x86: separate out setup_pcpu_4k() from setup_per_cpu_areas()

Impact: modularize percpu first chunk allocation

x86 is gonna have a few different strategies for the first chunk
allocation.  Modularize it by separating out the current allocation
mechanism into pcpu_alloc_bootmem() and setup_pcpu_4k().

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 102 insertions, 42 deletions

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index d928e8887201..4a17c96f4f6c 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 +42,52 @@ unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = {
 };
 EXPORT_SYMBOL(__per_cpu_offset);
 
+/**
+ * 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
+}
+
+/*
+ * 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;
 
@@ -56,6 +103,51 @@ 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
@@ -76,56 +168,24 @@ static inline void setup_percpu_segment(int cpu)
  */
 void __init setup_per_cpu_areas(void)
 {
-        ssize_t size = __per_cpu_end - __per_cpu_start;
-        unsigned int nr_cpu_pages = DIV_ROUND_UP(size, PAGE_SIZE);
-        static struct page **pages;
-        size_t pages_size;
-        unsigned int cpu, i, j;
+        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 for static per cpu data\n", size);
-
-        pages_size = nr_cpu_pages * num_possible_cpus() * sizeof(pages[0]);
-        pages = alloc_bootmem(pages_size);
-
-        j = 0;
-        for_each_possible_cpu(cpu) {
-                void *ptr;
-
-                for (i = 0; i < nr_cpu_pages; i++) {
-#ifndef CONFIG_NEED_MULTIPLE_NODES
-                        ptr = alloc_bootmem_pages(PAGE_SIZE);
-#else
-                        int node = early_cpu_to_node(cpu);
-
-                        if (!node_online(node) || !NODE_DATA(node)) {
-                                ptr = alloc_bootmem_pages(PAGE_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),
-                                                               PAGE_SIZE);
-                                pr_debug("per cpu data for cpu%d on node%d "
-                                         "at %016lx\n", cpu, node, __pa(ptr));
-                        }
-#endif
-                        memcpy(ptr, __per_cpu_load + i * PAGE_SIZE, PAGE_SIZE);
-                        pages[j++] = virt_to_page(ptr);
-                }
-        }
 
-        pcpu4k_pages = pages;
-        pcpu4k_nr_static_pages = nr_cpu_pages;
-        pcpu_unit_size = pcpu_setup_first_chunk(pcpu4k_get_page, size, 0, 0,
-                                                NULL, pcpu4k_populate_pte);
+        /* allocate percpu area */
+        ret = setup_pcpu_4k(static_size);
+        if (ret < 0)
+                panic("cannot allocate static percpu area (%zu bytes, err=%zd)",
+                      static_size, ret);
 
-        free_bootmem(__pa(pages), pages_size);
+        pcpu_unit_size = ret;
 
+        /* 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;