2 files changed, 121 insertions, 35 deletions

diff --git a/sys/ia64/ia64/machdep.c b/sys/ia64/ia64/machdep.c
index dc0501629a4a..00cab574a9f6 100644
--- a/sys/ia64/ia64/machdep.c
+++ b/sys/ia64/ia64/machdep.c
@@ -886,8 +886,9 @@ sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
 	mc = &sf.sf_uc.uc_mcontext;
 	mc->mc_special = tf->tf_special;
 	mc->mc_scratch = tf->tf_scratch;
+
 	if ((tf->tf_flags & FRAME_SYSCALL) == 0) {
-		mc->mc_flags |= IA64_MC_FLAGS_SCRATCH_VALID;
+		mc->mc_flags |= _MC_FLAGS_ASYNC_CONTEXT;
 		mc->mc_scratch_fp = tf->tf_scratch_fp;
 		/*
 		 * XXX High FP. If the process has never used the high FP,
@@ -896,7 +897,9 @@ sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
 		 * already there (ie get them from the CPU that has them)
 		 * and write them in the context.
 		 */
-	}
+	} else
+		mc->mc_flags |= _MC_FLAGS_SCRATCH_VALID;
+
 	save_callee_saved(&mc->mc_preserved);
 	save_callee_saved_fp(&mc->mc_preserved_fp);
 
@@ -992,22 +995,29 @@ sigreturn(struct thread *td,
 		return (EFAULT);
 
 	/*
-	 * XXX make sure ndirty in the current trapframe is less than
-	 * 0x1f8 so that if we throw away the current register stack,
-	 * we have reached the bottom of the kernel register stack.
-	 * See also exec_setregs.
-	 */
-
-	/*
-	 * Restore the user-supplied information
+	 * Restore the user-supplied information.
+	 * XXX Very much incomplete.
 	 */
 	mc = &uc.uc_mcontext;
 	tf->tf_special = mc->mc_special;
-	tf->tf_scratch = mc->mc_scratch;
-	if ((mc->mc_flags & IA64_MC_FLAGS_SCRATCH_VALID) != 0) {
+
+	if (mc->mc_flags & _MC_FLAGS_ASYNC_CONTEXT) {
+		tf->tf_scratch = mc->mc_scratch;
 		tf->tf_scratch_fp = mc->mc_scratch_fp;
 		/* XXX high FP. */
+	} else {
+		if ((mc->mc_flags & _MC_FLAGS_SCRATCH_VALID) == 0) {
+			tf->tf_scratch.gr15 = 0;
+			if (mc->mc_flags & _MC_FLAGS_RETURN_VALID) {
+				tf->tf_scratch.gr8 = mc->mc_scratch.gr8;
+				tf->tf_scratch.gr9 = mc->mc_scratch.gr9;
+				tf->tf_scratch.gr10 = mc->mc_scratch.gr10;
+				tf->tf_scratch.gr11 = mc->mc_scratch.gr11;
+			}
+		} else
+			tf->tf_scratch = mc->mc_scratch;
 	}
+
 	restore_callee_saved(&mc->mc_preserved);
 	restore_callee_saved_fp(&mc->mc_preserved_fp);
 
@@ -1043,10 +1053,8 @@ get_mcontext(struct thread *td, mcontext_t *mc, int clear_ret)
 	uint64_t bspst, *kstk, *ustk;
 
