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linux/arch/arc/kernel/ctx_sw_asm.S

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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 Based on 2 normalized pattern(s): 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 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 # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Enrico Weigelt <info@metux.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-04 10:11:33 +02:00
/* SPDX-License-Identifier: GPL-2.0-only */
ARC: Process-creation/scheduling/idle-loop Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-01-18 15:12:18 +05:30
/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* Vineetg: Aug 2009
* -Moved core context switch macro out of entry.S into this file.
* -This is the more "natural" hand written assembler
*/
ARC: Fix build breakage for !CONFIG_ARC_DW2_UNWIND Fixes: ec7ac6afd07b (ARC: switch to generic ENTRY/END assembler annotations) Reported-by: Anton Kolesov <akolesov@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2014-06-24 19:33:39 +05:30
#include <linux/linkage.h>
ARC: Process-creation/scheduling/idle-loop Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-01-18 15:12:18 +05:30
#include <asm/entry.h> /* For the SAVE_* macros */
#include <asm/asm-offsets.h>
ARC: __switch_to: asm with dwarf ops (vs. inline asm) __switch_to() is final step of context switch, swapping kernel modes stack (and callee regs) of outgoing task with next task. It is also the starting point of stack unwinging of a sleeping task and captures SP, FP, BLINK and the corresponding dwarf info. Back when dinosaurs still roamed around, ARC gas didn't support CFI pseudo ops and gcc was responsible for generating dwarf info. Thus it had to be written in "C" with inline asm to do the hand crafting of stack. The function prologue (and crucial saving of blink etc) was still gcc generated but not visible in code. Likewise dwarf info was missing. Now with modern tools, we can make things more obvious by writing the code in asm and adding approproate dwarf cfi pseudo ops. This is mostly non functional change, except for slight chnages to asm - ARCompact doesn't support MOV_S fp, sp, so we use MOV Signed-off-by: Vineet Gupta <vgupta@kernel.org>
2020-05-14 00:16:34 -07:00
; IN
; - r0: prev task (also current)
; - r1: next task
; OUT
; - r0: prev task (so r0 not touched)
ARC: Process-creation/scheduling/idle-loop Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-01-18 15:12:18 +05:30
.section .sched.text,"ax",@progbits
ARC: __switch_to: asm with dwarf ops (vs. inline asm) __switch_to() is final step of context switch, swapping kernel modes stack (and callee regs) of outgoing task with next task. It is also the starting point of stack unwinging of a sleeping task and captures SP, FP, BLINK and the corresponding dwarf info. Back when dinosaurs still roamed around, ARC gas didn't support CFI pseudo ops and gcc was responsible for generating dwarf info. Thus it had to be written in "C" with inline asm to do the hand crafting of stack. The function prologue (and crucial saving of blink etc) was still gcc generated but not visible in code. Likewise dwarf info was missing. Now with modern tools, we can make things more obvious by writing the code in asm and adding approproate dwarf cfi pseudo ops. This is mostly non functional change, except for slight chnages to asm - ARCompact doesn't support MOV_S fp, sp, so we use MOV Signed-off-by: Vineet Gupta <vgupta@kernel.org>
2020-05-14 00:16:34 -07:00
ENTRY_CFI(__switch_to)
/* save kernel stack frame regs of @prev task */
push blink
CFI_DEF_CFA_OFFSET 4
CFI_OFFSET r31, -4
push fp
CFI_DEF_CFA_OFFSET 8
CFI_OFFSET r27, -8
mov fp, sp
CFI_DEF_CFA_REGISTER r27
/* kernel mode callee regs of @prev */
ARC: Process-creation/scheduling/idle-loop Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-01-18 15:12:18 +05:30
SAVE_CALLEE_SAVED_KERNEL
ARC: __switch_to: move ksp to thread_info from thread_struct task's arch specific bits are carried in 2 places - embedded thread_struct in task_struct - associated thread_info (hoisted in task's stack page) and syntactically: (thread_info *)(task_struct->stack) ksp (dynamic kernel stack top) currently lives in thread_struct but given its deep location in task struct likely to cache miss when accessed from __switch_to(). Moving it to thread_info would be more efficient given proximity to frequently accessed items such as preempt_count thus very likely to be in cache, specially in schedular code. Note however that currently tsk.thread.ksp takes 1 memory access (off of tsk pointer) while new code tsk->stack.ksp would take 2, but likely to be in cache. Moreover if task is current the 2nd reference can be elided and instead derived from SP as (SP & ~(THREAD_SIZE - 1)) All of this also makes __switch_to() code simpler and we can see the 2 ways of retirving ksp (descrobed above) in new code. Signed-off-by: Vineet Gupta <vgupta@kernel.org>
2020-05-14 00:51:26 -07:00
/*
* save final SP to @prev->thread_info.ksp
* @prev is "current" so thread_info derived from SP
*/
GET_CURR_THR_INFO_FROM_SP r10
st sp, [r10, THREAD_INFO_KSP]
