mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-21 00:10:09 +00:00
2874c5fd28
Based on 1 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 as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
113 lines
3.1 KiB
C
113 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* This file contains the routines for handling the MMU on those
|
|
* PowerPC implementations where the MMU substantially follows the
|
|
* architecture specification. This includes the 6xx, 7xx, 7xxx,
|
|
* and 8260 implementations but excludes the 8xx and 4xx.
|
|
* -- paulus
|
|
*
|
|
* Derived from arch/ppc/mm/init.c:
|
|
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
|
|
*
|
|
* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
|
|
* and Cort Dougan (PReP) (cort@cs.nmt.edu)
|
|
* Copyright (C) 1996 Paul Mackerras
|
|
*
|
|
* Derived from "arch/i386/mm/init.c"
|
|
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/init.h>
|
|
#include <linux/export.h>
|
|
|
|
#include <asm/mmu_context.h>
|
|
|
|
/*
|
|
* On 32-bit PowerPC 6xx/7xx/7xxx CPUs, we use a set of 16 VSIDs
|
|
* (virtual segment identifiers) for each context. Although the
|
|
* hardware supports 24-bit VSIDs, and thus >1 million contexts,
|
|
* we only use 32,768 of them. That is ample, since there can be
|
|
* at most around 30,000 tasks in the system anyway, and it means
|
|
* that we can use a bitmap to indicate which contexts are in use.
|
|
* Using a bitmap means that we entirely avoid all of the problems
|
|
* that we used to have when the context number overflowed,
|
|
* particularly on SMP systems.
|
|
* -- paulus.
|
|
*/
|
|
#define NO_CONTEXT ((unsigned long) -1)
|
|
#define LAST_CONTEXT 32767
|
|
#define FIRST_CONTEXT 1
|
|
|
|
/*
|
|
* This function defines the mapping from contexts to VSIDs (virtual
|
|
* segment IDs). We use a skew on both the context and the high 4 bits
|
|
* of the 32-bit virtual address (the "effective segment ID") in order
|
|
* to spread out the entries in the MMU hash table. Note, if this
|
|
* function is changed then arch/ppc/mm/hashtable.S will have to be
|
|
* changed to correspond.
|
|
*
|
|
*
|
|
* CTX_TO_VSID(ctx, va) (((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \
|
|
* & 0xffffff)
|
|
*/
|
|
|
|
static unsigned long next_mmu_context;
|
|
static unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
|
|
|
|
unsigned long __init_new_context(void)
|
|
{
|
|
unsigned long ctx = next_mmu_context;
|
|
|
|
while (test_and_set_bit(ctx, context_map)) {
|
|
ctx = find_next_zero_bit(context_map, LAST_CONTEXT+1, ctx);
|
|
if (ctx > LAST_CONTEXT)
|
|
ctx = 0;
|
|
}
|
|
next_mmu_context = (ctx + 1) & LAST_CONTEXT;
|
|
|
|
return ctx;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__init_new_context);
|
|
|
|
/*
|
|
* Set up the context for a new address space.
|
|
*/
|
|
int init_new_context(struct task_struct *t, struct mm_struct *mm)
|
|
{
|
|
mm->context.id = __init_new_context();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Free a context ID. Make sure to call this with preempt disabled!
|
|
*/
|
|
void __destroy_context(unsigned long ctx)
|
|
{
|
|
clear_bit(ctx, context_map);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__destroy_context);
|
|
|
|
/*
|
|
* We're finished using the context for an address space.
|
|
*/
|
|
void destroy_context(struct mm_struct *mm)
|
|
{
|
|
preempt_disable();
|
|
if (mm->context.id != NO_CONTEXT) {
|
|
__destroy_context(mm->context.id);
|
|
mm->context.id = NO_CONTEXT;
|
|
}
|
|
preempt_enable();
|
|
}
|
|
|
|
/*
|
|
* Initialize the context management stuff.
|
|
*/
|
|
void __init mmu_context_init(void)
|
|
{
|
|
/* Reserve context 0 for kernel use */
|
|
context_map[0] = (1 << FIRST_CONTEXT) - 1;
|
|
next_mmu_context = FIRST_CONTEXT;
|
|
}
|