arch/arc/include/asm/entry-compact.h - kernel/bruno - Git at Google

 /*
  * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * Vineetg: March 2009 (Supporting 2 levels of Interrupts)
  *  Stack switching code can no longer reliably rely on the fact that
  *  if we are NOT in user mode, stack is switched to kernel mode.
  *  e.g. L2 IRQ interrupted a L1 ISR which had not yet completed
  *  it's prologue including stack switching from user mode
  *
  * Vineetg: Aug 28th 2008: Bug #94984
  *  -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap
  *   Normally CPU does this automatically, however when doing FAKE rtie,
  *   we also need to explicitly do this. The problem in macros
  *   FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit
  *   was being "CLEARED" rather then "SET". Actually "SET" clears ZOL context
  *
  * Vineetg: May 5th 2008
  *  -Modified CALLEE_REG save/restore macros to handle the fact that
  *      r25 contains the kernel current task ptr
  *  - Defined Stack Switching Macro to be reused in all intr/excp hdlrs
  *  - Shaved off 11 instructions from RESTORE_ALL_INT1 by using the
  *      address Write back load ld.ab instead of seperate ld/add instn
  *
  * Amit Bhor, Sameer Dhavale: Codito Technologies 2004
  */

 #ifndef __ASM_ARC_ENTRY_COMPACT_H
 #define __ASM_ARC_ENTRY_COMPACT_H

 #include <asm/asm-offsets.h>
 #include <asm/irqflags-compact.h>
 #include <asm/thread_info.h>	/* For THREAD_SIZE */

 /*--------------------------------------------------------------
  * Switch to Kernel Mode stack if SP points to User Mode stack
  *
  * Entry   : r9 contains pre-IRQ/exception/trap status32
  * Exit    : SP set to K mode stack
  *           SP at the time of entry (K/U) saved @ pt_regs->sp
  * Clobbers: r9
  *-------------------------------------------------------------*/

 .macro SWITCH_TO_KERNEL_STK

 	/* User Mode when this happened ? Yes: Proceed to switch stack */
 	bbit1   r9, STATUS_U_BIT, 88f

 	/* OK we were already in kernel mode when this event happened, thus can
 	 * assume SP is kernel mode SP. _NO_ need to do any stack switching
 	 */

 #ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
 	/* However....
 	 * If Level 2 Interrupts enabled, we may end up with a corner case:
 	 * 1. User Task executing
 	 * 2. L1 IRQ taken, ISR starts (CPU auto-switched to KERNEL mode)
 	 * 3. But before it could switch SP from USER to KERNEL stack
 	 *      a L2 IRQ "Interrupts" L1
 	 * Thay way although L2 IRQ happened in Kernel mode, stack is still
 	 * not switched.
 	 * To handle this, we may need to switch stack even if in kernel mode
 	 * provided SP has values in range of USER mode stack ( < 0x7000_0000 )
 	 */
 	brlo sp, VMALLOC_START, 88f

 	/* TODO: vineetg:
 	 * We need to be a bit more cautious here. What if a kernel bug in
 	 * L1 ISR, caused SP to go whaco (some small value which looks like
 	 * USER stk) and then we take L2 ISR.
 	 * Above brlo alone would treat it as a valid L1-L2 sceanrio
 	 * instead of shouting alound
 	 * The only feasible way is to make sure this L2 happened in
 	 * L1 prelogue ONLY i.e. ilink2 is less than a pre-set marker in
 	 * L1 ISR before it switches stack
 	 */

 #endif

     /*------Intr/Ecxp happened in kernel mode, SP already setup ------ */
 	/* save it nevertheless @ pt_regs->sp for uniformity */

 	b.d	66f
 	st	sp, [sp, PT_sp - SZ_PT_REGS]

 88: /*------Intr/Ecxp happened in user mode, "switch" stack ------ */

 	GET_CURR_TASK_ON_CPU   r9

 	/* With current tsk in r9, get it's kernel mode stack base */
 	GET_TSK_STACK_BASE  r9, r9

 	/* save U mode SP @ pt_regs->sp */
 	st	sp, [r9, PT_sp - SZ_PT_REGS]

 	/* final SP switch */
 	mov	sp, r9
 66:
 .endm

 /*------------------------------------------------------------
  * "FAKE" a rtie to return from CPU Exception context
  * This is to re-enable Exceptions within exception
  * Look at EV_ProtV to see how this is actually used
  *-------------------------------------------------------------*/

