libc: add {get,set,swap,make}context user context manipulation functions

Add the obsolescent SUSv3 family of user context manipulating functions
for arm, i386, mips, x86_64.

Signed-off-by: Timon ter Braak <timonterbraak@gmail.com>
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

37 files changed, 2174 insertions, 8 deletions

diff --git a/Rules.mak b/Rules.mak
index 96871e1ae..8943fbf85 100644
--- a/Rules.mak
+++ b/Rules.mak
@@ -813,3 +813,5 @@ SHARED_END_FILES:=$(LIBGCC_DIR)crtendS.o $(top_builddir)lib/crtn.o
 endif
 
 LOCAL_INSTALL_PATH := install_dir
+
+PTHREAD_GENERATE_MANGLE ?= -n "s/^.*@@@name@@@\([^@]*\)@@@value@@@[^0-9Xxa-fA-F-]*\([0-9Xxa-fA-F-][0-9Xxa-fA-F-]*\).*@@@end@@@.*\$$/\#define \1 \2/p"
diff --git a/extra/Configs/Config.arm b/extra/Configs/Config.arm
index 0bb2971a9..dc536434d 100644
--- a/extra/Configs/Config.arm
+++ b/extra/Configs/Config.arm
@@ -11,6 +11,7 @@ config FORCE_OPTIONS_FOR_ARCH
 	bool
 	default y
 	select ARCH_ANY_ENDIAN
+	select ARCH_HAS_UCONTEXT
 
 config CONFIG_ARM_EABI
 	bool "Build for EABI"
diff --git a/extra/Configs/Config.i386 b/extra/Configs/Config.i386
index 288aa5ebe..92cee3b83 100644
--- a/extra/Configs/Config.i386
+++ b/extra/Configs/Config.i386
@@ -12,6 +12,7 @@ config FORCE_OPTIONS_FOR_ARCH
 	default y
 	select ARCH_LITTLE_ENDIAN
 	select ARCH_HAS_MMU
+	select ARCH_HAS_UCONTEXT
 
 choice
 	prompt "Target x86 Processor Family"
diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in
index 4bb681207..62bcd9b6c 100644
--- a/extra/Configs/Config.in
+++ b/extra/Configs/Config.in
@@ -261,6 +261,9 @@ config ARCH_HAS_NO_LDSO
 	bool
 	select ARCH_HAS_NO_SHARED
 
+config ARCH_HAS_UCONTEXT
+	bool
+
 config HAVE_SHARED
 	bool "Enable shared libraries"
 	depends on !ARCH_HAS_NO_SHARED
@@ -678,6 +681,19 @@ config UCLIBC_SUSV3_LEGACY
 
 	  WARNING! ABI incompatibility.
 
+config UCLIBC_HAS_CONTEXT_FUNCS
+	bool "Use obsolescent context control functions"
+	depends on UCLIBC_SUSV3_LEGACY && ARCH_HAS_UCONTEXT
+	help
+	  Add into library the SuSv3 obsolescent functions used for context
+	  control. The setcontext family allows the implementation in C of
+	  advanced control flow patterns such as iterators, fibers, and
+	  coroutines. They may be viewed as an advanced version of
+	  setjmp/longjmp; whereas the latter allows only a single non-local jump
+	  up the stack, setcontext allows the creation of multiple cooperative
+	  threads of control, each with its own stack.
+	  These functions are: setcontext, getcontext, makecontext, swapcontext.
+
 config UCLIBC_SUSV3_LEGACY_MACROS
 	bool "Enable SuSv3 LEGACY macros"
 	help
diff --git a/extra/Configs/Config.mips b/extra/Configs/Config.mips
index 063b07cea..48e0b6489 100644
--- a/extra/Configs/Config.mips
+++ b/extra/Configs/Config.mips
@@ -11,6 +11,7 @@ config FORCE_OPTIONS_FOR_ARCH
 	bool
 	default y
 	select ARCH_ANY_ENDIAN
+	select ARCH_HAS_UCONTEXT
 
