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-rw-r--r--mm/sparse-vmemmap.c398
1 files changed, 398 insertions, 0 deletions
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
new file mode 100644
index 000000000..46ae54211
--- /dev/null
+++ b/mm/sparse-vmemmap.c
@@ -0,0 +1,398 @@
+// 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);
+}
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