Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) // SPDX-License-Identifier: GPL-2.0-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3)  * This file contains the routines for handling the MMU.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5)  *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7)  *  Derived from arch/ppc/mm/4xx_mmu.c:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8)  *  -- paulus
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10)  *  Derived from arch/ppc/mm/init.c:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11)  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13)  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14)  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)  *    Copyright (C) 1996 Paul Mackerras
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16)  *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18)  *  Derived from "arch/i386/mm/init.c"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19)  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) #include <linux/mm.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) #include <linux/init.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) #include <asm/tlbflush.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) #include <asm/mmu_context.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) mm_context_t next_mmu_context;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) atomic_t nr_free_contexts;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) struct mm_struct *context_mm[LAST_CONTEXT+1];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34)  * Initialize the context management stuff.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) void __init mmu_context_init(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 	 * The use of context zero is reserved for the kernel.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 	 * This code assumes FIRST_CONTEXT < 32.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 	context_map[0] = (1 << FIRST_CONTEXT) - 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 	next_mmu_context = FIRST_CONTEXT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 	atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48)  * Steal a context from a task that has one at the moment.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50)  * This isn't an LRU system, it just frees up each context in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51)  * turn (sort-of pseudo-random replacement :).  This would be the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52)  * place to implement an LRU scheme if anyone were motivated to do it.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) void steal_context(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) 	struct mm_struct *mm;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) 	/* free up context `next_mmu_context' */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) 	/* if we shouldn't free context 0, don't... */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) 	if (next_mmu_context < FIRST_CONTEXT)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) 		next_mmu_context = FIRST_CONTEXT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) 	mm = context_mm[next_mmu_context];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) 	flush_tlb_mm(mm);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) 	destroy_context(mm);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) }