 choice
 	prompt "Target ABI"
diff --git a/extra/Configs/Config.x86_64 b/extra/Configs/Config.x86_64
index 1b2808893..4c8c3a9bd 100644
--- a/extra/Configs/Config.x86_64
+++ b/extra/Configs/Config.x86_64
@@ -12,3 +12,4 @@ config FORCE_OPTIONS_FOR_ARCH
 	default y
 	select ARCH_LITTLE_ENDIAN
 	select ARCH_HAS_MMU
+	select ARCH_HAS_UCONTEXT
diff --git a/include/ucontext.h b/include/ucontext.h
index 14a12704e..f11db7794 100644
--- a/include/ucontext.h
+++ b/include/ucontext.h
@@ -15,17 +15,43 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+/* The System V ABI user-level context switching support functions
+   are marked obsolescent by SuSv3.  */
+
 #ifndef _UCONTEXT_H
 #define _UCONTEXT_H	1
 
 #include <features.h>
 
+#ifdef __UCLIBC_HAS_CONTEXT_FUNCS__
+
 /* Get machine dependent definition of data structures.  */
 #include <sys/ucontext.h>
 
-/* The System V ABI user-level context switching support functions
- * are marked obsolescent by SuSv3, and are not implemented by
- * uClibc.  This header is therefore empty.  */
+__BEGIN_DECLS
+
+/* Get user context and store it in variable pointed to by UCP.  */
+extern int getcontext (ucontext_t *__ucp) __THROW;
+
+/* Set user context from information of variable pointed to by UCP.  */
+extern int setcontext (const ucontext_t *__ucp) __THROW;
+
+/* Save current context in context variable pointed to by OUCP and set
+   context from variable pointed to by UCP.  */
+extern int swapcontext (ucontext_t *__restrict __oucp,
+			const ucontext_t *__restrict __ucp) __THROW;
+
+/* Manipulate user context UCP to continue with calling functions FUNC
+   and the ARGC-1 parameters following ARGC when the context is used
+   the next time in `setcontext' or `swapcontext'.
+
+   We cannot say anything about the parameters FUNC takes; `void'
+   is as good as any other choice.  */
+extern void makecontext (ucontext_t *__ucp, void (*__func) (void),
+			 int __argc, ...) __THROW;
+
+__END_DECLS
 
