diff options
Diffstat (limited to 'kernel/trap.c')
| -rw-r--r-- | kernel/trap.c | 29 |
1 files changed, 18 insertions, 11 deletions
diff --git a/kernel/trap.c b/kernel/trap.c index ca732f2..a63249e 100644 --- a/kernel/trap.c +++ b/kernel/trap.c @@ -48,7 +48,7 @@ usertrap(void) struct proc *p = myproc(); // save user program counter. - p->tf->epc = r_sepc(); + p->trapframe->epc = r_sepc(); if(r_scause() == 8){ // system call @@ -58,7 +58,7 @@ usertrap(void) // sepc points to the ecall instruction, // but we want to return to the next instruction. - p->tf->epc += 4; + p->trapframe->epc += 4; // an interrupt will change sstatus &c registers, // so don't enable until done with those registers. @@ -91,8 +91,9 @@ usertrapret(void) { struct proc *p = myproc(); - // turn off interrupts, since we're switching - // now from kerneltrap() to usertrap(). + // we're about to switch the destination of traps from + // kerneltrap() to usertrap(), so turn off interrupts until + // we're back in user space, where usertrap() is correct. intr_off(); // send syscalls, interrupts, and exceptions to trampoline.S @@ -100,10 +101,10 @@ usertrapret(void) // set up trapframe values that uservec will need when // the process next re-enters the kernel. - p->tf->kernel_satp = r_satp(); // kernel page table - p->tf->kernel_sp = p->kstack + PGSIZE; // process's kernel stack - p->tf->kernel_trap = (uint64)usertrap; - p->tf->kernel_hartid = r_tp(); // hartid for cpuid() + p->trapframe->kernel_satp = r_satp(); // kernel page table + p->trapframe->kernel_sp = p->kstack + PGSIZE; // process's kernel stack + p->trapframe->kernel_trap = (uint64)usertrap; + p->trapframe->kernel_hartid = r_tp(); // hartid for cpuid() // set up the registers that trampoline.S's sret will use // to get to user space. @@ -115,7 +116,7 @@ usertrapret(void) w_sstatus(x); // set S Exception Program Counter to the saved user pc. - w_sepc(p->tf->epc); + w_sepc(p->trapframe->epc); // tell trampoline.S the user page table to switch to. uint64 satp = MAKE_SATP(p->pagetable); @@ -129,7 +130,6 @@ usertrapret(void) // interrupts and exceptions from kernel code go here via kernelvec, // on whatever the current kernel stack is. -// must be 4-byte aligned to fit in stvec. void kerneltrap() { @@ -189,9 +189,16 @@ devintr() uartintr(); } else if(irq == VIRTIO0_IRQ){ virtio_disk_intr(); + } else if(irq){ + printf("unexpected interrupt irq=%d\n", irq); } - plic_complete(irq); + // the PLIC allows each device to raise at most one + // interrupt at a time; tell the PLIC the device is + // now allowed to interrupt again. + if(irq) + plic_complete(irq); + return 1; } else if(scause == 0x8000000000000001L){ // software interrupt from a machine-mode timer interrupt, |