1 files changed, 313 insertions, 28 deletions

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index d992e6cff73..3a97a4cf187 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 +42,295 @@ unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = {
 };
 EXPORT_SYMBOL(__per_cpu_offset);
 
+/*
+ * On x86_64 symbols referenced from code should be reachable using
+ * 32bit relocations.  Reserve space for static percpu variables in
+ * modules so that they are always served from the first chunk which
+ * is located at the percpu segment base.  On x86_32, anything can
+ * address anywhere.  No need to reserve space in the first chunk.
+ */
+#ifdef CONFIG_X86_64
+#define PERCPU_FIRST_CHUNK_RESERVE	PERCPU_MODULE_RESERVE
+#else
+#define PERCPU_FIRST_CHUNK_RESERVE	0
+#endif
+
+/**
+ * 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;
+	size_t ptrs_size, dyn_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;
+
+	/*
+	 * 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_MODULE_RESERVE +
+			       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;
+	}
+	dyn_size = pcpur_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;
+
+	/* 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,
+				     PERCPU_FIRST_CHUNK_RESERVE, dyn_size,
+				     PMD_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
+ * module and dynamic reserves and embedded into linear physical
+ * mapping so that it can use PMD mapping without additional TLB
+ * pressure.
+ */
+static ssize_t __init setup_pcpu_embed(size_t static_size)
+{
+	size_t reserve = PERCPU_MODULE_RESERVE + PERCPU_DYNAMIC_RESERVE;
+
+	/*
+	 * 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;
+
+	return pcpu_embed_first_chunk(static_size, PERCPU_FIRST_CHUNK_RESERVE,
+				      reserve - PERCPU_FIRST_CHUNK_RESERVE, -1);
+}
+
+/*
+ * 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,
+				     PERCPU_FIRST_CHUNK_RESERVE, -1,
+				     -1, 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 +351,35 @@ 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);
@@ -125,8 +412,6 @@ void __init setup_per_cpu_areas(void)
 		 */
 		if (cpu == boot_cpu_id)
 			switch_to_new_gdt(cpu);
-
-		DBG("PERCPU: cpu %4d %p\n", cpu, ptr);
 	}
 
 	/* indicate the early static arrays will soon be gone */