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User mode callee regs are explicitly collected before signal delivery or breakpoint trap. r25 is special for kernel as it serves as task pointer, so user mode value is clobbered very early. It is saved in pt_regs where generally only scratch (aka caller saved) regs are saved. The code to access the corresponding pt_regs location had a subtle bug as it was using load/store with scaling of offset, whereas the offset was already byte wise correct. So fix this by replacing LD.AS with a standard LD Cc: <stable@vger.kernel.org> Signed-off-by: Liav Rehana <liavr@mellanox.com> Reviewed-by: Alexey Brodkin <abrodkin@synopsys.com> [vgupta: rewrote title and commit log] Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
305 lines
6.7 KiB
C
305 lines
6.7 KiB
C
/*
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* Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
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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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#ifndef __ASM_ARC_ENTRY_H
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#define __ASM_ARC_ENTRY_H
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#include <asm/unistd.h> /* For NR_syscalls defination */
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#include <asm/arcregs.h>
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#include <asm/ptrace.h>
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#include <asm/processor.h> /* For VMALLOC_START */
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#include <asm/mmu.h>
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#ifdef CONFIG_ISA_ARCOMPACT
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#include <asm/entry-compact.h> /* ISA specific bits */
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#else
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#include <asm/entry-arcv2.h>
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#endif
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/* Note on the LD/ST addr modes with addr reg wback
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*
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* LD.a same as LD.aw
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*
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* LD.a reg1, [reg2, x] => Pre Incr
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* Eff Addr for load = [reg2 + x]
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*
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* LD.ab reg1, [reg2, x] => Post Incr
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* Eff Addr for load = [reg2]
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*/
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.macro PUSH reg
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st.a \reg, [sp, -4]
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.endm
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.macro PUSHAX aux
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lr r9, [\aux]
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PUSH r9
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.endm
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.macro POP reg
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ld.ab \reg, [sp, 4]
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.endm
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.macro POPAX aux
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POP r9
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sr r9, [\aux]
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.endm
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/*--------------------------------------------------------------
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* Helpers to save/restore Scratch Regs:
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* used by Interrupt/Exception Prologue/Epilogue
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*-------------------------------------------------------------*/
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.macro SAVE_R0_TO_R12
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PUSH r0
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PUSH r1
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PUSH r2
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PUSH r3
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PUSH r4
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PUSH r5
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PUSH r6
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PUSH r7
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PUSH r8
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PUSH r9
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PUSH r10
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PUSH r11
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PUSH r12
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.endm
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.macro RESTORE_R12_TO_R0
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POP r12
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POP r11
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POP r10
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POP r9
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POP r8
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POP r7
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POP r6
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POP r5
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POP r4
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POP r3
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POP r2
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POP r1
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POP r0
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#ifdef CONFIG_ARC_CURR_IN_REG
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ld r25, [sp, 12]
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#endif
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.endm
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/*--------------------------------------------------------------
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* Helpers to save/restore callee-saved regs:
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* used by several macros below
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*-------------------------------------------------------------*/
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.macro SAVE_R13_TO_R24
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PUSH r13
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PUSH r14
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PUSH r15
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PUSH r16
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PUSH r17
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PUSH r18
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PUSH r19
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PUSH r20
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PUSH r21
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PUSH r22
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PUSH r23
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PUSH r24
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.endm
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.macro RESTORE_R24_TO_R13
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POP r24
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POP r23
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POP r22
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POP r21
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POP r20
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POP r19
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POP r18
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POP r17
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POP r16
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POP r15
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POP r14
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POP r13
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.endm
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/*--------------------------------------------------------------
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* Collect User Mode callee regs as struct callee_regs - needed by
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* fork/do_signal/unaligned-access-emulation.
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* (By default only scratch regs are saved on entry to kernel)
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*
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* Special handling for r25 if used for caching Task Pointer.
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* It would have been saved in task->thread.user_r25 already, but to keep
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* the interface same it is copied into regular r25 placeholder in
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* struct callee_regs.
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*-------------------------------------------------------------*/
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.macro SAVE_CALLEE_SAVED_USER
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mov r12, sp ; save SP as ref to pt_regs
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SAVE_R13_TO_R24
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#ifdef CONFIG_ARC_CURR_IN_REG
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; Retrieve orig r25 and save it with rest of callee_regs
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ld r12, [r12, PT_user_r25]
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PUSH r12
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#else
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PUSH r25
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#endif
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.endm
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/*--------------------------------------------------------------
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* Save kernel Mode callee regs at the time of Contect Switch.
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*
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* Special handling for r25 if used for caching Task Pointer.
