linux-stable/arch/arc/include/asm/entry.h

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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*/
#ifndef __ASM_ARC_ENTRY_H
#define __ASM_ARC_ENTRY_H
#include <asm/unistd.h> /* For NR_syscalls defination */
#include <asm/arcregs.h>
#include <asm/ptrace.h>
#include <asm/processor.h> /* For VMALLOC_START */
#include <asm/mmu.h>
#ifdef __ASSEMBLY__
#ifdef CONFIG_ISA_ARCOMPACT
#include <asm/entry-compact.h> /* ISA specific bits */
#else
#include <asm/entry-arcv2.h>
#endif
/* Note on the LD/ST addr modes with addr reg wback
*
* LD.a same as LD.aw
*
* LD.a reg1, [reg2, x] => Pre Incr
* Eff Addr for load = [reg2 + x]
*
* LD.ab reg1, [reg2, x] => Post Incr
* Eff Addr for load = [reg2]
*/
.macro PUSH reg
st.a \reg, [sp, -4]
.endm
.macro PUSHAX aux
lr r9, [\aux]
PUSH r9
.endm
.macro POP reg
ld.ab \reg, [sp, 4]
.endm
.macro POPAX aux
POP r9
sr r9, [\aux]
.endm
/*--------------------------------------------------------------
* Helpers to save/restore Scratch Regs:
* used by Interrupt/Exception Prologue/Epilogue
*-------------------------------------------------------------*/
.macro SAVE_R0_TO_R12
PUSH r0
PUSH r1
PUSH r2
PUSH r3
PUSH r4
PUSH r5
PUSH r6
PUSH r7
PUSH r8
PUSH r9
PUSH r10
PUSH r11
PUSH r12
.endm
.macro RESTORE_R12_TO_R0
POP r12
POP r11
POP r10
POP r9
POP r8
POP r7
POP r6
POP r5
POP r4
POP r3
POP r2
POP r1
POP r0
ARC: pt_regs update #4: r25 saved/restored unconditionally (This is a VERY IMP change for low level interrupt/exception handling) ----------------------------------------------------------------------- WHAT ----------------------------------------------------------------------- * User 25 now saved in pt_regs->user_r25 (vs. tsk->thread_info.user_r25) * This allows Low level interrupt code to unconditionally save r25 (vs. the prev version which would only do it for U->K transition). Ofcourse for nested interrupts, only the pt_regs->user_r25 of bottom-most frame is useful. * simplifies the interrupt prologue/epilogue * Needed for ARCv2 ISA code and done here to keep design similar with ARCompact event handling ----------------------------------------------------------------------- WHY ------------------------------------------------------------------------- With CONFIG_ARC_CURR_IN_REG, r25 is used to cache "current" task pointer in kernel mode. So when entering kernel mode from User Mode - user r25 is specially safe-kept (it being a callee reg is NOT part of pt_regs which are saved by default on each interrupt/trap/exception) - r25 loaded with current task pointer. Further, if interrupt was taken in kernel mode, this is skipped since we know that r25 already has valid "current" pointer. With 2 level of interrupts in ARCompact ISA, detecting this is difficult but still possible, since we could be in kernel mode but r25 not already saved (in fact the stack itself might not have been switched). A. User mode B. L1 IRQ taken C. L2 IRQ taken (while on 1st line of L1 ISR) So in #C, although in kernel mode, r25 not saved (infact SP not switched at all) Given that ARcompact has manual stack switching, we could use a bit of trickey - The low level code would make sure that SP is only set to kernel mode value at the very end (after saving r25). So a non kernel mode SP, even if in kernel mode, meant r25 was NOT saved. The same paradigm won't work in ARCv2 ISA since SP is auto-switched so it's setting can't be delayed/constrained. Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-28 08:20:41 +00:00
.endm
/*--------------------------------------------------------------
* Helpers to save/restore callee-saved regs:
* used by several macros below
*-------------------------------------------------------------*/
.macro SAVE_R13_TO_R25
PUSH r13
PUSH r14
PUSH r15
PUSH r16
PUSH r17
PUSH r18
PUSH r19
PUSH r20
PUSH r21
PUSH r22
PUSH r23
PUSH r24
PUSH r25
.endm
.macro RESTORE_R25_TO_R13
POP r25
POP r24
POP r23
POP r22
POP r21
POP r20
POP r19
POP r18
POP r17
POP r16
POP r15
POP r14
POP r13
.endm
/*
* save user mode callee regs as struct callee_regs
* - needed by fork/do_signal/unaligned-access-emulation.
