Mapping Kernel to higher half causes crash

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amchk2025
Posts: 2
Joined: Thu Feb 20, 2025 10:12 pm

Mapping Kernel to higher half causes crash

Post by amchk2025 »

I have been working on getting paging to work. The identity mapping works fine, the kernel boots and everything works.
However, when I try to remap the kernel to top 1G and make the changes to the linker script, it gets stuck in a boot-loop.

The only thing being setup before enabling paging is the GDT, but as far as I understand it should not break because the identity mapping still exists. Everything else (interrupts, keyboard, text mode) is setup after enabling paging.

Paging Code:

Code: Select all

void init_pgdir(){
  kpgdir = kmalloc(sizeof(uint32_t)*1024); // 4K page directory

  int offset = 0;

  for(int i = 0; i < 1024;i++){
    kpgdir[i] = PAGING_IS_WRITEABLE;
  }

  
  for(int i = 0; i < 100; i++){ 
    uint32_t* pgtb = kmalloc(sizeof(uint32_t)*1024); // 4k page table

    for(int j = 0; j < 1024; j++){
      pgtb[j] = (offset + (j * 0x1000)) | PAGING_IS_WRITEABLE | PAGING_IS_PRESENT;
    }

    offset += (1024*4096);
    kpgdir[i] = ((uint32_t)pgtb) | 3;
    kpgdir[i+768] = ((uint32_t)pgtb) | 3;
  }

  paging_load_directory(kpgdir);
}
Linker Script:

Code: Select all

OUTPUT_FORMAT(elf32-i386)
ENTRY(start)

SECTIONS
{
    /* Virtual address where the kernel thinks it is */
    . = 0xC0100000;

    .text : AT(ADDR(.text) - 0xC0000000)
    {
        code = .; _code = .; __code = .;
        *(.text)
        . = ALIGN(4096);
    }

    .data : AT(ADDR(.data) - 0xC0000000)
    {
        data = .; _data = .; __data = .;
        *(.data)
        *(.rodata)
        . = ALIGN(4096);
    }

    .bss : AT(ADDR(.bss) - 0xC0000000)
    {
        bss = .; _bss = .; __bss = .;
        *(.bss)
        . = ALIGN(4096);
    }

    end = . - 0xC0000000;
}
Qemu "-d int" output:

