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>

1 files changed, 191 insertions, 0 deletions

diff --git a/libc/sysdeps/linux/mips/setcontext.S b/libc/sysdeps/linux/mips/setcontext.S
new file mode 100644
index 000000000..d3cde0e50
--- /dev/null
+++ b/libc/sysdeps/linux/mips/setcontext.S
@@ -0,0 +1,191 @@
+/* Set current context.
+   Copyright (C) 2009 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Maciej W. Rozycki <macro@codesourcery.com>.
+
+   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 <sys/asm.h>
+#include <sys/fpregdef.h>
+#include <sys/regdef.h>
+
+#include "ucontext_i.h"
+
+/* int setcontext (const ucontext_t *ucp) */
+
+	.text
+LOCALSZ = 0
+ARGSZ = 0
+MASK = 0x00000000
+#ifdef __PIC__
+LOCALSZ = 1						/* save gp */
+#endif
+#if _MIPS_SIM != _ABIO32
+ARGSZ = 1						/* save a0 */
+# ifdef __PIC__
+MASK = 0x10000000
+# endif
+#endif
+FRAMESZ = (((ARGSZ + LOCALSZ) * SZREG) + ALSZ) & ALMASK
+GPOFF = FRAMESZ - ((ARGSZ + 1) * SZREG)
+#if _MIPS_SIM != _ABIO32
+A0OFF = FRAMESZ - (1 * SZREG)				/* callee-allocated */
+#else
+A0OFF = FRAMESZ + (0 * SZREG)				/* caller-allocated */
+#endif
+
+NESTED (__setcontext, FRAMESZ, ra)
+	.mask	MASK, -(ARGSZ * SZREG)
+	.fmask	0x00000000, 0
+
+#ifdef __PIC__
+	SETUP_GP
+#endif
+
+	PTR_ADDIU sp, -FRAMESZ
+
+#ifdef __PIC__
+	SETUP_GP64 (GPOFF, __setcontext)
+	SAVE_GP (GPOFF)
+#endif
+
+#ifdef PROF
+	.set	noat
+	move	AT, ra
+	jal	_mcount
+	.set	at
+#endif
+
+	/* Check for the magic flag.  */
+	li	v0, 1
+	REG_L	v1, (0 * SZREG + MCONTEXT_GREGS)(a0)	/* zero */
+	bne	v0, v1, 98f
+
+	REG_S	a0, A0OFF(sp)
+
+/* rt_sigprocmask (SIG_SETMASK, &ucp->uc_sigmask, NULL, _NSIG8) */
+	li	a3, _NSIG8
+	move	a2, zero
+	PTR_ADDU a1, a0, UCONTEXT_SIGMASK
+	li	a0, SIG_SETMASK
+
+	li	v0, SYS_ify (rt_sigprocmask)
+	syscall
+	bnez	a3, 99f
+
+	REG_L	v0, A0OFF(sp)
+
+#ifdef __mips_hard_float
+# if _MIPS_SIM == _ABI64
+	l.d	fs0, (24 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs1, (25 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs2, (26 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs3, (27 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs4, (28 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs5, (29 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs6, (30 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs7, (31 * SZREG + MCONTEXT_FPREGS)(v0)
+
+# else  /* _MIPS_SIM != _ABI64 */
+	l.d	fs0, (20 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs1, (22 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs2, (24 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs3, (26 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs4, (28 * SZREG + MCONTEXT_FPREGS)(v0)
+	l.d	fs5, (30 * SZREG + MCONTEXT_FPREGS)(v0)
+
+# endif /* _MIPS_SIM != _ABI64 */
+
+	lw	v1, MCONTEXT_FPC_CSR(v0)
+	ctc1	v1, fcr31
+#endif /* __mips_hard_float */
+
+	/* Note the contents of argument registers will be random
+	   unless makecontext() has been called.  */
+	REG_L	a0, (4 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	a1, (5 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	a2, (6 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	a3, (7 * SZREG + MCONTEXT_GREGS)(v0)
+#if _MIPS_SIM != _ABIO32
+	REG_L	a4, (8 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	a5, (9 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	a6, (10 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	a7, (11 * SZREG + MCONTEXT_GREGS)(v0)
+#endif
+
+	REG_L	s0, (16 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	s1, (17 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	s2, (18 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	s3, (19 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	s4, (20 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	s5, (21 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	s6, (22 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	s7, (23 * SZREG + MCONTEXT_GREGS)(v0)
+#if ! defined (__PIC__) || _MIPS_SIM != _ABIO32
+	REG_L	gp, (28 * SZREG + MCONTEXT_GREGS)(v0)
+#endif
+	REG_L	sp, (29 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	fp, (30 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	ra, (31 * SZREG + MCONTEXT_GREGS)(v0)
+	REG_L	t9, MCONTEXT_PC(v0)
+
+	move	v0, zero
+	jr	t9
+
+98:
+	/* This is a context obtained from a signal handler.
+	   Perform a full restore by pushing the context
+	   passed onto a simulated signal frame on the stack
+	   and call the signal return syscall as if a signal
+	   handler exited normally.  */
+	PTR_ADDIU sp, -((RT_SIGFRAME_SIZE + ALSZ) & ALMASK)
+
+	/* Only ucontext is referred to from rt_sigreturn,
+	   copy it.  */
+	PTR_ADDIU t1, sp, RT_SIGFRAME_UCONTEXT
+	li	t3, ((UCONTEXT_SIZE + SZREG - 1) / SZREG) - 1
+0:
+	REG_L	t2, (a0)
+	PTR_ADDIU a0, SZREG
+	REG_S	t2, (t1)
+	PTR_ADDIU t1, SZREG
+	.set	noreorder
+	bgtz	t3, 0b
+	 addiu	t3, -1
+	.set	reorder
+
+/* rt_sigreturn () -- no arguments, sp points to struct rt_sigframe.  */
+	li	v0, SYS_ify (rt_sigreturn)
+	syscall
+
+	/* Restore the stack and fall through to the error
+	   path.  Successful rt_sigreturn never returns to
+	   its calling place.  */
+	PTR_ADDIU sp, ((RT_SIGFRAME_SIZE + ALSZ) & ALMASK)
+99:
+#ifdef __PIC__
+	PTR_LA	t9, JUMPTARGET (__syscall_error)
+	RESTORE_GP64
+	PTR_ADDIU sp, FRAMESZ
+	jr	t9
+
+#else  /* ! __PIC__ */
+
+	j	JUMPTARGET (__syscall_error)
+#endif /* ! __PIC__ */
+PSEUDO_END (__setcontext)
+
+weak_alias (__setcontext, setcontext)