Initial Spring 2016 commit.

kern/arch/mips/thread/threadstart.S

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
+ *	The President and Fellows of Harvard College.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * Assembler-level thread startup trampoline.
+ */
+
+#include <kern/mips/regdefs.h>
+
+   .text
+   .set noreorder
+
+   .globl mips_threadstart
+   .type mips_threadstart,@function
+   .ent mips_threadstart
+mips_threadstart:
+
+   /*
+    * This code doesn't take normal arguments. It's reached when
+    * switchframe_switch switches to a new thread. switchframe_switch
+    * does "j ra"; ra gets preloaded in switchframe_init to come here.
+    *
+    * Our arguments are in callee-save registers, as follows:
+    *
+    *   s0   entrypoint
+    *   s1   data1
+    *   s2   data2
+    *
+    * We need to rearrange these so as to call the normal C function
+    * thread_startup(void (*entrypoint)(), void *data1, unsigned long data2).
+    */
+
+   addiu sp, sp, -16    /* make our stack frame */
+
+   move ra, $0          /* clear return addr so we're top of the call stack */
+
+   move a0, s0          /* load arguments and call */
+   move a1, s1
+   j thread_startup
+   move a2, s2          /* (in delay slot) */
+
+   .end mips_threadstart