1 files changed, 138 insertions, 0 deletions
diff --git a/os/pc/x86break.c b/os/pc/x86break.c
new file mode 100644
index 00000000..db31fe4f
--- /dev/null
+++ b/os/pc/x86break.c
@@ -0,0 +1,138 @@
+#include "u.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "io.h"
+#include "ureg.h"
+#include "../port/error.h"
+
+//
+// from trap.c
+//
+
+uchar BREAK = 0xcc;
+static ulong skipflags;
+extern int (*breakhandler)(Ureg *ur, Proc*);
+static Bkpt *skip;
+int breakmatch(BkptCond *cond, Ureg *ur, Proc *p);
+void breaknotify(Bkpt *b, Proc *p);
+void breakrestore(Bkpt *b);
+Bkpt* breakclear(int id);
+
+void
+skiphandler(Ureg *ur, void*)
+{
+	if (skip == 0)
+		panic("single step outside of skip");
+
+	breakrestore( skip );
+	skip = 0;
+	ur->flags = skipflags;
+	if (up != 0)
+		up->state = Running;
+}
+
+void
+machbreakinit(void)
+{
+	breakhandler = breakhit;
+	trapenable(VectorDBG, skiphandler, nil, "bkpt.skip");
+}
+
+Instr
+machinstr(ulong addr)
+{
+	if (addr < KTZERO)
+		error(Ebadarg);
+	return *(uchar*)addr;
+}
+
+void
+machbreakset(ulong addr)
+{
+	if (addr < KTZERO)
+		error(Ebadarg);
+	*(uchar*)addr = BREAK;
+}
+
+void
+machbreakclear(ulong addr, Instr i)
+{
+	if (addr < KTZERO)
+		error(Ebadarg);
+	*(uchar*)addr = i;
+}
+
+//
+// Called from the exception handler when a breakpoint instruction has been
+// hit.  This cannot not be called unless at least one breakpoint with this
+// address is in the list of breakpoints.  (All breakpoint notifications must
+// previously have been set via setbreak())
+//
+//	foreach breakpoint in list
+//		if breakpoint matches conditions
+//			notify the break handler
+//	if no breakpoints matched the conditions
+//		pick a random breakpoint set to this address
+//
+//		set a breakpoint at the next instruction to be executed,
+//		and pass the current breakpoint to the "skiphandler"
+//
+//		clear the current breakpoint
+//
+//		Tell the scheduler to stop scheduling, so the caller is
+//		guaranteed to execute the instruction, followed by the
+//		added breakpoint.
+//
+//
+
+extern Bkpt *breakpoints;
+
+
+int
+breakhit(Ureg *ur, Proc *p)
+{
+	Bkpt *b;
+	int nmatched;
+
+	ur->pc--;
+
+	nmatched = 0;
+	for(b = breakpoints; b != nil; b = b->next) {
+		if(breakmatch(b->conditions, ur, p)) {
+			breaknotify(b, p);
+			++nmatched;
+		}
+	}
+
+	if (nmatched)
+		return 1;
+
+	if (skip != nil)
+		panic("x86break: non-nil skip in breakhit\n");
+
+	for(b = breakpoints; b != (Bkpt*) nil;  b = b->next) {
+		if(b->addr == ur->pc) {
+			if(breakclear(b->id) == 0)
+				panic("breakhit: breakclear() failed");
+			
+			skip = b;
+			skipflags = ur->flags;
+			if (p != 0)
+				p->state = Stopped;			/* this should disable scheduling */
+
+			if (ur->flags & (1 << 9)) {		/* mask all interrupts */
+				ur->flags &= ~(1<<9);
+			}
+			ur->flags |= (1 << 8);
+		}
+	}
+	return 1;
+}
+
+int
+isvalid_va(void*)
+{
+	return 1;
+}