+#endif
 
 #endif /* ucontext.h */
diff --git a/libc/.gitignore b/libc/.gitignore
new file mode 100644
index 000000000..f4c03059d
--- /dev/null
+++ b/libc/.gitignore
@@ -0,0 +1 @@
+ucontext_i.[chs]
diff --git a/libc/sysdeps/linux/Makefile.commonarch b/libc/sysdeps/linux/Makefile.commonarch
index c1bc5df30..ac89e7258 100644
--- a/libc/sysdeps/linux/Makefile.commonarch
+++ b/libc/sysdeps/linux/Makefile.commonarch
@@ -37,5 +37,23 @@ headers-y += $(ARCH_HEADERS_OUT)
 headers_clean-y += HEADERCLEAN_$(subst $(top_builddir),,$(ARCH_OUT))
 HEADERCLEAN_$(subst $(top_builddir),,$(ARCH_OUT)):
 	$(do_rm) $(ARCH_HEADERS_OUT)
-
 endif
+
+CFLAGS-ucontext_i.c = -S
+
+$(ARCH_OUT)/ucontext_i.c: $(ARCH_DIR)/ucontext_i.sym
+	$(do_awk) $(top_srcdir)extra/scripts/gen-as-const.awk $< > $@
+
+$(ARCH_OUT)/ucontext_i.s: $(ARCH_OUT)/ucontext_i.c
+	$(compile.c)
+
+$(ARCH_OUT)/ucontext_i.h: $(ARCH_OUT)/ucontext_i.s
+	$(do_sed) $(PTHREAD_GENERATE_MANGLE) $< > $@
+
+pregen-headers-$(UCLIBC_HAS_CONTEXT_FUNCS) += $(ARCH_OUT)/ucontext_i.h
+
+headers_clean-$(UCLIBC_HAS_CONTEXT_FUNCS) += \
+	HEADERCLEAN_$(subst $(top_builddir),,$(ARCH_OUT)/ucontext_i)
+
+HEADERCLEAN_$(subst $(top_builddir),,$(ARCH_OUT)/ucontext_i):
+	$(do_rm) $(addprefix $(ARCH_OUT)/ucontext_i., c h s)
diff --git a/libc/sysdeps/linux/arm/Makefile.arch b/libc/sysdeps/linux/arm/Makefile.arch
index 5fc3e545f..36d988bfd 100644
--- a/libc/sysdeps/linux/arm/Makefile.arch
+++ b/libc/sysdeps/linux/arm/Makefile.arch
@@ -43,3 +43,8 @@ libc-static-y += $(ARCH_OUT)/aeabi_lcsts.o $(ARCH_OUT)/aeabi_math.o \
 libc-nonshared-y += $(ARCH_OUT)/aeabi_lcsts.os $(ARCH_OUT)/aeabi_math.os \
 	$(ARCH_OUT)/aeabi_sighandlers.os $(ARCH_OUT)/aeabi_unwind_cpp_pr1.o
 endif
+
+ifeq ($(UCLIBC_HAS_CONTEXT_FUNCS),y)
+CSRC += makecontext.c
+SSRC += getcontext.S setcontext.S swapcontext.S
+endif
diff --git a/libc/sysdeps/linux/arm/getcontext.S b/libc/sysdeps/linux/arm/getcontext.S
new file mode 100644
index 000000000..a987c52f3
--- /dev/null
+++ b/libc/sysdeps/linux/arm/getcontext.S
@@ -0,0 +1,80 @@
+/* Copyright (C) 2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+#include "ucontext_i.h"
+
+	.syntax unified
+	.text
+
+/* int getcontext (ucontext_t *ucp) */
+
+ENTRY(__getcontext)
+	/* No need to save r0-r3, d0-d7, or d16-d31.  */
+	add	r1, r0, #MCONTEXT_ARM_R4
+	stmia   r1, {r4-r11}
+
+	/* Save R13 separately as Thumb can't STM it.  */
+	str     r13, [r0, #MCONTEXT_ARM_SP]
+	str     r14, [r0, #MCONTEXT_ARM_LR]
+	/* Return to LR */
+	str     r14, [r0, #MCONTEXT_ARM_PC]
+	/* Return zero */
+	mov     r2, #0
+	str     r2, [r0, #MCONTEXT_ARM_R0]
+
+	/* Save ucontext_t * across the next call.  */
+	mov	r4, r0
+
+	/* __sigprocmask(SIG_BLOCK, NULL, &(ucontext->uc_sigmask)) */
+	mov     r0, #SIG_BLOCK
+	mov     r1, #0
+	add     r2, r4, #UCONTEXT_SIGMASK
+	bl      PLTJMP(sigprocmask)
+
+#if defined __UCLIBC_HAS_FLOATS__ && ! defined __UCLIBC_HAS_SOFT_FLOAT__
+# ifdef __VFP_FP__
+	/* Store the VFP registers.  */
+	/* Following instruction is fstmiax ip!, {d8-d15}.  */
+	stc     p11, cr8, [r0], #64
