8d408b4be3
Impact: more latitude for first percpu chunk allocation The first percpu chunk serves the kernel static percpu area and may or may not contain extra room for further dynamic allocation. Initialization of the first chunk needs to be done before normal memory allocation service is up, so it has its own init path - pcpu_setup_static(). It seems archs need more latitude while initializing the first chunk for example to take advantage of large page mapping. This patch makes the following changes to allow this. * Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space to reserve in the first chunk for further dynamic allocation. * Rename pcpu_setup_static() to pcpu_setup_first_chunk(). * Make pcpu_setup_first_chunk() much more flexible by fetching page pointer by callback and adding optional @unit_size, @free_size and @base_addr arguments which allow archs to selectively part of chunk initialization to their likings. Signed-off-by: Tejun Heo <tj@kernel.org>
174 lines
4.8 KiB
C
174 lines
4.8 KiB
C
#ifndef __LINUX_PERCPU_H
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#define __LINUX_PERCPU_H
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#include <linux/preempt.h>
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#include <linux/slab.h> /* For kmalloc() */
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#include <linux/smp.h>
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#include <linux/cpumask.h>
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#include <asm/percpu.h>
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#ifndef PER_CPU_BASE_SECTION
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#ifdef CONFIG_SMP
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#define PER_CPU_BASE_SECTION ".data.percpu"
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#else
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#define PER_CPU_BASE_SECTION ".data"
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#endif
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#endif
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#ifdef CONFIG_SMP
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#ifdef MODULE
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#define PER_CPU_SHARED_ALIGNED_SECTION ""
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#else
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#define PER_CPU_SHARED_ALIGNED_SECTION ".shared_aligned"
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#endif
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#define PER_CPU_FIRST_SECTION ".first"
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#else
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#define PER_CPU_SHARED_ALIGNED_SECTION ""
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#define PER_CPU_FIRST_SECTION ""
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#endif
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#define DEFINE_PER_CPU_SECTION(type, name, section) \
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__attribute__((__section__(PER_CPU_BASE_SECTION section))) \
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PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
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#define DEFINE_PER_CPU(type, name) \
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DEFINE_PER_CPU_SECTION(type, name, "")
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#define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
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DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
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____cacheline_aligned_in_smp
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#define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
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DEFINE_PER_CPU_SECTION(type, name, ".page_aligned")
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#define DEFINE_PER_CPU_FIRST(type, name) \
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DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
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#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var)
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#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var)
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/* Enough to cover all DEFINE_PER_CPUs in kernel, including modules. */
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#ifndef PERCPU_ENOUGH_ROOM
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#ifdef CONFIG_MODULES
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#define PERCPU_MODULE_RESERVE 8192
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#else
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#define PERCPU_MODULE_RESERVE 0
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#endif
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#define PERCPU_ENOUGH_ROOM \
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(__per_cpu_end - __per_cpu_start + PERCPU_MODULE_RESERVE)
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#endif /* PERCPU_ENOUGH_ROOM */
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/*
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* Must be an lvalue. Since @var must be a simple identifier,
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* we force a syntax error here if it isn't.
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*/
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#define get_cpu_var(var) (*({ \
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extern int simple_identifier_##var(void); \
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preempt_disable(); \
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&__get_cpu_var(var); }))
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#define put_cpu_var(var) preempt_enable()
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#ifdef CONFIG_SMP
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#ifdef CONFIG_HAVE_DYNAMIC_PER_CPU_AREA
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/* minimum unit size, also is the maximum supported allocation size */
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#define PCPU_MIN_UNIT_SIZE (16UL << PAGE_SHIFT)
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/*
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* PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy
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* back on the first chunk if arch is manually allocating and mapping
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* it for faster access (as a part of large page mapping for example).
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* Note that dynamic percpu allocator covers both static and dynamic
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* areas, so these values are bigger than PERCPU_MODULE_RESERVE.
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*
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* On typical configuration with modules, the following values leave
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* about 8k of free space on the first chunk after boot on both x86_32
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* and 64 when module support is enabled. When module support is
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* disabled, it's much tighter.
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*/
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#ifndef PERCPU_DYNAMIC_RESERVE
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# if BITS_PER_LONG > 32
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# ifdef CONFIG_MODULES
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# define PERCPU_DYNAMIC_RESERVE (6 << PAGE_SHIFT)
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# else
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# define PERCPU_DYNAMIC_RESERVE (4 << PAGE_SHIFT)
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# endif
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# else
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# ifdef CONFIG_MODULES
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# define PERCPU_DYNAMIC_RESERVE (4 << PAGE_SHIFT)
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# else
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# define PERCPU_DYNAMIC_RESERVE (2 << PAGE_SHIFT)
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# endif
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# endif
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#endif /* PERCPU_DYNAMIC_RESERVE */
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extern void *pcpu_base_addr;
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typedef struct page * (*pcpu_get_page_fn_t)(unsigned int cpu, int pageno);
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typedef void (*pcpu_populate_pte_fn_t)(unsigned long addr);
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extern size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
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size_t static_size, size_t unit_size,
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size_t free_size, void *base_addr,
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pcpu_populate_pte_fn_t populate_pte_fn);
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/*
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* Use this to get to a cpu's version of the per-cpu object
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* dynamically allocated. Non-atomic access to the current CPU's
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* version should probably be combined with get_cpu()/put_cpu().
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*/
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#define per_cpu_ptr(ptr, cpu) SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)))
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#else /* CONFIG_HAVE_DYNAMIC_PER_CPU_AREA */
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struct percpu_data {
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void *ptrs[1];
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};
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#define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata)
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#define per_cpu_ptr(ptr, cpu) \
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({ \
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struct percpu_data *__p = __percpu_disguise(ptr); \
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(__typeof__(ptr))__p->ptrs[(cpu)]; \
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})
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#endif /* CONFIG_HAVE_DYNAMIC_PER_CPU_AREA */
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extern void *__alloc_percpu(size_t size, size_t align);
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extern void free_percpu(void *__pdata);
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#else /* CONFIG_SMP */
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#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
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static inline void *__alloc_percpu(size_t size, size_t align)
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{
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/*
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* Can't easily make larger alignment work with kmalloc. WARN
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* on it. Larger alignment should only be used for module
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* percpu sections on SMP for which this path isn't used.
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*/
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WARN_ON_ONCE(align > __alignof__(unsigned long long));
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return kzalloc(size, gfp);
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}
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static inline void free_percpu(void *p)
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{
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kfree(p);
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}
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#endif /* CONFIG_SMP */
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#define alloc_percpu(type) (type *)__alloc_percpu(sizeof(type), \
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__alignof__(type))
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#endif /* __LINUX_PERCPU_H */
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