arch: i386: simplify IDT setup

Simplify the interrupt descriptor table setup and frame assembly.

Signed-off-by: Danny Holman <dholman@gymli.org>

5 files changed, 128 insertions, 31 deletions

diff --git a/arch/i386/boot/crti.s b/arch/i386/boot/crti.s
index 4e1e4cb..8386b77 100644
--- a/arch/i386/boot/crti.s
+++ b/arch/i386/boot/crti.s
@@ -1,15 +1,15 @@
 .section .init
+
 .global _init
 .type _init, @function
-
 _init:
         pushl %ebp
         movl %esp, %ebp
 
 .section .fini
+
 .global _fini
 .type _fini, @function
-
 _fini:
         pushl %ebp
         movl %esp, %ebp
diff --git a/arch/i386/boot/idt.c b/arch/i386/boot/idt.c
index d741381..dbcfaa2 100644
--- a/arch/i386/boot/idt.c
+++ b/arch/i386/boot/idt.c
@@ -5,17 +5,113 @@
 #include <kernel/string.h>
 #include <stdint.h>
 
+#define SEGMENT_PRESENT         0x80
+#define SEGMENT_RING0           0x00
+#define SEGMENT_RING3           0x60
+#define SEGMENT_STORAGE         0x00
+#define SEGMENT_INTERRUPT       0x0E
+#define IDT_EXCEPTION           (SEGMENT_PRESENT | SEGMENT_INTERRUPT)
+#define IDT_INTERRUPT           (SEGMENT_PRESENT | SEGMENT_INTERRUPT)
+
+#define IDT_MAX_DESCRIPTORS     256
+
+struct idt_entry {
+        uint16_t        isr_low;
+        uint16_t        kernel_cs;
+        uint8_t         reserved;
+        uint8_t         flags;
+        uint16_t        isr_high;
+} __attribute__((packed));
+
+struct idt_ptr {
+        uint16_t        limit;
+        uint32_t        base;
+} __attribute__((packed));
+
 __attribute__((aligned(0x10)))
 struct idt_entry idt[256];
 struct idt_ptr idtr;
 
+char *exceptions[] = {
+        "Division by zero",
+        "Debug",
+        "Non-maskable interrupt",
+        "Breakpoint",
+        "Overflow",
+        "Out-of-bounds",
+        "Invalid opcode",
+        "FPU not available",
+        "Double fault",
+        "RESERVED",
+        "Invalid TSS",
+        "Segment not present",
+        "Stack fault",
+        "General protection fault",
+        "Page fault",
+        "RESERVED",
+        "FPU exception",
+        "Alignment check",
+        "Machine check",
+        "FPU-SIMD exception",
+        "Virtualization exception",
+        "Control protection"
+        "RESERVED",
+        "Hypervisor injection",
+        "VMM exception",
+        "Security exception",
+        "RESERVED",
+        "Triple fault",
+        "RESERVED"
+};
+
 __attribute__((noreturn))
-void exception_handler(struct isr_frame *frame) {
-        kprintf("Error: CPU exception: %d\n", frame->vector);
+void halt_catch_fire(struct isr_frame *frame) {
+        kprintf("Registers at interrupt:\n");
+        kprintf("\tEAX = %x\n", frame->eax);
+        kprintf("\tEBX = %x\n", frame->ebx);
+        kprintf("\tECX = %x\n", frame->ecx);
+        kprintf("\tEDX = %x\n", frame->edx);
+        kprintf("\tESI = %x\n", frame->esi);
+        kprintf("\tEDI = %x\n", frame->edi);
+        kprintf("\tESP = %x\n", frame->esp);
+        kprintf("\tEBP = %x\n", frame->ebp);
+        kprintf("\tEIP = %x\n", frame->eip);
+        kprintf("\tEFLAGS = %x\n", frame->eflags);
+        kprintf("Current code selector: %d\n", frame->cs);
         __asm__ volatile("cli;hlt");
 }
 
-extern void idt_set_gate(uint8_t num, void (*handler)(void), uint16_t cs, uint8_t flags) {
+__attribute__((noreturn))
+void exception_handler(struct isr_frame *frame) {
+        switch (frame->vector) {
+                default:
+                        kprintf("Unhandled exception: %s\n", exceptions[frame->vector]);
+                        halt_catch_fire(frame);
+        }
+}
+
+void irq_dispatch(uint8_t irq, struct isr_frame *frame) {
+        return;
+}
+
+__attribute__((noreturn))
+void interrupt_handler(struct isr_frame *frame) {
+        if (frame->vector < 32)
+                exception_handler(frame);
+        else if (frame->vector > 32 && frame->vector < 48)
+                irq_dispatch(frame->vector - 16, frame);
+        switch (frame->vector) {
+                case 0x80:
+                        syscall_dispatch(frame);
+                        break;
+                default:
+                        kprintf("Error: Unmapped interrupt: %d\n", frame->vector);
+                        halt_catch_fire(frame);
+                        __asm__ volatile("cli;hlt");
+        }
+}
+
+void idt_set_gate(uint8_t num, void (*handler)(void), uint16_t cs, uint8_t flags) {
         struct idt_entry *desc = &idt[num];
         desc->isr_low = (uint16_t)(((uint32_t)handler >> 0) & 0xFFFF);
         desc->isr_high = (uint16_t)(((uint32_t)handler >> 16) & 0xFFFF);
@@ -26,7 +122,7 @@ extern void idt_set_gate(uint8_t num, void (*handler)(void), uint16_t cs, uint8_
 
