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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/x86_64/swapcontext.S
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/x86_64/swapcontext.S')
-rw-r--r--libc/sysdeps/linux/x86_64/swapcontext.S121
1 files changed, 121 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/x86_64/swapcontext.S b/libc/sysdeps/linux/x86_64/swapcontext.S
new file mode 100644
index 000000000..6d2ebb823
--- /dev/null
+++ b/libc/sysdeps/linux/x86_64/swapcontext.S
@@ -0,0 +1,121 @@
+/* Save current context and install the given one.
+ Copyright (C) 2002-2012 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Andreas Jaeger <aj@suse.de>, 2002.
+
+ 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"
+
+
+/* int __swapcontext (ucontext_t *oucp, const ucontext_t *ucp);
+
+ Saves the machine context in oucp such that when it is activated,
+ it appears as if __swapcontextt() returned again, restores the
+ machine context in ucp and thereby resumes execution in that
+ context.
+
+ This implementation is intended to be used for *synchronous* context
+ switches only. Therefore, it does not have to save anything
+ other than the PRESERVED state. */
+
+ENTRY(__swapcontext)
+ /* Save the preserved registers, the registers used for passing args,
+ and the return address. */
+ movq %rbx, oRBX(%rdi)
+ movq %rbp, oRBP(%rdi)
+ movq %r12, oR12(%rdi)
+ movq %r13, oR13(%rdi)
+ movq %r14, oR14(%rdi)
+ movq %r15, oR15(%rdi)
+
+ movq %rdi, oRDI(%rdi)
+ movq %rsi, oRSI(%rdi)
+ movq %rdx, oRDX(%rdi)
+ movq %rcx, oRCX(%rdi)
+ movq %r8, oR8(%rdi)
+ movq %r9, oR9(%rdi)
+
+ movq (%rsp), %rcx
+ movq %rcx, oRIP(%rdi)
+ leaq 8(%rsp), %rcx /* Exclude the return address. */
+ movq %rcx, oRSP(%rdi)
+
+ /* 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. */
+ leaq oFPREGSMEM(%rdi), %rcx
+ movq %rcx, oFPREGS(%rdi)
+ /* Save the floating-point environment. */
+ fnstenv (%rcx)
+ stmxcsr oMXCSR(%rdi)
+
+
+ /* The syscall destroys some registers, save them. */
+ movq %rsi, %r12
+
+ /* Save the current signal mask and install the new one with
+ rt_sigprocmask (SIG_BLOCK, newset, oldset,_NSIG/8). */
+ leaq oSIGMASK(%rdi), %rdx
+ leaq oSIGMASK(%rsi), %rsi
+ movl $SIG_SETMASK, %edi
+ movl $_NSIG8,%r10d
+ movl $__NR_rt_sigprocmask, %eax
+ syscall
+ cmpq $-4095, %rax /* Check %rax for error. */
+ jae SYSCALL_ERROR_LABEL /* Jump to error handler if error. */
+
+ /* Restore destroyed registers. */
+ movq %r12, %rsi
+
+ /* Restore the floating-point context. Not the registers, only the
+ rest. */
+ movq oFPREGS(%rsi), %rcx
+ fldenv (%rcx)
+ ldmxcsr oMXCSR(%rsi)
+
+ /* Load the new stack pointer and the preserved registers. */
+ movq oRSP(%rsi), %rsp
+ movq oRBX(%rsi), %rbx
+ movq oRBP(%rsi), %rbp
+ movq oR12(%rsi), %r12
+ movq oR13(%rsi), %r13
+ movq oR14(%rsi), %r14
+ movq oR15(%rsi), %r15
+
+ /* The following ret should return to the address set with
+ getcontext. Therefore push the address on the stack. */
+ movq oRIP(%rsi), %rcx
+ pushq %rcx
+
+ /* Setup registers used for passing args. */
+ movq oRDI(%rsi), %rdi
+ movq oRDX(%rsi), %rdx
+ movq oRCX(%rsi), %rcx
+ movq oR8(%rsi), %r8
+ movq oR9(%rsi), %r9
+
+ /* Setup finally %rsi. */
+ movq oRSI(%rsi), %rsi
+
+ /* Clear rax to indicate success. */
+ xorl %eax, %eax
+L(pseudo_end):
+ ret
+PSEUDO_END(__swapcontext)
+
+weak_alias (__swapcontext, swapcontext)