mirror of https://gitee.com/openkylin/linux.git
142 lines
4.0 KiB
C
142 lines
4.0 KiB
C
/*
|
|
* Copyright (C) 2015 Synopsys, Inc. (www.synopsys.com)
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
*/
|
|
|
|
#include <linux/bootmem.h>
|
|
#include <linux/export.h>
|
|
#include <linux/highmem.h>
|
|
#include <asm/processor.h>
|
|
#include <asm/pgtable.h>
|
|
#include <asm/pgalloc.h>
|
|
#include <asm/tlbflush.h>
|
|
|
|
/*
|
|
* HIGHMEM API:
|
|
*
|
|
* kmap() API provides sleep semantics hence referred to as "permanent maps"
|
|
* It allows mapping LAST_PKMAP pages, using @last_pkmap_nr as the cursor
|
|
* for book-keeping
|
|
*
|
|
* kmap_atomic() can't sleep (calls pagefault_disable()), thus it provides
|
|
* shortlived ala "temporary mappings" which historically were implemented as
|
|
* fixmaps (compile time addr etc). Their book-keeping is done per cpu.
|
|
*
|
|
* Both these facts combined (preemption disabled and per-cpu allocation)
|
|
* means the total number of concurrent fixmaps will be limited to max
|
|
* such allocations in a single control path. Thus KM_TYPE_NR (another
|
|
* historic relic) is a small'ish number which caps max percpu fixmaps
|
|
*
|
|
* ARC HIGHMEM Details
|
|
*
|
|
* - the kernel vaddr space from 0x7z to 0x8z (currently used by vmalloc/module)
|
|
* is now shared between vmalloc and kmap (non overlapping though)
|
|
*
|
|
* - Both fixmap/pkmap use a dedicated page table each, hooked up to swapper PGD
|
|
* This means each only has 1 PGDIR_SIZE worth of kvaddr mappings, which means
|
|
* 2M of kvaddr space for typical config (8K page and 11:8:13 traversal split)
|
|
*
|
|
* - fixmap anyhow needs a limited number of mappings. So 2M kvaddr == 256 PTE
|
|
* slots across NR_CPUS would be more than sufficient (generic code defines
|
|
* KM_TYPE_NR as 20).
|
|
*
|
|
* - pkmap being preemptible, in theory could do with more than 256 concurrent
|
|
* mappings. However, generic pkmap code: map_new_virtual(), doesn't traverse
|
|
* the PGD and only works with a single page table @pkmap_page_table, hence
|
|
* sets the limit
|
|
*/
|
|
|
|
extern pte_t * pkmap_page_table;
|
|
static pte_t * fixmap_page_table;
|
|
|
|
void *kmap(struct page *page)
|
|
{
|
|
BUG_ON(in_interrupt());
|
|
if (!PageHighMem(page))
|
|
return page_address(page);
|
|
|
|
return kmap_high(page);
|
|
}
|
|
EXPORT_SYMBOL(kmap);
|
|
|
|
void *kmap_atomic(struct page *page)
|
|
{
|
|
int idx, cpu_idx;
|
|
unsigned long vaddr;
|
|
|
|
preempt_disable();
|
|
pagefault_disable();
|
|
if (!PageHighMem(page))
|
|
return page_address(page);
|
|
|
|
cpu_idx = kmap_atomic_idx_push();
|
|
idx = cpu_idx + KM_TYPE_NR * smp_processor_id();
|
|
vaddr = FIXMAP_ADDR(idx);
|
|
|
|
set_pte_at(&init_mm, vaddr, fixmap_page_table + idx,
|
|
mk_pte(page, kmap_prot));
|
|
|
|
return (void *)vaddr;
|
|
}
|
|
EXPORT_SYMBOL(kmap_atomic);
|
|
|
|
void __kunmap_atomic(void *kv)
|
|
{
|
|
unsigned long kvaddr = (unsigned long)kv;
|
|
|
|
if (kvaddr >= FIXMAP_BASE && kvaddr < (FIXMAP_BASE + FIXMAP_SIZE)) {
|
|
|
|
/*
|
|
* Because preemption is disabled, this vaddr can be associated
|
|
* with the current allocated index.
|
|
* But in case of multiple live kmap_atomic(), it still relies on
|
|
* callers to unmap in right order.
|
|
*/
|
|
int cpu_idx = kmap_atomic_idx();
|
|
int idx = cpu_idx + KM_TYPE_NR * smp_processor_id();
|
|
|
|
WARN_ON(kvaddr != FIXMAP_ADDR(idx));
|
|
|
|
pte_clear(&init_mm, kvaddr, fixmap_page_table + idx);
|
|
local_flush_tlb_kernel_range(kvaddr, kvaddr + PAGE_SIZE);
|
|
|
|
kmap_atomic_idx_pop();
|
|
}
|
|
|
|
pagefault_enable();
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL(__kunmap_atomic);
|
|
|
|
static noinline pte_t * __init alloc_kmap_pgtable(unsigned long kvaddr)
|
|
{
|
|
pgd_t *pgd_k;
|
|
pud_t *pud_k;
|
|
pmd_t *pmd_k;
|
|
pte_t *pte_k;
|
|
|
|
pgd_k = pgd_offset_k(kvaddr);
|
|
pud_k = pud_offset(pgd_k, kvaddr);
|
|
pmd_k = pmd_offset(pud_k, kvaddr);
|
|
|
|
pte_k = (pte_t *)alloc_bootmem_low_pages(PAGE_SIZE);
|
|
pmd_populate_kernel(&init_mm, pmd_k, pte_k);
|
|
return pte_k;
|
|
}
|
|
|
|
void __init kmap_init(void)
|
|
{
|
|
/* Due to recursive include hell, we can't do this in processor.h */
|
|
BUILD_BUG_ON(PAGE_OFFSET < (VMALLOC_END + FIXMAP_SIZE + PKMAP_SIZE));
|
|
|
|
BUILD_BUG_ON(KM_TYPE_NR > PTRS_PER_PTE);
|
|
pkmap_page_table = alloc_kmap_pgtable(PKMAP_BASE);
|
|
|
|
BUILD_BUG_ON(LAST_PKMAP > PTRS_PER_PTE);
|
|
fixmap_page_table = alloc_kmap_pgtable(FIXMAP_BASE);
|
|
}
|