From 2c1781e5e21955f91acc3389456fe7aa2f2fcd7c Mon Sep 17 00:00:00 2001
From: Sascha Wildner <saw@online.de>
Date: Tue, 20 Sep 2011 22:24:20 +0200
Subject: [PATCH] libc/x86_64: Bring back {get,make,signal}context().

---
 lib/libc/i386/gen/Makefile.inc      |    1 -
 lib/libc/x86_64/gen/Makefile.inc    |    1 +
 lib/libc/x86_64/gen/makecontext.c   |  107 +++++++++++++++++++++++++++++++++++
 lib/libc/x86_64/gen/signalcontext.c |  103 +++++++++++++++++++++++++++++++++
 lib/libc/x86_64/sys/Makefile.inc    |    2 +-
 lib/libc/x86_64/sys/getcontext.S    |   54 ++++++++++++++++++
 6 files changed, 266 insertions(+), 2 deletions(-)
 create mode 100644 lib/libc/x86_64/gen/makecontext.c
 create mode 100644 lib/libc/x86_64/gen/signalcontext.c
 create mode 100644 lib/libc/x86_64/sys/getcontext.S

diff --git a/lib/libc/i386/gen/Makefile.inc b/lib/libc/i386/gen/Makefile.inc
index c519a07..c395425 100644
--- a/lib/libc/i386/gen/Makefile.inc
+++ b/lib/libc/i386/gen/Makefile.inc
@@ -1,6 +1,5 @@
 #	@(#)Makefile.inc	8.1 (Berkeley) 6/4/93
 # $FreeBSD: src/lib/libc/i386/gen/Makefile.inc,v 1.10.2.1 2001/02/07 00:12:45 peter Exp $
-# $DragonFly: src/lib/libc/i386/gen/Makefile.inc,v 1.6 2007/01/16 07:16:23 dillon Exp $
 
