 2017 by Rottenheimer2

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