3 files changed, 153 insertions, 5 deletions

diff --git a/src/kernel/trap/handler.cc b/src/kernel/trap/handler.cc
index df4f202..4bb8c06 100644
--- a/src/kernel/trap/handler.cc
+++ b/src/kernel/trap/handler.cc
@@ -4,6 +4,7 @@
 #include "kernel/proc.h"
 #include "kernel/timer.h"
 
+extern void usertrapret();
 
 void panic(const char *s)
 {
@@ -123,4 +124,53 @@ namespace Trap
             }
         }
     }
+}
+
+extern "C" void usertrap()
+{
+    asm volatile("csrw stvec, %0" : : "r"(Trap::kernelvec));
+
+    uint64 scause;
+    asm volatile("csrr %0, scause" : "=r"(scause));
+
+    struct Proc *p = myproc();
+    
+    extern struct Proc procs[];
+    for(int i = 0; i < 10; ++i)
+        if(procs[i].state == RUNNING)
+            p = &procs[i];
+
+    uint64 sepc;
+    asm volatile("csrr %0, sepc" : "=r"(sepc));
+    p->tf->epc = sepc;
+
+    if(scause == 8)
+    {
+        p->tf->epc += 4;
+
+        uint64 syscall_num = p->tf->a7;
+
+        if (syscall_num == 1)
+        {
+            char c = (char)p->tf->a0;
+            Drivers::uart_putc(c);
+        }
+        else
+        {
+            Drivers::uart_puts("Unknown Syscall\n");
+        }
+    }
+    else if ((scause & (1L << 63)) && (scause & 0xF) == 5)
+    {
+        Timer::set_next_trigger();
+        ProcManager::yield();
+    }
+    else
+    {
+        Drivers::uart_puts("Unexpected User Trap!\n");
+        while (1)
+            ;
+    }
+
+    forkret();
 }
\ No newline at end of file
diff --git a/src/kernel/trap/trampoline.S b/src/kernel/trap/trampoline.S
new file mode 100644
index 0000000..478d345
--- /dev/null
+++ b/src/kernel/trap/trampoline.S
@@ -0,0 +1,98 @@
+.section .text
+.globl trampoline
+.globl uservec
+.globl userret
+
+.align 12
+trampoline:
+.align 4
+uservec:    
+    
+    csrrw a0, sscratch, a0
+
+    sd ra, 40(a0)
+    sd sp, 48(a0)
+    sd gp, 56(a0)
+    sd tp, 64(a0)
+    sd t0, 72(a0)
+    sd t1, 80(a0)
+    sd t2, 88(a0)
+    sd s0, 96(a0)
+    sd s1, 104(a0)
+    sd a1, 120(a0)
+    sd a2, 128(a0)
+    sd a3, 136(a0)
+    sd a4, 144(a0)
+    sd a5, 152(a0)
+    sd a6, 160(a0)
+    sd a7, 168(a0)
+    sd s2, 176(a0)
+    sd s3, 184(a0)
+    sd s4, 192(a0)
+    sd s5, 200(a0)
+    sd s6, 208(a0)
+    sd s7, 216(a0)
+    sd s8, 224(a0)
+    sd s9, 232(a0)
+    sd s10, 240(a0)
+    sd s11, 248(a0)
+    sd t3, 256(a0)
+    sd t4, 264(a0)
+    sd t5, 272(a0)
+    sd t6, 280(a0)
+
+    csrr t0, sscratch
+    sd t0, 112(a0)
+
+    ld sp, 8(a0)
+    ld tp, 32(a0)
+    ld t0, 16(a0)
+    ld t1, 0(a0)
+
+    csrw satp, t1
+    sfence.vma zero, zero
+
+    jr t0
+
+.align 4
+userret:
+    
+    csrw satp, a1
+    sfence.vma zero, zero
+
+    csrw sscratch, a0
+
+    ld ra, 40(a0)
+    ld sp, 48(a0)
+    ld gp, 56(a0)
+    ld tp, 64(a0)
+    ld t0, 72(a0)
+    ld t1, 80(a0)
+    ld t2, 88(a0)
+    ld s0, 96(a0)
+    ld s1, 104(a0)
+    ld a1, 120(a0)
+    ld a2, 128(a0)
+    ld a3, 136(a0)
+    ld a4, 144(a0)
+    ld a5, 152(a0)
+    ld a6, 160(a0)
+    ld a7, 168(a0)
+    ld s2, 176(a0)
+    ld s3, 184(a0)
+    ld s4, 192(a0)
+    ld s5, 200(a0)
+    ld s6, 208(a0)
+    ld s7, 216(a0)
+    ld s8, 224(a0)
+    ld s9, 232(a0)
+    ld s10, 240(a0)
+    ld s11, 248(a0)
+    ld t3, 256(a0)
+    ld t4, 264(a0)
+    ld t5, 272(a0)
+    ld t6, 280(a0)
+    
+    ld a0, 112(a0)
+    
+    sret
\ No newline at end of file
diff --git a/src/kernel/trap/trap.S b/src/kernel/trap/trap.S
index ffce52a..573248e 100644
--- a/src/kernel/trap/trap.S
+++ b/src/kernel/trap/trap.S
@@ -1,10 +1,11 @@
 .section .text
 .global kernelvec
-.align 4
+.global uservec
+.global userret
+.align 12
 
 kernelvec:
-    
-    addi sp, sp, -256
+    addi sp, sp, -288
     
     sd ra, 40(sp)
     sd sp, 48(sp)
@@ -82,6 +83,5 @@ kernelvec:
     ld t5, 272(sp)
     ld t6, 280(sp)
     
-    addi sp, sp, 256
-    
+    addi sp, sp, 288
     sret
\ No newline at end of file