Code: Select all

SMM: enter
EAX=00000000 EBX=00000000 ECX=02000000 EDX=02000628
ESI=0000000b EDI=02000000 EBP=000a0000 ESP=00006c5c
EIP=000eeb76 EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00cf9b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000044 CCD=ffffffff CCO=EFLAGS
EFER=0000000000000000
SMM: after RSM
EAX=00000000 EBX=00000000 ECX=02000000 EDX=02000628
ESI=0000000b EDI=02000000 EBP=000a0000 ESP=00006c5c
EIP=000eeb76 EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000044 CCD=00000000 CCO=EFLAGS
EFER=0000000000000000
SMM: enter
EAX=000000b5 EBX=000f8a66 ECX=00001234 EDX=00006cff
ESI=00006cc4 EDI=06fff5ce EBP=00006c84 ESP=00006c84
EIP=00008a63 EFL=00000006 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =dd00 000dd000 ffffffff 008f9300
CS =f000 000f0000 ffffffff 008f9b00
SS =0000 00000000 ffffffff 008f9300
DS =0000 00000000 ffffffff 008f9300
FS =0000 00000000 ffffffff 008f9300
GS =0000 00000000 ffffffff 008f9300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=00006c84 CCO=ADDL
EFER=0000000000000000
SMM: after RSM
EAX=000000b5 EBX=000f8a66 ECX=00001234 EDX=00006cff
ESI=00006cc4 EDI=06fff5ce EBP=00006c84 ESP=00006c84
EIP=000f8a66 EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000044 CCD=00000000 CCO=EFLAGS
EFER=0000000000000000
SMM: enter
EAX=000000b5 EBX=00008a80 ECX=00005678 EDX=06feae70
ESI=000ec440 EDI=06fff5ce EBP=00006c84 ESP=00006c84
EIP=000f8a7d EFL=00000012 [----A--] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000008 CCD=00006c70 CCO=ADDL
EFER=0000000000000000
SMM: after RSM
EAX=000000b5 EBX=00008a80 ECX=00005678 EDX=06feae70
ESI=000ec440 EDI=06fff5ce EBP=00006c84 ESP=00006c84
EIP=00008a80 EFL=00000006 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =dd00 000dd000 ffffffff 00809300
CS =f000 000f0000 ffffffff 00809b00
SS =0000 00000000 ffffffff 00809300
DS =0000 00000000 ffffffff 00809300
FS =0000 00000000 ffffffff 00809300
GS =0000 00000000 ffffffff 00809300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000004 CCD=00000001 CCO=EFLAGS
EFER=0000000000000000
Servicing hardware INT=0x08
SMM: enter
EAX=000000b5 EBX=000f8a66 ECX=00001234 EDX=000069ff
ESI=000069ae EDI=06fff5ce EBP=0000696e ESP=0000696e
EIP=00008a63 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =dd00 000dd000 ffffffff 008f9300
CS =f000 000f0000 ffffffff 008f9b00
SS =0000 00000000 ffffffff 008f9300
DS =0000 00000000 ffffffff 008f9300
FS =0000 00000000 ffffffff 008f9300
GS =c900 000c9000 ffffffff 008f9300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=0000696e CCO=ADDL
EFER=0000000000000000
SMM: after RSM
EAX=000000b5 EBX=000f8a66 ECX=00001234 EDX=000069ff
ESI=000069ae EDI=06fff5ce EBP=0000696e ESP=0000696e
EIP=000f8a66 EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000044 CCD=00000000 CCO=EFLAGS
EFER=0000000000000000
SMM: enter
EAX=000000b5 EBX=00008a80 ECX=00005678 EDX=00000005
ESI=00000000 EDI=06fff5ce EBP=0000696e ESP=0000696e
EIP=000f8a7d EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000044 CCD=00000000 CCO=EFLAGS
EFER=0000000000000000
SMM: after RSM
EAX=000000b5 EBX=00008a80 ECX=00005678 EDX=00000005
ESI=00000000 EDI=06fff5ce EBP=0000696e ESP=0000696e
EIP=00008a80 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =dd00 000dd000 ffffffff 00809300
CS =f000 000f0000 ffffffff 00809b00
SS =0000 00000000 ffffffff 00809300
DS =0000 00000000 ffffffff 00809300
FS =0000 00000000 ffffffff 00809300
GS =c900 000c9000 ffffffff 00809300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=00000001 CCO=EFLAGS
EFER=0000000000000000
SMM: enter
EAX=000000b5 EBX=000f8a66 ECX=00001234 EDX=000069ff
ESI=000069a8 EDI=06fff5ce EBP=00006968 ESP=00006968
EIP=00008a63 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =dd00 000dd000 ffffffff 00809300
CS =f000 000f0000 ffffffff 00809b00
SS =0000 00000000 ffffffff 00809300