 void idt_install(void) {
         idtr.limit = (uint16_t)sizeof(struct idt_entry) * 256 - 1;
-        idtr.base = (uint32_t)&idt[0];
+        idtr.base = (uint32_t)idt;
 
         idt_set_gate(0, isr_stub_0, 0x08, IDT_EXCEPTION);
         idt_set_gate(1, isr_stub_1, 0x08, IDT_EXCEPTION);
diff --git a/arch/i386/boot/isr.s b/arch/i386/boot/isr.s
index b5f8be5..76afa9f 100644
--- a/arch/i386/boot/isr.s
+++ b/arch/i386/boot/isr.s
@@ -4,6 +4,7 @@
 .global isr_stub_\num
 .type isr_stub_\num, @function
 isr_stub_\num:
+        cli
         pushl $\num
         jmp isr_frame_asm
 .endm
@@ -11,18 +12,32 @@ isr_stub_\num:
 .global isr_stub_\num
 .type isr_stub_\num, @function
 isr_stub_\num:
+        cli
         pushl $0
         pushl $\num
         jmp isr_frame_asm
 .endm
 
+.macro irq_stub num
+.global irq_stub_\num
+.type irq_stub_\num, @function
+irq_stub_\num:
+        cli
+        pushl $0
+        pushl $\num
+        jmp isr_frame_asm
+.endm
+
+.global syscall_stub
+syscall_stub:
+        pushl $0
+        pushl $0x80
+        jmp isr_frame_asm
+
 isr_frame_asm:
-        pushl %ebp
-        movl %esp, %ebp
         pushl %eax
         pushl %ebx
         pushl %ecx
-        pushl %ecx
         pushl %edx
         pushl %esi
         pushl %edi
@@ -36,22 +51,9 @@ isr_frame_asm:
         movl %cr4, %eax
         pushl %eax
 
-        movw %ds, %ax
-        pushl %eax
-        pushl $0
-        movw $0x10, %ax
-        movw %ax, %ds
-        movw %ax, %es
-        movw %ax, %ss
-
-        lea 0xC(%esp), %edi
+        lea -8(%esp), %edi
         pushl %edi
-        call exception_handler
-
-        popl %eax
-        popl %eax
-        movw %ax, %ds
-        movw %ax, %es
+        call interrupt_handler
 
         popl %eax
         movl %eax, %cr4
@@ -69,8 +71,7 @@ isr_frame_asm:
         popl %ebx
         popl %eax
 
-        popl %ebp
-        add $0x10, %esp
+        addl $4, %esp
         iret
 
 isr_no_err_stub 0
@@ -94,7 +95,7 @@ isr_err_stub    17
 isr_no_err_stub 18
 isr_no_err_stub 19
 isr_no_err_stub 20
-isr_no_err_stub 21
+isr_err_stub    21
 isr_no_err_stub 22
 isr_no_err_stub 23
 isr_no_err_stub 24
@@ -102,6 +103,6 @@ isr_no_err_stub 25
 isr_no_err_stub 26
 isr_no_err_stub 27
 isr_no_err_stub 28
-isr_no_err_stub 29
+isr_err_stub    29
 isr_err_stub    30
 isr_no_err_stub 31
diff --git a/arch/i386/include/kernel/idt.h b/arch/i386/include/kernel/idt.h
index 699eb96..190e15e 100644
--- a/arch/i386/include/kernel/idt.h
+++ b/arch/i386/include/kernel/idt.h
@@ -10,6 +10,7 @@
 #define SEGMENT_STORAGE         0x00
 #define SEGMENT_INTERRUPT       0x0E
 #define IDT_EXCEPTION           (SEGMENT_PRESENT | SEGMENT_INTERRUPT)
+#define IDT_INTERRUPT           (SEGMENT_PRESENT | SEGMENT_INTERRUPT)
 
 #define IDT_MAX_DESCRIPTORS     256
 
diff --git a/arch/i386/include/kernel/isr.h b/arch/i386/include/kernel/isr.h
index 61fe22f..9d88958 100644
--- a/arch/i386/include/kernel/isr.h
+++ b/arch/i386/include/kernel/isr.h
@@ -11,19 +11,18 @@ struct isr_frame {
 
         uint32_t edi;
         uint32_t esi;
+        uint32_t ebp;
+        uint32_t esp;
         uint32_t edx;
         uint32_t ecx;
         uint32_t ebx;
         uint32_t eax;
 
-        uint32_t ebp;
         uint32_t vector;
         uint32_t errno;
         uint32_t eip;
         uint32_t cs;
         uint32_t eflags;
-        uint32_t esp;
-        uint32_t dss;
 } __attribute__((packed));
 
 extern void isr_stub_0(void);