diff --git a/Documentation/core-api/percpu-counter-tree.rst b/Documentation/core-api/percpu-counter-tree.rst new file mode 100644 index 000000000000..196da056e7b4 --- /dev/null +++ b/Documentation/core-api/percpu-counter-tree.rst @@ -0,0 +1,75 @@ +======================================== +The Hierarchical Per-CPU Counters (HPCC) +======================================== + +:Author: Mathieu Desnoyers + +Introduction +============ + +Counters come in many varieties, each with their own trade offs: + + * A global atomic counter provides a fast read access to the current + sum, at the expense of cache-line bouncing on updates. This leads to + poor performance of frequent updates from various cores on large SMP + systems. + + * A per-cpu split counter provides fast updates to per-cpu counters, + at the expense of a slower aggregation (sum). The sum operation needs + to iterate over all per-cpu counters to calculate the current total. + +The hierarchical per-cpu counters attempt to provide the best of both +worlds (fast updates, and fast sum) by relaxing requirements on the sum +accuracy. It allows quickly querying an approximated sum value, along +with the possible min/max ranges of the associated precise sum. The +exact precise sum can still be calculated with an iteration on all +per-cpu counter, but the availability of an approximated sum value with +possible precise sum min/max ranges allows eliminating candidates which +are certainly outside of a known target range without the overhead of +precise sums. + +Overview +======== + +The herarchical per-cpu counters are organized as a tree with the tree +root at the bottom (last level) and the first level of the tree +consisting of per-cpu counters. + +The intermediate tree levels contain carry propagation counters. When +reaching a threshold (batch size), the carry is propagated down the +tree. + +This allows reading an approximated value at the root, which has a +bounded accuracy (minimum/maximum possible precise sum range) determined +by the tree topology. + +Use Cases +========= + +Use cases HPCC is meant to handle invove tracking resources which are +used across many CPUs to quickly sum as feedback for decision making to +apply throttling, quota limits, sort tasks, and perform memory or task +migration decisions. When considering approximated sums within the +accuracy range of the decision threshold, the user can either: + + * Be conservative and fast: Consider that the sum has reached the + limit as soon as the given limit is within the approximation range. + + * Be aggressive and fast: Consider that the sum is over the + limit only when the approximation range is over the given limit. + + * Be precise and slow: Do a precise comparison with the limit, which + requires a precise sum when the limit is within the approximated + range. + +One use-case for these hierarchical counters is to implement a two-pass +algorithm to speed up sorting picking a maximum/minimunm sum value from +a set. A first pass compares the approximated values, and then a second +pass only needs the precise sum for counter trees which are within the +possible precise sum range of the counter tree chosen by the first pass. + +Functions and structures +======================== + +.. kernel-doc:: include/linux/percpu_counter_tree.h +.. kernel-doc:: lib/percpu_counter_tree.c diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h index ac4129d1d741..612a6da6127a 100644 --- a/include/linux/kexec_handover.h +++ b/include/linux/kexec_handover.h @@ -35,6 +35,7 @@ void *kho_restore_vmalloc(const struct kho_vmalloc *preservation); int kho_add_subtree(const char *name, void *fdt); void kho_remove_subtree(void *fdt); int kho_retrieve_subtree(const char *name, phys_addr_t *phys); +bool pfn_is_kho_scratch(unsigned long pfn); void kho_memory_init(void); @@ -109,6 +110,11 @@ static inline int kho_retrieve_subtree(const char *name, phys_addr_t *phys) return -EOPNOTSUPP; } +static inline bool pfn_is_kho_scratch(unsigned long pfn) +{ + return false; +} + static inline void kho_memory_init(void) { } static inline void kho_populate(phys_addr_t fdt_phys, u64 fdt_len, diff --git a/include/linux/memblock.h b/include/linux/memblock.h index 6ec5e9ac0699..3e217414e12d 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -614,11 +614,9 @@ static inline void memtest_report_meminfo(struct seq_file *m) { } #ifdef CONFIG_MEMBLOCK_KHO_SCRATCH void memblock_set_kho_scratch_only(void); void memblock_clear_kho_scratch_only(void); -void memmap_init_kho_scratch_pages(void); #else static inline void memblock_set_kho_scratch_only(void) { } static inline void memblock_clear_kho_scratch_only(void) { } -static inline void memmap_init_kho_scratch_pages(void) {} #endif #endif /* _LINUX_MEMBLOCK_H */ diff --git a/include/linux/mm.h b/include/linux/mm.h index abb4963c1f06..b2e478b14c87 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3057,38 +3057,47 @@ static inline bool get_user_page_fast_only(unsigned long addr, { return get_user_pages_fast_only(addr, 1, gup_flags, pagep) == 1; } + +static inline struct percpu_counter_tree_level_item *get_rss_stat_items(struct mm_struct *mm) +{ + unsigned long ptr = (unsigned long)mm; + + ptr += offsetof(struct mm_struct, flexible_array); + return (struct percpu_counter_tree_level_item *)ptr; +} + /* * per-process(per-mm_struct) statistics. */ static inline unsigned long get_mm_counter(struct mm_struct *mm, int member) { - return percpu_counter_read_positive(&mm->rss_stat[member]); + return percpu_counter_tree_approximate_sum_positive(&mm->rss_stat[member]); } static inline unsigned long get_mm_counter_sum(struct mm_struct *mm, int member) { - return percpu_counter_sum_positive(&mm->rss_stat[member]); + return percpu_counter_tree_precise_sum_positive(&mm->rss_stat[member]); } void mm_trace_rss_stat(struct mm_struct *mm, int member); static inline void add_mm_counter(struct mm_struct *mm, int member, long value) { - percpu_counter_add(&mm->rss_stat[member], value); + percpu_counter_tree_add(&mm->rss_stat[member], value); mm_trace_rss_stat(mm, member); } static inline void inc_mm_counter(struct mm_struct *mm, int member) { - percpu_counter_inc(&mm->rss_stat[member]); + percpu_counter_tree_add(&mm->rss_stat[member], 1); mm_trace_rss_stat(mm, member); } static inline void dec_mm_counter(struct mm_struct *mm, int member) { - percpu_counter_dec(&mm->rss_stat[member]); + percpu_counter_tree_add(&mm->rss_stat[member], -1); mm_trace_rss_stat(mm, member); } diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 3cc8ae722886..1a808d78245d 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -18,7 +18,7 @@ #include #include #include -#include +#include #include #include #include @@ -1118,6 +1118,19 @@ typedef struct { DECLARE_BITMAP(__mm_flags, NUM_MM_FLAG_BITS); } __private mm_flags_t; +/* + * The alignment of the mm_struct flexible array is based on the largest + * alignment of its content: + * __alignof__(struct percpu_counter_tree_level_item) provides a + * cacheline aligned alignment on SMP systems, else alignment on + * unsigned long on UP systems. + */ +#ifdef CONFIG_SMP +# define __mm_struct_flexible_array_aligned __aligned(__alignof__(struct percpu_counter_tree_level_item)) +#else +# define __mm_struct_flexible_array_aligned __aligned(__alignof__(unsigned long)) +#endif + struct kioctx_table; struct iommu_mm_data; struct mm_struct { @@ -1263,7 +1276,7 @@ struct mm_struct { unsigned long saved_e_flags; #endif - struct percpu_counter rss_stat[NR_MM_COUNTERS]; + struct percpu_counter_tree rss_stat[NR_MM_COUNTERS]; struct linux_binfmt *binfmt; @@ -1374,10 +1387,13 @@ struct mm_struct { } __randomize_layout; /* - * The mm_cpumask needs to be at the end of mm_struct, because it - * is dynamically sized based on nr_cpu_ids. + * The rss hierarchical counter items, mm_cpumask, and mm_cid + * masks need to be at the end of mm_struct, because they are + * dynamically sized based on nr_cpu_ids. + * The content of the flexible array needs to be placed in + * decreasing alignment requirement order. */ - char flexible_array[] __aligned(__alignof__(unsigned long)); + char flexible_array[] __mm_struct_flexible_array_aligned; }; /* Copy value to the first system word of mm flags, non-atomically. */ @@ -1414,24 +1430,30 @@ static inline void __mm_flags_set_mask_bits_word(struct mm_struct *mm, MT_FLAGS_USE_RCU) extern struct mm_struct init_mm; -#define MM_STRUCT_FLEXIBLE_ARRAY_INIT \ -{ \ - [0 ... sizeof(cpumask_t) + MM_CID_STATIC_SIZE - 1] = 0 \ +#define MM_STRUCT_FLEXIBLE_ARRAY_INIT \ +{ \ + [0 ... (PERCPU_COUNTER_TREE_ITEMS_STATIC_SIZE * NR_MM_COUNTERS) + sizeof(cpumask_t) + MM_CID_STATIC_SIZE - 1] = 0 \ } -/* Pointer magic because the dynamic array size confuses some compilers. */ -static inline void mm_init_cpumask(struct mm_struct *mm) +static inline size_t get_rss_stat_items_size(void) { - unsigned