uclibc-ng/libc/sysdeps/linux/arm/setcontext.S

/* 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
	/* Point r0 at the VFP/iWMMXt save area (uc_regspace[]) before
	   restoring any coprocessor state.  Without this r0 still points
	   at the start of ucontext_t and we would read uc_flags etc.  */
	add     r0, r0, #UCONTEXT_REGSPACE

#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)