From dd8de9f381d202ca1e3d4043d34aabd4e3f7792f Mon Sep 17 00:00:00 2001
From: Zejun Zhao <jelly.zhao.42@gmail.com>
Date: Thu, 7 Aug 2025 02:01:35 +0800
Subject: [PATCH] Handle kernel page fault on RISC-V platforms

---
 ostd/src/arch/riscv/trap/mod.rs | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/ostd/src/arch/riscv/trap/mod.rs b/ostd/src/arch/riscv/trap/mod.rs
index ce6fd90a4..be7d9f5ee 100644
--- a/ostd/src/arch/riscv/trap/mod.rs
+++ b/ostd/src/arch/riscv/trap/mod.rs
@@ -20,6 +20,7 @@ use crate::{
     },
     cpu::{CpuId, PrivilegeLevel},
     irq::call_irq_callback_functions,
+    mm::MAX_USERSPACE_VADDR,
 };
 
 /// Initializes interrupt handling on RISC-V.
@@ -68,6 +69,15 @@ extern "C" fn trap_handler(f: &mut TrapFrame) {
 
     enable_local_if(was_irq_enabled);
     match exception {
+        CpuException::InstructionPageFault(fault_addr)
+        | CpuException::LoadPageFault(fault_addr)
+        | CpuException::StorePageFault(fault_addr) => {
+            if (0..MAX_USERSPACE_VADDR).contains(&fault_addr) {
+                handle_user_page_fault(f, &exception);
+            } else {
+                panic!("Cannot handle page fault in kernel space, exception: {:#x?}, trapframe: {:#x?}.", exception, f);
+            }
+        }
         CpuException::Unknown => {
             panic!(
                 "Cannot handle unknown exception, scause: {:#x}, trapframe: {:#x?}.",
@@ -130,3 +140,16 @@ pub fn inject_user_page_fault_handler(
 ) {
     USER_PAGE_FAULT_HANDLER.call_once(|| handler);
 }
+
+fn handle_user_page_fault(f: &mut TrapFrame, exception: &CpuException) {
+    let handler = USER_PAGE_FAULT_HANDLER
+        .get()
+        .expect("Page fault handler is missing");
+
+    handler(exception).unwrap_or_else(|_| {
+        panic!(
+            "Failed to handle page fault, exception: {:?}, trapframe: {:#x?}.",
+            exception, f
+        )
+    });
+}