From 06121c7075e91056820c674f192be460ef5eb656 Mon Sep 17 00:00:00 2001
From: Danny Holman <dholman@gymli.org>
Date: Sat, 15 Jan 2022 16:24:08 -0600
Subject: arch: i386: add support for IRQs and system calls

Add support for rudementary system calls and IRQ interrupts.

Signed-off-by: Danny Holman <dholman@gymli.org>
---
 arch/i386/boot/boot.s    |  4 ++++
 arch/i386/boot/idt.c     |  6 +++++-
 arch/i386/boot/pic.c     |  2 +-
 arch/i386/boot/syscall.c | 21 +++++++++++++++++++++
 arch/i386/boot/syscall.h |  9 +++++++++
 5 files changed, 40 insertions(+), 2 deletions(-)
 create mode 100644 arch/i386/boot/syscall.c
 create mode 100644 arch/i386/boot/syscall.h

(limited to 'arch/i386/boot')

diff --git a/arch/i386/boot/boot.s b/arch/i386/boot/boot.s
index 4b32ca2..91df039 100644
--- a/arch/i386/boot/boot.s
+++ b/arch/i386/boot/boot.s
@@ -71,6 +71,10 @@ _start:
         call idt_install
         call pic_remap
 
+        pushl $1
+        pushl print_hello
+        call register_syscall
+
         call kernel_main
         call jump_userspace
 
diff --git a/arch/i386/boot/idt.c b/arch/i386/boot/idt.c
index dbcfaa2..0789a17 100644
--- a/arch/i386/boot/idt.c
+++ b/arch/i386/boot/idt.c
@@ -1,4 +1,4 @@
-#include <kernel/idt.h>
+#include "syscall.h"
 #include <kernel/isr.h>
 #include <kernel/io.h>
 #include <kernel/pic.h>
@@ -157,6 +157,10 @@ void idt_install(void) {
         idt_set_gate(30, isr_stub_30, 0x08, IDT_EXCEPTION);
         idt_set_gate(31, isr_stub_31, 0x08, IDT_EXCEPTION);
 
+        idt_set_gate(128, syscall_stub, 0x08, IDT_INTERRUPT);
+
+        register_syscall(halt_catch_fire, 0);
+
         __asm__ volatile("lidt %0" : : "memory"(idtr));
         __asm__ volatile("sti");
 }
diff --git a/arch/i386/boot/pic.c b/arch/i386/boot/pic.c
index 607023c..69a0785 100644
--- a/arch/i386/boot/pic.c
+++ b/arch/i386/boot/pic.c
@@ -51,7 +51,7 @@ void irq_set_mask(uint8_t irq) {
         outb(port, data);
 }
 
-void irq_clear_mask(unsigned char irq) {
+void irq_clear_mask(uint8_t irq) {
         uint16_t port;
         uint8_t data;
 
diff --git a/arch/i386/boot/syscall.c b/arch/i386/boot/syscall.c
new file mode 100644
index 0000000..fb613b3
--- /dev/null
+++ b/arch/i386/boot/syscall.c
@@ -0,0 +1,21 @@
+#include "syscall.h"
+#include <kernel/io.h>
+#include <stddef.h>
+
+void *(*syscall_handlers[30])(struct isr_frame *frame);
+
+void syscall_dispatch(struct isr_frame *frame) {
+        if (syscall_handlers[frame->eax] != NULL)
+                syscall_handlers[frame->eax](frame);
+        else
+                kprintf("Error: Invalid system call number: %d\n", frame->eax);
+        __asm__ volatile("cli;hlt");
+}
+
+void register_syscall(void *handler(struct isr_frame*), int num) {
+        syscall_handlers[num] = handler;
+}
+
+void print_hello(struct isr_frame *frame) {
+        kprintf("Hello syscall\n");
+}
diff --git a/arch/i386/boot/syscall.h b/arch/i386/boot/syscall.h
new file mode 100644
index 0000000..376fb7c
--- /dev/null
+++ b/arch/i386/boot/syscall.h
@@ -0,0 +1,9 @@
+#ifndef I386_SYSCALL_H
+#define I386_SYSCALL_H
+
+#include <kernel/isr.h>
+
+void syscall_dispatch(struct isr_frame *frame);
+void register_syscall(void *handler(struct isr_frame*), int num);
+
+#endif
-- 
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