ARC: __switch_to: asm with dwarf ops (vs. inline asm) __switch_to() is final step of context switch, swapping kernel modes stack (and callee regs) of outgoing task with next task. It is also the starting point of stack unwinging of a sleeping task and captures SP, FP, BLINK and the corresponding dwarf info. Back when dinosaurs still roamed around, ARC gas didn't support CFI pseudo ops and gcc was responsible for generating dwarf info. Thus it had to be written in "C" with inline asm to do the hand crafting of stack. The function prologue (and crucial saving of blink etc) was still gcc generated but not visible in code. Likewise dwarf info was missing. Now with modern tools, we can make things more obvious by writing the code in asm and adding approproate dwarf cfi pseudo ops. This is mostly non functional change, except for slight chnages to asm - ARCompact doesn't support MOV_S fp, sp, so we use MOV Signed-off-by: Vineet Gupta <vgupta@kernel.org>
2020-05-14 00:16:34 -07:00
/* update @next in _current_task[] and GP register caching it */
SET_CURR_TASK_ON_CPU r1, r10
ARC: __switch_to: move ksp to thread_info from thread_struct task's arch specific bits are carried in 2 places - embedded thread_struct in task_struct - associated thread_info (hoisted in task's stack page) and syntactically: (thread_info *)(task_struct->stack) ksp (dynamic kernel stack top) currently lives in thread_struct but given its deep location in task struct likely to cache miss when accessed from __switch_to(). Moving it to thread_info would be more efficient given proximity to frequently accessed items such as preempt_count thus very likely to be in cache, specially in schedular code. Note however that currently tsk.thread.ksp takes 1 memory access (off of tsk pointer) while new code tsk->stack.ksp would take 2, but likely to be in cache. Moreover if task is current the 2nd reference can be elided and instead derived from SP as (SP & ~(THREAD_SIZE - 1)) All of this also makes __switch_to() code simpler and we can see the 2 ways of retirving ksp (descrobed above) in new code. Signed-off-by: Vineet Gupta <vgupta@kernel.org>
2020-05-14 00:51:26 -07:00
/* load SP from @next->thread_info.ksp */
ld r10, [r1, TASK_THREAD_INFO]
ld sp, [r10, THREAD_INFO_KSP]
ARC: __switch_to: asm with dwarf ops (vs. inline asm) __switch_to() is final step of context switch, swapping kernel modes stack (and callee regs) of outgoing task with next task. It is also the starting point of stack unwinging of a sleeping task and captures SP, FP, BLINK and the corresponding dwarf info. Back when dinosaurs still roamed around, ARC gas didn't support CFI pseudo ops and gcc was responsible for generating dwarf info. Thus it had to be written in "C" with inline asm to do the hand crafting of stack. The function prologue (and crucial saving of blink etc) was still gcc generated but not visible in code. Likewise dwarf info was missing. Now with modern tools, we can make things more obvious by writing the code in asm and adding approproate dwarf cfi pseudo ops. This is mostly non functional change, except for slight chnages to asm - ARCompact doesn't support MOV_S fp, sp, so we use MOV Signed-off-by: Vineet Gupta <vgupta@kernel.org>
2020-05-14 00:16:34 -07:00
/* restore callee regs, stack frame regs of @next */
ARC: Process-creation/scheduling/idle-loop Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-01-18 15:12:18 +05:30
RESTORE_CALLEE_SAVED_KERNEL
ARC: __switch_to: asm with dwarf ops (vs. inline asm) __switch_to() is final step of context switch, swapping kernel modes stack (and callee regs) of outgoing task with next task. It is also the starting point of stack unwinging of a sleeping task and captures SP, FP, BLINK and the corresponding dwarf info. Back when dinosaurs still roamed around, ARC gas didn't support CFI pseudo ops and gcc was responsible for generating dwarf info. Thus it had to be written in "C" with inline asm to do the hand crafting of stack. The function prologue (and crucial saving of blink etc) was still gcc generated but not visible in code. Likewise dwarf info was missing. Now with modern tools, we can make things more obvious by writing the code in asm and adding approproate dwarf cfi pseudo ops. This is mostly non functional change, except for slight chnages to asm - ARCompact doesn't support MOV_S fp, sp, so we use MOV Signed-off-by: Vineet Gupta <vgupta@kernel.org>
2020-05-14 00:16:34 -07:00
pop fp
CFI_RESTORE r27
CFI_DEF_CFA r28, 4
pop blink
CFI_RESTORE r31
CFI_DEF_CFA_OFFSET 0
j [blink]
ARC: dw2 unwind: enable cfi pseudo ops in string lib This uses a new set of annoations viz. ENTRY_CFI/END_CFI to enabel cfi ops generation. Note that we didn't change the normal ENTRY/EXIT as we don't actually want unwind info in the trap/exception/interrutp handlers which use these, as unwinder then gets confused (it keeps recursing vs. stopping). Semantically these are leaf routines and unwinding should stop when it hits those routines. Before ------ 28.52% 1.19% 9929 hackbench libuClibc-1.0.17.so [.] __write_nocancel | ---__write_nocancel |--8.95%--EV_Trap | --8.25%--sys_write | |--3.93%--sock_write_iter ... |--2.62%--memset <==== [LEAF entry as no unwind info] ^^^^^^ After ----- 29.46% 1.24% 13622 hackbench libuClibc-1.0.17.so [.] __write_nocancel | ---__write_nocancel |--9.31%--EV_Trap | --8.62%--sys_write | |--4.17%--sock_write_iter ... |--6.19%--sys_write | --6.19%--sock_write_iter | unix_stream_sendmsg | |--1.62%--sock_alloc_send_pskb | |--0.89%--sock_def_readable | |--0.88%--_raw_spin_unlock_irqrestore | |--0.69%--memset | | ^^^^^^ <==== [now in proper callframe] | | | --0.52%--skb_copy_datagram_from_iter Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2016-09-19 16:42:25 -07:00
END_CFI(__switch_to)
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