*/
.macro SAVE_CALLEE_SAVED_USER
SAVE_R13_TO_R25
.endm
/*
* restore user mode callee regs as struct callee_regs
* - could have been changed by ptrace tracer or unaligned-access fixup
*/
.macro RESTORE_CALLEE_SAVED_USER
RESTORE_R25_TO_R13
.endm
/*
* save/restore kernel mode callee regs at the time of context switch
*/
.macro SAVE_CALLEE_SAVED_KERNEL
SAVE_R13_TO_R25
.endm
.macro RESTORE_CALLEE_SAVED_KERNEL
RESTORE_R25_TO_R13
.endm
/*--------------------------------------------------------------
* Super FAST Restore callee saved regs by simply re-adjusting SP
*-------------------------------------------------------------*/
.macro DISCARD_CALLEE_SAVED_USER
add sp, sp, SZ_CALLEE_REGS
.endm
/*-------------------------------------------------------------
* given a tsk struct, get to the base of it's kernel mode stack
* tsk->thread_info is really a PAGE, whose bottom hoists stack
* which grows upwards towards thread_info
*------------------------------------------------------------*/
.macro GET_TSK_STACK_BASE tsk, out
/* Get task->thread_info (this is essentially start of a PAGE) */
ld \out, [\tsk, TASK_THREAD_INFO]
/* Go to end of page where stack begins (grows upwards) */
add2 \out, \out, (THREAD_SIZE)/4
.endm
/*
* @reg [OUT] thread_info->flags of "current"
*/
.macro GET_CURR_THR_INFO_FLAGS reg
GET_CURR_THR_INFO_FROM_SP \reg
ld \reg, [\reg, THREAD_INFO_FLAGS]
.endm
#ifdef CONFIG_SMP
/*
* Retrieve the current running task on this CPU
* - loads it from backing _current_task[] (and can't use the
* caching reg for current task
*/
.macro GET_CURR_TASK_ON_CPU reg
GET_CPU_ID \reg
ld.as \reg, [@_current_task, \reg]
.endm
/*-------------------------------------------------
* Save a new task as the "current" task on this CPU
* 1. Determine curr CPU id.
* 2. Use it to index into _current_task[ ]
*
* Coded differently than GET_CURR_TASK_ON_CPU (which uses LD.AS)
* because ST r0, [r1, offset] can ONLY have s9 @offset
* while LD can take s9 (4 byte insn) or LIMM (8 byte insn)
*/
.macro SET_CURR_TASK_ON_CPU tsk, tmp
GET_CPU_ID \tmp
add2 \tmp, @_current_task, \tmp
st \tsk, [\tmp]
#ifdef CONFIG_ARC_CURR_IN_REG
mov gp, \tsk
#endif
.endm
#else /* Uniprocessor implementation of macros */
.macro GET_CURR_TASK_ON_CPU reg
ld \reg, [@_current_task]
.endm
.macro SET_CURR_TASK_ON_CPU tsk, tmp
st \tsk, [@_current_task]
#ifdef CONFIG_ARC_CURR_IN_REG
mov gp, \tsk
#endif
.endm
#endif /* SMP / UNI */
/*
* Get the ptr to some field of Current Task at @off in task struct
* - Uses current task cached in reg if enabled
*/
#ifdef CONFIG_ARC_CURR_IN_REG
.macro GET_CURR_TASK_FIELD_PTR off, reg
add \reg, gp, \off
.endm
#else
.macro GET_CURR_TASK_FIELD_PTR off, reg
GET_CURR_TASK_ON_CPU \reg
add \reg, \reg, \off
.endm
#endif /* CONFIG_ARC_CURR_IN_REG */
#else /* !__ASSEMBLY__ */
extern void do_signal(struct pt_regs *);
extern void do_notify_resume(struct pt_regs *);
extern int do_privilege_fault(unsigned long, struct pt_regs *);
extern int do_extension_fault(unsigned long, struct pt_regs *);
extern int insterror_is_error(unsigned long, struct pt_regs *);
extern int do_memory_error(unsigned long, struct pt_regs *);
extern int trap_is_brkpt(unsigned long, struct pt_regs *);
extern int do_misaligned_error(unsigned long, struct pt_regs *);
extern int do_trap5_error(unsigned long, struct pt_regs *);
extern int do_misaligned_access(unsigned long, struct pt_regs *, struct callee_regs *);
extern void do_machine_check_fault(unsigned long, struct pt_regs *);
extern void do_non_swi_trap(unsigned long, struct pt_regs *);
extern void do_insterror_or_kprobe(unsigned long, struct pt_regs *);
extern void do_page_fault(unsigned long, struct pt_regs *);
#endif
#endif /* __ASM_ARC_ENTRY_H */