From b4ac798546638aee7a9dbae31e276b2ebc2d70c6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rom=C3=A1n=20C=C3=A1rdenas?= <rcardenas.rod@gmail.com>
Date: Wed, 26 Apr 2023 12:02:56 +0200
Subject: [PATCH] exception table

---
 CHANGELOG.md |  5 ++++
 link.x       | 15 +++++++++++
 src/lib.rs   | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 90 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 95f4e33..6d31b12 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+## Added
+
+- Standard exceptions enum 
+- __EXCEPTIONS array for dedicated handlers for each exception type.
+
 ## [v0.11.0] - 2023-01-18
 
 ### Changed
diff --git a/link.x b/link.x
index 1f52024..7cca90b 100644
--- a/link.x
+++ b/link.x
@@ -4,6 +4,21 @@ PROVIDE(_max_hart_id = 0);
 PROVIDE(_hart_stack_size = 2K);
 PROVIDE(_heap_size = 0);
 
+PROVIDE(InstrAddressMisaligned = ExceptionHandler);
+PROVIDE(InstrAccessFault = ExceptionHandler);
+PROVIDE(IlegalInstr = ExceptionHandler);
+PROVIDE(Breakpoint = ExceptionHandler);
+PROVIDE(LoadAddressMisaligned = ExceptionHandler);
+PROVIDE(LoadAccessFault = ExceptionHandler);
+PROVIDE(StoreAMOAddressMisaligned = ExceptionHandler);
+PROVIDE(StoreAMOAccessFault = ExceptionHandler);
+PROVIDE(EnvUserCall = ExceptionHandler);
+PROVIDE(EnvSupervisorCall = ExceptionHandler);
+PROVIDE(EnvMachineCall = ExceptionHandler);
+PROVIDE(InstrPageFault = ExceptionHandler);
+PROVIDE(LoadPageFault = ExceptionHandler);
+PROVIDE(StoreAMOPageFault = ExceptionHandler);
+
 PROVIDE(UserSoft = DefaultHandler);
 PROVIDE(SupervisorSoft = DefaultHandler);
 PROVIDE(MachineSoft = DefaultHandler);
diff --git a/src/lib.rs b/src/lib.rs
index 3027452..10e5825 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -464,7 +464,14 @@ pub extern "C" fn start_trap_rust(trap_frame: *const TrapFrame) {
         let cause = xcause::read();
 
         if cause.is_exception() {
-            ExceptionHandler(&*trap_frame)
+            if cause.code() < __EXCEPTIONS.len() {
+                match __EXCEPTIONS[cause.code()] {
+                    Some(handler) => handler(&*trap_frame),
+                    None => ExceptionHandler(&*trap_frame),
+                };
+            } else {
+                ExceptionHandler(&*trap_frame);
+            }
         } else {
             if cause.code() < __INTERRUPTS.len() {
                 let h = &__INTERRUPTS[cause.code()];
@@ -502,6 +509,68 @@ pub fn DefaultInterruptHandler() {
     }
 }
 
+/// Standard exception categories.
+#[doc(hidden)]
+#[repr(u32)]
+pub enum Exception {
+    InstrAddressMisaligned = 0,
+    InstrAccessFault = 1,
+    IlegalInstr = 2,
+    Breakpoint = 3,
+    LoadAddressMisaligned = 4,
+    LoadAccessFault = 5,
+    StoreAMOAddressMisaligned = 6,
+    StoreAMOAccessFault = 7,
+    EnvUserCall = 8,
+    EnvSupervisorCall = 9,
+    // Reserved = 10,
+    EnvMachineCall = 11,
+    InstrPageFault = 12,
+    LoadPageFault = 13,
+    // Reserved = 14,
+    StoreAMOPageFault = 15,
+}
+
+pub use self::Exception as exception;
+
+extern "C" {
+    fn InstrAddressMisaligned(trap_frame: &TrapFrame);
+    fn InstrAccessFault(trap_frame: &TrapFrame);
+    fn IlegalInstr(trap_frame: &TrapFrame);
+    fn Breakpoint(trap_frame: &TrapFrame);
+    fn LoadAddressMisaligned(trap_frame: &TrapFrame);
+    fn LoadAccessFault(trap_frame: &TrapFrame);
+    fn StoreAMOAddressMisaligned(trap_frame: &TrapFrame);
+    fn StoreAMOAccessFault(trap_frame: &TrapFrame);
+    fn EnvUserCall(trap_frame: &TrapFrame);
+    fn EnvSupervisorCall(trap_frame: &TrapFrame);
+    fn EnvMachineCall(trap_frame: &TrapFrame);
+    fn InstrPageFault(trap_frame: &TrapFrame);
+    fn LoadPageFault(trap_frame: &TrapFrame);
+    fn StoreAMOPageFault(trap_frame: &TrapFrame);
+}
+
+#[doc(hidden)]
+#[no_mangle]
+pub static __EXCEPTIONS: [Option<unsafe extern "C" fn(&TrapFrame)>; 16] = [
+    Some(InstrAddressMisaligned),
+    Some(InstrAccessFault),
+    Some(IlegalInstr),
+    Some(Breakpoint),
+    Some(LoadAddressMisaligned),
+    Some(LoadAccessFault),
+    Some(StoreAMOAddressMisaligned),
+    Some(StoreAMOAccessFault),
+    Some(EnvUserCall),
+    Some(EnvSupervisorCall),
+    None, // 10 is reserved
+    Some(EnvMachineCall),
+    Some(InstrPageFault),
+    Some(LoadPageFault),
+    None, // 14 is reserved
+    Some(StoreAMOPageFault),
+];
+
 /* Interrupts */
 #[doc(hidden)]
 pub enum Interrupt {