+	/* Store the floating-point status register.  */
+	/* Following instruction is fmrx r2, fpscr.  */
+	mrc     p10, 7, r1, cr1, cr0, 0
+	str     r1, [r0], #4
+# endif
+#endif
+#ifdef __IWMMXT__
+	/* Save the call-preserved iWMMXt registers.  */
+	/* Following instructions are wstrd wr10, [r0], #8 (etc.)  */
+	stcl    p1, cr10, [r0], #8
+	stcl    p1, cr11, [r0], #8
+	stcl    p1, cr12, [r0], #8
+	stcl    p1, cr13, [r0], #8
+	stcl    p1, cr14, [r0], #8
+	stcl    p1, cr15, [r0], #8
+#endif
+
+	/* Restore the clobbered R4 and LR.  */
+	ldr	r14, [r4, #MCONTEXT_ARM_LR]
+	ldr	r4, [r4, #MCONTEXT_ARM_R4]
+
+	mov	r0, #0
+	DO_RET(r14)
+
+END(__getcontext)
+weak_alias(__getcontext, getcontext)
diff --git a/libc/sysdeps/linux/arm/makecontext.c b/libc/sysdeps/linux/arm/makecontext.c
new file mode 100644
index 000000000..d6ae6f0d7
--- /dev/null
+++ b/libc/sysdeps/linux/arm/makecontext.c
@@ -0,0 +1,73 @@
+/* Copyright (C) 2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdarg.h>
+#include <ucontext.h>
+
+/* Number of arguments that go in registers.  */
+#define NREG_ARGS  4
+
+/* Take a context previously prepared via getcontext() and set to
+   call func() with the given int only args.  */
+void
+__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
+{
+  extern void __startcontext (void);
+  unsigned long *funcstack;
+  va_list vl;
+  unsigned long *regptr;
+  unsigned int reg;
+  int misaligned;
+
+  /* Start at the top of stack.  */
+  funcstack = (unsigned long *) (ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
+
+  /* Ensure the stack stays eight byte aligned.  */
+  misaligned = ((unsigned long) funcstack & 4) != 0;
+
+  if ((argc > NREG_ARGS) && (argc & 1) != 0)
+    misaligned = !misaligned;
+
+  if (misaligned)
+    funcstack -= 1;
+
+  va_start (vl, argc);
+
+  /* Reserve space for the on-stack arguments.  */
+  if (argc > NREG_ARGS)
+    funcstack -= (argc - NREG_ARGS);
+
+  ucp->uc_mcontext.arm_sp = (unsigned long) funcstack;
+  ucp->uc_mcontext.arm_pc = (unsigned long) func;
+
+  /* Exit to startcontext() with the next context in R4 */
+  ucp->uc_mcontext.arm_r4 = (unsigned long) ucp->uc_link;
+  ucp->uc_mcontext.arm_lr = (unsigned long) __startcontext;
+
+  /* The first four arguments go into registers.  */
+  regptr = &(ucp->uc_mcontext.arm_r0);
+
+  for (reg = 0; (reg < argc) && (reg < NREG_ARGS); reg++)
+    *regptr++ = va_arg (vl, unsigned long);
+
+  /* And the remainder on the stack.  */
+  for (; reg < argc; reg++)
+    *funcstack++ = va_arg (vl, unsigned long);
+
+  va_end (vl);
+}
+weak_alias (__makecontext, makecontext)
diff --git a/libc/sysdeps/linux/arm/setcontext.S b/libc/sysdeps/linux/arm/setcontext.S
new file mode 100644
index 000000000..a5c33a022
--- /dev/null
+++ b/libc/sysdeps/linux/arm/setcontext.S
@@ -0,0 +1,76 @@
+/* Copyright (C) 2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+#include "ucontext_i.h"
+
+	.syntax unified
+	.text
+
+/* int setcontext (const ucontext_t *ucp) */
+
+ENTRY(__setcontext)
+	mov	r4, r0
+
