swh:1:snp:77163734605b0ec556b01d897b7bb4a7e30d46b6
Tip revision: 1c23f9e627a7b412978b4e852793c5e3c3efc555 authored by Linus Torvalds on 22 August 2022, 00:32:54 UTC
Linux 6.0-rc2
Linux 6.0-rc2
Tip revision: 1c23f9e
sparse-vmemmap.c
// SPDX-License-Identifier: GPL-2.0
/*
* Virtual Memory Map support
*
* (C) 2007 sgi. Christoph Lameter.
*
* Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
* virt_to_page, page_address() to be implemented as a base offset
* calculation without memory access.
*
* However, virtual mappings need a page table and TLBs. Many Linux
* architectures already map their physical space using 1-1 mappings
* via TLBs. For those arches the virtual memory map is essentially
* for free if we use the same page size as the 1-1 mappings. In that
* case the overhead consists of a few additional pages that are
* allocated to create a view of memory for vmemmap.
*
* The architecture is expected to provide a vmemmap_populate() function
* to instantiate the mapping.
*/
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/memblock.h>
#include <linux/memremap.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <linux/sched.h>
#include <asm/dma.h>
#include <asm/pgalloc.h>
/*
* Allocate a block of memory to be used to back the virtual memory map
* or to back the page tables that are used to create the mapping.
* Uses the main allocators if they are available, else bootmem.
*/
static void * __ref __earlyonly_bootmem_alloc(int node,
unsigned long size,
unsigned long align,
unsigned long goal)
{
return memblock_alloc_try_nid_raw(size, align, goal,
MEMBLOCK_ALLOC_ACCESSIBLE, node);
}
void * __meminit vmemmap_alloc_block(unsigned long size, int node)
{
/* If the main allocator is up use that, fallback to bootmem. */
if (slab_is_available()) {
gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
int order = get_order(size);
static bool warned;
struct page *page;
page = alloc_pages_node(node, gfp_mask, order);
if (page)
return page_address(page);
if (!warned) {
warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
"vmemmap alloc failure: order:%u", order);
warned = true;
}
return NULL;
} else
return __earlyonly_bootmem_alloc(node, size, size,
__pa(MAX_DMA_ADDRESS));
}
static void * __meminit altmap_alloc_block_buf(unsigned long size,
struct vmem_altmap *altmap);
/* need to make sure size is all the same during early stage */
void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node,
struct vmem_altmap *altmap)
{
void *ptr;
if (altmap)
return altmap_alloc_block_buf(size, altmap);
ptr = sparse_buffer_alloc(size);
if (!ptr)
ptr = vmemmap_alloc_block(size, node);
return ptr;
}
static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
{
return altmap->base_pfn + altmap->reserve + altmap->alloc
+ altmap->align;
}
static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
{
unsigned long allocated = altmap->alloc + altmap->align;
if (altmap->free > allocated)
return altmap->free - allocated;
return 0;
}
static void * __meminit altmap_alloc_block_buf(unsigned long size,
struct vmem_altmap *altmap)
{
unsigned long pfn, nr_pfns, nr_align;
if (size & ~PAGE_MASK) {
pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
__func__, size);
return NULL;
}
pfn = vmem_altmap_next_pfn(altmap);
nr_pfns = size >> PAGE_SHIFT;
nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
nr_align = ALIGN(pfn, nr_align) - pfn;
if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
return NULL;
altmap->alloc += nr_pfns;
altmap->align += nr_align;
pfn += nr_align;
pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
__func__, pfn, altmap->alloc, altmap->align, nr_pfns);
return __va(__pfn_to_phys(pfn));
}
void __meminit vmemmap_verify(pte_t *pte, int node,
unsigned long start, unsigned long end)
{
unsigned long pfn = pte_pfn(*pte);
int actual_node = early_pfn_to_nid(pfn);
if (node_distance(actual_node, node) > LOCAL_DISTANCE)
pr_warn_once("[%lx-%lx] potential offnode page_structs\n",
start, end - 1);
}
pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
struct vmem_altmap *altmap,
struct page *reuse)
{
pte_t *pte = pte_offset_kernel(pmd, addr);
if (pte_none(*pte)) {
pte_t entry;
void *p;
if (!reuse) {
p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
if (!p)
return NULL;
} else {
/*
* When a PTE/PMD entry is freed from the init_mm
* there's a free_pages() call to this page allocated
* above. Thus this get_page() is paired with the
* put_page_testzero() on the freeing path.
* This can only called by certain ZONE_DEVICE path,
* and through vmemmap_populate_compound_pages() when
* slab is available.
