57e26e5745
ST.as only takes S9 (255) for offset. This was going out of range when accessing a task_struct field with 4k NR_CPUS (due to 128b of coumaks itself in there). Workaround by using an intermediate register to do the address scaling. There is some duplication of fix for ctx_sw.c and ctx_sw_asm.S however given that C version will go away soon I'm not bothering to factor out the common code. Reported-by: Noam Camus <noamc@ezchip.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
66 lines
1.7 KiB
ArmAsm
66 lines
1.7 KiB
ArmAsm
/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Vineetg: Aug 2009
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* -Moved core context switch macro out of entry.S into this file.
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* -This is the more "natural" hand written assembler
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*/
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#include <asm/entry.h> /* For the SAVE_* macros */
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#include <asm/asm-offsets.h>
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#include <asm/linkage.h>
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#define KSP_WORD_OFF ((TASK_THREAD + THREAD_KSP) / 4)
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;################### Low Level Context Switch ##########################
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.section .sched.text,"ax",@progbits
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.align 4
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.global __switch_to
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.type __switch_to, @function
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__switch_to:
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/* Save regs on kernel mode stack of task */
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st.a blink, [sp, -4]
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st.a fp, [sp, -4]
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SAVE_CALLEE_SAVED_KERNEL
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/* Save the now KSP in task->thread.ksp */
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#if KSP_WORD_OFF <= 255
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st.as sp, [r0, KSP_WORD_OFF]
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#else
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/* Workaround for NR_CPUS=4k as ST.as can only take s9 offset */
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add2 r24, r0, KSP_WORD_OFF
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st sp, [r24]
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#endif
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/*
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* Return last task in r0 (return reg)
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* On ARC, Return reg = First Arg reg = r0.
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* Since we already have last task in r0,
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* don't need to do anything special to return it
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*/
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/* hardware memory barrier */
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sync
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/*
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* switch to new task, contained in r1
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* Temp reg r3 is required to get the ptr to store val
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*/
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SET_CURR_TASK_ON_CPU r1, r3
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/* reload SP with kernel mode stack pointer in task->thread.ksp */
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ld.as sp, [r1, (TASK_THREAD + THREAD_KSP)/4]
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/* restore the registers */
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RESTORE_CALLEE_SAVED_KERNEL
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ld.ab fp, [sp, 4]
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ld.ab blink, [sp, 4]
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j [blink]
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ARC_EXIT __switch_to
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