+#if defined __UCLIBC_HAS_FLOATS__ && ! defined __UCLIBC_HAS_SOFT_FLOAT__
+# ifdef __VFP_FP__
+	/* Following instruction is vldmia r0!, {d8-d15}.  */
+	ldc     p11, cr8, [r0], #64
+	/* Restore the floating-point status register.  */
+	ldr     r1, [r0], #4
+	/* Following instruction is fmxr fpscr, r1.  */
+	mcr     p10, 7, r1, cr1, cr0, 0
+# endif
+#endif
+
+#ifdef __IWMMXT__
+	/* Restore the call-preserved iWMMXt registers.  */
+	/* Following instructions are wldrd wr10, [r0], #8 (etc.)  */
+	ldcl    p1, cr10, [r0], #8
+	ldcl    p1, cr11, [r0], #8
+	ldcl    p1, cr12, [r0], #8
+	ldcl    p1, cr13, [r0], #8
+	ldcl    p1, cr14, [r0], #8
+	ldcl    p1, cr15, [r0], #8
+#endif
+
+	/* Now bring back the signal status.  */
+	mov	r0, #SIG_SETMASK
+	add	r1, r4, #UCONTEXT_SIGMASK
+	mov	r2, #0
+	bl	PLTJMP(sigprocmask)
+
+        /* Loading r0-r3 makes makecontext easier.  */
+        add     r14, r4, #MCONTEXT_ARM_R0
+        ldmia   r14, {r0-r11}
+        ldr     r13, [r14, #(MCONTEXT_ARM_SP - MCONTEXT_ARM_R0)]
+        add     r14, r14, #(MCONTEXT_ARM_LR - MCONTEXT_ARM_R0)
+        ldmia   r14, {r14, pc}
+
+END(setcontext)
+weak_alias(__setcontext, setcontext)
+
+	/* Called when a makecontext() context returns.  Start the
+	   context in R4 or fall through to exit().  */
+ENTRY(__startcontext)
+        movs    r0, r4
+        bne     PLTJMP(__setcontext)
+
+        @ New context was 0 - exit
+        b       PLTJMP(_exit)
+END(__startcontext)
diff --git a/libc/sysdeps/linux/arm/swapcontext.S b/libc/sysdeps/linux/arm/swapcontext.S
new file mode 100644
index 000000000..ba6e31c4d
--- /dev/null
+++ b/libc/sysdeps/linux/arm/swapcontext.S
@@ -0,0 +1,63 @@
+/* Copyright (C) 2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+#include "ucontext_i.h"
+
+	.syntax unified
+	.text
+
+/* int swapcontext (ucontext_t *oucp, const ucontext_t *ucp) */
+
+ENTRY(swapcontext)
+
+	/* Have getcontext() do most of the work then fix up
+	   LR afterwards.  Save R3 to keep the stack aligned.  */
+	push	{r0,r1,r3,r14}
+	cfi_adjust_cfa_offset (16)
+	cfi_rel_offset (r0,0)
+	cfi_rel_offset (r1,4)
+	cfi_rel_offset (r3,8)
+	cfi_rel_offset (r14,12)
+
+	bl	__getcontext
+	mov	r4, r0
+
+	pop	{r0,r1,r3,r14}
+	cfi_adjust_cfa_offset (-16)
+	cfi_restore (r0)
+	cfi_restore (r1)
+	cfi_restore (r3)
+	cfi_restore (r14)
+
+	/* Exit if getcontext() failed.  */
+	cmp 	r4, #0
+	itt	ne
+	movne	r0, r4
+	RETINSTR(ne, r14)
+
+	/* Fix up LR and the PC.  */
+	str	r13,[r0, #MCONTEXT_ARM_SP]
+	str	r14,[r0, #MCONTEXT_ARM_LR]
+	str	r14,[r0, #MCONTEXT_ARM_PC]
+
+	/* And swap using swapcontext().  */
+	mov	r0, r1
+	b	__setcontext
+
+END(swapcontext)
diff --git a/libc/sysdeps/linux/arm/ucontext_i.sym b/libc/sysdeps/linux/arm/ucontext_i.sym
new file mode 100644
index 000000000..965032260
--- /dev/null
+++ b/libc/sysdeps/linux/arm/ucontext_i.sym
@@ -0,0 +1,30 @@
+#include <inttypes.h>
+#include <signal.h>
+#include <stddef.h>
+#include <sys/ucontext.h>
+
+SIG_BLOCK
+SIG_SETMASK
+
+-- Offsets of the fields in the ucontext_t structure.
+#define ucontext(member)	offsetof (ucontext_t, member)
