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#include "kernel/trap.h"
#include "kernel/riscv.h"
#include "kernel/proc.h"
#include "drivers/uart.h"
#include "kernel/syscall.h"
#include "kernel/mm.h"
#include "kernel/timer.h"
#include "drivers/plic.h"
#include "drivers/virtio.h"
#include "lib/string.h"
extern "C" void kernelvec();
// Handle Function
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)
;
}
// Trap Implementation
namespace Trap
{
void init()
{
Drivers::uart_puts("[Trap] Global init done.\n");
}
// Each CPU core needs to call this function when starting to set its own stvec
void inithart()
{
w_stvec((uint64)kernelvec);
// Ensure that the S-Mode interrupt enable bit (SIE) is cleared during initialization
// Interrupt enabling will be done by the scheduler when the first process runs
w_sstatus(r_sstatus() & ~SSTATUS_SIE);
// Enable the external interrupt, clock interrupt, and software interrupt bits in S-Mode (in SIE register)
uint64 sie = r_sie();
sie |= SIE_SEIE | SIE_STIE | SIE_SSIE;
w_sie(sie);
Drivers::uart_puts("[Trap] Hart initialized (stvec set).\n");
}
// Device Interrupt Check
int devintr()
{
uint64 scause = r_scause();
bool is_interrupt = (scause & 0x8000000000000000L) != 0;
uint64 code = scause & 0xff;
if (is_interrupt && code == 9)
{
// Supervisor External Interrupt (IRQ 9)
int irq = PLIC::claim();
if (irq == 10)
{
Drivers::uart_intr();
// Debug
// Drivers::uart_puts("[Interrupt] UART Input detected!\n");
}
else if (irq >= 1 && irq <= 8)
{
VirtIO::intr();
// Debug
// Drivers::uart_puts("[Interrupt] VirtIO disk finished!\n");
}
if (irq > 0)
{
PLIC::complete(irq);
}
return 1;
}
else if (is_interrupt && code == 5)
{
// Supervisor Timer Interrupt (IRQ 5)
Timer::set_next_trigger();
// w_sip(r_sip() & ~2);
return 2;
}
return 0;
}
}
// Exception Handling Entry
extern "C" void kerneltrap(struct Trapframe *tf)
{
uint64 sepc = r_sepc();
uint64 sstatus = r_sstatus();
uint64 scause = r_scause();
if ((sstatus & SSTATUS_SPP) == 0)
panic("kerneltrap: not from supervisor mode");
if (intr_get() != 0)
panic("kerneltrap: interrupts enabled");
if (Trap::devintr() == 0)
{
Drivers::uart_puts("\n--- KERNEL EXCEPTION ---\n");
Drivers::uart_puts("scause: ");
Drivers::print_hex(scause);
Drivers::uart_puts("\n");
Drivers::uart_puts("sepc: ");
Drivers::print_hex(sepc);
Drivers::uart_puts("\n");
Drivers::uart_puts("stval: ");
Drivers::print_hex(r_stval());
Drivers::uart_puts("\n");
panic("kerneltrap exception");
}
w_sepc(sepc);
w_sstatus(sstatus);
}
extern "C" void usertrap()
{
// Drivers::uart_puts("[Debug] Entered usertrap!\n");
int which_dev = 0;
if ((r_sstatus() & SSTATUS_SPP) != 0)
panic("usertrap: not from user mode");
w_stvec((uint64)kernelvec);
struct Proc *p = myproc();
if (!p)
panic("usertrap: no process");
p->tf->epc = r_sepc();
uint64 scause = r_scause();
uint64 stval = r_stval();
if (scause == 8) // Syscall
{
if (p->state == ZOMBIE)
ProcManager::exit(-1);
p->tf->epc += 4;
intr_on();
syscall();
intr_off();
}
else if (scause == 15) // Store Page Fault
{
uint64 pte = VM::walkaddr(p->pagetable, stval);
// Drivers::uart_puts("[Debug] Faulting PTE:");
// Drivers::print_hex(pte);
// Drivers::uart_puts("\n");
if (VM::handle_cow_fault(p->pagetable, PGROUNDDOWN(stval)) != 0)
{
Drivers::uart_puts("usertrap: cow failed at ");
Drivers::print_hex(stval);
Drivers::uart_puts("\n");
p->state = ZOMBIE;
ProcManager::exit(-1);
}
}
else if ((which_dev = Trap::devintr()) != 0)
{
if (which_dev == 2)
{
ProcManager::yield();
}
}
else
{
Drivers::uart_puts("\nusertrap(): unexpected scause ");
Drivers::print_hex(scause);
Drivers::uart_puts(" pid=");
Drivers::uart_put_int(p->pid);
Drivers::uart_puts(" sepc=");
Drivers::print_hex(p->tf->epc);
Drivers::uart_puts(" stval=");
Drivers::print_hex(stval);
Drivers::uart_puts("\n");
p->state = ZOMBIE;
ProcManager::exit(-1);
}
if (p->state == ZOMBIE)
ProcManager::exit(-1);
usertrapret();
}
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