makecontext lib call.

Submitted by: Suleiman Souhlal <refugee@segfaulted.com>

lib/libc/powerpc/gen/Makefile.inc

@@ -1,7 +1,8 @@
 # $FreeBSD$
 
-SRCS += fabs.S flt_rounds.c fpgetmask.c fpgetround.c fpgetsticky.c \
-	fpsetmask.c fpsetround.c fpsetsticky.c frexp.c infinity.c isinf.c \
-	ldexp.c modf.c _setjmp.S setjmp.S sigsetjmp.S syncicache.c
+SRCS += _ctx_start.S fabs.S flt_rounds.c fpgetmask.c fpgetround.c \
+	fpgetsticky.c fpsetmask.c fpsetround.c fpsetsticky.c frexp.c \
+	infinity.c isinf.c ldexp.c makecontext.c modf.c _setjmp.S \
+	setjmp.S sigsetjmp.S syncicache.c
 
 

lib/libc/powerpc/gen/_ctx_start.S

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2004 Suleiman Souhlal
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ */
+
+ #include <machine/asm.h>
+
+ __FBSDID("$FreeBSD$");
+
+	.globl  CNAME(_ctx_done)
+	.globl  CNAME(abort)
+
+ ENTRY(_ctx_start)
+	mtlr	%r14
+	blrl			/* branch to start function */
+	mr	%r3,%r15	/* pass pointer to ucontext as argument */
+	bl	PIC_PLT(CNAME(_ctx_done)) /* branch to ctxt completion func */
+	/*
+	 * we should never return from the
+	 * above branch.
+	 */
+	bl	PIC_PLT(CNAME(abort))	/* abort */

lib/libc/powerpc/gen/makecontext.c

@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2004 Suleiman Souhlal
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+
+#include <stdarg.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <ucontext.h>
+
+__weak_reference(__makecontext, makecontext);
+
+void _ctx_done(ucontext_t *ucp);
+void _ctx_start(void);
+
+void
+_ctx_done(ucontext_t *ucp)
+{
+	if (ucp->uc_link == NULL)
+		exit(0);
+	else {
+		/* invalidate context */
+		ucp->uc_mcontext.mc_len = 0;
+
+		setcontext((const ucontext_t *)ucp->uc_link);
+
+		abort(); /* should never return from above call */
+	}
+}
+
+void
+__makecontext(ucontext_t *ucp, void (*start)(void), int argc, ...)
+{
+	mcontext_t *mc;
+	char *sp;
+	va_list ap;
+	int i, regargs, stackargs;
+
+	/* Sanity checks */
+	if ((ucp == NULL) || (argc < 0) || (argc > NCARGS)
+	    || (ucp->uc_stack.ss_sp == NULL)
+	    || (ucp->uc_stack.ss_size < MINSIGSTKSZ)) {
+		/* invalidate context */
+		ucp->uc_mcontext.mc_len = 0;
+		return;
+	}
+
+	/*
+	 * The stack must have space for the frame pointer, saved
+	 * link register, overflow arguments, and be 16-byte
+	 * aligned.
+	 */
+	stackargs = (argc > 8) ? argc - 8 : 0;
+	sp = (char *) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size
+		- sizeof(uint32_t)*(stackargs + 2);
+	sp = (char *)((uint32_t)sp & ~0x1f);
+
+	mc = &ucp->uc_mcontext;
+
+	/*
+	 * Up to 8 register args. Assumes all args are 32-bit and
+	 * integer only. Not sure how to cater for floating point,
+	 * although 64-bit args will work if aligned correctly
+	 * in the arg list.
+	 */
+	regargs = (argc > 8) ? 8 : argc;
+	va_start(ap, argc);
+	for (i = 0; i < regargs; i++)
+		mc->mc_gpr[3 + i] = va_arg(ap, uint32_t);
+
+	/*
+	 * Overflow args go onto the stack
+	 */
+	if (argc > 8) {
+		uint32_t *argp;
+
+		/* Skip past frame pointer and saved LR */
+		argp = (uint32_t *)sp + 2;
+
+		for (i = 0; i < stackargs; i++)
+			*argp++ = va_arg(ap, uint32_t);
+	}
+	va_end(ap);
+
+	/*
+	 * Use caller-saved regs 14/15 to hold params that _ctx_start
+	 * will use to invoke the user-supplied func
+	 */
+	mc->mc_lr = (uint32_t) _ctx_start;
+	mc->mc_gpr[1] = (uint32_t) sp;		/* new stack pointer */
+	mc->mc_gpr[14] = (uint32_t) start;	/* r14 <- start */
+	mc->mc_gpr[15] = (uint32_t) ucp;	/* r15 <- ucp */
+}