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Diffstat (limited to 'arch/x86/kernel/setup_percpu.c')
-rw-r--r--arch/x86/kernel/setup_percpu.c365
1 files changed, 339 insertions, 26 deletions
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index d992e6cff73..2d946a8f78b 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -7,6 +7,7 @@
#include <linux/crash_dump.h>
#include <linux/smp.h>
#include <linux/topology.h>
+#include <linux/pfn.h>
#include <asm/sections.h>
#include <asm/processor.h>
#include <asm/setup.h>
@@ -41,6 +42,321 @@ unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = {
};
EXPORT_SYMBOL(__per_cpu_offset);
+/**
+ * pcpu_need_numa - determine percpu allocation needs to consider NUMA
+ *
+ * If NUMA is not configured or there is only one NUMA node available,
+ * there is no reason to consider NUMA. This function determines
+ * whether percpu allocation should consider NUMA or not.
+ *
+ * RETURNS:
+ * true if NUMA should be considered; otherwise, false.
+ */
+static bool __init pcpu_need_numa(void)
+{
+#ifdef CONFIG_NEED_MULTIPLE_NODES
+ pg_data_t *last = NULL;
+ unsigned int cpu;
+
+ for_each_possible_cpu(cpu) {
+ int node = early_cpu_to_node(cpu);
+
+ if (node_online(node) && NODE_DATA(node) &&
+ last && last != NODE_DATA(node))
+ return true;
+
+ last = NODE_DATA(node);
+ }
+#endif
+ return false;
+}
+
+/**
+ * pcpu_alloc_bootmem - NUMA friendly alloc_bootmem wrapper for percpu
+ * @cpu: cpu to allocate for
+ * @size: size allocation in bytes
+ * @align: alignment
+ *
+ * Allocate @size bytes aligned at @align for cpu @cpu. This wrapper
+ * does the right thing for NUMA regardless of the current
+ * configuration.
+ *
+ * RETURNS:
+ * Pointer to the allocated area on success, NULL on failure.
+ */
+static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
+ unsigned long align)
+{
+ const unsigned long goal = __pa(MAX_DMA_ADDRESS);
+#ifdef CONFIG_NEED_MULTIPLE_NODES
+ int node = early_cpu_to_node(cpu);
+ void *ptr;
+
+ if (!node_online(node) || !NODE_DATA(node)) {
+ ptr = __alloc_bootmem_nopanic(size, align, goal);
+ pr_info("cpu %d has no node %d or node-local memory\n",
+ cpu, node);
+ pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
+ cpu, size, __pa(ptr));
+ } else {
+ ptr = __alloc_bootmem_node_nopanic(NODE_DATA(node),
+ size, align, goal);
+ pr_debug("per cpu data for cpu%d %lu bytes on node%d at "
+ "%016lx\n", cpu, size, node, __pa(ptr));
+ }
+ return ptr;
+#else
+ return __alloc_bootmem_nopanic(size, align, goal);
+#endif
+}
+
+/*
+ * Remap allocator
+ *
+ * This allocator uses PMD page as unit. A PMD page is allocated for
+ * each cpu and each is remapped into vmalloc area using PMD mapping.
+ * As PMD page is quite large, only part of it is used for the first
+ * chunk. Unused part is returned to the bootmem allocator.
+ *
+ * So, the PMD pages are mapped twice - once to the physical mapping
+ * and to the vmalloc area for the first percpu chunk. The double
+ * mapping does add one more PMD TLB entry pressure but still is much
+ * better than only using 4k mappings while still being NUMA friendly.
+ */
+#ifdef CONFIG_NEED_MULTIPLE_NODES
+static size_t pcpur_size __initdata;
+static void **pcpur_ptrs __initdata;
+
+static struct page * __init pcpur_get_page(unsigned int cpu, int pageno)
+{
+ size_t off = (size_t)pageno << PAGE_SHIFT;
+
+ if (off >= pcpur_size)
+ return NULL;
+
+ return virt_to_page(pcpur_ptrs[cpu] + off);
+}
+
+static ssize_t __init setup_pcpu_remap(size_t static_size)
+{
+ static struct vm_struct vm;
+ pg_data_t *last;
+ size_t ptrs_size;
+ unsigned int cpu;
+ ssize_t ret;
+
+ /*
+ * If large page isn't supported, there's no benefit in doing
+ * this. Also, on non-NUMA, embedding is better.
+ */
+ if (!cpu_has_pse || pcpu_need_numa())
+ return -EINVAL;
+
+ last = NULL;
+ for_each_possible_cpu(cpu) {
+ int node = early_cpu_to_node(cpu);
+
+ if (node_online(node) && NODE_DATA(node) &&
+ last && last != NODE_DATA(node))
+ goto proceed;
+
+ last = NODE_DATA(node);
+ }
+ return -EINVAL;
+
+proceed:
+ /*
+ * Currently supports only single page. Supporting multiple
+ * pages won't be too difficult if it ever becomes necessary.