 .macro FAKE_RET_FROM_EXCPN

 	lr	r9, [status32]
 	bclr	r9, r9, STATUS_AE_BIT
 	or	r9, r9, (STATUS_E1_MASK|STATUS_E2_MASK)
 	sr	r9, [erstatus]
 	mov	r9, 55f
 	sr	r9, [eret]
 	rtie
 55:
 .endm

 /*--------------------------------------------------------------
  * For early Exception/ISR Prologue, a core reg is temporarily needed to
  * code the rest of prolog (stack switching). This is done by stashing
  * it to memory (non-SMP case) or SCRATCH0 Aux Reg (SMP).
  *
  * Before saving the full regfile - this reg is restored back, only
  * to be saved again on kernel mode stack, as part of pt_regs.
  *-------------------------------------------------------------*/
 .macro PROLOG_FREEUP_REG	reg, mem
 #ifdef CONFIG_SMP
 	sr  \reg, [ARC_REG_SCRATCH_DATA0]
 #else
 	st  \reg, [\mem]
 #endif
 .endm

 .macro PROLOG_RESTORE_REG	reg, mem
 #ifdef CONFIG_SMP
 	lr  \reg, [ARC_REG_SCRATCH_DATA0]
 #else
 	ld  \reg, [\mem]
 #endif
 .endm

 /*--------------------------------------------------------------
  * Exception Entry prologue
  * -Switches stack to K mode (if not already)
  * -Saves the register file
  *
  * After this it is safe to call the "C" handlers
  *-------------------------------------------------------------*/
 .macro EXCEPTION_PROLOGUE

 	/* Need at least 1 reg to code the early exception prologue */
 	PROLOG_FREEUP_REG r9, @ex_saved_reg1

 	/* U/K mode at time of exception (stack not switched if already K) */
 	lr  r9, [erstatus]

 	/* ARC700 doesn't provide auto-stack switching */
 	SWITCH_TO_KERNEL_STK

 #ifdef CONFIG_ARC_CURR_IN_REG
 	/* Treat r25 as scratch reg (save on stack) and load with "current" */
 	PUSH    r25
 	GET_CURR_TASK_ON_CPU   r25
 #else
 	sub     sp, sp, 4
 #endif

 	st.a	r0, [sp, -8]    /* orig_r0 needed for syscall (skip ECR slot) */
 	sub	sp, sp, 4	/* skip pt_regs->sp, already saved above */

 	/* Restore r9 used to code the early prologue */
 	PROLOG_RESTORE_REG  r9, @ex_saved_reg1

 	/* now we are ready to save the regfile */
 	SAVE_R0_TO_R12
 	PUSH	gp
 	PUSH	fp
 	PUSH	blink
 	PUSHAX	eret
 	PUSHAX	erstatus
 	PUSH	lp_count
 	PUSHAX	lp_end
 	PUSHAX	lp_start
 	PUSHAX	erbta

 	lr	r9, [ecr]
 	st      r9, [sp, PT_event]    /* EV_Trap expects r9 to have ECR */
 .endm

 /*--------------------------------------------------------------
  * Restore all registers used by system call or Exceptions
  * SP should always be pointing to the next free stack element
  * when entering this macro.
  *
  * NOTE:
  *
  * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg
  * for memory load operations. If used in that way interrupts are deffered
  * by hardware and that is not good.
  *-------------------------------------------------------------*/
 .macro EXCEPTION_EPILOGUE
 	POPAX	erbta
 	POPAX	lp_start
 	POPAX	lp_end

 	POP	r9
 	mov	lp_count, r9	;LD to lp_count is not allowed

 	POPAX	erstatus
 	POPAX	eret
 	POP	blink
 	POP	fp
 	POP	gp
 	RESTORE_R12_TO_R0

 	ld  sp, [sp] /* restore original sp */
 	/* orig_r0, ECR, user_r25 skipped automatically */
 .endm

 /* Dummy ECR values for Interrupts */
 #define event_IRQ1		0x0031abcd
 #define event_IRQ2		0x0032abcd

 .macro INTERRUPT_PROLOGUE  LVL

 	/* free up r9 as scratchpad */
 	PROLOG_FREEUP_REG r9, @int\LVL\()_saved_reg

 	/* Which mode (user/kernel) was the system in when intr occured */
 	lr  r9, [status32_l\LVL\()]

