exception - Heap Gives Page Fault -

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i getting page fault means accessing invalid address. higher half kernel design chose follow. not see leads page fault. here kernel.c++

#include "types.h" #include "gdt.h" #include "stdio.h" #include "serial.h" #include "mem.h" #include "idt.h" #include "timer.h" #include "isr.h" #include "kbd.h" #include "mouse.h" #include "irq.h" #include "string.h" #include "terminal.h" #include "multiboot.h" #include "pmm.h" #include "heap.h"     //call class constructor //for global objects before //calling kernel typedef void (*constructor)(); extern "c" constructor start_ctors; extern "c" constructor end_ctors; extern "c" void callconstructors() {     for(constructor* = &start_ctors; != &end_ctors; i++)        (*i)(); }    extern "c" void kernelmain(uint32_t kernel_virtual_end,         uint32_t  kernel_physical_end,         uint32_t placeholder,         uint32_t kernel_physical_start, uint32_t  kernel_virtual_start,         multiboot_info_t *multiboot_structure,uint32_t magicnumber         )   {          cls();        printf("******kernel info********\n");        printf("kernel start virtual 0x%x\n" , kernel_virtual_start);        printf("kernel start physical 0x%x\n" , kernel_physical_start);        printf("kernel end virtual 0x%x\n" , kernel_virtual_end);        printf("kernel end physical 0x%x\n" , kernel_physical_end);        printf("magic 0x%x\n" , magicnumber);        printf("*************************"); //     printf("********ram info*********\n"); // // //     printf("memory upper : %d \n", multiboot_structure->mem_upper); //     printf("memory lower : %d \n", multiboot_structure->mem_lower); // //     printf("*************************\n");           gdt gt;        idt idt;        isr isr;        irq irq;        serialport sp;        isr.install_isrs();        irq.install_irqs();         timer timer;         timer.install_timer();         kbd kbd;          kbd.install_kbd_driver();           mouse mouse;         mouse.install_mouse_driver();         __asm__ __volatile__ ("sti");           phyiscalmemorymanager pmm(multiboot_structure);          kheap       kheap;         char        *ptr;          heap heap((&kheap));         heap.k_addblock(&kheap, (0x100000+0xc0000000), (0x100000+0xc0000000));         //ptr = (char*)heap.k_malloc(&kheap, 256);         //heap.k_free(&kheap, ptr);     while(1);    err:        while(1); }

ok can see commented out last lines.. k_malloc() there causing chaos . reason malloc's() bellow 0xc0100000 , minumum size can go kernel, because using virtual addresses and, 1mb grub related stuff. saying here heap.c++ :