+ */
+ pcpur_size = PFN_ALIGN(static_size + PERCPU_DYNAMIC_RESERVE);
+ if (pcpur_size > PMD_SIZE) {
+ pr_warning("PERCPU: static data is larger than large page, "
+ "can't use large page\n");
+ return -EINVAL;
+ }
+
+ /* allocate pointer array and alloc large pages */
+ ptrs_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpur_ptrs[0]));
+ pcpur_ptrs = alloc_bootmem(ptrs_size);
+
+ for_each_possible_cpu(cpu) {
+ pcpur_ptrs[cpu] = pcpu_alloc_bootmem(cpu, PMD_SIZE, PMD_SIZE);
+ if (!pcpur_ptrs[cpu])
+ goto enomem;
+
+ /*
+ * Only use pcpur_size bytes and give back the rest.
+ *
+ * Ingo: The 2MB up-rounding bootmem is needed to make
+ * sure the partial 2MB page is still fully RAM - it's
+ * not well-specified to have a PAT-incompatible area
+ * (unmapped RAM, device memory, etc.) in that hole.
+ */
+ free_bootmem(__pa(pcpur_ptrs[cpu] + pcpur_size),
+ PMD_SIZE - pcpur_size);
+
+ memcpy(pcpur_ptrs[cpu], __per_cpu_load, static_size);
+ }
+
+ /* allocate address and map */
+ vm.flags = VM_ALLOC;
+ vm.size = num_possible_cpus() * PMD_SIZE;
+ vm_area_register_early(&vm, PMD_SIZE);
+
+ for_each_possible_cpu(cpu) {
+ pmd_t *pmd;
+
+ pmd = populate_extra_pmd((unsigned long)vm.addr
+ + cpu * PMD_SIZE);
+ set_pmd(pmd, pfn_pmd(page_to_pfn(virt_to_page(pcpur_ptrs[cpu])),
+ PAGE_KERNEL_LARGE));
+ }
+
+ /* we're ready, commit */
+ pr_info("PERCPU: Remapped at %p with large pages, static data "
+ "%zu bytes\n", vm.addr, static_size);
+
+ ret = pcpu_setup_first_chunk(pcpur_get_page, static_size, PMD_SIZE,
+ pcpur_size - static_size, vm.addr, NULL);
+ goto out_free_ar;
+
+enomem:
+ for_each_possible_cpu(cpu)
+ if (pcpur_ptrs[cpu])
+ free_bootmem(__pa(pcpur_ptrs[cpu]), PMD_SIZE);
+ ret = -ENOMEM;
+out_free_ar:
+ free_bootmem(__pa(pcpur_ptrs), ptrs_size);
+ return ret;
+}
+#else
+static ssize_t __init setup_pcpu_remap(size_t static_size)
+{
+ return -EINVAL;
+}
+#endif
+
+/*
+ * Embedding allocator
+ *
+ * The first chunk is sized to just contain the static area plus
+ * PERCPU_DYNAMIC_RESERVE and allocated as a contiguous area using
+ * bootmem allocator and used as-is without being mapped into vmalloc
+ * area. This enables the first chunk to piggy back on the linear
+ * physical PMD mapping and doesn't add any additional pressure to
+ * TLB.
+ */
+static void *pcpue_ptr __initdata;
+static size_t pcpue_unit_size __initdata;
+
+static struct page * __init pcpue_get_page(unsigned int cpu, int pageno)
+{
+ return virt_to_page(pcpue_ptr + cpu * pcpue_unit_size
+ + ((size_t)pageno << PAGE_SHIFT));
+}
+
+static ssize_t __init setup_pcpu_embed(size_t static_size)
+{
+ unsigned int cpu;
+
+ /*
+ * If large page isn't supported, there's no benefit in doing
+ * this. Also, embedding allocation doesn't play well with
+ * NUMA.
+ */
+ if (!cpu_has_pse || pcpu_need_numa())
+ return -EINVAL;
+
+ /* allocate and copy */
+ pcpue_unit_size = PFN_ALIGN(static_size + PERCPU_DYNAMIC_RESERVE);
+ pcpue_unit_size = max(pcpue_unit_size, PCPU_MIN_UNIT_SIZE);
+ pcpue_ptr = pcpu_alloc_bootmem(0, num_possible_cpus() * pcpue_unit_size,
+ PAGE_SIZE);
+ if (!pcpue_ptr)
+ return -ENOMEM;
+
+ for_each_possible_cpu(cpu)
+ memcpy(pcpue_ptr + cpu * pcpue_unit_size, __per_cpu_load,
+ static_size);
+
+ /* we're ready, commit */
+ pr_info("PERCPU: Embedded %zu pages at %p, static data %zu bytes\n",
+ pcpue_unit_size >> PAGE_SHIFT, pcpue_ptr, static_size);
+
+ return pcpu_setup_first_chunk(pcpue_get_page, static_size,
+ pcpue_unit_size,
+ pcpue_unit_size - static_size, pcpue_ptr,
+ NULL);
+}
+
+/*
+ * 4k page allocator
+ *
+ * This is the basic allocator. Static percpu area is allocated
+ * page-by-page and most of initialization is done by the generic
+ * setup function.