long cpu_bitmap = (unsigned long)mm; - - cpu_bitmap += offsetof(struct mm_struct, flexible_array); - cpumask_clear((struct cpumask *)cpu_bitmap); + return percpu_counter_tree_items_size() * NR_MM_COUNTERS; } /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */ static inline cpumask_t *mm_cpumask(struct mm_struct *mm) { - return (struct cpumask *)&mm->flexible_array; + unsigned long ptr = (unsigned long)mm; + + ptr += offsetof(struct mm_struct, flexible_array); + /* Skip RSS stats counters. */ + ptr += get_rss_stat_items_size(); + return (struct cpumask *)ptr; +} + +static inline void mm_init_cpumask(struct mm_struct *mm) +{ + cpumask_clear((struct cpumask *)mm_cpumask(mm)); } #ifdef CONFIG_LRU_GEN @@ -1523,6 +1545,8 @@ static inline cpumask_t *mm_cpus_allowed(struct mm_struct *mm) unsigned long bitmap = (unsigned long)mm; bitmap += offsetof(struct mm_struct, flexible_array); + /* Skip RSS stats counters. */ + bitmap += get_rss_stat_items_size(); /* Skip cpu_bitmap */ bitmap += cpumask_size(); return (struct cpumask *)bitmap; diff --git a/include/linux/percpu_counter_tree.h b/include/linux/percpu_counter_tree.h new file mode 100644 index 000000000000..828c763edd4a --- /dev/null +++ b/include/linux/percpu_counter_tree.h @@ -0,0 +1,367 @@ +/* SPDX-License-Identifier: GPL-2.0+ OR MIT */ +/* SPDX-FileCopyrightText: 2025 Mathieu Desnoyers */ + +#ifndef _PERCPU_COUNTER_TREE_H +#define _PERCPU_COUNTER_TREE_H + +#include +#include +#include + +#ifdef CONFIG_SMP + +#if NR_CPUS == (1U << 0) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 0 +#elif NR_CPUS <= (1U << 1) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 1 +#elif NR_CPUS <= (1U << 2) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 3 +#elif NR_CPUS <= (1U << 3) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 7 +#elif NR_CPUS <= (1U << 4) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 7 +#elif NR_CPUS <= (1U << 5) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 11 +#elif NR_CPUS <= (1U << 6) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 21 +#elif NR_CPUS <= (1U << 7) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 21 +#elif NR_CPUS <= (1U << 8) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 37 +#elif NR_CPUS <= (1U << 9) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 73 +#elif NR_CPUS <= (1U << 10) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 149 +#elif NR_CPUS <= (1U << 11) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 293 +#elif NR_CPUS <= (1U << 12) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 585 +#elif NR_CPUS <= (1U << 13) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 1173 +#elif NR_CPUS <= (1U << 14) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 2341 +#elif NR_CPUS <= (1U << 15) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 4681 +#elif NR_CPUS <= (1U << 16) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 4681 +#elif NR_CPUS <= (1U << 17) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 8777 +#elif NR_CPUS <= (1U << 18) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 17481 +#elif NR_CPUS <= (1U << 19) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 34953 +#elif NR_CPUS <= (1U << 20) +# define PERCPU_COUNTER_TREE_STATIC_NR_ITEMS 69905 +#else +# error "Unsupported number of CPUs." +#endif + +struct percpu_counter_tree_level_item { + atomic_long_t count; /* + * Count the number of carry for this tree item. + * The carry counter is kept at the order of the + * carry accounted for at this tree level. + */ +} ____cacheline_aligned_in_smp; + +#define PERCPU_COUNTER_TREE_ITEMS_STATIC_SIZE \ + (PERCPU_COUNTER_TREE_STATIC_NR_ITEMS * sizeof(struct percpu_counter_tree_level_item)) + +struct percpu_counter_tree { + /* Fast-path fields. */ + unsigned long __percpu *level0; /* Pointer to per-CPU split counters (tree level 0). */ + unsigned long level0_bit_mask; /* Bit mask to apply to detect carry propagation from tree level 0. */ + union { + unsigned long *i; /* Approximate sum for single-CPU topology. */ + atomic_long_t *a; /* Approximate sum for SMP topology. */ + } approx_sum; + long bias; /* Bias to apply to counter precise and approximate values. */ + + /* Slow-path fields. */ + struct percpu_counter_tree_level_item *items; /* Array of tree items for levels 1 to N. */ + unsigned long batch_size; /* + * The batch size is the increment step at level 0 which + * triggers a carry propagation. The batch size is required + * to be greater than 1, and a power of 2. + */ + /* + * The tree approximate sum is guaranteed to be within this accuracy range: + * (precise_sum - approx_accuracy_range.under) <= approx_sum <= (precise_sum + approx_accuracy_range.over). + * This accuracy is derived from the hardware topology and the tree batch_size. + * The "under" accuracy is larger than the "over" accuracy because the negative range of a + * two's complement signed integer is one unit larger than the positive range. This delta + * is summed for each tree item, which leads to a significantly larger "under" accuracy range + * compared to the "over" accuracy range. + */ + struct { + unsigned long under; + unsigned long over; + } approx_accuracy_range; +}; + +size_t percpu_counter_tree_items_size(void); +int percpu_counter_tree_init_many(struct percpu_counter_tree *counters, struct percpu_counter_tree_level_item *items, + unsigned int nr_counters, unsigned long batch_size, gfp_t gfp_flags); +int percpu_counter_tree_init(struct percpu_counter_tree *counter, struct percpu_counter_tree_level_item *items, + unsigned long batch_size, gfp_t gfp_flags); +void percpu_counter_tree_destroy_many(struct percpu_counter_tree *counter, unsigned int nr_counters); +void percpu_counter_tree_destroy(struct percpu_counter_tree *counter); +void percpu_counter_tree_add(struct percpu_counter_tree *counter, long inc); +long percpu_counter_tree_precise_sum(struct percpu_counter_tree *counter); +int percpu_counter_tree_approximate_compare(struct percpu_counter_tree *a, struct percpu_counter_tree *b); +int percpu_counter_tree_approximate_compare_value(struct percpu_counter_tree *counter, long v); +int percpu_counter_tree_precise_compare(struct percpu_counter_tree *a, struct percpu_counter_tree *b); +int percpu_counter_tree_precise_compare_value(struct percpu_counter_tree *counter, long v); +void percpu_counter_tree_set(struct percpu_counter_tree *counter, long v); +int percpu_counter_tree_subsystem_init(void); + +/** + * percpu_counter_tree_approximate_sum() - Return approximate counter sum. + * @counter: The counter to sum. + * + * Querying the approximate sum is fast, but it is only accurate within + * the bounds delimited by percpu_counter_tree_approximate_accuracy_range(). + * This is meant to be used when speed is preferred over accuracy. + * + * Return: The current approximate counter sum. + */ +static inline +long percpu_counter_tree_approximate_sum(struct percpu_counter_tree *counter) +{ + unsigned long v; + + if (!counter->level0_bit_mask) + v = READ_ONCE(*counter->approx_sum.i); + else + v = atomic_long_read(counter->approx_sum.a); + return (long) (v + (unsigned long)READ_ONCE(counter->bias)); +} + +/** + * percpu_counter_tree_approximate_accuracy_range - Query the accuracy range for a counter tree. + * @counter: Counter to query. + * @under: Pointer to a variable to be incremented of the approximation + * accuracy range below the precise sum. + * @over: Pointer to a variable to be incremented of the approximation + * accuracy range above the precise sum. + * + * Query the accuracy range limits for the counter. + * Because of two's complement binary representation, the "under" range is typically + * slightly larger than the "over" range. + * Those values are derived from the hardware topology and the counter tree batch size. + * They are invariant for a given counter tree. + * Using this function should not be typically required, see the following functions instead: + * * percpu_counter_tree_approximate_compare(), + * * percpu_counter_tree_approximate_compare_value(), + * * percpu_counter_tree_precise_compare(), + * * percpu_counter_tree_precise_compare_value(). + */ +static inline +void percpu_counter_tree_approximate_accuracy_range(struct percpu_counter_tree *counter, + unsigned long *under, unsigned long *over) +{ + *under += counter->approx_accuracy_range.under; + *over += counter->approx_accuracy_range.over; +} + +#else /* !CONFIG_SMP */ + +#define PERCPU_COUNTER_TREE_ITEMS_STATIC_SIZE 0 + +struct percpu_counter_tree_level_item; + +struct percpu_counter_tree { + atomic_long_t count; +}; + +static inline +size_t percpu_counter_tree_items_size(void) +{ + return 0; +} + +static inline +int percpu_counter_tree_init_many(struct percpu_counter_tree *counters, struct percpu_counter_tree_level_item *items, + unsigned int nr_counters, unsigned long batch_size, gfp_t gfp_flags) +{ + for (unsigned int i = 0; i < nr_counters; i++) + atomic_long_set(&counters[i].count, 0); + return 0; +} + +static inline +int percpu_counter_tree_init(struct percpu_counter_tree *counter, struct percpu_counter_tree_level_item *items, + unsigned long batch_size, gfp_t gfp_flags) +{ + return percpu_counter_tree_init_many(counter, items, 1, batch_size, gfp_flags); +} + +static inline +void percpu_counter_tree_destroy_many(struct percpu_counter_tree *counter, unsigned int nr_counters) +{ +} + +static inline +void percpu_counter_tree_destroy(struct percpu_counter_tree *counter) +{ +} + +static inline +long percpu_counter_tree_precise_sum(struct percpu_counter_tree *counter) +{ + return atomic_long_read(&counter->count); +} + +static inline +int percpu_counter_tree_precise_compare(struct percpu_counter_tree *a, struct percpu_counter_tree *b) +{ + long count_a = percpu_counter_tree_precise_sum(a), + count_b = percpu_counter_tree_precise_sum(b); + + if (count_a == count_b) + return 0; + if (count_a < count_b) + return -1; + return 1; +} + +static inline +int percpu_counter_tree_precise_compare_value(struct percpu_counter_tree *counter, long v) +{ + long count = percpu_counter_tree_precise_sum(counter); + + if (count == v) + return 0; + if (count < v) + return -1; + return 1; +} + +static inline +int percpu_counter_tree_approximate_compare(struct percpu_counter_tree *a, struct percpu_counter_tree *b) +{ + return percpu_counter_tree_precise_compare(a, b); +} + +static inline +int percpu_counter_tree_approximate_compare_value(struct percpu_counter_tree *counter, long v) +{ + return percpu_counter_tree_precise_compare_value(counter, v); +} + +static inline +void percpu_counter_tree_set(struct percpu_counter_tree *counter, long v) +{ + atomic_long_set(&counter->count, v); +} + +static inline +void percpu_counter_tree_approximate_accuracy_range(struct percpu_counter_tree *counter, + unsigned long *under, unsigned long *over) +{ +} + +static inline +void percpu_counter_tree_add(struct percpu_counter_tree *counter, long inc) +{ + atomic_long_add(inc, &counter->count); +} + +static inline +long percpu_counter_tree_approximate_sum(struct percpu_counter_tree *counter) +{ + return percpu_counter_tree_precise_sum(counter); +} + +static inline +int percpu_counter_tree_subsystem_init(void) +{ + return 0; +} + +#endif /* CONFIG_SMP */ + +/** + * percpu_counter_tree_approximate_sum_positive() - Return a positive approximate counter sum. + * @counter: The counter to sum. + * + * Return an approximate counter sum which is guaranteed to be greater + * or equal to 0. + * + * Return: The current positive approximate counter sum. + */ +static inline +long percpu_counter_tree_approximate_sum_positive(struct percpu_counter_tree *counter) +{ + long v = percpu_counter_tree_approximate_sum(counter); + return v > 0 ? v : 0; +} + +/** + * percpu_counter_tree_precise_sum_positive() - Return a positive precise counter sum. + * @counter: The counter to sum. + * + * Return a precise counter sum which is guaranteed to be greater + * or equal to 0. + * + * Return: The current positive precise counter sum. + */ +static inline +long percpu_counter_tree_precise_sum_positive(struct percpu_counter_tree *counter) +{ + long v = percpu_counter_tree_precise_sum(counter); + return v > 0 ? v : 0; +} + +/** + * percpu_counter_tree_approximate_min_max_range() - Return the approximation min and max precise values. + * @approx_sum: Approximated sum. + * @under: Tree accuracy range (under). + * @over: Tree accuracy range (over). + * @precise_min: Minimum possible value for precise sum (output). + * @precise_max: Maximum possible value for precise sum (output). + * + * Calculate the minimum and maximum precise values for a given + * approximation and (under, over) accuracy range. + * + * The range of the approximation as a function of the precise sum is expressed as: + * + * approx_sum >= precise_sum - approx_accuracy_range.under + * approx_sum <= precise_sum + approx_accuracy_range.over + * + * Therefore, the range of the precise sum as a function of the approximation is expressed as: + * + * precise_sum <= approx_sum + approx_accuracy_range.under + * precise_sum >= approx_sum - approx_accuracy_range.over + */ +static inline +void percpu_counter_tree_approximate_min_max_range(long approx_sum, unsigned long under, unsigned long over, + long *precise_min, long *precise_max) +{ + *precise_min = approx_sum - over; + *precise_max = approx_sum + under; +} + +/** + * percpu_counter_tree_approximate_min_max() - Return the tree approximation, min and max possible precise values. + * @counter: The counter to sum. + * @approx_sum: Approximate sum (output). + * @precise_min: Minimum possible value for precise sum (output). + * @precise_max: Maximum possible value for precise sum (output). + * + * Return the approximate sum, minimum and maximum precise values for + * a counter. + */ +static inline +void percpu_counter_tree_approximate_min_max(struct percpu_counter_tree *counter, + long *approx_sum, long *precise_min, long *precise_max) +{ + unsigned long under = 0, over = 0; + long v = percpu_counter_tree_approximate_sum(counter); + + percpu_counter_tree_approximate_accuracy_range(counter, &under, &over); + percpu_counter_tree_approximate_min_max_range(v, under, over, precise_min, precise_max); + *approx_sum = v; +} + +#endif /* _PERCPU_COUNTER_TREE_H */ diff --git a/include/linux/vdso_datastore.h b/include/linux/vdso_datastore.h index a91fa24b06e0..0b530428db71 100644 --- a/include/linux/vdso_datastore.h +++ b/include/linux/vdso_datastore.h @@ -2,9 +2,15 @@ #ifndef _LINUX_VDSO_DATASTORE_H #define _LINUX_VDSO_DATASTORE_H +#ifdef CONFIG_HAVE_GENERIC_VDSO #include extern const struct vm_special_mapping vdso_vvar_mapping; struct vm_area_struct *vdso_install_vvar_mapping(struct mm_struct *mm, unsigned long addr); +void __init vdso_setup_data_pages(void); +#else /* !CONFIG_HAVE_GENERIC_VDSO */ +static inline void vdso_setup_data_pages(void) { } +#endif /* CONFIG_HAVE_GENERIC_VDSO */ + #endif /* _LINUX_VDSO_DATASTORE_H */ diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h index cd7920c81f85..290ccb9fd25d 100644 --- a/include/trace/events/kmem.h +++ b/include/trace/events/kmem.h @@ -448,7 +448,7 @@ TRACE_EVENT(rss_stat, */ __entry->curr = current->mm == mm && !(current->flags & PF_KTHREAD); __entry->member = member; - __entry->size = (percpu_counter_sum_positive(&mm->rss_stat[member]) + __entry->size = (percpu_counter_tree_approximate_sum_positive(&mm->rss_stat[member]) << PAGE_SHIFT); ), diff --git a/init/main.c b/init/main.c index 1cb395dd94e4..453ac9dff2da 100644 --- a/init/main.c +++ b/init/main.c @@ -105,6 +105,8 @@ #include #include #include +#include +#include #include #include @@ -1067,6 +1069,7 @@ void start_kernel(void) vfs_caches_init_early(); sort_main_extable(); trap_init(); + percpu_counter_tree_subsystem_init(); mm_core_init(); maple_tree_init(); poking_init(); @@ -1119,6 +1122,7 @@ void start_kernel(void) srcu_init(); hrtimers_init(); softirq_init(); + vdso_setup_data_pages(); timekeeping_init(); time_init(); diff --git a/kernel/fork.c b/kernel/fork.c index bc2bf58b93b6..0de4c8727055 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -134,6 +134,11 @@ */ #define MAX_THREADS FUTEX_TID_MASK +/* + * Batch size of rss stat approximation + */ +#define RSS_STAT_BATCH_SIZE 32 + /* * Protected counters by write_lock_irq(&tasklist_lock) */ @@ -627,14 +632,12 @@ static void check_mm(struct mm_struct *mm) "Please make sure 'struct resident_page_types[]' is updated as well"); for (i = 0; i < NR_MM_COUNTERS; i++) { - long x = percpu_counter_sum(&mm->rss_stat[i]); - - if (unlikely(x)) { + if (unlikely(percpu_counter_tree_precise_compare_value(&mm->rss_stat[i], 0) != 0)) pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld Comm:%s Pid:%d\n", - mm, resident_page_types[i], x, + mm, resident_page_types[i], + percpu_counter_tree_precise_sum(&mm->rss_stat[i]), current->comm, task_pid_nr(current)); - } } if (mm_pgtables_bytes(mm)) @@ -732,7 +735,7 @@ void __mmdrop(struct mm_struct *mm) put_user_ns(mm->user_ns); mm_pasid_drop(mm); mm_destroy_cid(mm); - percpu_counter_destroy_many(mm->rss_stat, NR_MM_COUNTERS); + percpu_counter_tree_destroy_many(mm->rss_stat, NR_MM_COUNTERS); free_mm(mm); } @@ -1125,8 +1128,9 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, if (mm_alloc_cid(mm, p)) goto fail_cid; - if (percpu_counter_init_many(mm->rss_stat, 0, GFP_KERNEL_ACCOUNT, - NR_MM_COUNTERS)) + if (percpu_counter_tree_init_many(mm->rss_stat, get_rss_stat_items(mm), + NR_MM_COUNTERS, RSS_STAT_BATCH_SIZE, + GFP_KERNEL_ACCOUNT)) goto fail_pcpu; mm->user_ns = get_user_ns(user_ns); @@ -3008,7 +3012,7 @@ void __init mm_cache_init(void) * dynamically sized based on the maximum CPU number this system * can have, taking hotplug into account (nr_cpu_ids). */ - mm_size = sizeof(struct