DS =0000 00000000 ffffffff 00809300
FS =0000 00000000 ffffffff 00809300
GS =c900 000c9000 ffffffff 00809300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=00006968 CCO=ADDL
EFER=0000000000000000
SMM: after RSM
EAX=000000b5 EBX=000f8a66 ECX=00001234 EDX=000069ff
ESI=000069a8 EDI=06fff5ce EBP=00006968 ESP=00006968
EIP=000f8a66 EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000044 CCD=00000000 CCO=EFLAGS
EFER=0000000000000000
SMM: enter
EAX=000000b5 EBX=00008a80 ECX=00005678 EDX=00000003
ESI=06fd3300 EDI=06fff5ce EBP=00006968 ESP=00006968
EIP=000f8a7d EFL=00000012 [----A--] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000008 CCD=00006954 CCO=ADDL
EFER=0000000000000000
SMM: after RSM
EAX=000000b5 EBX=00008a80 ECX=00005678 EDX=00000003
ESI=06fd3300 EDI=06fff5ce EBP=00006968 ESP=00006968
EIP=00008a80 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =dd00 000dd000 ffffffff 00809300
CS =f000 000f0000 ffffffff 00809b00
SS =0000 00000000 ffffffff 00809300
DS =0000 00000000 ffffffff 00809300
FS =0000 00000000 ffffffff 00809300
GS =c900 000c9000 ffffffff 00809300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=00000001 CCO=EFLAGS
EFER=0000000000000000
SMM: enter
EAX=000000b5 EBX=000f8a66 ECX=00001234 EDX=000069ff
ESI=000069ae EDI=06fff5ce EBP=0000696e ESP=0000696e
EIP=00008a63 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =dd00 000dd000 ffffffff 00809300
CS =f000 000f0000 ffffffff 00809b00
SS =0000 00000000 ffffffff 00809300
DS =0000 00000000 ffffffff 00809300
FS =0000 00000000 ffffffff 00809300
GS =c900 000c9000 ffffffff 00809300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=0000696e CCO=ADDL
EFER=0000000000000000
SMM: after RSM
EAX=000000b5 EBX=000f8a66 ECX=00001234 EDX=000069ff
ESI=000069ae EDI=06fff5ce EBP=0000696e ESP=0000696e
EIP=000f8a66 EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000044 CCD=00000000 CCO=EFLAGS
EFER=0000000000000000
SMM: enter
EAX=000000b5 EBX=00008a80 ECX=00005678 EDX=00000005
ESI=00000000 EDI=06fff5ce EBP=0000696e ESP=0000696e
EIP=000f8a7d EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000044 CCD=00000000 CCO=EFLAGS
EFER=0000000000000000
SMM: after RSM
EAX=000000b5 EBX=00008a80 ECX=00005678 EDX=00000005
ESI=00000000 EDI=06fff5ce EBP=0000696e ESP=0000696e
EIP=00008a80 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =dd00 000dd000 ffffffff 00809300
CS =f000 000f0000 ffffffff 00809b00
SS =0000 00000000 ffffffff 00809300
DS =0000 00000000 ffffffff 00809300
FS =0000 00000000 ffffffff 00809300
GS =c900 000c9000 ffffffff 00809300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=00000001 CCO=EFLAGS
EFER=0000000000000000
SMM: enter
EAX=000000b5 EBX=000f8a66 ECX=00001234 EDX=000069ff
ESI=000069a8 EDI=06fff5ce EBP=00006968 ESP=00006968
EIP=00008a63 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =dd00 000dd000 ffffffff 00809300
CS =f000 000f0000 ffffffff 00809b00
SS =0000 00000000 ffffffff 00809300
DS =0000 00000000 ffffffff 00809300
FS =0000 00000000 ffffffff 00809300
GS =c900 000c9000 ffffffff 00809300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=00006968 CCO=ADDL
EFER=0000000000000000
SMM: after RSM
EAX=000000b5 EBX=000f8a66 ECX=00001234 EDX=000069ff
ESI=000069a8 EDI=06fff5ce EBP=00006968 ESP=00006968
EIP=000f8a66 EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000044 CCD=00000000 CCO=EFLAGS
EFER=0000000000000000
SMM: enter
EAX=000000b5 EBX=00008a80 ECX=00005678 EDX=00000003
ESI=06f33300 EDI=06fff5ce EBP=00006968 ESP=00006968
EIP=000f8a7d EFL=00000012 [----A--] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000f7460 00000037
IDT=     000f749e 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000008 CCD=00006954 CCO=ADDL
EFER=0000000000000000
SMM: after RSM
EAX=000000b5 EBX=00008a80 ECX=00005678 EDX=00000003
