ab0db651af
The x86-64 doesn't just add two levels to page tables to support 64 bit addresses, but is a different processor. For example, calling conventions, system calls, and segmentation are different from 32-bit x86. Segmentation is basically gone, but gs/fs in combination with MSRs can be used to hold a per-core pointer. In general, x86-64 is more straightforward than 32-bit x86. The port uses code from sv6 and the xv6 "rsc-amd64" branch. A summary of the changes is as follows: - Booting: switch to grub instead of xv6's bootloader (pass -kernel to qemu), because xv6's boot loader doesn't understand 64bit ELF files. And, we don't care anymore about booting. - Makefile: use -m64 instead of -m32 flag for gcc, delete boot loader, xv6.img, bochs, and memfs. For now dont' use -O2, since usertests with -O2 is bigger than MAXFILE! - Update gdb.tmpl to be for i386 or x86-64 - Console/printf: use stdarg.h and treat 64-bit addresses different from ints (32-bit) - Update elfhdr to be 64 bit - entry.S/entryother.S: add code to switch to 64-bit mode: build a simple page table in 32-bit mode before switching to 64-bit mode, share code for entering boot processor and APs, and tweak boot gdt. The boot gdt is the gdt that the kernel proper also uses. (In 64-bit mode, the gdt/segmentation and task state mostly disappear.) - exec.c: fix passing argv (64-bit now instead of 32-bit). - initcode.c: use syscall instead of int. - kernel.ld: load kernel very high, in top terabyte. 64 bits is a lot of address space! - proc.c: initial return is through new syscall path instead of trapret. - proc.h: update struct cpu to have some scratch space since syscall saves less state than int, update struct context to reflect x86-64 calling conventions. - swtch: simplify for x86-64 calling conventions. - syscall: add fetcharg to handle x86-64 calling convetions (6 arguments are passed through registers), and fetchaddr to read a 64-bit value from user space. - sysfile: update to handle pointers from user space (e.g., sys_exec), which are 64 bits. - trap.c: no special trap vector for sys calls, because x86-64 has a different plan for system calls. - trapasm: one plan for syscalls and one plan for traps (interrupt and exceptions). On x86-64, the kernel is responsible for switching user/kernel stacks. To do, xv6 keeps some scratch space in the cpu structure, and uses MSR GS_KERN_BASE to point to the core's cpu structure (using swapgs). - types.h: add uint64, and change pde_t to uint64 - usertests: exit() when fork fails, which helped in tracking down one of the bugs in the switch from 32-bit to 64-bit - vectors: update to make them 64 bits - vm.c: use bootgdt in kernel too, program MSRs for syscalls and core-local state (for swapgs), walk 4 levels in walkpgdir, add DEVSPACETOP, use task segment to set kernel stack for interrupts (but simpler than in 32-bit mode), add an extra argument to freevm (size of user part of address space) to avoid checking all entries till KERNBASE (there are MANY TB before the top 1TB). - x86: update trapframe to have 64-bit entries, which is what the processor pushes on syscalls and traps. simplify lgdt and lidt, using struct desctr, which needs the gcc directives packed and aligned. TODO: - use int32 instead of int? - simplify curproc(). xv6 has per-cpu state again, but this time it must have it. - avoid repetition in walkpgdir - fix validateint() in usertests.c - fix bugs (e.g., observed one a case of entering kernel with invalid gs or proc
120 lines
2.6 KiB
C
120 lines
2.6 KiB
C
#include "types.h"
|
|
#include "defs.h"
|
|
#include "param.h"
|
|
#include "memlayout.h"
|
|
#include "mmu.h"
|
|
#include "proc.h"
|
|
#include "x86.h"
|
|
#include "traps.h"
|
|
#include "spinlock.h"
|
|
|
|
// Interrupt descriptor table (shared by all CPUs).