mm_struct) + cpumask_size() + mm_cid_size(); + mm_size = sizeof(struct mm_struct) + cpumask_size() + mm_cid_size() + get_rss_stat_items_size(); mm_cachep = kmem_cache_create_usercopy("mm_struct", mm_size, ARCH_MIN_MMSTRUCT_ALIGN, diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index cc68a3692905..ce2786faf044 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -1333,6 +1333,23 @@ int kho_retrieve_subtree(const char *name, phys_addr_t *phys) } EXPORT_SYMBOL_GPL(kho_retrieve_subtree); +bool pfn_is_kho_scratch(unsigned long pfn) +{ + unsigned int i; + phys_addr_t scratch_start, scratch_end, phys = __pfn_to_phys(pfn); + + for (i = 0; i < kho_scratch_cnt; i++) { + scratch_start = kho_scratch[i].addr; + scratch_end = kho_scratch[i].addr + kho_scratch[i].size; + + if (scratch_start <= phys && phys < scratch_end) + return true; + } + + return false; +} +EXPORT_SYMBOL_GPL(pfn_is_kho_scratch); + static __init int kho_out_fdt_setup(void) { void *root = kho_out.fdt; @@ -1421,12 +1438,27 @@ static __init int kho_init(void) } fs_initcall(kho_init); +static void __init kho_init_scratch_pages(void) +{ + if (!IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT)) + return; + + for (int i = 0; i < kho_scratch_cnt; i++) { + unsigned long pfn = PFN_DOWN(kho_scratch[i].addr); + unsigned long end_pfn = PFN_UP(kho_scratch[i].addr + kho_scratch[i].size); + int nid = early_pfn_to_nid(pfn); + + for (; pfn < end_pfn; pfn++) + init_deferred_page(pfn, nid); + } +} + static void __init kho_release_scratch(void) { phys_addr_t start, end; u64 i; - memmap_init_kho_scratch_pages(); + kho_init_scratch_pages(); /* * Mark scratch mem as CMA before we return it. That way we @@ -1453,6 +1485,7 @@ void __init kho_memory_init(void) kho_mem_deserialize(phys_to_virt(kho_in.mem_map_phys)); } else { kho_reserve_scratch(); + kho_init_scratch_pages(); } } diff --git a/lib/Kconfig b/lib/Kconfig index 0f2fb9610647..0b8241e5b548 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -52,6 +52,18 @@ config PACKING_KUNIT_TEST When in doubt, say N. +config PERCPU_COUNTER_TREE_TEST + tristate "Hierarchical Per-CPU counter test" if !KUNIT_ALL_TESTS + depends on KUNIT + default KUNIT_ALL_TESTS + help + This builds Kunit tests for the hierarchical per-cpu counters. + + For more information on KUnit and unit tests in general, + please refer to the KUnit documentation in Documentation/dev-tools/kunit/. + + When in doubt, say N. + config BITREVERSE tristate diff --git a/lib/Makefile b/lib/Makefile index 1b9ee167517f..abc32420b581 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -181,6 +181,7 @@ obj-$(CONFIG_TEXTSEARCH_KMP) += ts_kmp.o obj-$(CONFIG_TEXTSEARCH_BM) += ts_bm.o obj-$(CONFIG_TEXTSEARCH_FSM) += ts_fsm.o obj-$(CONFIG_SMP) += percpu_counter.o +obj-$(CONFIG_SMP) += percpu_counter_tree.o obj-$(CONFIG_AUDIT_GENERIC) += audit.o obj-$(CONFIG_AUDIT_COMPAT_GENERIC) += compat_audit.o diff --git a/lib/percpu_counter_tree.c b/lib/percpu_counter_tree.c new file mode 100644 index 000000000000..beb1144e6450 --- /dev/null +++ b/lib/percpu_counter_tree.c @@ -0,0 +1,702 @@ +// SPDX-License-Identifier: GPL-2.0+ OR MIT +// SPDX-FileCopyrightText: 2025 Mathieu Desnoyers + +/* + * Split Counters With Tree Approximation Propagation + * + * * Propagation diagram when reaching batch size thresholds (± batch size): + * + * Example diagram for 8 CPUs: + * + * log2(8) = 3 levels + * + * At each level, each pair propagates its values to the next level when + * reaching the batch size thresholds. + * + * Counters at levels 0, 1, 2 can be kept on a single byte ([-128 .. +127] range), + * although it may be relevant to keep them on "long" counters for + * simplicity. (complexity vs memory footprint tradeoff) + * + * Counter at level 3 can be kept on a "long" counter. + * + * Level 0: 0 1 2 3 4 5 6 7 + * | / | / | / | / + * | / | / | / | / + * | / | / | / | / + * Level 1: 0 1 2 3 + * | / | / + * | / | / + * | / | / + * Level 2: 0 1 + * | / + * | / + * | / + * Level 3: 0 + * + * * Approximation accuracy: + * + * BATCH(level N): Level N batch size. + * + * Example for BATCH(level 0) = 32. + * + * BATCH(level 0) = 32 + * BATCH(level 1) = 64 + * BATCH(level 2) = 128 + * BATCH(level N) = BATCH(level 0) * 2^N + * + * per-counter global + * accuracy accuracy + * Level 0: [ -32 .. +31] ±256 (8 * 32) + * Level 1: [ -64 .. +63] ±256 (4 * 64) + * Level 2: [-128 .. +127] ±256 (2 * 128) + * Total: ------ ±768 (log2(nr_cpu_ids) * BATCH(level 0) * nr_cpu_ids) + * + * Note that the global accuracy can be calculated more precisely + * by taking into account that the positive accuracy range is + * 31 rather than 32. + * + * ----- + * + * Approximate Sum Carry Propagation + * + * Let's define a number of counter bits for each level, e.g.: + * + * log2(BATCH(level 0)) = log2(32) = 5 + * Let's assume, for this example, a 32-bit architecture (sizeof(long) == 4). + * + * nr_bit value_mask range + * Level 0: 5 bits v 0 .. +31 + * Level 1: 1 bit (v & ~((1UL << 5) - 1)) 0 .. +63 + * Level 2: 1 bit (v & ~((1UL << 6) - 1)) 0 .. +127 + * Level 3: 25 bits (v & ~((1UL << 7) - 1)) 0 .. 2^32-1 + * + * Note: Use a "long" per-cpu counter at level 0 to allow precise sum. + * + * Note: Use cacheline aligned counters at levels above 0 to prevent false sharing. + * If memory footprint is an issue, a specialized allocator could be used + * to eliminate padding. + * + * Example with expanded values: + * + * counter_add(counter, inc): + * + * if (!inc) + * return; + * + * res = percpu_add_return(counter @ Level 0, inc); + * orig = res - inc; + * if (inc < 0) { + * inc = -(-inc & ~0b00011111); // Clear used bits + * // xor bit 5: underflow + * if ((inc ^ orig ^ res) & 0b00100000) + * inc -= 0b00100000; + * } else { + * inc &= ~0b00011111; // Clear used bits + * // xor bit 5: overflow + * if ((inc ^ orig ^ res) & 0b00100000) + * inc += 0b00100000; + * } + * if (!inc) + * return; + * + * res = atomic_long_add_return(counter @ Level 1, inc); + * orig = res - inc; + * if (inc < 0) { + * inc = -(-inc & ~0b00111111); // Clear used bits + * // xor bit 6: underflow + * if ((inc ^ orig ^ res) & 0b01000000) + * inc -= 0b01000000; + * } else { + * inc &= ~0b00111111; // Clear used bits + * // xor bit 6: overflow + * if ((inc ^ orig ^ res) & 0b01000000) + * inc += 0b01000000; + * } + * if (!inc) + * return; + * + * res = atomic_long_add_return(counter @ Level 2, inc); + * orig = res - inc; + * if (inc < 0) { + * inc = -(-inc & ~0b01111111); // Clear used bits + * // xor bit 7: underflow + * if ((inc ^ orig ^ res) & 0b10000000) + * inc -= 0b10000000; + * } else { + * inc &= ~0b01111111; // Clear used bits + * // xor bit 7: overflow + * if ((inc ^ orig ^ res) & 0b10000000) + * inc += 0b10000000; + * } + * if (!inc) + * return; + * + * atomic_long_add(counter @ Level 3, inc); + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#define MAX_NR_LEVELS 5 + +/* + * The counter configuration is selected at boot time based on the + * hardware topology. + */ +struct counter_config { + unsigned int nr_items; /* + * nr_items is the number of items in the tree for levels 1 + * up to and including the final level (approximate sum). + * It excludes the level 0 per-CPU counters. + */ + unsigned char nr_levels; /* + * nr_levels is the number of hierarchical counter tree levels. + * It excludes the final level (approximate sum). + */ + unsigned char n_arity_order[MAX_NR_LEVELS]; /* + * n-arity of tree nodes for each level from + * 0 to (nr_levels - 1). + */ +}; + +static const struct counter_config per_nr_cpu_order_config[] = { + [0] = { .nr_items = 0, .nr_levels = 0, .n_arity_order = { 0 } }, + [1] = { .nr_items = 1, .nr_levels = 1, .n_arity_order = { 1 } }, + [2] = { .nr_items = 3, .nr_levels = 2, .n_arity_order = { 1, 1 } }, + [3] = { .nr_items = 7, .nr_levels = 3, .n_arity_order = { 1, 1, 1 } }, + [4] = { .nr_items = 7, .nr_levels = 3, .n_arity_order = { 2, 1, 1 } }, + [5] = { .nr_items = 11, .nr_levels = 3, .n_arity_order = { 2, 2, 1 } }, + [6] = { .nr_items = 21, .nr_levels = 3, .n_arity_order = { 2, 2, 2 } }, + [7] = { .nr_items = 21, .nr_levels = 3, .n_arity_order = { 3, 2, 2 } }, + [8] = { .nr_items = 37, .nr_levels = 3, .n_arity_order = { 3, 3, 2 } }, + [9] = { .nr_items = 73, .nr_levels = 3, .n_arity_order = { 3, 3, 3 } }, + [10] = { .nr_items = 149, .nr_levels = 4, .n_arity_order = { 3, 3, 2, 2 } }, + [11] = { .nr_items = 293, .nr_levels = 4, .n_arity_order = { 3, 3, 3, 2 } }, + [12] = { .nr_items = 585, .nr_levels = 4, .n_arity_order = { 3, 3, 3, 3 } }, + [13] = { .nr_items = 1173, .nr_levels = 5, .n_arity_order = { 3, 3, 3, 2, 2 } }, + [14] = { .nr_items = 2341, .nr_levels = 5, .n_arity_order = { 3, 3, 3, 3, 2 } }, + [15] = { .nr_items = 4681, .nr_levels = 5, .n_arity_order = { 3, 3, 3, 3, 3 } }, + [16] = { .nr_items = 4681, .nr_levels = 5, .n_arity_order = { 4, 3, 3, 3, 3 } }, + [17] = { .nr_items = 8777, .nr_levels = 