 	SWITCH_TO_KERNEL_STK

 #ifdef CONFIG_ARC_CURR_IN_REG
 	/* Treat r25 as scratch reg (save on stack) and load with "current" */
 	PUSH    r25
 	GET_CURR_TASK_ON_CPU   r25
 #else
 	sub     sp, sp, 4
 #endif

 	PUSH	0x003\LVL\()abcd    /* Dummy ECR */
 	sub	sp, sp, 8	    /* skip orig_r0 (not needed)
 				       skip pt_regs->sp, already saved above */

 	/* Restore r9 used to code the early prologue */
 	PROLOG_RESTORE_REG  r9, @int\LVL\()_saved_reg

 	SAVE_R0_TO_R12
 	PUSH	gp
 	PUSH	fp
 	PUSH	blink
 	PUSH	ilink\LVL\()
 	PUSHAX	status32_l\LVL\()
 	PUSH	lp_count
 	PUSHAX	lp_end
 	PUSHAX	lp_start
 	PUSHAX	bta_l\LVL\()
 .endm

 /*--------------------------------------------------------------
  * Restore all registers used by interrupt handlers.
  *
  * NOTE:
  *
  * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg
  * for memory load operations. If used in that way interrupts are deffered
  * by hardware and that is not good.
  *-------------------------------------------------------------*/
 .macro INTERRUPT_EPILOGUE  LVL
 	POPAX	bta_l\LVL\()
 	POPAX	lp_start
 	POPAX	lp_end

 	POP	r9
 	mov	lp_count, r9	;LD to lp_count is not allowed

 	POPAX	status32_l\LVL\()
 	POP	ilink\LVL\()
 	POP	blink
 	POP	fp
 	POP	gp
 	RESTORE_R12_TO_R0

 	ld  sp, [sp] /* restore original sp */
 	/* orig_r0, ECR, user_r25 skipped automatically */
 .endm

 /* Get thread_info of "current" tsk */
 .macro GET_CURR_THR_INFO_FROM_SP  reg
 	bic \reg, sp, (THREAD_SIZE - 1)
 .endm

 /* Get CPU-ID of this core */
 .macro  GET_CPU_ID  reg
 	lr  \reg, [identity]
 	lsr \reg, \reg, 8
 	bmsk \reg, \reg, 7
 .endm

 #endif  /* __ASM_ARC_ENTRY_COMPACT_H */
	/*
	* Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
	* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* Vineetg: March 2009 (Supporting 2 levels of Interrupts)
	* Stack switching code can no longer reliably rely on the fact that
	* if we are NOT in user mode, stack is switched to kernel mode.
	* e.g. L2 IRQ interrupted a L1 ISR which had not yet completed
	* it's prologue including stack switching from user mode
	*
	* Vineetg: Aug 28th 2008: Bug #94984
	* -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap
	* Normally CPU does this automatically, however when doing FAKE rtie,
	* we also need to explicitly do this. The problem in macros
	* FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit
	* was being "CLEARED" rather then "SET". Actually "SET" clears ZOL context
	*
	* Vineetg: May 5th 2008
	* -Modified CALLEE_REG save/restore macros to handle the fact that
	* r25 contains the kernel current task ptr
	* - Defined Stack Switching Macro to be reused in all intr/excp hdlrs
	* - Shaved off 11 instructions from RESTORE_ALL_INT1 by using the
	* address Write back load ld.ab instead of seperate ld/add instn
	*
	* Amit Bhor, Sameer Dhavale: Codito Technologies 2004
	*/

	#ifndef __ASM_ARC_ENTRY_COMPACT_H
	#define __ASM_ARC_ENTRY_COMPACT_H

	#include <asm/asm-offsets.h>
	#include <asm/irqflags-compact.h>
	#include <asm/thread_info.h> /* For THREAD_SIZE */

	/*--------------------------------------------------------------
	* Switch to Kernel Mode stack if SP points to User Mode stack
	*
	* Entry : r9 contains pre-IRQ/exception/trap status32
	* Exit : SP set to K mode stack
	* SP at the time of entry (K/U) saved @ pt_regs->sp
	* Clobbers: r9
	-------------------------------------------------------------/