|
|
struct intgate idt[256];
|
|
extern uint64 vectors[]; // in vectors.S: array of 256 entry pointers
|
|
struct spinlock tickslock;
|
|
uint ticks;
|
|
|
|
void
|
|
tvinit(void)
|
|
{
|
|
int i;
|
|
|
|
for(i=0; i<256; i++) {
|
|
idt[i] = INTDESC(KCSEG, vectors[i], INT_P | SEG_INTR64);
|
|
}
|
|
idtinit();
|
|
|
|
initlock(&tickslock, "time");
|
|
}
|
|
|
|
void
|
|
idtinit(void)
|
|
{
|
|
struct desctr dtr;
|
|
|
|
dtr.limit = sizeof(idt) - 1;
|
|
dtr.base = (uint64)idt;
|
|
lidt((void *)&dtr.limit);
|
|
}
|
|
|
|
//PAGEBREAK: 41
|
|
void
|
|
trap(struct trapframe *tf)
|
|
{
|
|
if(tf->trapno == T_SYSCALL){
|
|
if(myproc()->killed)
|
|
exit();
|
|
myproc()->tf = tf;
|
|
syscall();
|
|
if(myproc()->killed)
|
|
exit();
|
|
return;
|
|
}
|
|
|
|
switch(tf->trapno){
|
|
case T_IRQ0 + IRQ_TIMER:
|
|
if(cpuid() == 0){
|
|
acquire(&tickslock);
|
|
ticks++;
|
|
wakeup(&ticks);
|
|
release(&tickslock);
|
|
}
|
|
lapiceoi();
|
|
break;
|
|
case T_IRQ0 + IRQ_IDE:
|
|
ideintr();
|
|
lapiceoi();
|
|
break;
|
|
case T_IRQ0 + IRQ_IDE+1:
|
|
// Bochs generates spurious IDE1 interrupts.
|
|
break;
|
|
case T_IRQ0 + IRQ_KBD:
|
|
kbdintr();
|
|
lapiceoi();
|
|
break;
|
|
case T_IRQ0 + IRQ_COM1:
|
|
uartintr();
|
|
lapiceoi();
|
|
break;
|
|
case T_IRQ0 + 7:
|
|
case T_IRQ0 + IRQ_SPURIOUS:
|
|
cprintf("cpu%d: spurious interrupt at %x:%x\n",
|
|
cpuid(), tf->cs, tf->rip);
|
|
lapiceoi();
|
|
break;
|
|
|
|
//PAGEBREAK: 13
|
|
default:
|
|
if(myproc() == 0 || (tf->cs&3) == 0){
|
|
// In kernel, it must be our mistake.
|
|
cprintf("unexpected trap %d from cpu %d eip %x (cr2=0x%x)\n",
|
|
tf->trapno, cpuid(), tf->rip, rcr2());
|
|
panic("trap");
|
|
}
|
|
// In user space, assume process misbehaved.
|
|
cprintf("pid %d %s: trap %d err %d on cpu %d "
|
|
"eip 0x%x addr 0x%x--kill proc\n",
|
|
myproc()->pid, myproc()->name, tf->trapno,
|
|
tf->err, cpuid(), tf->rip, rcr2());
|
|
myproc()->killed = 1;
|
|
}
|
|
|
|
// Force process exit if it has been killed and is in user space.
|
|
// (If it is still executing in the kernel, let it keep running
|
|
// until it gets to the regular system call return.)
|
|
if(myproc() && myproc()->killed && (tf->cs&3) == DPL_USER)
|
|
exit();
|
|
|
|
// Force process to give up CPU on clock tick.
|
|
// If interrupts were on while locks held, would need to check nlock.
|
|
if(myproc() && myproc()->state == RUNNING &&
|
|
tf->trapno == T_IRQ0+IRQ_TIMER)
|
|
yield();
|
|
|
|
// Check if the process has been killed since we yielded
|
|
if(myproc() && myproc()->killed && (tf->cs&3) == DPL_USER)
|
|
exit();
|
|
}
|
|
|
|
|