5, .n_arity_order = { 4, 4, 3, 3, 3 } }, + [18] = { .nr_items = 17481, .nr_levels = 5, .n_arity_order = { 4, 4, 4, 3, 3 } }, + [19] = { .nr_items = 34953, .nr_levels = 5, .n_arity_order = { 4, 4, 4, 4, 3 } }, + [20] = { .nr_items = 69905, .nr_levels = 5, .n_arity_order = { 4, 4, 4, 4, 4 } }, +}; + +static const struct counter_config *counter_config; /* Hierarchical counter configuration for the hardware topology. */ +static unsigned int nr_cpus_order; /* Order of nr_cpu_ids. */ +static unsigned long accuracy_multiplier; /* Calculate accuracy for a given batch size (multiplication factor). */ + +static +int __percpu_counter_tree_init(struct percpu_counter_tree *counter, + unsigned long batch_size, gfp_t gfp_flags, + unsigned long __percpu *level0, + struct percpu_counter_tree_level_item *items) +{ + /* Batch size must be greater than 1, and a power of 2. */ + if (WARN_ON(batch_size <= 1 || (batch_size & (batch_size - 1)))) + return -EINVAL; + counter->batch_size = batch_size; + counter->bias = 0; + counter->level0 = level0; + counter->items = items; + if (!nr_cpus_order) { + counter->approx_sum.i = per_cpu_ptr(counter->level0, 0); + counter->level0_bit_mask = 0; + } else { + counter->approx_sum.a = &counter->items[counter_config->nr_items - 1].count; + counter->level0_bit_mask = 1UL << get_count_order(batch_size); + } + /* + * Each tree item signed integer has a negative range which is + * one unit greater than the positive range. + */ + counter->approx_accuracy_range.under = batch_size * accuracy_multiplier; + counter->approx_accuracy_range.over = (batch_size - 1) * accuracy_multiplier; + return 0; +} + +/** + * percpu_counter_tree_init_many() - Initialize many per-CPU counter trees. + * @counters: An array of @nr_counters counters to initialize. + * Their memory is provided by the caller. + * @items: Pointer to memory area where to store tree items. + * This memory is provided by the caller. + * Its size needs to be at least @nr_counters * percpu_counter_tree_items_size(). + * @nr_counters: The number of counter trees to initialize + * @batch_size: The batch size is the increment step at level 0 which triggers a + * carry propagation. + * The batch size is required to be greater than 1, and a power of 2. + * @gfp_flags: gfp flags to pass to the per-CPU allocator. + * + * Initialize many per-CPU counter trees using a single per-CPU + * allocator invocation for @nr_counters counters. + * + * Return: + * * %0: Success + * * %-EINVAL: - Invalid @batch_size argument + * * %-ENOMEM: - Out of memory + */ +int percpu_counter_tree_init_many(struct percpu_counter_tree *counters, struct percpu_counter_tree_level_item *items, + unsigned int nr_counters, unsigned long batch_size, gfp_t gfp_flags) +{ + void __percpu *level0, *level0_iter; + size_t counter_size = sizeof(*counters->level0), + items_size = percpu_counter_tree_items_size(); + void *items_iter; + unsigned int i; + int ret; + + memset(items, 0, items_size * nr_counters); + level0 = __alloc_percpu_gfp(nr_counters * counter_size, + __alignof__(*counters->level0), gfp_flags); + if (!level0) + return -ENOMEM; + level0_iter = level0; + items_iter = items; + for (i = 0; i < nr_counters; i++) { + ret = __percpu_counter_tree_init(&counters[i], batch_size, gfp_flags, level0_iter, items_iter); + if (ret) + goto free_level0; + level0_iter += counter_size; + items_iter += items_size; + } + return 0; + +free_level0: + free_percpu(level0); + return ret; +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_init_many); + +/** + * percpu_counter_tree_init() - Initialize one per-CPU counter tree. + * @counter: Counter to initialize. + * Its memory is provided by the caller. + * @items: Pointer to memory area where to store tree items. + * This memory is provided by the caller. + * Its size needs to be at least percpu_counter_tree_items_size(). + * @batch_size: The batch size is the increment step at level 0 which triggers a + * carry propagation. + * The batch size is required to be greater than 1, and a power of 2. + * @gfp_flags: gfp flags to pass to the per-CPU allocator. + * + * Initialize one per-CPU counter tree. + * + * Return: + * * %0: Success + * * %-EINVAL: - Invalid @batch_size argument + * * %-ENOMEM: - Out of memory + */ +int percpu_counter_tree_init(struct percpu_counter_tree *counter, struct percpu_counter_tree_level_item *items, + unsigned long batch_size, gfp_t gfp_flags) +{ + return percpu_counter_tree_init_many(counter, items, 1, batch_size, gfp_flags); +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_init); + +/** + * percpu_counter_tree_destroy_many() - Destroy many per-CPU counter trees. + * @counters: Array of counters trees to destroy. + * @nr_counters: The number of counter trees to destroy. + * + * Release internal resources allocated for @nr_counters per-CPU counter trees. + */ + +void percpu_counter_tree_destroy_many(struct percpu_counter_tree *counters, unsigned int nr_counters) +{ + free_percpu(counters->level0); +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_destroy_many); + +/** + * percpu_counter_tree_destroy() - Destroy one per-CPU counter tree. + * @counter: Counter to destroy. + * + * Release internal resources allocated for one per-CPU counter tree. + */ +void percpu_counter_tree_destroy(struct percpu_counter_tree *counter) +{ + return percpu_counter_tree_destroy_many(counter, 1); +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_destroy); + +static +long percpu_counter_tree_carry(long orig, long res, long inc, unsigned long bit_mask) +{ + if (inc < 0) { + inc = -(-inc & ~(bit_mask - 1)); + /* + * xor bit_mask: underflow. + * + * If inc has bit set, decrement an additional bit if + * there is _no_ bit transition between orig and res. + * Else, inc has bit cleared, decrement an additional + * bit if there is a bit transition between orig and + * res. + */ + if ((inc ^ orig ^ res) & bit_mask) + inc -= bit_mask; + } else { + inc &= ~(bit_mask - 1); + /* + * xor bit_mask: overflow. + * + * If inc has bit set, increment an additional bit if + * there is _no_ bit transition between orig and res. + * Else, inc has bit cleared, increment an additional + * bit if there is a bit transition between orig and + * res. + */ + if ((inc ^ orig ^ res) & bit_mask) + inc += bit_mask; + } + return inc; +} + +/* + * It does not matter through which path the carry propagates up the + * tree, therefore there is no need to disable preemption because the + * cpu number is only used to favor cache locality. + */ +static +void percpu_counter_tree_add_slowpath(struct percpu_counter_tree *counter, long inc) +{ + unsigned int level_items, nr_levels = counter_config->nr_levels, + level, n_arity_order; + unsigned long bit_mask; + struct percpu_counter_tree_level_item *item = counter->items; + unsigned int cpu = raw_smp_processor_id(); + + WARN_ON_ONCE(!nr_cpus_order); /* Should never be called for 1 cpu. */ + + n_arity_order = counter_config->n_arity_order[0]; + bit_mask = counter->level0_bit_mask << n_arity_order; + level_items = 1U << (nr_cpus_order - n_arity_order); + + for (level = 1; level < nr_levels; level++) { + /* + * For the purpose of carry propagation, the + * intermediate level counters only need to keep track + * of the bits relevant for carry propagation. We + * therefore don't care about higher order bits. + * Note that this optimization is unwanted if the + * intended use is to track counters within intermediate + * levels of the topology. + */ + if (abs(inc) & (bit_mask - 1)) { + atomic_long_t *count = &item[cpu & (level_items - 1)].count; + unsigned long orig, res; + + res = atomic_long_add_return_relaxed(inc, count); + orig = res - inc; + inc = percpu_counter_tree_carry(orig, res, inc, bit_mask); + if (likely(!inc)) + return; + } + item += level_items; + n_arity_order = counter_config->n_arity_order[level]; + level_items >>= n_arity_order; + bit_mask <<= n_arity_order; + } + atomic_long_add(inc, counter->approx_sum.a); +} + +/** + * percpu_counter_tree_add() - Add to a per-CPU counter tree. + * @counter: Counter added to. + * @inc: Increment value (either positive or negative). + * + * Add @inc to a per-CPU counter tree. This is a fast-path which will + * typically increment per-CPU counters as long as there is no carry + * greater or equal to the counter tree batch size. + */ +void percpu_counter_tree_add(struct percpu_counter_tree *counter, long inc) +{ + unsigned long bit_mask = counter->level0_bit_mask, orig, res; + + res = this_cpu_add_return(*counter->level0, inc); + orig = res - inc; + inc = percpu_counter_tree_carry(orig, res, inc, bit_mask); + if (likely(!inc)) + return; + percpu_counter_tree_add_slowpath(counter, inc); +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_add); + +static +long percpu_counter_tree_precise_sum_unbiased(struct percpu_counter_tree *counter) +{ + unsigned long sum = 0; + int