135 lines
3.5 KiB
C
135 lines
3.5 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>
|
|
|
|
/*
|
|
* Room for two PTE pointers, usually the kernel and current user pointers
|
|
* to their respective root page table.
|
|
*/
|
|
void *abatron_pteptrs[2];
|
|
|
|
/*
|
|
* 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
|
|
|
|
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();
|
|
mm->context.sr0 = CTX_TO_VSID(mm->context.id, 0);
|
|
|
|
if (IS_ENABLED(CONFIG_PPC_KUEP))
|
|
mm->context.sr0 |= SR_NX;
|
|
if (!kuap_is_disabled())
|
|
mm->context.sr0 |= SR_KS;
|
|
|
|
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;
|
|
}
|
|
|
|
void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk)
|
|
{
|
|
long id = next->context.id;
|
|
|
|
if (id < 0)
|
|
panic("mm_struct %p has no context ID", next);
|
|
|
|
isync();
|
|
|
|
update_user_segments(next->context.sr0);
|
|
|
|
if (IS_ENABLED(CONFIG_BDI_SWITCH))
|
|
abatron_pteptrs[1] = next->pgd;
|
|
|
|
if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
|
|
mtspr(SPRN_SDR1, rol32(__pa(next->pgd), 4) & 0xffff01ff);
|
|
|
|
mb(); /* sync */
|
|
isync();
|
|
}
|
|
EXPORT_SYMBOL(switch_mmu_context);
|