	.macro SWITCH_TO_KERNEL_STK

	/* User Mode when this happened ? Yes: Proceed to switch stack */
	bbit1 r9, STATUS_U_BIT, 88f

	/* OK we were already in kernel mode when this event happened, thus can
	* assume SP is kernel mode SP. _NO_ need to do any stack switching
	*/

	#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
	/* However....
	* If Level 2 Interrupts enabled, we may end up with a corner case:
	* 1. User Task executing
	* 2. L1 IRQ taken, ISR starts (CPU auto-switched to KERNEL mode)
	* 3. But before it could switch SP from USER to KERNEL stack
	* a L2 IRQ "Interrupts" L1
	* Thay way although L2 IRQ happened in Kernel mode, stack is still
	* not switched.
	* To handle this, we may need to switch stack even if in kernel mode
	* provided SP has values in range of USER mode stack ( < 0x7000_0000 )
	*/
	brlo sp, VMALLOC_START, 88f

	/* TODO: vineetg:
	* We need to be a bit more cautious here. What if a kernel bug in
	* L1 ISR, caused SP to go whaco (some small value which looks like
	* USER stk) and then we take L2 ISR.
	* Above brlo alone would treat it as a valid L1-L2 sceanrio
	* instead of shouting alound
	* The only feasible way is to make sure this L2 happened in
	* L1 prelogue ONLY i.e. ilink2 is less than a pre-set marker in
	* L1 ISR before it switches stack
	*/

	#endif

	/------Intr/Ecxp happened in kernel mode, SP already setup ------ /
	/* save it nevertheless @ pt_regs->sp for uniformity */

	b.d 66f
	st sp, [sp, PT_sp - SZ_PT_REGS]

	88: /------Intr/Ecxp happened in user mode, "switch" stack ------ /

	GET_CURR_TASK_ON_CPU r9

	/* With current tsk in r9, get it's kernel mode stack base */
	GET_TSK_STACK_BASE r9, r9

	/* save U mode SP @ pt_regs->sp */
	st sp, [r9, PT_sp - SZ_PT_REGS]

	/* final SP switch */
	mov sp, r9
	66:
	.endm

	/*------------------------------------------------------------
	* "FAKE" a rtie to return from CPU Exception context
	* This is to re-enable Exceptions within exception
	* Look at EV_ProtV to see how this is actually used
	-------------------------------------------------------------/

	.macro FAKE_RET_FROM_EXCPN

	lr r9, [status32]
	bclr r9, r9, STATUS_AE_BIT
	or r9, r9, (STATUS_E1_MASK\|STATUS_E2_MASK)
	sr r9, [erstatus]
	mov r9, 55f
	sr r9, [eret]
	rtie
	55:
	.endm

	/*--------------------------------------------------------------
	* For early Exception/ISR Prologue, a core reg is temporarily needed to
	* code the rest of prolog (stack switching). This is done by stashing
	* it to memory (non-SMP case) or SCRATCH0 Aux Reg (SMP).
	*
	* Before saving the full regfile - this reg is restored back, only
	* to be saved again on kernel mode stack, as part of pt_regs.
	-------------------------------------------------------------/
	.macro PROLOG_FREEUP_REG reg, mem
	#ifdef CONFIG_SMP
	sr \reg, [ARC_REG_SCRATCH_DATA0]
	#else
	st \reg, [\mem]
	#endif
	.endm

	.macro PROLOG_RESTORE_REG reg, mem
	#ifdef CONFIG_SMP
	lr \reg, [ARC_REG_SCRATCH_DATA0]
	#else
	ld \reg, [\mem]
	#endif
	.endm

	/*--------------------------------------------------------------
	* Exception Entry prologue
	* -Switches stack to K mode (if not already)
	* -Saves the register file
	*
	* After this it is safe to call the "C" handlers
	-------------------------------------------------------------/
	.macro EXCEPTION_PROLOGUE

	/* Need at least 1 reg to code the early exception prologue */
	PROLOG_FREEUP_REG r9, @ex_saved_reg1

	/* U/K mode at time of exception (stack not switched if already K) */
	lr r9, [erstatus]

