v4.19.13 snapshot.
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
new file mode 100644
index 0000000..70b7123
--- /dev/null
+++ b/include/linux/percpu.h
@@ -0,0 +1,154 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_PERCPU_H
+#define __LINUX_PERCPU_H
+
+#include <linux/mmdebug.h>
+#include <linux/preempt.h>
+#include <linux/smp.h>
+#include <linux/cpumask.h>
+#include <linux/printk.h>
+#include <linux/pfn.h>
+#include <linux/init.h>
+
+#include <asm/percpu.h>
+
+/* enough to cover all DEFINE_PER_CPUs in modules */
+#ifdef CONFIG_MODULES
+#define PERCPU_MODULE_RESERVE (8 << 10)
+#else
+#define PERCPU_MODULE_RESERVE 0
+#endif
+
+/* minimum unit size, also is the maximum supported allocation size */
+#define PCPU_MIN_UNIT_SIZE PFN_ALIGN(32 << 10)
+
+/* minimum allocation size and shift in bytes */
+#define PCPU_MIN_ALLOC_SHIFT 2
+#define PCPU_MIN_ALLOC_SIZE (1 << PCPU_MIN_ALLOC_SHIFT)
+
+/* number of bits per page, used to trigger a scan if blocks are > PAGE_SIZE */
+#define PCPU_BITS_PER_PAGE (PAGE_SIZE >> PCPU_MIN_ALLOC_SHIFT)
+
+/*
+ * This determines the size of each metadata block. There are several subtle
+ * constraints around this constant. The reserved region must be a multiple of
+ * PCPU_BITMAP_BLOCK_SIZE. Additionally, PCPU_BITMAP_BLOCK_SIZE must be a
+ * multiple of PAGE_SIZE or PAGE_SIZE must be a multiple of
+ * PCPU_BITMAP_BLOCK_SIZE to align with the populated page map. The unit_size
+ * also has to be a multiple of PCPU_BITMAP_BLOCK_SIZE to ensure full blocks.
+ */
+#define PCPU_BITMAP_BLOCK_SIZE PAGE_SIZE
+#define PCPU_BITMAP_BLOCK_BITS (PCPU_BITMAP_BLOCK_SIZE >> \
+ PCPU_MIN_ALLOC_SHIFT)
+
+/*
+ * Percpu allocator can serve percpu allocations before slab is
+ * initialized which allows slab to depend on the percpu allocator.
+ * The following two parameters decide how much resource to
+ * preallocate for this. Keep PERCPU_DYNAMIC_RESERVE equal to or
+ * larger than PERCPU_DYNAMIC_EARLY_SIZE.
+ */
+#define PERCPU_DYNAMIC_EARLY_SLOTS 128
+#define PERCPU_DYNAMIC_EARLY_SIZE (12 << 10)
+
+/*
+ * PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy
+ * back on the first chunk for dynamic percpu allocation if arch is
+ * manually allocating and mapping it for faster access (as a part of
+ * large page mapping for example).
+ *
+ * The following values give between one and two pages of free space
+ * after typical minimal boot (2-way SMP, single disk and NIC) with
+ * both defconfig and a distro config on x86_64 and 32. More
+ * intelligent way to determine this would be nice.
+ */
+#if BITS_PER_LONG > 32
+#define PERCPU_DYNAMIC_RESERVE (28 << 10)
+#else
+#define PERCPU_DYNAMIC_RESERVE (20 << 10)
+#endif
+
+extern void *pcpu_base_addr;
+extern const unsigned long *pcpu_unit_offsets;
+
+struct pcpu_group_info {
+ int nr_units; /* aligned # of units */
+ unsigned long base_offset; /* base address offset */
+ unsigned int *cpu_map; /* unit->cpu map, empty
+ * entries contain NR_CPUS */
+};
+
+struct pcpu_alloc_info {
+ size_t static_size;
+ size_t reserved_size;
+ size_t dyn_size;
+ size_t unit_size;
+ size_t atom_size;
+ size_t alloc_size;
+ size_t __ai_size; /* internal, don't use */
+ int nr_groups; /* 0 if grouping unnecessary */
+ struct pcpu_group_info groups[];
+};
+
+enum pcpu_fc {
+ PCPU_FC_AUTO,
+ PCPU_FC_EMBED,
+ PCPU_FC_PAGE,
+
+ PCPU_FC_NR,
+};
+extern const char * const pcpu_fc_names[PCPU_FC_NR];
+
+extern enum pcpu_fc pcpu_chosen_fc;
+
+typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size,
+ size_t align);
+typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
+typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);
+typedef int (pcpu_fc_cpu_distance_fn_t)(unsigned int from, unsigned int to);
+
+extern struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
+ int nr_units);
+extern void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai);
+
+extern int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
+ void *base_addr);
+
+#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
+extern int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
+ size_t atom_size,
+ pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
+ pcpu_fc_alloc_fn_t alloc_fn,
+ pcpu_fc_free_fn_t free_fn);
+#endif
+
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+extern int __init pcpu_page_first_chunk(size_t reserved_size,
+ pcpu_fc_alloc_fn_t alloc_fn,
+ pcpu_fc_free_fn_t free_fn,
+ pcpu_fc_populate_pte_fn_t populate_pte_fn);
+#endif
+
+extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align);
+extern bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr);
+extern bool is_kernel_percpu_address(unsigned long addr);
+
+#if !defined(CONFIG_SMP) || !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
+extern void __init setup_per_cpu_areas(void);
+#endif
+
+extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp);
+extern void __percpu *__alloc_percpu(size_t size, size_t align);
+extern void free_percpu(void __percpu *__pdata);
+extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
+
+#define alloc_percpu_gfp(type, gfp) \
+ (typeof(type) __percpu *)__alloc_percpu_gfp(sizeof(type), \
+ __alignof__(type), gfp)
+#define alloc_percpu(type) \
+ (typeof(type) __percpu *)__alloc_percpu(sizeof(type), \
+ __alignof__(type))
+
+extern unsigned long pcpu_nr_pages(void);
+
+#endif /* __LINUX_PERCPU_H */