1 /* 2 * linux/arch/arm/mm/context.c 3 * 4 * Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 #include <linux/init.h> 11 #include <linux/sched.h> 12 #include <linux/mm.h> 13 14 #include <asm/mmu_context.h> 15 #include <asm/tlbflush.h> 16 17 unsigned int cpu_last_asid = { 1 << ASID_BITS }; 18 19 /* 20 * We fork()ed a process, and we need a new context for the child 21 * to run in. We reserve version 0 for initial tasks so we will 22 * always allocate an ASID. The ASID 0 is reserved for the TTBR 23 * register changing sequence. 24 */ 25 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm) 26 { 27 mm->context.id = 0; 28 } 29 30 void __new_context(struct mm_struct *mm) 31 { 32 unsigned int asid; 33 34 asid = ++cpu_last_asid; 35 if (asid == 0) 36 asid = cpu_last_asid = 1 << ASID_BITS; 37 38 /* 39 * If we've used up all our ASIDs, we need 40 * to start a new version and flush the TLB. 41 */ 42 if ((asid & ~ASID_MASK) == 0) { 43 asid = ++cpu_last_asid; 44 /* set the reserved ASID before flushing the TLB */ 45 asm("mcr p15, 0, %0, c13, c0, 1 @ set reserved context ID\n" 46 : 47 : "r" (0)); 48 isb(); 49 flush_tlb_all(); 50 } 51 52 mm->context.id = asid; 53 } 54