cpu; + + for_each_possible_cpu(cpu) + sum += *per_cpu_ptr(counter->level0, cpu); + return (long) sum; +} + +/** + * percpu_counter_tree_precise_sum() - Return precise counter sum. + * @counter: The counter to sum. + * + * Querying the precise sum is relatively expensive because it needs to + * iterate over all CPUs. + * This is meant to be used when accuracy is preferred over speed. + * + * Return: The current precise counter sum. + */ +long percpu_counter_tree_precise_sum(struct percpu_counter_tree *counter) +{ + return percpu_counter_tree_precise_sum_unbiased(counter) + READ_ONCE(counter->bias); +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_precise_sum); + +static +int compare_delta(long delta, unsigned long accuracy_pos, unsigned long accuracy_neg) +{ + if (delta >= 0) { + if (delta <= accuracy_pos) + return 0; + else + return 1; + } else { + if (-delta <= accuracy_neg) + return 0; + else + return -1; + } +} + +/** + * percpu_counter_tree_approximate_compare - Approximated comparison of two counter trees. + * @a: First counter to compare. + * @b: Second counter to compare. + * + * Evaluate an approximate comparison of two counter trees. + * This approximation comparison is fast, and provides an accurate + * answer if the counters are found to be either less than or greater + * than the other. However, if the approximated comparison returns + * 0, the counters respective sums are found to be within the two + * counters accuracy range. + * + * Return: + * * %0 - Counters @a and @b do not differ by more than the sum of their respective + * accuracy ranges. + * * %-1 - Counter @a less than counter @b. + * * %1 - Counter @a is greater than counter @b. + */ +int percpu_counter_tree_approximate_compare(struct percpu_counter_tree *a, struct percpu_counter_tree *b) +{ + return compare_delta(percpu_counter_tree_approximate_sum(a) - percpu_counter_tree_approximate_sum(b), + a->approx_accuracy_range.over + b->approx_accuracy_range.under, + a->approx_accuracy_range.under + b->approx_accuracy_range.over); +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_approximate_compare); + +/** + * percpu_counter_tree_approximate_compare_value - Approximated comparison of a counter tree against a given value. + * @counter: Counter to compare. + * @v: Value to compare. + * + * Evaluate an approximate comparison of a counter tree against a given value. + * This approximation comparison is fast, and provides an accurate + * answer if the counter is found to be either less than or greater + * than the value. However, if the approximated comparison returns + * 0, the value is within the counter accuracy range. + * + * Return: + * * %0 - The value @v is within the accuracy range of the counter. + * * %-1 - The value @v is less than the counter. + * * %1 - The value @v is greater than the counter. + */ +int percpu_counter_tree_approximate_compare_value(struct percpu_counter_tree *counter, long v) +{ + return compare_delta(v - percpu_counter_tree_approximate_sum(counter), + counter->approx_accuracy_range.under, + counter->approx_accuracy_range.over); +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_approximate_compare_value); + +/** + * percpu_counter_tree_precise_compare - Precise comparison of two counter trees. + * @a: First counter to compare. + * @b: Second counter to compare. + * + * Evaluate a precise comparison of two counter trees. + * As an optimization, it uses the approximate counter comparison + * to quickly compare counters which are far apart. Only cases where + * counter sums are within the accuracy range require precise counter + * sums. + * + * Return: + * * %0 - Counters are equal. + * * %-1 - Counter @a less than counter @b. + * * %1 - Counter @a is greater than counter @b. + */ +int percpu_counter_tree_precise_compare(struct percpu_counter_tree *a, struct percpu_counter_tree *b) +{ + long count_a = percpu_counter_tree_approximate_sum(a), + count_b = percpu_counter_tree_approximate_sum(b); + unsigned long accuracy_a, accuracy_b; + long delta = count_a - count_b; + int res; + + res = compare_delta(delta, + a->approx_accuracy_range.over + b->approx_accuracy_range.under, + a->approx_accuracy_range.under + b->approx_accuracy_range.over); + /* The values are distanced enough for an accurate approximated comparison. */ + if (res) + return res; + + /* + * The approximated comparison is within the accuracy range, therefore at least one + * precise sum is needed. Sum the counter which has the largest accuracy first. + */ + if (delta >= 0) { + accuracy_a = a->approx_accuracy_range.under; + accuracy_b = b->approx_accuracy_range.over; + } else { + accuracy_a = a->approx_accuracy_range.over; + accuracy_b = b->approx_accuracy_range.under; + } + if (accuracy_b < accuracy_a) { + count_a = percpu_counter_tree_precise_sum(a); + res = compare_delta(count_a - count_b, + b->approx_accuracy_range.under, + b->approx_accuracy_range.over); + if (res) + return res; + /* Precise sum of second counter is required. */ + count_b = percpu_counter_tree_precise_sum(b); + } else { + count_b = percpu_counter_tree_precise_sum(b); + res = compare_delta(count_a - count_b, + a->approx_accuracy_range.over, + a->approx_accuracy_range.under); + if (res) + return res; + /* Precise sum of second counter is required. */ + count_a = percpu_counter_tree_precise_sum(a); + } + if (count_a - count_b < 0) + return -1; + if (count_a - count_b > 0) + return 1; + return 0; +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_precise_compare); + +/** + * percpu_counter_tree_precise_compare_value - Precise comparison of a counter tree against a given value. + * @counter: Counter to compare. + * @v: Value to compare. + * + * Evaluate a precise comparison of a counter tree against a given value. + * As an optimization, it uses the approximate counter comparison + * to quickly identify whether the counter and value are far apart. + * Only cases where the value is within the counter accuracy range + * require a precise counter sum. + * + * Return: + * * %0 - The value @v is equal to the counter. + * * %-1 - The value @v is less than the counter. + * * %1 - The value @v is greater than the counter. + */ +int percpu_counter_tree_precise_compare_value(struct percpu_counter_tree *counter, long v) +{ + long count = percpu_counter_tree_approximate_sum(counter); + int res; + + res = compare_delta(v - count, + counter->approx_accuracy_range.under, + counter->approx_accuracy_range.over); + /* The values are distanced enough for an accurate approximated comparison. */ + if (res) + return res; + + /* Precise sum is required. */ + count = percpu_counter_tree_precise_sum(counter); + if (v - count < 0) + return -1; + if (v - count > 0) + return 1; + return 0; +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_precise_compare_value); + +static +void percpu_counter_tree_set_bias(struct percpu_counter_tree *counter, long bias) +{ + WRITE_ONCE(counter->bias, bias); +} + +/** + * percpu_counter_tree_set - Set the counter tree sum to a given value. + * @counter: Counter to set. + * @v: Value to set. + * + * Set the counter sum to a given value. It can be useful for instance + * to reset the counter sum to 0. Note that even after setting the + * counter sum to a given value, the counter sum approximation can + * return any value within the accuracy range around that value. + */ +void percpu_counter_tree_set(struct percpu_counter_tree *counter, long v) +{ + percpu_counter_tree_set_bias(counter, + v - percpu_counter_tree_precise_sum_unbiased(counter)); +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_set); + +/* + * percpu_counter_tree_items_size - Query the size required for counter tree items. + * + * Query the size of the memory area required to hold the counter tree + * items. This depends on the hardware topology and is invariant after + * boot. + * + * Return: Size required to hold tree items. + */ +size_t percpu_counter_tree_items_size(void) +{ + if (!nr_cpus_order) + return 0; + return counter_config->nr_items * sizeof(struct percpu_counter_tree_level_item); +} +EXPORT_SYMBOL_GPL(percpu_counter_tree_items_size); + +static void __init calculate_accuracy_topology(void) +{ + unsigned int nr_levels = counter_config->nr_levels, level; + unsigned int level_items = 1U << nr_cpus_order; + unsigned long batch_size = 1; + + for (level = 0; level < nr_levels; level++) { + unsigned int n_arity_order = counter_config->n_arity_order[level]; + + /* + * The accuracy multiplier is derived from a batch size of 1 + * to speed up calculating the accuracy at tree initialization. + */ + accuracy_multiplier += batch_size * level_items; + batch_size <<= n_arity_order; + level_items >>= n_arity_order; + } +} + +int __init percpu_counter_tree_subsystem_init(void) +{ + nr_cpus_order = get_count_order(nr_cpu_ids); + if (WARN_ON_ONCE(nr_cpus_order >= ARRAY_SIZE(per_nr_cpu_order_config))) { + printk(KERN_ERR "Unsupported number of CPUs (%u)\n", nr_cpu_ids); + return -1; + } + counter_config = &per_nr_cpu_order_config[nr_cpus_order]; + calculate_accuracy_topology(); + return 0; +} diff --git a/lib/tests/Makefile b/lib/tests/Makefile index 05f74edbc62b..d282aa23d273 100644 --- a/lib/tests/Makefile +++ b/lib/tests/Makefile @@ -56,4 +56,6 @@ obj-$(CONFIG_UTIL_MACROS_KUNIT) += util_macros_kunit.o obj-$(CONFIG_RATELIMIT_KUNIT_TEST) += test_ratelimit.o obj-$(CONFIG_UUID_KUNIT_TEST) += uuid_kunit.o +obj-$(CONFIG_PERCPU_COUNTER_TREE_TEST) += percpu_counter_tree_kunit.o + obj-$(CONFIG_TEST_RUNTIME_MODULE) += module/ diff --git a/lib/tests/percpu_counter_tree_kunit.c b/lib/tests/percpu_counter_tree_kunit.c new file mode 100644 index 000000000000..a79176655c4b --- /dev/null +++ b/lib/tests/percpu_counter_tree_kunit.c @@ -0,0 +1,399 @@ +// SPDX-License-Identifier: GPL-2.0+ OR MIT +// SPDX-FileCopyrightText: 2026 Mathieu Desnoyers + +#include +#include +#include +#include +#include + +struct multi_thread_test_data { + long increment; + int nr_inc; + int counter_index; +}; + +#define NR_COUNTERS 2 + +/* Hierarchical per-CPU counter instances. */ +static struct percpu_counter_tree counter[NR_COUNTERS]; +static struct percpu_counter_tree_level_item *items; + +/* Global atomic counters for validation. */ +static atomic_long_t global_counter[NR_COUNTERS]; + +static DECLARE_WAIT_QUEUE_HEAD(kernel_threads_wq); +static atomic_t kernel_threads_to_run; + +static void complete_work(void) +{ + if (atomic_dec_and_test(&kernel_threads_to_run)) + wake_up(&kernel_threads_wq); +} + +static void hpcc_print_info(struct kunit *test) +{ + kunit_info(test, "Running test with %d CPUs\n", num_online_cpus()); +} + +static void add_to_counter(int counter_index, unsigned int nr_inc, long increment) +{ + unsigned int i; + + for (i = 0; i < nr_inc; i++) { + percpu_counter_tree_add(&counter[counter_index], increment); + atomic_long_add(increment, &global_counter[counter_index]); + } +} + +static void check_counters(struct kunit *test) +{ + int counter_index; + + /* Compare each counter with its global counter. */ + for (counter_index = 0; counter_index < NR_COUNTERS; counter_index++) { + long v = atomic_long_read(&global_counter[counter_index]); + long approx_sum = percpu_counter_tree_approximate_sum(&counter[counter_index]); + unsigned long under_accuracy = 0, over_accuracy = 0; + long precise_min, precise_max; + + /* Precise comparison. */ + KUNIT_EXPECT_EQ(test, percpu_counter_tree_precise_sum(&counter[counter_index]), v); + KUNIT_EXPECT_EQ(test, 0, percpu_counter_tree_precise_compare_value(&counter[counter_index], v)); + + /* Approximate comparison. */ + KUNIT_EXPECT_EQ(test, 0, percpu_counter_tree_approximate_compare_value(&counter[counter_index], v)); + + /* Accuracy limits checks. */ + percpu_counter_tree_approximate_accuracy_range(&counter[counter_index], &under_accuracy, &over_accuracy); + + KUNIT_EXPECT_GE(test, (long)(approx_sum - (v - under_accuracy)), 0); + KUNIT_EXPECT_LE(test, (long)(approx_sum - (v + over_accuracy)), 0); + KUNIT_EXPECT_GT(test, (long)(approx_sum - (v - under_accuracy - 1)), 0); + KUNIT_EXPECT_LT(test, (long)(approx_sum - (v + over_accuracy + 1)), 0); + + /* Precise min/max range check. */ + percpu_counter_tree_approximate_min_max_range(approx_sum, under_accuracy, over_accuracy, &precise_min, &precise_max); + + KUNIT_EXPECT_GE(test, v - precise_min, 0); + KUNIT_EXPECT_LE(test, v - precise_max, 0); + KUNIT_EXPECT_GT(test, v - (precise_min - 1), 0); + KUNIT_EXPECT_LT(test, v - (precise_max + 1), 0); + } + /* Compare each counter with the second counter. */ + KUNIT_EXPECT_EQ(test, percpu_counter_tree_precise_sum(&counter[0]), percpu_counter_tree_precise_sum(&counter[1])); + KUNIT_EXPECT_EQ(test, 0, percpu_counter_tree_precise_compare(&counter[0], &counter[1])); + KUNIT_EXPECT_EQ(test, 0, percpu_counter_tree_approximate_compare(&counter[0], &counter[1])); +} + +static int multi_thread_worker_fn(void *data) +{ + struct multi_thread_test_data *td = data; + + add_to_counter(td->counter_index, td->nr_inc, td->increment); + complete_work(); + kfree(td); + return 0; +} + +static void test_run_on_specific_cpu(struct kunit *test, int target_cpu, int counter_index, unsigned int nr_inc, long increment) +{ + struct task_struct *task; + struct multi_thread_test_data *td = kzalloc(sizeof(struct multi_thread_test_data), GFP_KERNEL); + + KUNIT_EXPECT_PTR_NE(test, td, NULL); + td->increment = increment; + td->nr_inc = nr_inc; + td->counter_index = counter_index; + atomic_inc(&kernel_threads_to_run); + task = kthread_run_on_cpu(multi_thread_worker_fn, td, target_cpu, "kunit_multi_thread_worker"); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, task); +} + +static void init_kthreads(void) +{ + atomic_set(&kernel_threads_to_run, 1); +} + +static void fini_kthreads(void) +{ + /* Release our own reference. */ + complete_work(); + /* Wait for all others threads to run. */ + wait_event(kernel_threads_wq, (atomic_read(&kernel_threads_to_run) == 0)); +} + +static void test_sync_kthreads(void) +{ + fini_kthreads(); + init_kthreads(); +} + +static void init_counters(struct kunit *test, unsigned long batch_size) +{ + int i, ret; + + items = kzalloc(percpu_counter_tree_items_size() * NR_COUNTERS, GFP_KERNEL); + KUNIT_EXPECT_PTR_NE(test, items, NULL); + ret = percpu_counter_tree_init_many(counter, items, NR_COUNTERS, batch_size, GFP_KERNEL); + KUNIT_EXPECT_EQ(test, ret, 0); + + for (i = 0; i < NR_COUNTERS; i++) + atomic_long_set(&global_counter[i], 0); +} + +static void fini_counters(void) +{ + percpu_counter_tree_destroy_many(counter, NR_COUNTERS); + kfree(items); +} + +enum up_test_inc_type { + INC_ONE, + INC_MINUS_ONE, + INC_RANDOM, +}; + +/* + * Single-threaded tests. Those use many threads to run on various CPUs, + * but synchronize for completion of each thread before running the + * next, effectively making sure there are no concurrent updates. + */ +static void do_hpcc_test_single_thread(struct kunit *test, int _cpu0, int _cpu1, enum up_test_inc_type type) +{ + unsigned long batch_size_order = 5; + int cpu0 = _cpu0; + int cpu1 = _cpu1; + int i; + + init_counters(test, 1UL << batch_size_order); + init_kthreads(); + for (i = 0; i < 10000; i++) { + long increment; + + switch (type) { + case INC_ONE: + increment = 1; + break; + case INC_MINUS_ONE: + increment = -1; + break; + case INC_RANDOM: + increment = (long) get_random_long() % 50000; + break; + } + if (_cpu0 < 0) + cpu0 = cpumask_any_distribute(cpu_online_mask); + if (_cpu1 < 0) + cpu1 = cpumask_any_distribute(cpu_online_mask); + test_run_on_specific_cpu(test, cpu0, 0, 1, increment); + test_sync_kthreads(); + test_run_on_specific_cpu(test, cpu1, 1, 1, increment); + test_sync_kthreads(); + check_counters(test); + } + fini_kthreads(); + fini_counters(); +} + +static void hpcc_test_single_thread_first(struct kunit *test) +{ + int cpu = cpumask_first(cpu_online_mask); + + do_hpcc_test_single_thread(test, cpu, cpu, INC_ONE); + do_hpcc_test_single_thread(test, cpu, cpu, INC_MINUS_ONE); + do_hpcc_test_single_thread(test, cpu, cpu, INC_RANDOM); +} + +static void hpcc_test_single_thread_first_random(struct kunit *test) +{ + int cpu = cpumask_first(cpu_online_mask); + + do_hpcc_test_single_thread(test, cpu, -1, INC_ONE); + do_hpcc_test_single_thread(test, cpu, -1, INC_MINUS_ONE); + do_hpcc_test_single_thread(test, cpu, -1, INC_RANDOM); +} + +static void hpcc_test_single_thread_random(struct kunit *test) +{ + do_hpcc_test_single_thread(test, -1, -1, INC_ONE); + do_hpcc_test_single_thread(test, -1, -1, INC_MINUS_ONE); + do_hpcc_test_single_thread(test, -1, -1, INC_RANDOM); +} + +/* Multi-threaded SMP tests. */ + +static void do_hpcc_multi_thread_increment_each_cpu(struct kunit *test, unsigned long batch_size, unsigned int nr_inc, long increment) +{ + int cpu; + + init_counters(test, batch_size); + init_kthreads(); + for_each_online_cpu(cpu) { + test_run_on_specific_cpu(test, cpu, 0, nr_inc, increment); + test_run_on_specific_cpu(test, cpu, 1, nr_inc, increment); + } + fini_kthreads(); + check_counters(test); + fini_counters(); +} + +static void do_hpcc_multi_thread_increment_even_cpus(struct kunit *test, unsigned long batch_size, unsigned int nr_inc, long increment) +{ + int cpu; + + init_counters(test, batch_size); + init_kthreads(); + for_each_online_cpu(cpu) { + test_run_on_specific_cpu(test, cpu, 0, nr_inc, increment); + test_run_on_specific_cpu(test, cpu & ~1, 1, nr_inc, increment); /* even cpus. */ + } + fini_kthreads(); + check_counters(test); + fini_counters(); +} + +static void do_hpcc_multi_thread_increment_single_cpu(struct kunit *test, unsigned long batch_size, unsigned int nr_inc, long increment) +{ + int cpu; + + init_counters(test, batch_size); + init_kthreads(); + for_each_online_cpu(cpu) { + test_run_on_specific_cpu(test, cpu, 