	/* ARC700 doesn't provide auto-stack switching */
	SWITCH_TO_KERNEL_STK

	#ifdef CONFIG_ARC_CURR_IN_REG
	/* Treat r25 as scratch reg (save on stack) and load with "current" */
	PUSH r25
	GET_CURR_TASK_ON_CPU r25
	#else
	sub sp, sp, 4
	#endif

	st.a r0, [sp, -8] /* orig_r0 needed for syscall (skip ECR slot) */
	sub sp, sp, 4 /* skip pt_regs->sp, already saved above */

	/* Restore r9 used to code the early prologue */
	PROLOG_RESTORE_REG r9, @ex_saved_reg1

	/* now we are ready to save the regfile */
	SAVE_R0_TO_R12
	PUSH gp
	PUSH fp
	PUSH blink
	PUSHAX eret
	PUSHAX erstatus
	PUSH lp_count
	PUSHAX lp_end
	PUSHAX lp_start
	PUSHAX erbta

	lr r9, [ecr]
	st r9, [sp, PT_event] /* EV_Trap expects r9 to have ECR */
	.endm

	/*--------------------------------------------------------------
	* Restore all registers used by system call or Exceptions
	* SP should always be pointing to the next free stack element
	* when entering this macro.
	*
	* NOTE:
	*
	* It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg
	* for memory load operations. If used in that way interrupts are deffered
	* by hardware and that is not good.
	-------------------------------------------------------------/
	.macro EXCEPTION_EPILOGUE
	POPAX erbta
	POPAX lp_start
	POPAX lp_end

	POP r9
	mov lp_count, r9 ;LD to lp_count is not allowed

	POPAX erstatus
	POPAX eret
	POP blink
	POP fp
	POP gp
	RESTORE_R12_TO_R0

	ld sp, [sp] /* restore original sp */
	/* orig_r0, ECR, user_r25 skipped automatically */
	.endm

	/* Dummy ECR values for Interrupts */
	#define event_IRQ1 0x0031abcd
	#define event_IRQ2 0x0032abcd

	.macro INTERRUPT_PROLOGUE LVL

	/* free up r9 as scratchpad */
	PROLOG_FREEUP_REG r9, @int\LVL\()_saved_reg

	/* Which mode (user/kernel) was the system in when intr occured */
	lr r9, [status32_l\LVL\()]

	SWITCH_TO_KERNEL_STK

	#ifdef CONFIG_ARC_CURR_IN_REG
	/* Treat r25 as scratch reg (save on stack) and load with "current" */
	PUSH r25
	GET_CURR_TASK_ON_CPU r25
	#else
	sub sp, sp, 4
	#endif

	PUSH 0x003\LVL\()abcd /* Dummy ECR */
	sub sp, sp, 8 /* skip orig_r0 (not needed)
	skip pt_regs->sp, already saved above */

	/* Restore r9 used to code the early prologue */
	PROLOG_RESTORE_REG r9, @int\LVL\()_saved_reg

	SAVE_R0_TO_R12
	PUSH gp
	PUSH fp
	PUSH blink
	PUSH ilink\LVL\()
	PUSHAX status32_l\LVL\()
	PUSH lp_count
	PUSHAX lp_end
	PUSHAX lp_start
	PUSHAX bta_l\LVL\()
	.endm

	/*--------------------------------------------------------------
	* Restore all registers used by interrupt handlers.
	*
	* NOTE:
	*
	* It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg
	* for memory load operations. If used in that way interrupts are deffered
	* by hardware and that is not good.
	-------------------------------------------------------------/
	.macro INTERRUPT_EPILOGUE LVL
	POPAX bta_l\LVL\()
	POPAX lp_start
	POPAX lp_end

	POP r9
	mov lp_count, r9 ;LD to lp_count is not allowed

	POPAX status32_l\LVL\()
	POP ilink\LVL\()
	POP blink
	POP fp
	POP gp
	RESTORE_R12_TO_R0

	ld sp, [sp] /* restore original sp */
	/* orig_r0, ECR, user_r25 skipped automatically */
	.endm

	/* Get thread_info of "current" tsk */
	.macro GET_CURR_THR_INFO_FROM_SP reg
	bic \reg, sp, (THREAD_SIZE - 1)
	.endm

	/* Get CPU-ID of this core */
	.macro GET_CPU_ID reg
	lr \reg, [identity]
	lsr \reg, \reg, 8
	bmsk \reg, \reg, 7
	.endm

	#endif /* __ASM_ARC_ENTRY_COMPACT_H */