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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/tile/kernel/entry.S
10817 views
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/*

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 * Copyright 2010 Tilera Corporation. All Rights Reserved.

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 *

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 *   This program is free software; you can redistribute it and/or

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 *   modify it under the terms of the GNU General Public License

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 *   as published by the Free Software Foundation, version 2.

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 *

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 *   This program is distributed in the hope that it will be useful, but

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 *   WITHOUT ANY WARRANTY; without even the implied warranty of

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 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or

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 *   NON INFRINGEMENT.  See the GNU General Public License for

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 *   more details.

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 */

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#include <linux/linkage.h>

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#include <linux/unistd.h>

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#include <asm/irqflags.h>

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#include <asm/processor.h>

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#include <arch/abi.h>

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#include <arch/spr_def.h>

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#ifdef __tilegx__

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#define bnzt bnezt

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#endif

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STD_ENTRY(current_text_addr)

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	{ move r0, lr; jrp lr }

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	STD_ENDPROC(current_text_addr)

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/*

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 * Implement execve().  The i386 code has a note that forking from kernel

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 * space results in no copy on write until the execve, so we should be

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 * careful not to write to the stack here.

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 */

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STD_ENTRY(kernel_execve)

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	moveli TREG_SYSCALL_NR_NAME, __NR_execve

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	swint1

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	jrp lr

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	STD_ENDPROC(kernel_execve)

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/*

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 * We don't run this function directly, but instead copy it to a page

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 * we map into every user process.  See vdso_setup().

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 *

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 * Note that libc has a copy of this function that it uses to compare

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 * against the PC when a stack backtrace ends, so if this code is

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 * changed, the libc implementation(s) should also be updated.

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 */

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	.pushsection .data

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ENTRY(__rt_sigreturn)

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	moveli TREG_SYSCALL_NR_NAME,__NR_rt_sigreturn

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	swint1

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	ENDPROC(__rt_sigreturn)

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	ENTRY(__rt_sigreturn_end)

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	.popsection

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STD_ENTRY(dump_stack)

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	{ move r2, lr; lnk r1 }

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	{ move r4, r52; addli r1, r1, dump_stack - . }

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	{ move r3, sp; j _dump_stack }

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	jrp lr   /* keep backtracer happy */

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	STD_ENDPROC(dump_stack)

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STD_ENTRY(KBacktraceIterator_init_current)

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	{ move r2, lr; lnk r1 }

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	{ move r4, r52; addli r1, r1, KBacktraceIterator_init_current - . }

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	{ move r3, sp; j _KBacktraceIterator_init_current }

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	jrp lr   /* keep backtracer happy */

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	STD_ENDPROC(KBacktraceIterator_init_current)

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/*

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 * Reset our stack to r1/r2 (sp and ksp0+cpu respectively), then

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 * free the old stack (passed in r0) and re-invoke cpu_idle().

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 * We update sp and ksp0 simultaneously to avoid backtracer warnings.

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 */

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STD_ENTRY(cpu_idle_on_new_stack)

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	{

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	 move sp, r1

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	 mtspr SPR_SYSTEM_SAVE_K_0, r2

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	}

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	jal free_thread_info

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	j cpu_idle

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	STD_ENDPROC(cpu_idle_on_new_stack)

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/* Loop forever on a nap during SMP boot. */

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STD_ENTRY(smp_nap)

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	nap

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	j smp_nap /* we are not architecturally guaranteed not to exit nap */

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	jrp lr    /* clue in the backtracer */

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	STD_ENDPROC(smp_nap)

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/*

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 * Enable interrupts racelessly and then nap until interrupted.

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 * Architecturally, we are guaranteed that enabling interrupts via

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 * mtspr to INTERRUPT_CRITICAL_SECTION only interrupts at the next PC.

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 * This function's _cpu_idle_nap address is special; see intvec.S.

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 * When interrupted at _cpu_idle_nap, we bump the PC forward 8, and

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 * as a result return to the function that called _cpu_idle().

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 */

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STD_ENTRY(_cpu_idle)

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	movei r1, 1

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	mtspr INTERRUPT_CRITICAL_SECTION, r1

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	IRQ_ENABLE(r2, r3)             /* unmask, but still with ICS set */

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	mtspr INTERRUPT_CRITICAL_SECTION, zero

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	.global _cpu_idle_nap

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_cpu_idle_nap:

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	nap

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	jrp lr

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	STD_ENDPROC(_cpu_idle)

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