/*
* MMU context allocation for 64-bit kernels.
*
* Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org>
*
* 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.
*
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/pkeys.h>
#include <linux/spinlock.h>
#include <linux/idr.h>
#include <linux/export.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
static DEFINE_SPINLOCK(mmu_context_lock);
static DEFINE_IDA(mmu_context_ida);
static int alloc_context_id(int min_id, int max_id)
{
int index, err;
again:
if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
return -ENOMEM;
spin_lock(&mmu_context_lock);
err = ida_get_new_above(&mmu_context_ida, min_id, &index);
spin_unlock(&mmu_context_lock);
if (err == -EAGAIN)
goto again;
else if (err)
return err;
if (index > max_id) {
spin_lock(&mmu_context_lock);
ida_remove(&mmu_context_ida, index);
spin_unlock(&mmu_context_lock);
return -ENOMEM;
}
return index;
}
void hash__reserve_context_id(int id)
{
int rc, result = 0;
do {
if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
break;
spin_lock(&mmu_context_lock);
rc = ida_get_new_above(&mmu_context_ida, id, &result);
spin_unlock(&mmu_context_lock);
} while (rc == -EAGAIN);
WARN(result != id, "mmu: Failed to reserve context id %d (rc %d)\n", id, result);
}
int hash__alloc_context_id(void)
{
unsigned long max;
if (mmu_has_feature(MMU_FTR_68_BIT_VA))
max = MAX_USER_CONTEXT;
else
max = MAX_USER_CONTEXT_65BIT_VA;
return alloc_context_id(MIN_USER_CONTEXT, max);
}
EXPORT_SYMBOL_GPL(hash__alloc_context_id);
static int hash__init_new_context(struct mm_struct *mm)
{
int index;
index = hash__alloc_context_id();
if (index < 0)
return index;
/*
* The old code would re-promote on fork, we don't do that when using
* slices as it could cause problem promoting slices that have been
* forced down to 4K.
*
* For book3s we have MMU_NO_CONTEXT set to be ~0. Hence check
* explicitly against context.id == 0. This ensures that we properly
* initialize context slice details for newly allocated mm's (which will
* have id == 0) and don't alter context slice inherited via fork (which
* will have id != 0).
*
* We should not be calling init_new_context() on init_mm. Hence a
* check against 0 is OK.
*/
if (mm->context.id == 0)
slice_init_new_context_exec(mm);
subpage_prot_init_new_context(mm);
pkey_mm_init(mm);
return index;
}
static int radix__init_new_context(struct mm_struct *mm)
{
unsigned long rts_field;
int index, max_id;
max_id = (1 << mmu_pid_bits) - 1;
index = alloc_context_id(mmu_base_pid, max_id);
if (index < 0)
return index;
/*
* set the process table entry,
*/
rts_field = radix__get_tree_size();
process_tb[index].prtb0 = cpu_to_be64(rts_field | __pa(mm->pgd) | RADIX_PGD_INDEX_SIZE);
/*
* Order the above store with subsequent update of the PID
* register (at which point HW can start loading/caching
* the entry) and the corresponding load by the MMU from
* the L2 cache.
*/
asm volatile("ptesync;isync" : : : "memory");
mm->context.npu_context = NULL;
return index;
}
int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
int index;
if (radix_enabled())
index = radix__init_new_context(mm);
else
index = hash__init_new_context(mm);
if (index < 0)
return index;
mm->context.id = index;
mm->context.pte_frag = NULL;
mm->context.pmd_frag = NULL;
#ifdef CONFIG_SPAPR_TCE_IOMMU
mm_iommu_init(mm);
#endif
atomic_set(&mm->context.active_cpus, 0);
atomic_set(&mm->context.copros, 0);
return 0;
}
void __destroy_context(int context_id)
{
spin_lock(&mmu_context_lock);
ida_remove(&mmu_context_ida, context_id);
spin_unlock(&mmu_context_lock);
}
EXPORT_SYMBOL_GPL(__destroy_context);
static void destroy_contexts(mm_context_t *ctx)
{
int index, context_id;
spin_lock(&mmu_context_lock);
for (index = 0; index < ARRAY_SIZE(ctx->extended_id); index++) {
context_id = ctx->extended_id[index];
if (context_id)
ida_remove(&mmu_context_ida, context_id);
}
spin_unlock(&mmu_context_lock);
}
static void pte_frag_destroy(void *pte_frag)
{
int count;
struct page *page;
page = virt_to_page(pte_frag);
/* drop all the pending references */
count = ((unsigned long)pte_frag & ~PAGE_MASK) >> PTE_FRAG_SIZE_SHIFT;
/* We allow PTE_FRAG_NR fragments from a PTE page */
if (page_ref_sub_and_test(page, PTE_FRAG_NR - count)) {
pgtable_page_dtor(page);
free_unref_page(page);
}
}
static void pmd_frag_destroy(void *pmd_frag)
{
int count;
struct page *page;
page = virt_to_page(pmd_frag);
/* drop all the pending references */
count = ((unsigned long)pmd_frag & ~PAGE_MASK) >> PMD_FRAG_SIZE_SHIFT;
/* We allow PTE_FRAG_NR fragments from a PTE page */
if (page_ref_sub_and_test(page, PMD_FRAG_NR - count)) {
pgtable_pmd_page_dtor(page);
free_unref_page(page);
}
}
static void destroy_pagetable_page(struct mm_struct *mm)
{
void *frag;
frag = mm->context.pte_frag;
if (frag)
pte_frag_destroy(frag);
frag = mm->context.pmd_frag;
if (frag)
pmd_frag_destroy(frag);
return;
}
void destroy_context(struct mm_struct *mm)
{
#ifdef CONFIG_SPAPR_TCE_IOMMU
WARN_ON_ONCE(!list_empty(&mm->context.iommu_group_mem_list));
#endif
if (radix_enabled())
WARN_ON(process_tb[mm->context.id].prtb0 != 0);
else
subpage_prot_free(mm);
destroy_pagetable_page(mm);
destroy_contexts(&mm->context);
mm->context.id = MMU_NO_CONTEXT;
}
void arch_exit_mmap(struct mm_struct *mm)
{
if (radix_enabled()) {
/*
* Radix doesn't have a valid bit in the process table
* entries. However we know that at least P9 implementation
* will avoid caching an entry with an invalid RTS field,
* and 0 is invalid. So this will do.
*
* This runs before the "fullmm" tlb flush in exit_mmap,
* which does a RIC=2 tlbie to clear the process table
* entry. See the "fullmm" comments in tlb-radix.c.
*
* No barrier required here after the store because
* this process will do the invalidate, which starts with
* ptesync.
*/
process_tb[mm->context.id].prtb0 = 0;
}
}
#ifdef CONFIG_PPC_RADIX_MMU
void radix__switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
{
if (cpu_has_feature(CPU_FTR_POWER9_DD1)) {
isync();
mtspr(SPRN_PID, next->context.id);
isync();
asm volatile(PPC_INVALIDATE_ERAT : : :"memory");
} else {
mtspr(SPRN_PID, next->context.id);
isync();
}
}
#endif
