1/*
  2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
  3 *
  4 *   This program is free software; you can redistribute it and/or
  5 *   modify it under the terms of the GNU General Public License
  6 *   as published by the Free Software Foundation, version 2.
  7 *
  8 *   This program is distributed in the hope that it will be useful, but
  9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 11 *   NON INFRINGEMENT.  See the GNU General Public License for
 12 *   more details.
 13 */
 14
 15#include <linux/linkage.h>
 16#include <linux/unistd.h>
 17#include <asm/irqflags.h>
 18#include <asm/processor.h>
 19#include <arch/abi.h>
 20#include <arch/spr_def.h>
 21
 22#ifdef __tilegx__
 23#define bnzt bnezt
 24#endif
 25
 26STD_ENTRY(current_text_addr)
 27	{ move r0, lr; jrp lr }
 28	STD_ENDPROC(current_text_addr)
 29
 30/*
 31 * Implement execve().  The i386 code has a note that forking from kernel
 32 * space results in no copy on write until the execve, so we should be
 33 * careful not to write to the stack here.
 34 */
 35STD_ENTRY(kernel_execve)
 36	moveli TREG_SYSCALL_NR_NAME, __NR_execve
 37	swint1
 38	jrp lr
 39	STD_ENDPROC(kernel_execve)
 40
 41/*
 42 * We don't run this function directly, but instead copy it to a page
 43 * we map into every user process.  See vdso_setup().
 44 *
 45 * Note that libc has a copy of this function that it uses to compare
 46 * against the PC when a stack backtrace ends, so if this code is
 47 * changed, the libc implementation(s) should also be updated.
 48 */
 49	.pushsection .data
 50ENTRY(__rt_sigreturn)
 51	moveli TREG_SYSCALL_NR_NAME,__NR_rt_sigreturn
 52	swint1
 53	ENDPROC(__rt_sigreturn)
 54	ENTRY(__rt_sigreturn_end)
 55	.popsection
 56
 57STD_ENTRY(dump_stack)
 58	{ move r2, lr; lnk r1 }
 59	{ move r4, r52; addli r1, r1, dump_stack - . }
 60	{ move r3, sp; j _dump_stack }
 61	jrp lr   /* keep backtracer happy */
 62	STD_ENDPROC(dump_stack)
 63
 64STD_ENTRY(KBacktraceIterator_init_current)
 65	{ move r2, lr; lnk r1 }
 66	{ move r4, r52; addli r1, r1, KBacktraceIterator_init_current - . }
 67	{ move r3, sp; j _KBacktraceIterator_init_current }
 68	jrp lr   /* keep backtracer happy */
 69	STD_ENDPROC(KBacktraceIterator_init_current)
 70
 71/*
 72 * Reset our stack to r1/r2 (sp and ksp0+cpu respectively), then
 73 * free the old stack (passed in r0) and re-invoke cpu_idle().
 74 * We update sp and ksp0 simultaneously to avoid backtracer warnings.
 75 */
 76STD_ENTRY(cpu_idle_on_new_stack)
 77	{
 78	 move sp, r1
 79	 mtspr SPR_SYSTEM_SAVE_K_0, r2
 80	}
 81	jal free_thread_info
 82	j cpu_idle
 83	STD_ENDPROC(cpu_idle_on_new_stack)
 84
 85/* Loop forever on a nap during SMP boot. */
 86STD_ENTRY(smp_nap)
 87	nap
 88	j smp_nap /* we are not architecturally guaranteed not to exit nap */
 89	jrp lr    /* clue in the backtracer */
 90	STD_ENDPROC(smp_nap)
 91
 92/*
 93 * Enable interrupts racelessly and then nap until interrupted.
 94 * Architecturally, we are guaranteed that enabling interrupts via
 95 * mtspr to INTERRUPT_CRITICAL_SECTION only interrupts at the next PC.
 96 * This function's _cpu_idle_nap address is special; see intvec.S.
 97 * When interrupted at _cpu_idle_nap, we bump the PC forward 8, and
 98 * as a result return to the function that called _cpu_idle().
 99 */
100STD_ENTRY(_cpu_idle)
101	movei r1, 1
102	mtspr INTERRUPT_CRITICAL_SECTION, r1
103	IRQ_ENABLE(r2, r3)             /* unmask, but still with ICS set */
104	mtspr INTERRUPT_CRITICAL_SECTION, zero
105	.global _cpu_idle_nap
106_cpu_idle_nap:
107	nap
108	jrp lr
109	STD_ENDPROC(_cpu_idle)