#include "heap.h"   int heap::k_addblock(kheaplcab *heap, uintptr_t addr, uint32_t size) {         kheapblocklcab          *hb;         kheaphdrlcab            *hdr;          hb = (kheapblocklcab*)addr;         hb->size = size;         hb->used = 0;         hb->next = heap->fblock;         heap->fblock = hb;          hdr = (kheaphdrlcab*)&hb[1];         hdr->flagsize = hb->size - (sizeof(kheapblocklcab) + 32);          ++heap->bcnt;          hb->lastdsize = 0;         hb->lastdhdr = 0;          return 1; }  /*     behind , forward see if can merge chunks. */ void heap::k_free(kheaplcab *heap, void *ptr) {     kheaphdrlcab                *hdr, *phdr, *nhdr;     kheapblocklcab              *hb;     uint32_t                        sz;     uint8_t                     fg;       hdr = (kheaphdrlcab*)ptr;     hdr[-1].flagsize &= ~0x80000000;       phdr = 0;     /* find block located in */     (hb = heap->fblock; hb; hb = hb->next)     {         if (((uintptr_t)ptr > (uintptr_t)hb) && ((uintptr_t)ptr < (uintptr_t)hb + hb->size))         {              hdr = (kheaphdrlcab*)((uintptr_t)ptr - sizeof(kheaphdrlcab));               hdr->flagsize &= ~0x80000000;              hb->used -= hdr->flagsize;               if (hdr->prevsize)             {                 phdr = (kheaphdrlcab*)((uintptr_t)&hdr - (sizeof(kheaphdrlcab) + hdr->prevsize));             }             else             {                 phdr = 0;             }              /* next header */             nhdr = (kheaphdrlcab*)((uintptr_t)&hdr[1] + hdr->flagsize);             if ((uintptr_t)nhdr >= ((uintptr_t)hb + hb->size))             {                 nhdr = 0;             }              if (nhdr)             {                 if (!(nhdr->flagsize & 0x80000000))                 {                     /* combine */                     hdr->flagsize += sizeof(kheaphdrlcab) + nhdr->flagsize;                     hb->used -= sizeof(kheaphdrlcab);                     /* set next header prevsize */                     nhdr = (kheaphdrlcab*)((uintptr_t)&hdr[1] + hdr->flagsize);                     nhdr->prevsize = hdr->flagsize;                 }             }               if (phdr)             {                 if (!(phdr->flagsize & 0x80000000))                 {                     phdr->flagsize += sizeof(kheaphdrlcab) + hdr->flagsize;                     hb->used -= sizeof(kheaphdrlcab);                     hdr = phdr;                     nhdr = (kheaphdrlcab*)((uintptr_t)&hdr[1] + hdr->flagsize);                     if ((uintptr_t)nhdr < (uintptr_t)hb + sizeof(kheapblocklcab) + hb->size)                     {                         nhdr->prevsize = hdr->flagsize;                     }                 }             }              /* optimization */             if (hdr->flagsize > hb->lastdsize)             {                 hb->lastdsize = hdr->flagsize;                 hb->lastdhdr = hdr;             }              return;         }     }      printf("uhoh ptr:%p\n", ptr);     (hb = heap->fblock; hb; hb = hb->next) {         printf("lcab free looking @ block:%p next:%p ptr:%p end:%p\n", hb, hb->next, ptr, (uintptr_t)hb + hb->size);         if (((uintptr_t)ptr > (uintptr_t)hb)) {             printf("above\n");             if (((uintptr_t)ptr < ((uintptr_t)hb + hb->size))) {                 printf("found\n");             }         }     }     (;;);     /* uhoh.. should not happen.. */     return; }  /*     allocate chunk of memory specified size, , if     no memory chunk can found return zero. */ void* heap::k_malloc(kheaplcab *heap, uint32_t size) {     kheapblocklcab      *hb;     kheaphdrlcab        *hdr, *_hdr, *phdr;     uint32_t            sz;     uint8_t             fg;     uint32_t            checks;     uint32_t            bc;      checks = 0;     bc =0;       (hb = heap->fblock; hb; hb = hb->next) {         if ((hb->size - hb->used) >= (size + sizeof(kheaphdrlcab))) {             ++bc;              hdr = (kheaphdrlcab*)&hb[1];               phdr = 0;             while ((uintptr_t)hdr < ((uintptr_t)hb + hb->size)) {                 ++checks;                  fg = hdr->flagsize >> 31;                 sz = hdr->flagsize & 0x7fffffff;                  if (!fg)                 {                      if (sz >= size)                     {                          if (sz > (size + sizeof(kheaphdrlcab) + 16))                         {                              _hdr = (kheaphdrlcab*)((uintptr_t)&hdr[1] + size);                             _hdr->flagsize = sz - (size + sizeof(kheaphdrlcab));                             _hdr->prevsize = size;                             hdr->flagsize = 0x80000000 | size;                             hb->used += sizeof(kheaphdrlcab);                          }                         else                         {                             hdr->flagsize |= 0x80000000;                         }                         hb->used += size;                           return &hdr[1];                     }                 }                 phdr = hdr;                 hdr = (kheaphdrlcab*)((uintptr_t)&hdr[1] + sz);             }          }     }      return 0; }   heap::heap(kheaplcab *heap) {     heap->fblock = 0;     heap->bcnt = 0; }  heap::~heap() {  }

the problem malloc() think , because when coment out, works fine. accessing invalid address in function :

void* heap::k_malloc(kheaplcab *heap, uint32_t size) {     kheapblocklcab      *hb;     kheaphdrlcab        *hdr, *_hdr, *phdr;     uint32_t            sz;     uint8_t             fg;     uint32_t            checks;     uint32_t            bc;      checks = 0;     bc =0;       (hb = heap->fblock; hb; hb = hb->next) {         if ((hb->size - hb->used) >= (size + sizeof(kheaphdrlcab))) {             ++bc;              hdr = (kheaphdrlcab*)&hb[1];               phdr = 0;             while ((uintptr_t)hdr < ((uintptr_t)hb + hb->size)) {                 ++checks;                  fg = hdr->flagsize >> 31;                 sz = hdr->flagsize & 0x7fffffff;                  if (!fg)                 {                      if (sz >= size)                     {                          if (sz > (size + sizeof(kheaphdrlcab) + 16))                         {                              _hdr = (kheaphdrlcab*)((uintptr_t)&hdr[1] + size);                             _hdr->flagsize = sz - (size + sizeof(kheaphdrlcab));                             _hdr->prevsize = size;                             hdr->flagsize = 0x80000000 | size;                             hb->used += sizeof(kheaphdrlcab);                          }                         else                         {                             hdr->flagsize |= 0x80000000;                         }                         hb->used += size;                           return &hdr[1];                     }                 }                 phdr = hdr;                 hdr = (kheaphdrlcab*)((uintptr_t)&hdr[1] + sz);             }          }     }      return 0; }

. appreciated. here full source code in github : https://github.com/amanuel2/os_mirror


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