Commit MD parts of a loosely functional AMD64 port. This is based on

a heavily stripped down FreeBSD/i386 (brutally stripped down actually) to
attempt to get a stable base to start from.  There is a lot missing still.
Worth noting:
- The kernel runs at 1GB in order to cheat with the pmap code.  pmap uses
  a variation of the PAE code in order to avoid having to worry about 4
  levels of page tables yet.
- It boots in 64 bit "long mode" with a tiny trampoline embedded in the
  i386 loader.  This simplifies locore.s greatly.
- There are still quite a few fragments of i386-specific code that have
  not been translated yet, and some that I cheated and wrote dumb C
  versions of (bcopy etc).
- It has both int 0x80 for syscalls (but using registers for argument
  passing, as is native on the amd64 ABI), and the 'syscall' instruction
  for syscalls.  int 0x80 preserves all registers, 'syscall' does not.
- I have tried to minimize looking at the NetBSD code, except in a couple
  of places (eg: to find which register they use to replace the trashed
  %rcx register in the syscall instruction).  As a result, there is not a
  lot of similarity.  I did look at NetBSD a few times while debugging to
  get some ideas about what I might have done wrong in my first attempt.

1 files changed, 12 insertions, 23 deletions

diff --git a/sys/amd64/include/critical.h b/sys/amd64/include/critical.h
index 7cc7ff2..dc5119c 100644
--- a/sys/amd64/include/critical.h
+++ b/sys/amd64/include/critical.h
@@ -23,7 +23,6 @@ __BEGIN_DECLS
 /*
  * Prototypes - see <arch>/<arch>/critical.c
  */
-void cpu_unpend(void);
 void cpu_critical_fork_exit(void);
 void cpu_thread_link(struct thread *td);
 
@@ -34,12 +33,15 @@ void cpu_thread_link(struct thread *td);
  *
  *	This routine is called from critical_enter() on the 0->1 transition
  *	of td_critnest, prior to it being incremented to 1.
- *
- *	If new-style critical section handling we do not have to do anything.
- *	However, as a side effect any interrupts occuring while td_critnest
- *	is non-zero will be deferred.
  */
-#define cpu_critical_enter()
+static __inline void
+cpu_critical_enter(void)
+{
+	struct thread *td;
+
+	td = curthread;
+	td->td_md.md_savecrit = intr_disable();
+}
 
 /*
  *	cpu_critical_exit:
@@ -47,27 +49,14 @@ void cpu_thread_link(struct thread *td);
  *	This routine is called from critical_exit() on a 1->0 transition
  *	of td_critnest, after it has been decremented to 0.  We are
  *	exiting the last critical section.
- *
- *	Note that the td->critnest (1->0) transition interrupt race against
- *	our int_pending/unpend() check below is handled by the interrupt
- *	code for us, so we do not have to do anything fancy.
  */
 static __inline void
 cpu_critical_exit(void)
 {
-	/*
-	 * We may have to schedule pending interrupts.  Create
-	 * conditions similar to an interrupt context and call
-	 * unpend().
-	 *
-	 * note: we do this even if we are in an interrupt
-	 * nesting level.  Deep nesting is protected by
-	 * critical_*() and if we conditionalized it then we
-	 * would have to check int_pending again whenever
-	 * we decrement td_intr_nesting_level to 0.
-	 */
-	if (PCPU_GET(int_pending))
-		cpu_unpend();
+	struct thread *td;
+
+	td = curthread;
+	intr_restore(td->td_md.md_savecrit);
 }
 
 #else /* !__GNUC__ */