 SRCS+=	fpclassifyl.c infinityl.c isfinitel.c isinfl.c isnanl.c \
 	ldexp.c makecontext.c nanf.c signbitl.c \
diff --git a/lib/libc/x86_64/gen/Makefile.inc b/lib/libc/x86_64/gen/Makefile.inc
index adfbeb1..6c4acf0 100644
--- a/lib/libc/x86_64/gen/Makefile.inc
+++ b/lib/libc/x86_64/gen/Makefile.inc
@@ -6,5 +6,6 @@ SRCS+=	_setjmp.S rfork_thread.S setjmp.S sigsetjmp.S \
 	fpclassifyl.c nanf.c signbitl.c flt_rounds.c \
 	infinityl.c isinfl.c isfinitel.c isnanl.c \
 	ldexp.c \
+	makecontext.c signalcontext.c \
 	fpgetmask.S fpsetmask.S fpgetround.S fpsetround.S \
 	fpgetsticky.S fpsetsticky.S
diff --git a/lib/libc/x86_64/gen/makecontext.c b/lib/libc/x86_64/gen/makecontext.c
new file mode 100644
index 0000000..5c1a859
--- /dev/null
+++ b/lib/libc/x86_64/gen/makecontext.c
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2003 Marcel Moolenaar
+ * 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 ``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 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.
+ *
+ * $FreeBSD: src/lib/libc/amd64/gen/makecontext.c,v 1.2 2003/12/05 01:36:44 peter Exp $
+ */
+
+
+#include <sys/types.h>
+#include <sys/ucontext.h>
+#include <stdarg.h>
+#include <stdlib.h>
+
+typedef void (*func_t)(uint64_t, uint64_t, uint64_t, uint64_t, uint64_t,
+    uint64_t);
+
+/* Prototypes */
+static void ctx_wrapper(ucontext_t *ucp, func_t func, uint64_t *args);
+
+__weak_reference(__makecontext, makecontext);
+
+void
+__makecontext(ucontext_t *ucp, void (*start)(void), int argc, ...)
+{
+	uint64_t *args;
+	uint64_t *sp;
+	va_list ap;
+	int i;
+
+	/* A valid context is required. */
+	if ((ucp == NULL) || (ucp->uc_mcontext.mc_len != sizeof(mcontext_t)))
+		return;
+	else if ((argc < 0) || (argc > 6) || (ucp->uc_stack.ss_sp == NULL) ||
+	    (ucp->uc_stack.ss_size < MINSIGSTKSZ)) {
+		/*
+		 * This should really return -1 with errno set to ENOMEM
+		 * or something, but the spec says that makecontext is
+		 * a void function.   At least make sure that the context
+		 * isn't valid so it can't be used without an error.
+		 */
+		ucp->uc_mcontext.mc_len = 0;
+		return;
+	}
+
+	/* Align the stack to 16 bytes. */
+	sp = (uint64_t *)(ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
+	sp = (uint64_t *)((uint64_t)sp & -15UL);
+
+	/* Allocate space for a maximum of 6 arguments on the stack. */
+	args = sp - 6;
+
+	/*
+	 * Account for arguments on stack and do the funky C entry alignment.
+	 * This means that we need an 8-byte-odd alignment since the ABI expects
+	 * the return address to be pushed, thus breaking the 16 byte alignment.
+	 */
+	sp -= 7;
+
+	/* Add the arguments: */
+	va_start(ap, argc);
+	for (i = 0; i < argc; i++)
+		args[i] = va_arg(ap, uint64_t);
+	va_end(ap);
+	for (i = argc; i < 6; i++)
+		args[i] = 0;
+
+	ucp->uc_mcontext.mc_rdi = (register_t)ucp;
+	ucp->uc_mcontext.mc_rsi = (register_t)start;
+	ucp->uc_mcontext.mc_rdx = (register_t)args;
+	ucp->uc_mcontext.mc_rbp = (register_t)sp;
+	ucp->uc_mcontext.mc_rbx = (register_t)sp;
+	ucp->uc_mcontext.mc_rsp = (register_t)sp;
+	ucp->uc_mcontext.mc_rip = (register_t)ctx_wrapper;
+}
+
+static void
+ctx_wrapper(ucontext_t *ucp, func_t func, uint64_t *args)
+{
+	(*func)(args[0], args[1], args[2], args[3], args[4], args[5]);
+	if (ucp->uc_link == NULL)
+		exit(0);
+	setcontext((const ucontext_t *)ucp->uc_link);
+	/* should never get here */
+	abort();
+	/* NOTREACHED */
+}
diff --git a/lib/libc/x86_64/gen/signalcontext.c b/lib/libc/x86_64/gen/signalcontext.c
new file mode 100644
index 0000000..5f8f735
--- /dev/null
+++ b/lib/libc/x86_64/gen/signalcontext.c
@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2003 Marcel Moolenaar
+ * 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 ``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 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.
+ *
+ * $FreeBSD: src/lib/libc/amd64/gen/signalcontext.c,v 1.2 2003/07/26 12:58:28 davidxu Exp $
+ */
+
+#include <sys/types.h>
+#include <sys/ucontext.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <strings.h>
+
+typedef void (*handler_t)(uint64_t, uint64_t, uint64_t);
+
+/* Prototypes */
+static void ctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args);
+
+__weak_reference(__signalcontext, signalcontext);
+
+int
+__signalcontext(ucontext_t *ucp, int sig, __sighandler_t *func)
+{
+	uint64_t *args;
+	siginfo_t *sig_si;
+	ucontext_t *sig_uc;
+	uint64_t sp;
+
+	/* Bail out if we don't have a valid ucontext pointer. */
+	if (ucp == NULL)
+		abort();
+
+	/*
+	 * Build a signal frame and copy the arguments of signal handler
+	 * 'func' onto the stack. We only need 3 arguments, but we
+	 * create room for 4 so that we are 16-byte aligned.
+	 */
+	sp = (ucp->uc_mcontext.mc_rsp - sizeof(ucontext_t)) & ~15UL;
+	sig_uc = (ucontext_t *)sp;
+	bcopy(ucp, sig_uc, sizeof(*sig_uc));
+	sp = (sp - sizeof(siginfo_t)) & ~15UL;
+	sig_si = (siginfo_t *)sp;
+	bzero(sig_si, sizeof(*sig_si));
+	sig_si->si_signo = sig;
+	sp -= 4 * sizeof(uint64_t);
+	args = (uint64_t *)sp;
+	args[0] = sig;
+	args[1] = (intptr_t)sig_si;
+	args[2] = (intptr_t)sig_uc;
+	args[3] = 0;
+	sp -= 16;
+
+	/*
+	 * Setup the ucontext of the signal handler.
+	 */
+	bzero(&ucp->uc_mcontext, sizeof(ucp->uc_mcontext));
+	ucp->uc_link = sig_uc;
+	sigdelset(&ucp->uc_sigmask, sig);
+
+	ucp->uc_mcontext.mc_len = sizeof(mcontext_t);
+	ucp->uc_mcontext.mc_rdi = (register_t)ucp;
+	ucp->uc_mcontext.mc_rsi = (register_t)func;
+	ucp->uc_mcontext.mc_rdx = (register_t)args;
+	ucp->uc_mcontext.mc_rbp = (register_t)sp;
+	ucp->uc_mcontext.mc_rbx = (register_t)sp;
+	ucp->uc_mcontext.mc_rsp = (register_t)sp;
+	ucp->uc_mcontext.mc_rip = (register_t)ctx_wrapper;
+	return (0);
+}
+
+static void
+ctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args)
+{
+
+	(*func)(args[0], args[1], args[2]);
+	if (ucp->uc_link == NULL)
+		exit(0);
+	setcontext((const ucontext_t *)ucp->uc_link);
+	/* should never get here */
+	abort();
+	/* NOTREACHED */
+}
diff --git a/lib/libc/x86_64/sys/Makefile.inc b/lib/libc/x86_64/sys/Makefile.inc
index 5145e76..4ba301a 100644
--- a/lib/libc/x86_64/sys/Makefile.inc
+++ b/lib/libc/x86_64/sys/Makefile.inc
@@ -3,7 +3,7 @@
 
