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#include "kernel/trap.h"
#include "common/types.h"
#include "drivers/uart.h"
#include "kernel/proc.h"
#include "kernel/timer.h"
#include "kernel/syscall.h"
#include "kernel/riscv.h"
extern void usertrapret();
extern void forkret();
void panic(const char *s)
{
Drivers::uart_puts("\n\n!!! KERNEL PANIC !!!\n");
Drivers::uart_puts(s);
Drivers::uart_puts("\nSystem Halted.\n");
while (1)
;
}
namespace Trap
{
void init()
{
uint64 stvec_val = (uint64)kernelvec;
asm volatile("csrw stvec, %0" : : "r"(stvec_val));
uint64 sstatus;
asm volatile("csrr %0, sstatus" : "=r"(sstatus));
sstatus &= ~(1L << 1);
asm volatile("csrw sstatus, %0" : : "r"(sstatus));
Drivers::uart_puts("[Trap] Initialized stvec to: ");
Drivers::print_hex(stvec_val);
Drivers::uart_puts("\n");
}
extern "C" void kerneltrap(struct Trapframe *tf)
{
uint64 scause, stval, sepc;
asm volatile("csrr %0, scause" : "=r"(scause));
asm volatile("csrr %0, stval" : "=r"(stval));
asm volatile("csrr %0, sepc" : "=r"(sepc));
if (scause & (1L << 63))
{
uint64 cause_code = scause & 0x7FFFFFFFFFFFFFFFL;
switch (cause_code)
{
case 1:
Drivers::uart_puts("[IRQ] Software Interrupt (Unexpected)\n");
break;
case 5:
Drivers::uart_puts("[IRQ] Timer Interrupt\n");
Timer::set_next_trigger();
ProcManager::yield();
break;
case 9:
Drivers::uart_puts("[IRQ] External Interrupt\n");
break;
default:
Drivers::uart_puts("[IRQ] Unknown Interrupt: ");
Drivers::print_hex(cause_code);
Drivers::uart_puts("\n");
break;
}
}
else
{
switch (scause)
{
case 8:
Drivers::uart_puts("[Syscall] ecall from Kernel Mode? Panic.\n");
panic("Kernel Ecall");
break;
case 12:
case 13:
case 15:
Drivers::uart_puts("\n--- PAGE FAULT ---\n");
Drivers::uart_puts("Cause Code: ");
Drivers::print_hex(scause);
Drivers::uart_puts("\n");
Drivers::uart_puts("Fault Addr (stval): ");
Drivers::print_hex(stval);
Drivers::uart_puts("\n");
Drivers::uart_puts("Instruction (sepc): ");
Drivers::print_hex(sepc);
Drivers::uart_puts("\n");
if (stval == 0)
{
panic("Null Pointer Dereference!");
}
else if (stval < 0x80000000)
{
panic("Invalid Low Memory Access!");
}
else
{
panic("Segmentation Fault (Unmapped Area)");
}
break;
case 2:
Drivers::uart_puts("\n--- ILLEGAL INSTRUCTION ---\n");
Drivers::uart_puts("Instruction (sepc): ");
Drivers::print_hex(sepc);
Drivers::uart_puts("\n");
panic("CPU encountered an unknown opcode");
break;
default:
Drivers::uart_puts("\n--- UNHANDLED EXCEPTION ---\n");
Drivers::uart_puts("Cause: ");
Drivers::print_hex(scause);
Drivers::uart_puts("\n");
Drivers::uart_puts("sepc: ");
Drivers::print_hex(sepc);
Drivers::uart_puts("\n");
panic("System Halt");
break;
}
}
}
}
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[];
if (!p)
{
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)
{
intr_on();
p->tf->epc += 4;
syscall();
intr_off();
}
else if ((scause & (1L << 63)) && (scause & 0xF) == 5)
{
Drivers::uart_puts("\nTick\n");
Timer::set_next_trigger();
ProcManager::yield();
}
else
{
Drivers::uart_puts("Unexpected User Trap!\n");
Drivers::print_hex(scause);
while (1)
;
}
usertrapret();
}
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