feat(kernel): add vectors.S and Exceptions.h/c as a stub for future exceptions handling

Kernel/CMakeLists.txt

@@ -5,7 +5,7 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 file(GLOB_RECURSE KERNEL_SOURCES CMAKE_CONFIGURE_DEPENDS 
     ${CMAKE_CURRENT_SOURCE_DIR}/Source/KernelMain.c
     ${CMAKE_CURRENT_SOURCE_DIR}/Source/Arch/entry.S
-#    ${CMAKE_CURRENT_SOURCE_DIR}/Source/IO/*.c
+    ${CMAKE_CURRENT_SOURCE_DIR}/Source/Arch/vectors.S
     ${CMAKE_CURRENT_SOURCE_DIR}/Source/**/*.c
 )
 

Kernel/Include/Arch/Exceptions.h

@@ -0,0 +1,67 @@
+#pragma once
+#include <types.h>
+
+typedef struct ExceptionsContext {
+    UInt64 x0;
+    UInt64 x1;
+    UInt64 x2;
+    UInt64 x3;
+    UInt64 x4;
+    UInt64 x5;
+    UInt64 x6;
+    UInt64 x7;
+    UInt64 x8;
+    UInt64 x9;
+    UInt64 x10;
+    UInt64 x11;
+    UInt64 x12;
+    UInt64 x13;
+    UInt64 x14;
+    UInt64 x15;
+    UInt64 x16;
+    UInt64 x17;
+    UInt64 x18;
+    UInt64 x19;
+    UInt64 x20;
+    UInt64 x21;
+    UInt64 x22;
+    UInt64 x23;
+    UInt64 x24;
+    UInt64 x25;
+    UInt64 x26;
+    UInt64 x27;
+    UInt64 x28;
+    UInt64 x29; // fp
+    UInt64 x30; // lr
+    UInt64 elr_el1; // pc
+    UInt64 spsr_el1; // cpu status
+    UInt64 esr_el1; // error reason
+} ExceptionsContext;
+
+typedef enum ExceptionsType {
+    // curr el with sp0 (EL1t)
+    // usually dont happen cuz we switch to sp_el1, but just in case
+    ExceptionsSyncEl1t,
+    ExceptionsIRQEl1t,
+    ExceptionsFIQEl1t,
+    ExceptionsSErrorEl1t,
+
+    // curr el with sp1 (EL1h)
+    // exception in kernel space
+    ExceptionsSyncEl1h,
+    ExceptionsIRQEl1h,
+    ExceptionsFIQEl1h,
+    ExceptionsSErrorEl1h,
+
+    // lower EL 64-bit from userspace
+    ExceptionsSyncEl064,
+    ExceptionsIRQEl064,
+    ExceptionsFIQEl064,
+    ExceptionsSErrorEl064,
+
+    // lower EL 32-bit from userspace
+    ExceptionsSyncEl032,
+    ExceptionsIRQEl032,
+    ExceptionsFIQEl032,
+    ExceptionsSErrorEl032,
+} ExceptionsType;

Kernel/Source/Arch/Exceptions.c

@@ -0,0 +1,10 @@
+#include <Arch/Exceptions.h>
+#include <Arch/CPU.h>
+#include <IO/IOSerial.h>
+
+void ExceptionsHandler(ExceptionsContext* context, ExceptionsType type) {
+    IOSerialPutString("Exception occurred");
+    while (1) {
+        CPUWaitForInterrupt();
+    }
+}

Kernel/Source/Arch/entry.S

@@ -1,5 +1,6 @@
 .section .text.boot, "ax"
 .global _start
 _start:
+    bl ExceptionsVectorsInit
     bl KernelMain
     b .

Kernel/Source/Arch/vectors.S

@@ -0,0 +1,90 @@
+.macro ventry type
+    .align 7
+    sub sp, sp, #272 // save 272 bytes of stack
+    stp x0, x1, [sp, #0] // move stack 
+    mov x1, #\type // move type to x1
+    b ExceptionsTrapEntry
+.endm
+
+.section .text.vectors
+.align 11
+.global vectors
+ExceptionsVectorsTable:
+    // EL1t (curr EL with SP0)
+    ventry 0 // Sync
+    ventry 1 // IRQ
+    ventry 2 // FIQ
+    ventry 3 // SError
+
+    // EL1h (curr EL with SP1)
+    ventry 4 // Sync
+    ventry 5 // IRQ
+    ventry 6 // FIQ
+    ventry 7 // SError
+
+    // EL0 (lower EL 64-bit from userspace)
+    ventry 8 // Sync
+    ventry 9 // IRQ
+    ventry 10 // FIQ
+    ventry 11 // SError
+
+    // EL0 (lower EL 32-bit from userspace)
+    ventry 12; ventry 13; ventry 14; ventry 15
+
+ExceptionsTrapEntry:
+    stp x2, x3, [sp, #16 * 1]
+    stp x4, x5, [sp, #16 * 2]
+    stp x6, x7, [sp, #16 * 3]
+    stp x8, x9, [sp, #16 * 4]
+    stp x10, x11, [sp, #16 * 5]
+    stp x12, x13, [sp, #16 * 6]
+    stp x14, x15, [sp, #16 * 7]
+    stp x16, x17, [sp, #16 * 8]
+    stp x18, x19, [sp, #16 * 9]
+    stp x20, x21, [sp, #16 * 10]
+    stp x22, x23, [sp, #16 * 11]
+    stp x24, x25, [sp, #16 * 12]
+    stp x26, x27, [sp, #16 * 13]
+    stp x28, x29, [sp, #16 * 14]
+
+    mrs x21, elr_el1
+    mrs x22, spsr_el1
+    mrs x23, esr_el1
+
+    stp x30, x21, [sp, #16 * 15]
+    stp x22, x23, [sp, #16 * 16]
+
+    mov x0, sp
+    bl ExceptionsHandler
+
+    ldp x22, x23, [sp, #16 * 16]
+    msr spsr_el1, x22
+
+    ldp x30, x21, [sp, #16 * 15]
+    msr elr_el1, x21
+
+    ldp x28, x29, [sp, #16 * 14]
+    ldp x26, x27, [sp, #16 * 13]
+    ldp x24, x25, [sp, #16 * 12]
+    ldp x22, x23, [sp, #16 * 11]
+    ldp x20, x21, [sp, #16 * 10]
+    ldp x18, x19, [sp, #16 * 9]
+    ldp x16, x17, [sp, #16 * 8]
+    ldp x14, x15, [sp, #16 * 7]
+    ldp x12, x13, [sp, #16 * 6]
+    ldp x10, x11, [sp, #16 * 5]
+    ldp x8, x9, [sp, #16 * 4]
+    ldp x6, x7, [sp, #16 * 3]
+    ldp x4, x5, [sp, #16 * 2]
+    ldp x2, x3, [sp, #16 * 1]
+    ldp x0, x1, [sp, #0]
+
+    add sp, sp, #272
+    eret
+
+.global ExceptionsVectorsInit
+ExceptionsVectorsInit:
+    adr x0, ExceptionsVectorsTable
+    msr vbar_el1, x0
+    isb
+    ret

Kernel/Source/KernelMain.c

@@ -3,4 +3,6 @@
 
 void KernelMain(void) {
     IOSerialPutString("Meow nya!!\n");
+    __asm__ volatile ("brk #0");
+    IOSerialPutString("How\r\n");
 }