 	tf = td->td_frame;
+	bzero(mc, sizeof(*mc));
 	s = tf->tf_special;
-	s.pfs = s.cfm;
-	s.rp = s.iip;
-	s.cfm = s.iip = 0;
 	if (s.ndirty != 0) {
 		__asm __volatile("mov	ar.rsc=0;;");
 		__asm __volatile("mov	%0=ar.bspstore" : "=r"(bspst));
@@ -1068,19 +1076,32 @@ get_mcontext(struct thread *td, mcontext_t *mc, int clear_ret)
 		}
 		s.bspstore = (uintptr_t)ustk;
 	}
+	if (tf->tf_flags & FRAME_SYSCALL) {
+		s.pfs = s.cfm;
+		s.rp = s.iip;
+		s.cfm = s.iip = 0;
+		/*
+		 * Put the syscall return values in the context. We need this
+		 * for swapcontext() to work. Note that we don't use gr11 in
+		 * the kernel, but the runtime specification defines it as a
+		 * return register, just like gr8-gr10.
+		 */
+		mc->mc_flags |= _MC_FLAGS_RETURN_VALID;
+		if (!clear_ret) {
+			mc->mc_scratch.gr8 = tf->tf_scratch.gr8;
+			mc->mc_scratch.gr9 = tf->tf_scratch.gr9;
+			mc->mc_scratch.gr10 = tf->tf_scratch.gr10;
+			mc->mc_scratch.gr11 = tf->tf_scratch.gr11;
+		}
+	} else {
+		mc->mc_flags |= _MC_FLAGS_ASYNC_CONTEXT;
+		mc->mc_scratch = tf->tf_scratch;
+		mc->mc_scratch_fp = tf->tf_scratch_fp;
+		/* XXX High FP */
+	}
 	mc->mc_special = s;
 	save_callee_saved(&mc->mc_preserved);
 	save_callee_saved_fp(&mc->mc_preserved_fp);
-	/*
-	 * Put the syscall return values in the context. We need this
-	 * for swapcontext() to work. Note that we don't use gr11 in
-	 * the kernel, but the runtime specification defines it as a
-	 * return register, just like gr8-gr10.
-	 */
-	mc->mc_scratch.gr8 = (clear_ret) ? 0 : tf->tf_scratch.gr8;
-	mc->mc_scratch.gr9 = (clear_ret) ? 0 : tf->tf_scratch.gr9;
-	mc->mc_scratch.gr10 = (clear_ret) ? 0 : tf->tf_scratch.gr10;
-	mc->mc_scratch.gr11 = (clear_ret) ? 0 : tf->tf_scratch.gr11;
 	return (0);
 }
 
@@ -1092,19 +1113,34 @@ set_mcontext(struct thread *td, const mcontext_t *mc)
 
 	tf = td->td_frame;
 	s = mc->mc_special;
-	s.cfm = s.pfs;
-	s.iip = s.rp;
-	s.pfs = tf->tf_special.pfs;
-	s.rp = tf->tf_special.rp;
 	/* Only copy the user mask from the new context. */
 	s.psr = (s.psr & 0x1f) | (tf->tf_special.psr & ~0x1f);
+	if (mc->mc_flags & _MC_FLAGS_ASYNC_CONTEXT) {
+		tf->tf_scratch = mc->mc_scratch;
+		tf->tf_scratch_fp = mc->mc_scratch_fp;
+		/* XXX High FP */
+	} else {
+		s.cfm = s.pfs;
+		s.pfs = tf->tf_special.pfs;
+		s.iip = s.rp;
+		s.rp = tf->tf_special.rp;
+		if ((mc->mc_flags & _MC_FLAGS_SCRATCH_VALID) == 0) {
+			if (mc->mc_flags & _MC_FLAGS_RETURN_VALID) {
+				tf->tf_scratch.gr8 = mc->mc_scratch.gr8;
+				tf->tf_scratch.gr9 = mc->mc_scratch.gr9;
+				tf->tf_scratch.gr10 = mc->mc_scratch.gr10;
+				tf->tf_scratch.gr11 = mc->mc_scratch.gr11;
+			}
+		} else
+			tf->tf_scratch = mc->mc_scratch;
+	}
 	tf->tf_special = s;
 	restore_callee_saved(&mc->mc_preserved);
 	restore_callee_saved_fp(&mc->mc_preserved_fp);
-	tf->tf_scratch.gr8 = mc->mc_scratch.gr8;
-	tf->tf_scratch.gr9 = mc->mc_scratch.gr9;
-	tf->tf_scratch.gr10 = mc->mc_scratch.gr10;
-	tf->tf_scratch.gr11 = mc->mc_scratch.gr11;
+
+	if (mc->mc_flags & _MC_FLAGS_KSE_SET_MBOX)
+		suword((caddr_t)mc->mc_special.ifa, mc->mc_special.isr);
+
 	return (0);
 }
 
