Switch T_SYSCALL to interrupt gate, call sti before syscall handling.

2ee21cd7 · Silas Boyd-Wickizer · 778e40e8 · 2ee21cd7
--- a/trap.c
+++ b/trap.c
@@ -42,11 +42,8 @@ extern u64 trapentry[];
 void
 trap(struct trapframe *tf)
 {
-  // XXX(sbw) eventually these should be moved into trapasm.S
-  cli();
  writegs(KDSEG);
  writemsr(MSR_GS_BASE, (u64)&cpus[cpunum()].cpu);
-  sti();

  if (tf->trapno == T_NMI) {
    // The only locks that we can acquire during NMI are ones
@@ -58,6 +55,7 @@ trap(struct trapframe *tf)

  // XXX(sbw) sysenter/sysexit
  if(tf->trapno == T_SYSCALL){
+    sti();
    if(myproc()->killed) {
      mtstart(trap, myproc());
      exit();
@@ -180,7 +178,7 @@ inittrap(void)
    idt[i] = INTDESC(KCSEG, entry, bits);
  }
  entry = trapentry[T_SYSCALL];
-  idt[T_SYSCALL] = INTDESC(KCSEG, entry, SEG_DPL(3) | SEG_TRAP64 |INT_P);
+  idt[T_SYSCALL] = INTDESC(KCSEG, entry, SEG_DPL(3) | SEG_INTR64 |INT_P);
 }

 void