diff options
Diffstat (limited to 'trap.c')
| -rw-r--r-- | trap.c | 57 |
1 files changed, 35 insertions, 22 deletions
@@ -11,28 +11,16 @@ uint ticks; extern char trampout[], trampin[]; -void kerneltrap(); +// in kernelvec.S, calls kerneltrap(). +void kernelvec(); void trapinit(void) { int i; - // send interrupts and exceptions to kerneltrap(). - w_stvec((uint64)kerneltrap); - - // set up the riscv Platform Level Interrupt Controller - // to send uart interrupts to hart 0 S-Mode. - - // qemu makes UART0 be interrupt number 10. - int irq = 10; - // set uart's priority to be non-zero (otherwise disabled). - *(uint*)(0x0c000000L + irq*4) = 1; - // set uart's enable bit for hart 0 S-mode. - *(uint*)0x0c002080 = (1 << irq); - - // set hart 0 S-mode priority threshold to 0. - *(uint*)0x0c201000 = 0; + // set up to take exceptions and traps while in the kernel. + w_stvec((uint64)kernelvec); initlock(&tickslock, "time"); } @@ -49,7 +37,7 @@ usertrap(void) // send interrupts and exceptions to kerneltrap(), // since we're now in the kernel. - w_stvec((uint64)kerneltrap); + w_stvec((uint64)kernelvec); struct proc *p = myproc(); @@ -83,8 +71,9 @@ usertrapret(void) { struct proc *p = myproc(); - // XXX turn off interrupts, since we're switching + // turn off interrupts, since we're switching // now from kerneltrap() to usertrap(). + intr_off(); // send interrupts and exceptions to trampoline.S w_stvec(TRAMPOLINE + (trampin - trampout)); @@ -101,6 +90,7 @@ usertrapret(void) // set S Previous Privilege mode to User. unsigned long x = r_sstatus(); x &= ~SSTATUS_SPP; // clear SPP to 0 for user mode + x |= SSTATUS_SPIE; // enable interrupts in user mode w_sstatus(x); // set S Exception Program Counter to the saved user pc. @@ -121,11 +111,34 @@ usertrapret(void) void __attribute__ ((aligned (4))) kerneltrap() { - if((r_sstatus() & SSTATUS_SPP) == 0) + uint64 sstatus = r_sstatus(); + uint64 scause = r_scause(); + + if((sstatus & SSTATUS_SPP) == 0) panic("kerneltrap: not from supervisor mode"); - printf("scause 0x%x\n", r_scause()); - printf("sepc=%p stval=%p\n", r_sepc(), r_stval()); + if((scause & 0x8000000000000000L) && + (scause & 0xff) == 9){ + // supervisor external interrupt, via PLIC. + int irq = plic_claim(); + + if(irq == UART0_IRQ){ + uartintr(); + } else { + printf("stray interrupt irq=%d\n", irq); + } + + plic_complete(irq); + } else { + printf("scause 0x%p\n", scause); + printf("sepc=%p stval=%p\n", r_sepc(), r_stval()); + panic("kerneltrap"); + } + + // turn off interrupts to ensure we + // return with the correct sstatus. + intr_off(); - panic("kerneltrap"); + // restore previous interrupt status. + w_sstatus(sstatus); } |