From 497e4a1b2f6f9181518e9887991c0464bd8f6bcf Mon Sep 17 00:00:00 2001
From: Richard Qin <richard.qin.x@gmail.com>
Date: Wed, 10 Dec 2025 01:19:32 +0800
Subject: feat: Add initial Supervisor Mode Trap Handler

Implement the initial mechanism for handling traps and exceptions in Supervisor Mode.

Set up the stvec Control and Status Register (CSR) to direct all S-Mode Traps (Interrupts and Exceptions) to a unified assembly entry point.

Implemented assembly code for saving and restoring the Trap Context (register state).

Provides the foundational framework necessary for future Timer Interrupts and System Calls.
---
 src/kernel/main.cc | 46 ++++++++++++++++++++++++++++++----------------
 1 file changed, 30 insertions(+), 16 deletions(-)

(limited to 'src/kernel/main.cc')

diff --git a/src/kernel/main.cc b/src/kernel/main.cc
index beda9dc..2fa10a2 100644
--- a/src/kernel/main.cc
+++ b/src/kernel/main.cc
@@ -1,20 +1,21 @@
 #include "drivers/uart.h"
 #include "kernel/pmm.h"
 #include "kernel/mm.h"
+#include "kernel/trap.h"
 
-void print_hex(uint64_t val)
-{
-    char buf[17];
-    buf[16] = 0;
-    const char *digits = "0123456789ABCDEF";
-    for (int i = 15; i >= 0; i--)
-    {
-        buf[i] = digits[val & 0xf];
-        val >>= 4;
-    }
-    Drivers::uart_puts("0x");
-    Drivers::uart_puts(buf);
-}
+// void print_hex(uint64_t val)
+// {
+//     char buf[17];
+//     buf[16] = 0;
+//     const char *digits = "0123456789ABCDEF";
+//     for (int i = 15; i >= 0; i--)
+//     {
+//         buf[i] = digits[val & 0xf];
+//         val >>= 4;
+//     }
+//     Drivers::uart_puts("0x");
+//     Drivers::uart_puts(buf);
+// }
 
 extern "C" void kernel_main()
 {
@@ -33,11 +34,11 @@ extern "C" void kernel_main()
     void *p2 = PMM::alloc_page();
 
     Drivers::uart_puts("Allocated Page 1: ");
-    print_hex((uint64_t)p1);
+    Drivers::print_hex((uint64_t)p1);
     Drivers::uart_puts("\n");
 
     Drivers::uart_puts("Allocated Page 2: ");
-    print_hex((uint64_t)p2);
+    Drivers::print_hex((uint64_t)p2);
     Drivers::uart_puts("\n");
 
     Drivers::uart_puts("[Kernel] Freeing Page 1...\n");
@@ -45,7 +46,7 @@ extern "C" void kernel_main()
 
     void *p3 = PMM::alloc_page();
     Drivers::uart_puts("Allocated Page 3: ");
-    print_hex((uint64_t)p3);
+    Drivers::print_hex((uint64_t)p3);
     Drivers::uart_puts("\n");
 
     if (p3 == p1)
@@ -63,6 +64,19 @@ extern "C" void kernel_main()
     VM::kvminithart();
     Drivers::uart_puts("[Boot] MMU ENABLED! We are now using virtual addresses.\n");
 
+    Trap::init();
+    Drivers::uart_puts("[Boot] Trap Handler Installed.\n");
+
+    Drivers::uart_puts("\n[Test] Triggering Page Fault by reading 0x0...\n");
+    volatile int *p = (int *)0x0;
+    int crash = *p;
+    (void)crash;
+
+    Drivers::uart_puts("[Test Failed] Shuold not reach here.\n");
+
+    Drivers::uart_puts("\n[Test] Triggering Store Fault on Text Segment...\n");
+    *(int*)0x80000000 = 1234;
+
     while (1)
     {
 
-- 
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