+#define mcontext(member)	ucontext (uc_mcontext.member)
+
+UCONTEXT_FLAGS			ucontext (uc_flags)
+UCONTEXT_LINK			ucontext (uc_link)
+UCONTEXT_STACK			ucontext (uc_stack)
+UCONTEXT_MCONTEXT		ucontext (uc_mcontext)
+UCONTEXT_SIGMASK		ucontext (uc_sigmask)
+
+UCONTEXT_REGSPACE		ucontext (uc_regspace)
+
+MCONTEXT_TRAP_NO		mcontext (trap_no)
+MCONTEXT_ERROR_CODE		mcontext (error_code)
+MCONTEXT_OLDMASK		mcontext (oldmask)
+MCONTEXT_ARM_R0		mcontext (arm_r0)
+MCONTEXT_ARM_R4		mcontext (arm_r4)
+MCONTEXT_ARM_SP		mcontext (arm_sp)
+MCONTEXT_ARM_LR		mcontext (arm_lr)
+MCONTEXT_ARM_PC		mcontext (arm_pc)
+MCONTEXT_ARM_CPSR		mcontext (arm_cpsr)
+MCONTEXT_FAULT_ADDRESS		mcontext (fault_address)
diff --git a/libc/sysdeps/linux/i386/Makefile.arch b/libc/sysdeps/linux/i386/Makefile.arch
index a3bf32f56..e7fd28eea 100644
--- a/libc/sysdeps/linux/i386/Makefile.arch
+++ b/libc/sysdeps/linux/i386/Makefile.arch
@@ -18,3 +18,7 @@ endif
 ifneq ($(UCLIBC_HAS_THREADS_NATIVE),y)
 SSRC += vfork.S clone.S
 endif
+
+ifeq ($(UCLIBC_HAS_CONTEXT_FUNCS),y)
+SSRC += makecontext.S setcontext.S getcontext.S swapcontext.S
+endif
diff --git a/libc/sysdeps/linux/i386/getcontext.S b/libc/sysdeps/linux/i386/getcontext.S
new file mode 100644
index 000000000..3221b597c
--- /dev/null
+++ b/libc/sysdeps/linux/i386/getcontext.S
@@ -0,0 +1,84 @@
+/* Save current context.
+   Copyright (C) 2001-2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2001.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+#include "ucontext_i.h"
+
+
+ENTRY(__getcontext)
+	/* Load address of the context data structure.  */
+	movl	4(%esp), %eax
+
+	/* Return value of getcontext.  EAX is the only register whose
+	   value is not preserved.  */
+	movl	$0, oEAX(%eax)
+
+	/* Save the 32-bit register values and the return address.  */
+	movl	%ecx, oECX(%eax)
+	movl	%edx, oEDX(%eax)
+	movl	%edi, oEDI(%eax)
+	movl	%esi, oESI(%eax)
+	movl	%ebp, oEBP(%eax)
+	movl	(%esp), %ecx
+	movl	%ecx, oEIP(%eax)
+	leal	4(%esp), %ecx		/* Exclude the return address.  */
+	movl	%ecx, oESP(%eax)
+	movl	%ebx, oEBX(%eax)
+
+	/* Save the FS segment register.  We don't touch the GS register
+	   since it is used for threads.  */
+	xorl	%edx, %edx
+	movw	%fs, %dx
+	movl	%edx, oFS(%eax)
+
+	/* We have separate floating-point register content memory on the
+	   stack.  We use the __fpregs_mem block in the context.  Set the
+	   links up correctly.  */
+	leal	oFPREGSMEM(%eax), %ecx
+	movl	%ecx, oFPREGS(%eax)
+	/* Save the floating-point context.  */
+	fnstenv	(%ecx)
+	/* And load it right back since the processor changes the mask.
+	   Intel thought this opcode to be used in interrupt handlers which
+	   would block all exceptions.  */
+	fldenv	(%ecx)
+
+	/* Save the current signal mask.  */
+	pushl	%ebx
+	cfi_adjust_cfa_offset (4)
+	cfi_rel_offset (ebx, 0)
+	leal	oSIGMASK(%eax), %edx
+	xorl	%ecx, %ecx
+	movl	$SIG_BLOCK, %ebx
+	movl	$__NR_sigprocmask, %eax
+	ENTER_KERNEL
+	popl	%ebx
+	cfi_adjust_cfa_offset (-4)
+	cfi_restore (ebx)
+	cmpl	$-4095, %eax		/* Check %eax for error.  */