diff --git a/sys/ia64/include/ucontext.h b/sys/ia64/include/ucontext.h
index e5fae653092a..66f8ffff0075 100644
--- a/sys/ia64/include/ucontext.h
+++ b/sys/ia64/include/ucontext.h
@@ -33,10 +33,60 @@
 
 #include <machine/_regset.h>
 
+/*
+ * The mc_flags field provides the necessary clues when dealing with the gory
+ * details of ia64 specific contexts. A comprehensive explanation is added for
+ * everybody's sanity, including the author's.
+ *
+ * The first and foremost variation in the context is synchronous contexts
+ * (= synctx) versus asynchronous contexts (= asynctx). A synctx is created
+ * synchronously WRT program execution and has the advantage that none of the
+ * scratch registers have to be saved. They are assumed to be clobbered by the
+ * call to the function that creates the context. An asynctx needs to have the
+ * scratch registers preserved because it can describe any point in a thread's
+ * (or process') execution.
+ *
+ * Below a description of the flags and their meaning:
+ *
+ *	_MC_FLAGS_ASYNC_CONTEXT
+ *		If set, indicates that mc_scratch and mc_scratch_fp are both
+ *		valid. IFF not set, _MC_FLAGS_RETURN_VALID indicates if the
+ *		return registers are valid or not.
+ *	_MC_FLAGS_HIGHFP_VALID
+ *		If set, indicates that the high FP registers (f32-f127) are
+ *		valid. This flag is very likely not going to be set for any
+ *		sensible synctx, but is not explicitly disallowed. Any synctx
+ *		that has this flag may or may not have the high FP registers
+ *		restored. In short: don't do it.
+ *	_MC_FLAGS_KSE_SET_MBOX
+ *		This flag is special to setcontext(2) and swapcontext(2). It
+ *		instructs the kernel to write the value in mc_special.isr to
+ *		the memory address pointed to by mc_special.ifa. This allows
+ *		the kernel to switch to a new context in a KSE based threaded
+ *		program. Note that this is a non-srandard extension to the
+ *		otherwise standard system calls and use of this flag should be
+ *		limited to KSE.
+ *	_MC_FLAGS_RETURN_VALID
+ *		If set and _MC_FLAGS_ASYNC_CONTEXT is not set indicates that
+ *		the ABI defined return registers are valid. Both getcontext(2)
+ *		and swapcontext(2) need to save the system call return values.
+ *		Any synctx that does not have this flag may still have the
+ *		return registers restored from the context.
+ *	_MC_FLAGS_SCRATCH_VALID
+ *		If set and _MC_FLAGS_ASYNC_CONTEXT is not set indicates that
+ *		the scratch registers, but not the FP registers are valid.
+ *		This flag is set in contexts passed to signal handlers. This
+ *		flag is a superset of _MC_FLAGS_RETURN_VALID. If both flags
+ *		are set, this flag takes precedence.
+ */
+
 typedef struct __mcontext {
 	unsigned long		mc_flags;
-#define	IA64_MC_FLAGS_SCRATCH_VALID	1
-#define	IA64_MC_FLAGS_HIGHFP_VALID	2
+#define	_MC_FLAGS_ASYNC_CONTEXT		0x0001
+#define	_MC_FLAGS_HIGHFP_VALID		0x0002
+#define	_MC_FLAGS_KSE_SET_MBOX		0x0004
+#define	_MC_FLAGS_RETURN_VALID		0x0008
+#define	_MC_FLAGS_SCRATCH_VALID		0x0010
 	unsigned long		_reserved_;
 	struct _special		mc_special;
 	struct _callee_saved	mc_preserved;