*/
get_page(reuse);
p = page_to_virt(reuse);
}
entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
set_pte_at(&init_mm, addr, pte, entry);
}
return pte;
}
static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
{
void *p = vmemmap_alloc_block(size, node);
if (!p)
return NULL;
memset(p, 0, size);
return p;
}
pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
{
pmd_t *pmd = pmd_offset(pud, addr);
if (pmd_none(*pmd)) {
void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
if (!p)
return NULL;
pmd_populate_kernel(&init_mm, pmd, p);
}
return pmd;
}
pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
{
pud_t *pud = pud_offset(p4d, addr);
if (pud_none(*pud)) {
void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
if (!p)
return NULL;
pud_populate(&init_mm, pud, p);
}
return pud;
}
p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
{
p4d_t *p4d = p4d_offset(pgd, addr);
if (p4d_none(*p4d)) {
void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
if (!p)
return NULL;
p4d_populate(&init_mm, p4d, p);
}
return p4d;
}
pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
{
pgd_t *pgd = pgd_offset_k(addr);
if (pgd_none(*pgd)) {
void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
if (!p)
return NULL;
pgd_populate(&init_mm, pgd, p);
}
return pgd;
}
static pte_t * __meminit vmemmap_populate_address(unsigned long addr, int node,
struct vmem_altmap *altmap,
struct page *reuse)
{
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
pgd = vmemmap_pgd_populate(addr, node);
if (!pgd)
return NULL;
p4d = vmemmap_p4d_populate(pgd, addr, node);
if (!p4d)
return NULL;
pud = vmemmap_pud_populate(p4d, addr, node);
if (!pud)
return NULL;
pmd = vmemmap_pmd_populate(pud, addr, node);
if (!pmd)
return NULL;
pte = vmemmap_pte_populate(pmd, addr, node, altmap, reuse);
if (!pte)
return NULL;
vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
return pte;
}
static int __meminit vmemmap_populate_range(unsigned long start,
unsigned long end, int node,
struct vmem_altmap *altmap,
struct page *reuse)
{
unsigned long addr = start;
pte_t *pte;
for (; addr < end; addr += PAGE_SIZE) {
pte = vmemmap_populate_address(addr, node, altmap, reuse);
if (!pte)
return -ENOMEM;
}
return 0;
}
int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
int node, struct vmem_altmap *altmap)
{
return vmemmap_populate_range(start, end, node, altmap, NULL);
}
/*
* For compound pages bigger than section size (e.g. x86 1G compound
* pages with 2M subsection size) fill the rest of sections as tail
* pages.
*
* Note that memremap_pages() resets @nr_range value and will increment
* it after each range successful onlining. Thus the value or @nr_range
* at section memmap populate corresponds to the in-progress range
* being onlined here.
*/
static bool __meminit reuse_compound_section(unsigned long start_pfn,
struct dev_pagemap *pgmap)
{
unsigned long nr_pages = pgmap_vmemmap_nr(pgmap);
unsigned long offset = start_pfn -
PHYS_PFN(pgmap->ranges[pgmap->nr_range].start);
return !IS_ALIGNED(offset, nr_pages) && nr_pages > PAGES_PER_SUBSECTION;
}
static pte_t * __meminit compound_section_tail_page(unsigned long addr)
{
pte_t *pte;
addr -= PAGE_SIZE;
/*
* Assuming sections are populated sequentially, the previous section's
* page data can be reused.
*/
pte = pte_offset_kernel(pmd_off_k(addr), addr);
if (!pte)
return NULL;
return pte;
}
static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
unsigned long start,
unsigned long end, int node,
struct dev_pagemap *pgmap)
{
unsigned long size, addr;
pte_t *pte;
int rc;
if (reuse_compound_section(start_pfn, pgmap)) {
pte = compound_section_tail_page(start);
if (!pte)
return -ENOMEM;
/*
* Reuse the page that was populated in the prior iteration
* with just tail struct pages.
*/
return vmemmap_populate_range(start, end, node, NULL,
pte_page(*pte));
}
size = min(end - start, pgmap_vmemmap_nr(pgmap) * sizeof(struct page));
for (addr = start; addr < end; addr += size) {
unsigned long next, last = addr + size;
/* Populate the head page vmemmap page */
pte = vmemmap_populate_address(addr, node, NULL, NULL);
if (!pte)
return -ENOMEM;
/* Populate the tail pages vmemmap page */
next = addr + PAGE_SIZE;
pte = vmemmap_populate_address(next, node, NULL, NULL);
if (!pte)
return -ENOMEM;
/*
* Reuse the previous page for the rest of tail pages
* See layout diagram in Documentation/mm/vmemmap_dedup.rst
*/
next += PAGE_SIZE;
rc = vmemmap_populate_range(next, last, node, NULL,
pte_page(*pte));
if (rc)
return -ENOMEM;
}
return 0;
}
struct page * __meminit __populate_section_memmap(unsigned long pfn,
unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
struct dev_pagemap *pgmap)
{
unsigned long start = (unsigned long) pfn_to_page(pfn);
unsigned long end = start + nr_pages * sizeof(struct page);
int r;
if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
!IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
return NULL;
if (is_power_of_2(sizeof(struct page)) &&
pgmap && pgmap_vmemmap_nr(pgmap) > 1 && !altmap)
r = vmemmap_populate_compound_pages(pfn, start, end, nid, pgmap);
else
r = vmemmap_populate(start, end, nid, altmap);
if (r < 0)
return NULL;
return pfn_to_page(pfn);
}