File: setcontext.S

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/* Copyright (C) 2001-2016 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
     Contributed by David Mosberger-Tang <davidm@hpl.hp.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 <features.h>

#include "ucontext_i.h"

/*  __setcontext (const ucontext_t *ucp)

  Restores the machine context in UCP and thereby resumes execution
  in that context.

  This implementation in intended to be used for *synchronous* context
  switches only.  Therefore, it does not have to restore anything
  other than the PRESERVED state.  */

ENTRY(__setcontext)
	.prologue
	.body
	alloc r11 = ar.pfs, 1, 0, 4, 0

	// sigprocmask (SIG_SETMASK, &sc->sc_mask, NULL):

	mov r3 = SC_MASK
	mov out0 = SIG_SETMASK
	;;
	add out1 = r3, in0
	mov out2 = 0
	mov out3 = 8	// sizeof kernel sigset_t

	invala
	DO_CALL(__NR_rt_sigprocmask)
	add r2 = SC_NAT, r32

	add r3 = SC_RNAT, r32			// r3 <- &sc_ar_rnat
	add rPOS = SC_GR, r32			// rPOS <- &sc_gr[0]
	;;
	ld8 rNAT = [r2], (SC_BSP-SC_NAT)
	extr.u rPOS = rPOS, 3, 6		// get NaT bit number for r0
	;;
	ld8 rBSP = [r2], (SC_UNAT-SC_BSP)
	ld8 rRNAT = [r3], (SC_FPSR-SC_RNAT)
	/*
	 * Rotate NaT bits by rPOS positions to the left:
	 */
	sub rCPOS = 64, rPOS
	;;
	ld8 rUNAT = [r2], (SC_PFS-SC_UNAT)
	ld8 rFPSR = [r3], (SC_LC-SC_FPSR)
	shl rTMP = rNAT, rPOS
	;;
	ld8 rPFS = [r2], (SC_PR-SC_PFS)
	ld8 rLC = [r3], (SC_BR+0*8-SC_LC)
	shr.u rNAT = rNAT, rCPOS
	;;
	ld8 rPR = [r2], (SC_BR+1*8-SC_PR)
	ld8 rB0 = [r3], 16
	or rNAT = rNAT, rTMP
	;;
	ld8 rB1 = [r2], 16
	ld8 rB2 = [r3], 16
	;;
	mov.m ar.unat = rNAT
	mov.m rRSC = ar.rsc
	;;
	ld8 rB3 = [r2], 16
	ld8 rB4 = [r3], (SC_GR+1*8-(SC_BR+4*8))
	;;
	ld8 rB5 = [r2], (SC_GR+4*8-(SC_BR+5*8))
	ld8.fill r1 = [r3], (5*8 - 1*8)
	;;
	ld8.fill r4 = [r2], 16
	ld8.fill r5 = [r3], 16
	mov b0 = rB0
	;;
	ld8.fill r6 = [r2], 48
	ld8.fill r7 = [r3], (SC_FR+2*16-(SC_GR+7*8))
	;;
	ld8.fill sp = [r2], (SC_FR+3*16-(SC_GR+12*8))
	mov.m ar.fpsr = rFPSR
	mov.i ar.pfs = rPFS
	;;
	ldf.fill f3 = [r2], 16
	ldf.fill f2 = [r3], 48
	mov b1 = rB1
	;;
	ldf.fill f4 = [r2], (16*16-4*16)
	ldf.fill f5 = [r3], (17*16-5*16)
	mov b2 = rB2
	;;
	ldf.fill f16 = [r2], 32
	ldf.fill f17 = [r3], 32
	mov b3 = rB3
	;;
	ldf.fill f18 = [r2], 32
	ldf.fill f19 = [r3], 32
	mov b4 = rB4
	;;
	ldf.fill f20 = [r2], 32
	ldf.fill f21 = [r3], 32
	mov b5 = rB5
	;;
	ldf.fill f22 = [r2], 32
	ldf.fill f23 = [r3], 32
	mov r8 = 0
	;;
	ldf.fill f24 = [r2], 32
	ldf.fill f25 = [r3], 32
	mov r9 = 0
	;;
	ldf.fill f26 = [r2], 32
	ldf.fill f27 = [r3], 32
	dep rTMP = 0, rRSC, 16, 14	// clear ar.rsc.loadrs
	;;
	ldf.fill f28 = [r2], 32
	ldf.fill f29 = [r3], 32
	and rTMP = ~0x3, rTMP		// clear ar.rsc.mode
	;;
	ldf.fill f30 = [r2], 32
	ldf.fill f31 = [r3], 32
	mov pr = rPR, -1
	;;
	mov.m ar.rsc = rTMP		// put RSE into enforced lazy mode
	;;
	loadrs				// drop dirty partition
	;;
	mov.m ar.bspstore = rBSP
	mov.m ar.unat = rUNAT
	mov.i ar.lc = rLC
	;;
	mov.m ar.rnat = rRNAT
	mov.m ar.rsc = rRSC
	ret
END(__setcontext)

weak_alias (__setcontext, setcontext)