Merge branch 'interrupts'
This commit is contained in:
commit
fe3d7ad832
@ -2,6 +2,7 @@
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#define IDT_H
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#define IDT_H
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#include "types.h"
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#include "types.h"
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#include "isr.h"
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struct IDT {
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struct IDT {
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uint32_t base;
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uint32_t base;
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@ -20,37 +21,4 @@ struct IDT createIDT(uint32_t base, uint16_t selector, uint8_t flags);
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void encodeIDT(uint8_t* idtEntry, struct IDT source);
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void encodeIDT(uint8_t* idtEntry, struct IDT source);
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void initializeIDT();
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void initializeIDT();
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extern void isr0 ();
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extern void isr1 ();
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extern void isr2 ();
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extern void isr3 ();
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extern void isr4 ();
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extern void isr5 ();
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extern void isr6 ();
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extern void isr7 ();
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extern void isr8 ();
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extern void isr9 ();
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extern void isr10();
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extern void isr11();
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extern void isr12();
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extern void isr13();
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extern void isr14();
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extern void isr15();
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extern void isr16();
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extern void isr17();
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extern void isr18();
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extern void isr19();
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extern void isr20();
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extern void isr21();
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extern void isr22();
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extern void isr23();
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extern void isr24();
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extern void isr25();
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extern void isr26();
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extern void isr27();
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extern void isr28();
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extern void isr29();
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extern void isr30();
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extern void isr31();
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#endif // IDT_H
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#endif // IDT_H
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@ -10,4 +10,40 @@ struct registers{
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uint32_t eip, cs, eflags, useresp, ss;
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uint32_t eip, cs, eflags, useresp, ss;
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} __attribute__((packed));
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} __attribute__((packed));
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extern void isr_common_stub();
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extern void isr_handler(struct registers regs);
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extern void isr0 ();
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extern void isr1 ();
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extern void isr2 ();
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extern void isr3 ();
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extern void isr4 ();
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extern void isr5 ();
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extern void isr6 ();
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extern void isr7 ();
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extern void isr8 ();
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extern void isr9 ();
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extern void isr10();
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extern void isr11();
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extern void isr12();
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extern void isr13();
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extern void isr14();
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extern void isr15();
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extern void isr16();
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extern void isr17();
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extern void isr18();
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extern void isr19();
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extern void isr20();
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extern void isr21();
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extern void isr22();
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extern void isr23();
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extern void isr24();
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extern void isr25();
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extern void isr26();
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extern void isr27();
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extern void isr28();
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extern void isr29();
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extern void isr30();
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extern void isr31();
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#endif // ISR_H
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#endif // ISR_H
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71
src/boot.s
71
src/boot.s
@ -5,45 +5,24 @@ FLAGS equ MBALIGN | MEMINFO ; this is the Multiboot 'flag' field
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MAGIC equ 0x1BADB002 ; 'magic number' lets bootloader find the header
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MAGIC equ 0x1BADB002 ; 'magic number' lets bootloader find the header
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CHECKSUM equ -(MAGIC + FLAGS) ; checksum of above, to prove we are multiboot
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CHECKSUM equ -(MAGIC + FLAGS) ; checksum of above, to prove we are multiboot
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; Declare a multiboot header that marks the program as a kernel. These are magic
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; values that are documented in the multiboot standard. The bootloader will
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; search for this signature in the first 8 KiB of the kernel file, aligned at a
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; 32-bit boundary. The signature is in its own section so the header can be
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; forced to be within the first 8 KiB of the kernel file.
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section .multiboot
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section .multiboot
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align 4
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align 4
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dd MAGIC
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dd MAGIC
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dd FLAGS
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dd FLAGS
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dd CHECKSUM
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dd CHECKSUM
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; The multiboot standard does not define the value of the stack pointer register
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; (esp) and it is up to the kernel to provide a stack. This allocates room for a
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; small stack by creating a symbol at the bottom of it, then allocating 16384
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; bytes for it, and finally creating a symbol at the top. The stack grows
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; downwards on x86. The stack is in its own section so it can be marked nobits,
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; which means the kernel file is smaller because it does not contain an
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; uninitialized stack. The stack on x86 must be 16-byte aligned according to the
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; System V ABI standard and de-facto extensions. The compiler will assume the
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; stack is properly aligned and failure to align the stack will result in
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; undefined behavior.
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section .bss
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section .bss
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align 16
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align 16
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stack_bottom:
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stack_bottom:
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resb 16384 ; 16 KiB
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resb 16384 ; 16 KiB
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stack_top:
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stack_top:
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; The linker script specifies _start as the entry point to the kernel and the
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; bootloader will jump to this position once the kernel has been loaded. It
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; doesn't make sense to return from this function as the bootloader is gone.
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; Declare _start as a function symbol with the given symbol size.
