2011-10-31 18:39:14 -05:00
|
|
|
/*
|
|
|
|
|
* Context switch support for Hexagon
|
|
|
|
|
*
|
2012-09-19 16:22:02 -05:00
|
|
|
* Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
|
2011-10-31 18:39:14 -05:00
|
|
|
*
|
|
|
|
|
* This program is free software; you can redistribute it and/or modify
|
|
|
|
|
* it under the terms of the GNU General Public License version 2 and
|
|
|
|
|
* only version 2 as published by the Free Software Foundation.
|
|
|
|
|
*
|
|
|
|
|
* This program 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 General Public License for more details.
|
|
|
|
|
*
|
|
|
|
|
* You should have received a copy of the GNU General Public License
|
|
|
|
|
* along with this program; if not, write to the Free Software
|
|
|
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
|
|
|
|
|
* 02110-1301, USA.
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
#include <asm/asm-offsets.h>
|
|
|
|
|
|
|
|
|
|
.text
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* The register used as a fast-path thread information pointer
|
|
|
|
|
* is determined as a kernel configuration option. If it happens
|
|
|
|
|
* to be a callee-save register, we're going to be saving and
|
|
|
|
|
* restoring it twice here.
|
|
|
|
|
*
|
|
|
|
|
* This code anticipates a revised ABI where R20-23 are added
|
|
|
|
|
* to the set of callee-save registers, but this should be
|
|
|
|
|
* backward compatible to legacy tools.
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* void switch_to(struct task_struct *prev,
|
|
|
|
|
* struct task_struct *next, struct task_struct *last);
|
|
|
|
|
*/
|
|
|
|
|
.p2align 2
|
|
|
|
|
.globl __switch_to
|
|
|
|
|
.type __switch_to, @function
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* When we exit the wormhole, we need to store the previous task
|
|
|
|
|
* in the new R0's pointer. Technically it should be R2, but they should
|
|
|
|
|
* be the same; seems like a legacy thing. In short, don't butcher
|
|
|
|
|
* R0, let it go back out unmolested.
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
__switch_to:
|
|
|
|
|
/*
|
|
|
|
|
* Push callee-saves onto "prev" stack.
|
|
|
|
|
* Here, we're sneaky because the LR and FP
|
|
|
|
|
* storage of the thread_stack structure
|
|
|
|
|
* is automagically allocated by allocframe,
|
|
|
|
|
* so we pass struct size less 8.
|
|
|
|
|
*/
|
|
|
|
|
allocframe(#(_SWITCH_STACK_SIZE - 8));
|
|
|
|
|
memd(R29+#(_SWITCH_R2726))=R27:26;
|
|
|
|
|
memd(R29+#(_SWITCH_R2524))=R25:24;
|
|
|
|
|
memd(R29+#(_SWITCH_R2322))=R23:22;
|
|
|
|
|
memd(R29+#(_SWITCH_R2120))=R21:20;
|
|
|
|
|
memd(R29+#(_SWITCH_R1918))=R19:18;
|
|
|
|
|
memd(R29+#(_SWITCH_R1716))=R17:16;
|
|
|
|
|
/* Stash thread_info pointer in task_struct */
|
|
|
|
|
memw(R0+#_TASK_THREAD_INFO) = THREADINFO_REG;
|
|
|
|
|
memw(R0 +#(_TASK_STRUCT_THREAD + _THREAD_STRUCT_SWITCH_SP)) = R29;
|
|
|
|
|
/* Switch to "next" stack and restore callee saves from there */
|
|
|
|
|
R29 = memw(R1 + #(_TASK_STRUCT_THREAD + _THREAD_STRUCT_SWITCH_SP));
|
|
|
|
|
{
|
|
|
|
|
R27:26 = memd(R29+#(_SWITCH_R2726));
|
|
|
|
|
R25:24 = memd(R29+#(_SWITCH_R2524));
|
|
|
|
|
}
|
|
|
|
|
{
|
|
|
|
|
R23:22 = memd(R29+#(_SWITCH_R2322));
|
|
|
|
|
R21:20 = memd(R29+#(_SWITCH_R2120));
|
|
|
|
|
}
|
|
|
|
|
{
|
|
|
|
|
R19:18 = memd(R29+#(_SWITCH_R1918));
|
|
|
|
|
R17:16 = memd(R29+#(_SWITCH_R1716));
|
|
|
|
|
}
|
|
|
|
|
{
|
|
|
|
|
/* THREADINFO_REG is currently one of the callee-saved regs
|
|
|
|
|
* above, and so be sure to re-load it last.
|
|
|
|
|
*/
|
|
|
|
|
THREADINFO_REG = memw(R1 + #_TASK_THREAD_INFO);
|
|
|
|
|
R31:30 = memd(R29+#_SWITCH_FP);
|
|
|
|
|
}
|
|
|
|
|
{
|
|
|
|
|
R29 = add(R29,#_SWITCH_STACK_SIZE);
|
|
|
|
|
jumpr R31;
|
|
|
|
|
}
|
|
|
|
|
.size __switch_to, .-__switch_to
|