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* Kernel simply skips saving it since it will be loaded with
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* incoming task pointer anyways
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*-------------------------------------------------------------*/
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.macro SAVE_CALLEE_SAVED_KERNEL
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SAVE_R13_TO_R24
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#ifdef CONFIG_ARC_CURR_IN_REG
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sub sp, sp, 4
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#else
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PUSH r25
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#endif
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.endm
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/*--------------------------------------------------------------
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* Opposite of SAVE_CALLEE_SAVED_KERNEL
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*-------------------------------------------------------------*/
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.macro RESTORE_CALLEE_SAVED_KERNEL
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#ifdef CONFIG_ARC_CURR_IN_REG
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add sp, sp, 4 /* skip usual r25 placeholder */
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#else
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POP r25
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#endif
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RESTORE_R24_TO_R13
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.endm
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/*--------------------------------------------------------------
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* Opposite of SAVE_CALLEE_SAVED_USER
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*
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* ptrace tracer or unaligned-access fixup might have changed a user mode
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* callee reg which is saved back to usual r25 storage location
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*-------------------------------------------------------------*/
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.macro RESTORE_CALLEE_SAVED_USER
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#ifdef CONFIG_ARC_CURR_IN_REG
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POP r12
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#else
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POP r25
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#endif
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RESTORE_R24_TO_R13
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; SP is back to start of pt_regs
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#ifdef CONFIG_ARC_CURR_IN_REG
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st r12, [sp, PT_user_r25]
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#endif
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.endm
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/*--------------------------------------------------------------
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* Super FAST Restore callee saved regs by simply re-adjusting SP
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*-------------------------------------------------------------*/
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.macro DISCARD_CALLEE_SAVED_USER
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add sp, sp, SZ_CALLEE_REGS
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.endm
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/*-------------------------------------------------------------
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* given a tsk struct, get to the base of it's kernel mode stack
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* tsk->thread_info is really a PAGE, whose bottom hoists stack
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* which grows upwards towards thread_info
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*------------------------------------------------------------*/
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.macro GET_TSK_STACK_BASE tsk, out
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/* Get task->thread_info (this is essentially start of a PAGE) */
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ld \out, [\tsk, TASK_THREAD_INFO]
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/* Go to end of page where stack begins (grows upwards) */
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add2 \out, \out, (THREAD_SIZE)/4
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.endm
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/*
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* @reg [OUT] thread_info->flags of "current"
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*/
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.macro GET_CURR_THR_INFO_FLAGS reg
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GET_CURR_THR_INFO_FROM_SP \reg
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ld \reg, [\reg, THREAD_INFO_FLAGS]
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.endm
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#ifdef CONFIG_SMP
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/*-------------------------------------------------
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* Retrieve the current running task on this CPU
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* 1. Determine curr CPU id.
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* 2. Use it to index into _current_task[ ]
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*/
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.macro GET_CURR_TASK_ON_CPU reg
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GET_CPU_ID \reg
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ld.as \reg, [@_current_task, \reg]
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.endm
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/*-------------------------------------------------
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* Save a new task as the "current" task on this CPU
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* 1. Determine curr CPU id.
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* 2. Use it to index into _current_task[ ]
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*
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* Coded differently than GET_CURR_TASK_ON_CPU (which uses LD.AS)
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* because ST r0, [r1, offset] can ONLY have s9 @offset
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* while LD can take s9 (4 byte insn) or LIMM (8 byte insn)
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*/
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.macro SET_CURR_TASK_ON_CPU tsk, tmp
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GET_CPU_ID \tmp
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add2 \tmp, @_current_task, \tmp
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st \tsk, [\tmp]
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#ifdef CONFIG_ARC_CURR_IN_REG
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mov r25, \tsk
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#endif
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.endm
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#else /* Uniprocessor implementation of macros */
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.macro GET_CURR_TASK_ON_CPU reg
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ld \reg, [@_current_task]
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.endm
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.macro SET_CURR_TASK_ON_CPU tsk, tmp
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st \tsk, [@_current_task]
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#ifdef CONFIG_ARC_CURR_IN_REG
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mov r25, \tsk
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#endif
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.endm
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#endif /* SMP / UNI */
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/* ------------------------------------------------------------------
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* Get the ptr to some field of Current Task at @off in task struct
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* -Uses r25 for Current task ptr if that is enabled
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*/
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#ifdef CONFIG_ARC_CURR_IN_REG
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.macro GET_CURR_TASK_FIELD_PTR off, reg
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add \reg, r25, \off
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.endm
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#else
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.macro GET_CURR_TASK_FIELD_PTR off, reg
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GET_CURR_TASK_ON_CPU \reg
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add \reg, \reg, \off
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.endm
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#endif /* CONFIG_ARC_CURR_IN_REG */
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#endif /* __ASM_ARC_ENTRY_H */
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