+	jae	SYSCALL_ERROR_LABEL	/* Jump to error handler if error.  */
+
+	/* All done, return 0 for success.  */
+	xorl	%eax, %eax
+L(pseudo_end):
+	ret
+PSEUDO_END(__getcontext)
+
+weak_alias (__getcontext, getcontext)
diff --git a/libc/sysdeps/linux/i386/makecontext.S b/libc/sysdeps/linux/i386/makecontext.S
new file mode 100644
index 000000000..d12799d80
--- /dev/null
+++ b/libc/sysdeps/linux/i386/makecontext.S
@@ -0,0 +1,123 @@
+/* Create new context.
+   Copyright (C) 2001,2002,2005,2007,2008,2009 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2001.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+#include "ucontext_i.h"
+
+
+ENTRY(__makecontext)
+	movl	4(%esp), %eax
+
+	/* Load the address of the function we are supposed to run.  */
+	movl	8(%esp), %ecx
+
+	/* Compute the address of the stack.  The information comes from
+	   to us_stack element.  */
+	movl	oSS_SP(%eax), %edx
+	movl	%ecx, oEIP(%eax)
+	addl	oSS_SIZE(%eax), %edx
+
+	/* Remember the number of parameters for the exit handler since
+	   it has to remove them.  We store the number in the EBX register
+	   which the function we will call must preserve.  */
+	movl	12(%esp), %ecx
+	movl	%ecx, oEBX(%eax)
+
+	/* Make room on the new stack for the parameters.
+	   Room for the arguments, return address (== L(exitcode)) and
+	   oLINK pointer is needed.  One of the pointer sizes is subtracted
+	   after aligning the stack.  */
+	negl	%ecx
+	leal	-4(%edx,%ecx,4), %edx
+	negl	%ecx
+
+	/* Align the stack.  */
+	andl	$0xfffffff0, %edx
+	subl	$4, %edx
+
+	/* Store the future stack pointer.  */
+	movl	%edx, oESP(%eax)
+
+	/* Put the next context on the new stack (from the uc_link
+	   element).  */
+	movl	oLINK(%eax), %eax
+	movl	%eax, 4(%edx,%ecx,4)
+
+	/* Copy all the parameters.  */
+	jecxz	2f
+1:	movl	12(%esp,%ecx,4), %eax
+	movl	%eax, (%edx,%ecx,4)
+	decl	%ecx
+	jnz	1b
+2:
+
+	/* If the function we call returns we must continue with the
+	   context which is given in the uc_link element.  To do this
+	   set the return address for the function the user provides
+	   to a little bit of helper code which does the magic (see
+	   below).  */
+#ifdef __PIC__
+	call	1f
+	cfi_adjust_cfa_offset (4)
+1:	popl	%ecx
+	cfi_adjust_cfa_offset (-4)
+	addl	$L(exitcode)-1b, %ecx
+	movl	%ecx, (%edx)
+#else
+	movl	$L(exitcode), (%edx)
+#endif
+	/* 'makecontext' returns no value.  */
+L(pseudo_end):
+	ret
+
+	/* This is the helper code which gets called if a function which
+	   is registered with 'makecontext' returns.  In this case we
+	   have to install the context listed in the uc_link element of
+	   the context 'makecontext' manipulated at the time of the
+	   'makecontext' call.  If the pointer is NULL the process must
+	   terminate.  */
+	cfi_endproc
+L(exitcode):
+	/* This removes the parameters passed to the function given to
+	   'makecontext' from the stack.  EBX contains the number of
+	   parameters (see above).  */
+	leal	(%esp,%ebx,4), %esp
+
+#ifdef	__PIC__
+	call	1f
+1:	popl	%ebx
+	addl	$_GLOBAL_OFFSET_TABLE_+[.