trapasm.S fixes.

ef62aebd · Silas Boyd-Wickizer · c883a275 · ef62aebd · ef62aebd · ef62aebd
--- a/Makefile
+++ b/Makefile
@@ -76,7 +76,7 @@ clean:

 QEMUOPTS = -smp $(CPUS) -m 512 -nographic
 qemu: kernel
-	$(QEMU) $(QEMUOPTS) -kernel kernel #-S -s
+	$(QEMU) $(QEMUOPTS) -kernel kernel

 ud0: kernel
 	rsync -avP kernel amsterdam.csail.mit.edu:/tftpboot/ud0/kernel.xv6
--- a/proc.c
+++ b/proc.c
@@ -179,9 +179,12 @@ inituser(void)
  if(copyout(p->vmap, 0, _binary_initcode_start, (uptr)_binary_initcode_size) < 0)
    panic("userinit: copyout");
  memset(p->tf, 0, sizeof(*p->tf));
+  p->tf->cs = UCSEG | 0x3;
+  p->tf->ds = UDSEG | 0x3;
+  p->tf->ss = p->tf->ds;
  p->tf->rflags = FL_IF;
  p->tf->rsp = PGSIZE;
-  p->tf->rip = 0;  // beginning of initcode.S
+  p->tf->rip = 0x0;  // beginning of initcode.S

  safestrcpy(p->name, "initcode", sizeof(p->name));
  p->cwd = 0; // forkret will fix in the process's context

--- a/trapasm.S
+++ b/trapasm.S
@@ -34,7 +34,9 @@ trapcommon:
        pushq   %r13
        pushq   %r14
        pushq   %r15
-
+        movw    %ds, %ax
+        pushw   %ax
+        
        # Set up data and per-cpu segments.
        movw    $KDSEG, %ax
        movw    %ax, %ds
@@ -47,10 +49,9 @@ trapcommon:
 .globl trapret
 .align 8
 trapret:
-        movw $UDSEG, %ax
+        popw %ax
        movw %ax, %ds
        movw %ax, %es
-        movw %ax, %ss
        // XXX(sbw) we should do something with fs, gs, gs.base
        
        popq    %r15
@@ -68,8 +69,8 @@ trapret:
        popq    %rdx
        popq    %rsi
        popq    %rdi
-        addq    $0x12, %rsp  // trapno, err
-        iret
+        addq    $0x16, %rsp  // trapno, err
+        iretq
        
 .data
 .align 8

--- a/x86.h
+++ b/x86.h
@@ -127,9 +127,19 @@ static inline void lcr3(u64 val)
  __asm volatile("movq %0,%%cr3" : : "r" (val));
 }

+static inline uptr
+rcr2(void)
+{
+  uptr val;
+  __asm volatile("movq %%cr2,%0" : "=r" (val));
+  return val;
+}
+
 // Layout of the trap frame built on the stack by the
 // hardware and by trapasm.S, and passed to trap().
 struct trapframe {
+  u16 ds;
+
  // amd64 ABI callee saved registers
  u64 r15;
  u64 r14;