+ */
+static struct page **pcpu4k_pages __initdata;
+static int pcpu4k_nr_static_pages __initdata;
+
+static struct page * __init pcpu4k_get_page(unsigned int cpu, int pageno)
+{
+ if (pageno < pcpu4k_nr_static_pages)
+ return pcpu4k_pages[cpu * pcpu4k_nr_static_pages + pageno];
+ return NULL;
+}
+
+static void __init pcpu4k_populate_pte(unsigned long addr)
+{
+ populate_extra_pte(addr);
+}
+
+static ssize_t __init setup_pcpu_4k(size_t static_size)
+{
+ size_t pages_size;
+ unsigned int cpu;
+ int i, j;
+ ssize_t ret;
+
+ pcpu4k_nr_static_pages = PFN_UP(static_size);
+
+ /* unaligned allocations can't be freed, round up to page size */
+ pages_size = PFN_ALIGN(pcpu4k_nr_static_pages * num_possible_cpus()
+ * sizeof(pcpu4k_pages[0]));
+ pcpu4k_pages = alloc_bootmem(pages_size);
+
+ /* allocate and copy */
+ j = 0;
+ for_each_possible_cpu(cpu)
+ for (i = 0; i < pcpu4k_nr_static_pages; i++) {
+ void *ptr;
+
+ ptr = pcpu_alloc_bootmem(cpu, PAGE_SIZE, PAGE_SIZE);
+ if (!ptr)
+ goto enomem;
+
+ memcpy(ptr, __per_cpu_load + i * PAGE_SIZE, PAGE_SIZE);
+ pcpu4k_pages[j++] = virt_to_page(ptr);
+ }
+
+ /* we're ready, commit */
+ pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n",
+ pcpu4k_nr_static_pages, static_size);
+
+ ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size, 0, 0, NULL,
+ pcpu4k_populate_pte);
+ goto out_free_ar;
+
+enomem:
+ while (--j >= 0)
+ free_bootmem(__pa(page_address(pcpu4k_pages[j])), PAGE_SIZE);
+ ret = -ENOMEM;
+out_free_ar:
+ free_bootmem(__pa(pcpu4k_pages), pages_size);
+ return ret;
+}
+
static inline void setup_percpu_segment(int cpu)
{
#ifdef CONFIG_X86_32
@@ -61,38 +377,35 @@ static inline void setup_percpu_segment(int cpu)
*/
void __init setup_per_cpu_areas(void)
{
- ssize_t size;
- char *ptr;
- int cpu;
-
- /* Copy section for each CPU (we discard the original) */
- size = roundup(PERCPU_ENOUGH_ROOM, PAGE_SIZE);
+ size_t static_size = __per_cpu_end - __per_cpu_start;
+ unsigned int cpu;
+ unsigned long delta;
+ size_t pcpu_unit_size;
+ ssize_t ret;
pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%d nr_node_ids:%d\n",
NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);
- pr_info("PERCPU: Allocating %zd bytes of per cpu data\n", size);
+ /*
+ * Allocate percpu area. If PSE is supported, try to make use
+ * of large page mappings. Please read comments on top of
+ * each allocator for details.
+ */
+ ret = setup_pcpu_remap(static_size);
+ if (ret < 0)
+ ret = setup_pcpu_embed(static_size);
+ if (ret < 0)
+ ret = setup_pcpu_4k(static_size);
+ if (ret < 0)
+ panic("cannot allocate static percpu area (%zu bytes, err=%zd)",
+ static_size, ret);
- for_each_possible_cpu(cpu) {
-#ifndef CONFIG_NEED_MULTIPLE_NODES
- ptr = alloc_bootmem_pages(size);
-#else
- int node = early_cpu_to_node(cpu);
- if (!node_online(node) || !NODE_DATA(node)) {
- ptr = alloc_bootmem_pages(size);
- pr_info("cpu %d has no node %d or node-local memory\n",
- cpu, node);
- pr_debug("per cpu data for cpu%d at %016lx\n",
- cpu, __pa(ptr));
- } else {
- ptr = alloc_bootmem_pages_node(NODE_DATA(node), size);
- pr_debug("per cpu data for cpu%d on node%d at %016lx\n",
- cpu, node, __pa(ptr));
- }
-#endif
+ pcpu_unit_size = ret;
- memcpy(ptr, __per_cpu_load, __per_cpu_end - __per_cpu_start);
- per_cpu_offset(cpu) = ptr - __per_cpu_start;
+ /* alrighty, percpu areas up and running */
+ delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
+ for_each_possible_cpu(cpu) {
+ per_cpu_offset(cpu) = delta + cpu * pcpu_unit_size;
per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
per_cpu(cpu_number, cpu) = cpu;
setup_percpu_segment(cpu);