ESI=06f33300 EDI=06fff5ce EBP=00006968 ESP=00006968
EIP=00008a80 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =dd00 000dd000 ffffffff 00809300
CS =f000 000f0000 ffffffff 00809b00
SS =0000 00000000 ffffffff 00809300
DS =0000 00000000 ffffffff 00809300
FS =0000 00000000 ffffffff 00809300
GS =c900 000c9000 ffffffff 00809300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=00000001 CCO=EFLAGS
EFER=0000000000000000
check_exception old: 0xffffffff new 0x6
     0: v=06 e=0000 i=0 cpl=0 IP=0008:00000003 pc=00000003 SP=0010:c0104fb8 env->regs[R_EAX]=00000000
EAX=00000000 EBX=00009500 ECX=00100660 EDX=00000000
ESI=00000000 EDI=00000fff EBP=00000000 ESP=c0104fb8
EIP=00000003 EFL=00000282 [--S----] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00cf9a00 DPL=0 CS32 [-R-]
SS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000ca2b4 00000027
IDT=     00000000 000003ff
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=f000ff54 CCO=INCL
EFER=0000000000000000
check_exception old: 0xffffffff new 0xd
     1: v=0d e=0032 i=0 cpl=0 IP=0008:00000003 pc=00000003 SP=0010:c0104fb8 env->regs[R_EAX]=00000000
EAX=00000000 EBX=00009500 ECX=00100660 EDX=00000000
ESI=00000000 EDI=00000fff EBP=00000000 ESP=c0104fb8
EIP=00000003 EFL=00000282 [--S----] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00cf9a00 DPL=0 CS32 [-R-]
SS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000ca2b4 00000027
IDT=     00000000 000003ff
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=f000ff54 CCO=INCL
EFER=0000000000000000
check_exception old: 0xd new 0xd
     2: v=08 e=0000 i=0 cpl=0 IP=0008:00000003 pc=00000003 SP=0010:c0104fb8 env->regs[R_EAX]=00000000
EAX=00000000 EBX=00009500 ECX=00100660 EDX=00000000
ESI=00000000 EDI=00000fff EBP=00000000 ESP=c0104fb8
EIP=00000003 EFL=00000282 [--S----] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
CS =0008 00000000 ffffffff 00cf9a00 DPL=0 CS32 [-R-]
SS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
DS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
FS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
GS =0010 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     000ca2b4 00000027
IDT=     00000000 000003ff
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=00000000 DR1=00000000 DR2=00000000 DR3=00000000 
DR6=ffff0ff0 DR7=00000400
CCS=00000000 CCD=f000ff54 CCO=INCL
EFER=0000000000000000
check_exception old: 0x8 new 0xd
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nullplan
Member
Member
Posts: 1855
Joined: Wed Aug 30, 2017 8:24 am

Re: Mapping Kernel to higher half causes crash

Post by nullplan »

The QEMU log says that first you have an Undefined Opcode exception at IP=0008:00000003, and then multiple general protection faults at the same address. I haven't read your paging code in detail: Are you still identity mapping? Because you need the identity map in addition to the logical map to turn on paging.
Carpe diem!
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amchk2025
Posts: 2
Joined: Thu Feb 20, 2025 10:12 pm

Re: Mapping Kernel to higher half causes crash

Post by amchk2025 »

Yes I'm identity mapping along with mapping to 0xC0000000. Both PDE's point to the same page tables.

Thanks.
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Octocontrabass
Member
Member
Posts: 5722
Joined: Mon Mar 25, 2013 7:01 pm

Re: Mapping Kernel to higher half causes crash

Post by Octocontrabass »

amchk2025 wrote: ↑Thu Feb 20, 2025 10:23 pm

Code: Select all

ESP=c0104fb8
CR0=00000011
Your stack is located outside RAM. The first time a function tries to return to its caller, the CPU pops 0 instead of the correct return address and begins executing the IVT at address 0. This causes an exception, and since you also don't have a valid IDT, the CPU triple faults.
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