Support efault fixup for riscv

kernel/src/arch/riscv32/board/k210/linker.ld

@@ -17,6 +17,9 @@ SECTIONS
     .text : {
         stext = .;
         *(.text.entry)
+        _copy_user_start = .;
+        *(.text.copy_user)
+        _copy_user_end = .;
         *(.text .text.*)
         . = ALIGN(4K);
         etext = .;

kernel/src/arch/riscv32/board/rocket_chip/linker.ld

@@ -17,6 +17,9 @@ SECTIONS
     .text : {
         stext = .;
         *(.text.entry)
+        _copy_user_start = .;
+        *(.text.copy_user)
+        _copy_user_end = .;
         *(.text .text.*)
         . = ALIGN(4K);
         etext = .;

kernel/src/arch/riscv32/board/u540/linker.ld

@@ -17,6 +17,9 @@ SECTIONS
     .text : {
         stext = .;
         *(.text.entry)
+        _copy_user_start = .;
+        *(.text.copy_user)
+        _copy_user_end = .;
         *(.text .text.*)
         . = ALIGN(4K);
         etext = .;

kernel/src/arch/riscv32/boot/linker.ld

@@ -22,6 +22,9 @@ SECTIONS
     .text : {
         stext = .;
         *(.text.entry)
+        _copy_user_start = .;
+        *(.text.copy_user)
+        _copy_user_end = .;
         *(.text .text.*)
         . = ALIGN(4K);
         etext = .;

kernel/src/arch/riscv32/boot/linker64.ld

@@ -17,6 +17,9 @@ SECTIONS
     .text : {
         stext = .;
         *(.text.entry)
+        _copy_user_start = .;
+        *(.text.copy_user)
+        _copy_user_end = .;
         *(.text .text.*)
         . = ALIGN(4K);
         etext = .;

kernel/src/arch/riscv32/interrupt.rs

@@ -132,6 +132,15 @@ fn page_fault(tf: &mut TrapFrame) {
     trace!("\nEXCEPTION: Page Fault @ {:#x}", addr);
 
     if !crate::memory::handle_page_fault(addr) {
+        extern "C" {
+            fn _copy_user_start();
+            fn _copy_user_end();
+        }
+        if tf.sepc >= _copy_user_start as usize && tf.sepc < _copy_user_end as usize {
+            debug!("fixup for addr {:x?}", addr);
+            tf.sepc = crate::memory::read_user_fixup as usize;
+            return;
+        }
         crate::trap::error(tf);
     }
 }

user

@@ -1 +1 @@
-Subproject commit ad822e6d3b626b598874bb52a407e90f549c5ab9
+Subproject commit bf02e72b85784af3555c7abe6b985aefc215023e