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Subject[PATCH 08/10] x86: separate out setup_pcpu_4k() from setup_per_cpu_areas()
Date
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>
---
arch/x86/kernel/setup_percpu.c | 144 ++++++++++++++++++++++++++++------------
1 files changed, 102 insertions(+), 42 deletions(-)
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index d928e88..4a17c96 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;
--
1.6.0.2


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