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section .text
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section .text
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global reloadSegments ; Flush GDT
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global reloadSegments ; Flush GDT
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reloadSegments:
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reloadSegments:
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; Reload CS register containing code selector:
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JMP 0x08:reload_CS ; 0x08 points at the new code selector
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JMP 0x08:reload_CS ; 0x08 points at the new code selector
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reload_CS:
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reload_CS:
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; Reload data segment registers:
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MOV AX, 0x10 ; 0x10 points at the new data selector
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MOV AX, 0x10 ; 0x10 points at the new data selector
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MOV DS, AX
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MOV DS, AX
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MOV ES, AX
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MOV ES, AX
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@ -56,7 +35,7 @@ reload_CS:
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[GLOBAL isr%1] ; %1 accesses the first parameter.
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[GLOBAL isr%1] ; %1 accesses the first parameter.
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isr%1:
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isr%1:
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cli
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cli
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push byte 0
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push byte %1
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push byte %1
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push byte %1
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jmp isr_common_stub
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jmp isr_common_stub
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%endmacro
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%endmacro
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@ -102,12 +81,8 @@ ISR_NOERRCODE 29
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ISR_NOERRCODE 30
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ISR_NOERRCODE 30
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ISR_NOERRCODE 31
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ISR_NOERRCODE 31
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[EXTERN isr_handler]
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[EXTERN isr_handler]
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; This is our common ISR stub. It saves the processor state, sets
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; up for kernel mode segments, calls the C-level fault handler,
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; and finally restores the stack frame.
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isr_common_stub:
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isr_common_stub:
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pusha ; Pushes edi,esi,ebp,esp,ebx,edx,ecx,eax
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pusha ; Pushes edi,esi,ebp,esp,ebx,edx,ecx,eax
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@ -133,54 +108,12 @@ isr_common_stub:
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sti
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sti
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iret ; pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP
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iret ; pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP
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global _start:function (_start.end - _start)
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global _start:function (_start.end - _start)
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_start:
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_start:
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; The bootloader has loaded us into 32-bit protected mode on a x86
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; machine. Interrupts are disabled. Paging is disabled. The processor
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; state is as defined in the multiboot standard. The kernel has full
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; control of the CPU. The kernel can only make use of hardware features
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; and any code it provides as part of itself. There's no printf
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; function, unless the kernel provides its own <stdio.h> header and a
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; printf implementation. There are no security restrictions, no
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; safeguards, no debugging mechanisms, only what the kernel provides
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; itself. It has absolute and complete power over the
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; machine.
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; To set up a stack, we set the esp register to point to the top of our
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; stack (as it grows downwards on x86 systems). This is necessarily done
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; in assembly as languages such as C cannot function without a stack.
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mov esp, stack_top
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mov esp, stack_top
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; This is a good place to initialize crucial processor state before the
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; high-level kernel is entered. It's best to minimize the early
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; environment where crucial features are offline. Note that the
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; processor is not fully initialized yet: Features such as floating
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; point instructions and instruction set extensions are not initialized
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; yet. The GDT should be loaded here. Paging should be enabled here.
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; C++ features such as global constructors and exceptions will require
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; runtime support to work as well.
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; Enter the high-level kernel. The ABI requires the stack is 16-byte
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; aligned at the time of the call instruction (which afterwards pushes
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; the return pointer of size 4 bytes). The stack was originally 16-byte
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; aligned above and we've since pushed a multiple of 16 bytes to the
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; stack since (pushed 0 bytes so far) and the alignment is thus
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; preserved and the call is well defined.
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; note, that if you are building on Windows, C functions may have "_" prefix in assembly: _kernel_main
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extern kernel_main
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extern kernel_main
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call kernel_main
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call kernel_main
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; If the system has nothing more to do, put the computer into an
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; infinite loop. To do that:
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; 1) Disable interrupts with cli (clear interrupt enable in eflags).
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; They are already disabled by the bootloader, so this is not needed.
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; Mind that you might later enable interrupts and return from
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; kernel_main (which is sort of nonsensical to do).
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; 2) Wait for the next interrupt to arrive with hlt (halt instruction).
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; Since they are disabled, this will lock up the computer.
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; 3) Jump to the hlt instruction if it ever wakes up due to a
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; non-maskable interrupt occurring or due to system management mode.
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cli
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cli
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.hang: hlt
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.hang: hlt
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@ -1,4 +1,5 @@
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#include "gdt.h"
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#include "gdt.h"
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#include "print.h"
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extern void reloadSegments();
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extern void reloadSegments();
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@ -11,6 +12,10 @@ void encodeGDT(uint8_t* gdtEntry, struct GDT source) {
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// Size: 1 (32 bit protected mode)
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// Size: 1 (32 bit protected mode)
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gdtEntry[6] = 0xC0;
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gdtEntry[6] = 0xC0;
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}
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}
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else if (source.limit == 0) {
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// Don't set any granularity for null entry
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gdtEntry[6] = 0;
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}
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else {
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else {
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// Granularity: 0 (1 byte segments)
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// Granularity: 0 (1 byte segments)
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// Size: 1
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// Size: 1
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@ -15,7 +15,6 @@ void kernel_main(void) {
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initializeIDT();
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initializeIDT();
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printToMonitor("Hello\n");
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printToMonitor("Hello\n");
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printIntToMonitor(10, 10);
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printIntToMonitor(10, 10);
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asm ("int $0x3");
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asm("int $0x01");
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asm ("int $0x4");
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}
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}
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