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authorFlorian Fainelli <florian@openwrt.org>2013-01-09 16:17:21 +0100
committerBernhard Reutner-Fischer <rep.dot.nop@gmail.com>2013-01-10 10:56:19 +0100
commita8dc90eaaa5e6474beac828558d969b1aafee4af (patch)
treeed22c27193dcc91697f6b8782da9a9abd08d42b1 /libc/sysdeps/linux/arm/makecontext.c
parentdf3a5fcc8d1c3402289375c92df705e978fab58d (diff)
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>
Diffstat (limited to 'libc/sysdeps/linux/arm/makecontext.c')
-rw-r--r--libc/sysdeps/linux/arm/makecontext.c73
1 files changed, 73 insertions, 0 deletions
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)