 SRCS+=	amd64_get_fsbase.c amd64_get_gsbase.c amd64_set_fsbase.c amd64_set_gsbase.c
 
-MDASM=	vfork.S brk.S cerror.S exect.S pipe.S ptrace.S \
+MDASM=	vfork.S brk.S cerror.S exect.S getcontext.S pipe.S ptrace.S \
 	reboot.S sbrk.S setlogin.S sigreturn.S
 
 # Don't generate default code for these syscalls:
diff --git a/lib/libc/x86_64/sys/getcontext.S b/lib/libc/x86_64/sys/getcontext.S
new file mode 100644
index 0000000..3507982
--- /dev/null
+++ b/lib/libc/x86_64/sys/getcontext.S
@@ -0,0 +1,54 @@
+/*-
+ * Copyright (c) 2003 Peter Wemm <peter@FreeBSD.org>
+ * 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.
+ *
+ * $FreeBSD: src/lib/libc/amd64/sys/getcontext.S,v 1.2 2003/09/04 00:31:45 peter Exp $
+ */
+
+#include <machine/asm.h>
+#include <SYS.h>
+
+/*
+ * This has to be magic to handle the multiple returns.
+ * Otherwise, the setcontext() syscall will return here and we'll
+ * pop off the return address and go to the *setcontext* call.
+ */
+	.weak	_getcontext
+	.set	_getcontext,__sys_getcontext
+	.weak	getcontext
+	.set	getcontext,__sys_getcontext
+ENTRY(__sys_getcontext)
+	movq	(%rsp),%rsi	/* save getcontext return address */
+	mov	$SYS_getcontext,%rax
+	KERNCALL
+	jb	1f
+	addq	$8,%rsp		/* remove stale (setcontext) return address */
+	jmp	*%rsi		/* restore return address */
+1:
+#ifdef PIC
+	movq	PIC_GOT(HIDENAME(cerror)),%rdx
+	jmp	*%rdx
+#else
+	jmp	HIDENAME(cerror)
+#endif
-- 
1.6.6.1