0, nr_inc, increment); + test_run_on_specific_cpu(test, cpumask_first(cpu_online_mask), 1, nr_inc, increment); + } + fini_kthreads(); + check_counters(test); + fini_counters(); +} + +static void do_hpcc_multi_thread_increment_random_cpu(struct kunit *test, unsigned long batch_size, unsigned int nr_inc, long increment) +{ + int cpu; + + init_counters(test, batch_size); + init_kthreads(); + for_each_online_cpu(cpu) { + test_run_on_specific_cpu(test, cpu, 0, nr_inc, increment); + test_run_on_specific_cpu(test, cpumask_any_distribute(cpu_online_mask), 1, nr_inc, increment); + } + fini_kthreads(); + check_counters(test); + fini_counters(); +} + +static void hpcc_test_multi_thread_batch_increment(struct kunit *test) +{ + unsigned long batch_size_order; + + for (batch_size_order = 2; batch_size_order < 10; batch_size_order++) { + unsigned int nr_inc; + + for (nr_inc = 1; nr_inc < 1024; nr_inc *= 2) { + long increment; + + for (increment = 1; increment < 100000; increment *= 10) { + do_hpcc_multi_thread_increment_each_cpu(test, 1UL << batch_size_order, nr_inc, increment); + do_hpcc_multi_thread_increment_even_cpus(test, 1UL << batch_size_order, nr_inc, increment); + do_hpcc_multi_thread_increment_single_cpu(test, 1UL << batch_size_order, nr_inc, increment); + do_hpcc_multi_thread_increment_random_cpu(test, 1UL << batch_size_order, nr_inc, increment); + } + } + } +} + +static void hpcc_test_multi_thread_random_walk(struct kunit *test) +{ + unsigned long batch_size_order = 5; + int loop; + + for (loop = 0; loop < 100; loop++) { + int i; + + init_counters(test, 1UL << batch_size_order); + init_kthreads(); + for (i = 0; i < 1000; i++) { + long increment = (long) get_random_long() % 512; + unsigned int nr_inc = ((unsigned long) get_random_long()) % 1024; + + test_run_on_specific_cpu(test, cpumask_any_distribute(cpu_online_mask), 0, nr_inc, increment); + test_run_on_specific_cpu(test, cpumask_any_distribute(cpu_online_mask), 1, nr_inc, increment); + } + fini_kthreads(); + check_counters(test); + fini_counters(); + } +} + +static void hpcc_test_init_one(struct kunit *test) +{ + struct percpu_counter_tree pct; + struct percpu_counter_tree_level_item *counter_items; + int ret; + + counter_items = kzalloc(percpu_counter_tree_items_size(), GFP_KERNEL); + KUNIT_EXPECT_PTR_NE(test, counter_items, NULL); + ret = percpu_counter_tree_init(&pct, counter_items, 32, GFP_KERNEL); + KUNIT_EXPECT_EQ(test, ret, 0); + + percpu_counter_tree_destroy(&pct); + kfree(counter_items); +} + +static void hpcc_test_set(struct kunit *test) +{ + static long values[] = { + 5, 100, 127, 128, 255, 256, 4095, 4096, 500000, 0, + -5, -100, -127, -128, -255, -256, -4095, -4096, -500000, + }; + struct percpu_counter_tree pct; + struct percpu_counter_tree_level_item *counter_items; + int i, ret; + + counter_items = kzalloc(percpu_counter_tree_items_size(), GFP_KERNEL); + KUNIT_EXPECT_PTR_NE(test, counter_items, NULL); + ret = percpu_counter_tree_init(&pct, counter_items, 32, GFP_KERNEL); + KUNIT_EXPECT_EQ(test, ret, 0); + + for (i = 0; i < ARRAY_SIZE(values); i++) { + long v = values[i]; + + percpu_counter_tree_set(&pct, v); + KUNIT_EXPECT_EQ(test, percpu_counter_tree_precise_sum(&pct), v); + KUNIT_EXPECT_EQ(test, 0, percpu_counter_tree_approximate_compare_value(&pct, v)); + + percpu_counter_tree_add(&pct, v); + KUNIT_EXPECT_EQ(test, percpu_counter_tree_precise_sum(&pct), 2 * v); + KUNIT_EXPECT_EQ(test, 0, percpu_counter_tree_approximate_compare_value(&pct, 2 * v)); + + percpu_counter_tree_add(&pct, -2 * v); + KUNIT_EXPECT_EQ(test, percpu_counter_tree_precise_sum(&pct), 0); + KUNIT_EXPECT_EQ(test, 0, percpu_counter_tree_approximate_compare_value(&pct, 0)); + } + + percpu_counter_tree_destroy(&pct); + kfree(counter_items); +} + +static struct kunit_case hpcc_test_cases[] = { + KUNIT_CASE(hpcc_print_info), + KUNIT_CASE(hpcc_test_single_thread_first), + KUNIT_CASE(hpcc_test_single_thread_first_random), + KUNIT_CASE(hpcc_test_single_thread_random), + KUNIT_CASE(hpcc_test_multi_thread_batch_increment), + KUNIT_CASE(hpcc_test_multi_thread_random_walk), + KUNIT_CASE(hpcc_test_init_one), + KUNIT_CASE(hpcc_test_set), + {} +}; + +static struct kunit_suite hpcc_test_suite = { + .name = "percpu_counter_tree", + .test_cases = hpcc_test_cases, +}; + +kunit_test_suite(hpcc_test_suite); + +MODULE_DESCRIPTION("Test cases for hierarchical per-CPU counters"); +MODULE_LICENSE("Dual MIT/GPL"); diff --git a/lib/vdso/datastore.c b/lib/vdso/datastore.c index a565c30c71a0..faebf5b7cd6e 100644 --- a/lib/vdso/datastore.c +++ b/lib/vdso/datastore.c @@ -1,64 +1,92 @@ // SPDX-License-Identifier: GPL-2.0-only -#include -#include +#include +#include #include #include #include #include #include -/* - * The vDSO data page. - */ +static u8 vdso_initdata[VDSO_NR_PAGES * PAGE_SIZE] __aligned(PAGE_SIZE) __initdata = {}; + #ifdef CONFIG_GENERIC_GETTIMEOFDAY -static union { - struct vdso_time_data data; - u8 page[PAGE_SIZE]; -} vdso_time_data_store __page_aligned_data; -struct vdso_time_data *vdso_k_time_data = &vdso_time_data_store.data; -static_assert(sizeof(vdso_time_data_store) == PAGE_SIZE); +struct vdso_time_data *vdso_k_time_data __refdata = + (void *)&vdso_initdata[VDSO_TIME_PAGE_OFFSET * PAGE_SIZE]; + +static_assert(sizeof(struct vdso_time_data) <= PAGE_SIZE); #endif /* CONFIG_GENERIC_GETTIMEOFDAY */ #ifdef CONFIG_VDSO_GETRANDOM -static union { - struct vdso_rng_data data; - u8 page[PAGE_SIZE]; -} vdso_rng_data_store __page_aligned_data; -struct vdso_rng_data *vdso_k_rng_data = &vdso_rng_data_store.data; -static_assert(sizeof(vdso_rng_data_store) == PAGE_SIZE); +struct vdso_rng_data *vdso_k_rng_data __refdata = + (void *)&vdso_initdata[VDSO_RNG_PAGE_OFFSET * PAGE_SIZE]; + +static_assert(sizeof(struct vdso_rng_data) <= PAGE_SIZE); #endif /* CONFIG_VDSO_GETRANDOM */ #ifdef CONFIG_ARCH_HAS_VDSO_ARCH_DATA -static union { - struct vdso_arch_data data; - u8 page[VDSO_ARCH_DATA_SIZE]; -} vdso_arch_data_store __page_aligned_data; -struct vdso_arch_data *vdso_k_arch_data = &vdso_arch_data_store.data; +struct vdso_arch_data *vdso_k_arch_data __refdata = + (void *)&vdso_initdata[VDSO_ARCH_PAGES_START * PAGE_SIZE]; #endif /* CONFIG_ARCH_HAS_VDSO_ARCH_DATA */ +void __init vdso_setup_data_pages(void) +{ + unsigned int order = get_order(VDSO_NR_PAGES * PAGE_SIZE); + struct page *pages; + + /* + * Allocate the data pages dynamically. SPARC does not support mapping + * static pages to be mapped into userspace. + * It is also a requirement for mlockall() support. + * + * Do not use folios. In time namespaces the pages are mapped in a different order + * to userspace, which is not handled by the folio optimizations in finish_fault(). + */ + pages = alloc_pages(GFP_KERNEL, order); + if (!pages) + panic("Unable to allocate VDSO storage pages"); + + /* The pages are mapped one-by-one into userspace and each one needs to be refcounted. */ + split_page(pages, order); + + /* Move the data already written by other subsystems to the new pages */ + memcpy(page_address(pages), vdso_initdata, VDSO_NR_PAGES * PAGE_SIZE); + + if (IS_ENABLED(CONFIG_GENERIC_GETTIMEOFDAY)) + vdso_k_time_data = page_address(pages + VDSO_TIME_PAGE_OFFSET); + + if (IS_ENABLED(CONFIG_VDSO_GETRANDOM)) + vdso_k_rng_data = page_address(pages + VDSO_RNG_PAGE_OFFSET); + + if (IS_ENABLED(CONFIG_ARCH_HAS_VDSO_ARCH_DATA)) + vdso_k_arch_data = page_address(pages + VDSO_ARCH_PAGES_START); +} + static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, struct vm_area_struct *vma, struct vm_fault *vmf) { - struct page *timens_page = find_timens_vvar_page(vma); - unsigned long addr, pfn; - vm_fault_t err; + struct page *page, *timens_page; + + timens_page = find_timens_vvar_page(vma); switch (vmf->pgoff) { case VDSO_TIME_PAGE_OFFSET: if (!IS_ENABLED(CONFIG_GENERIC_GETTIMEOFDAY)) return VM_FAULT_SIGBUS; - pfn = __phys_to_pfn(__pa_symbol(vdso_k_time_data)); + page = virt_to_page(vdso_k_time_data); if (timens_page) { /* * Fault in VVAR page too, since it will be accessed * to get clock data anyway. */ + unsigned long addr; + vm_fault_t err; + addr = vmf->address + VDSO_TIMENS_PAGE_OFFSET * PAGE_SIZE; - err = vmf_insert_pfn(vma, addr, pfn); + err = vmf_insert_page(vma, addr, page); if (unlikely(err & VM_FAULT_ERROR)) return err; - pfn = page_to_pfn(timens_page); + page = timens_page; } break; case VDSO_TIMENS_PAGE_OFFSET: @@ -71,24 +99,25 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, */ if (!IS_ENABLED(CONFIG_TIME_NS) || !timens_page) return VM_FAULT_SIGBUS; - pfn = __phys_to_pfn(__pa_symbol(vdso_k_time_data)); + page = virt_to_page(vdso_k_time_data); break; case VDSO_RNG_PAGE_OFFSET: if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM)) return VM_FAULT_SIGBUS; - pfn = __phys_to_pfn(__pa_symbol(vdso_k_rng_data)); + page = virt_to_page(vdso_k_rng_data); break; case VDSO_ARCH_PAGES_START ... VDSO_ARCH_PAGES_END: if (!IS_ENABLED(CONFIG_ARCH_HAS_VDSO_ARCH_DATA)) return VM_FAULT_SIGBUS; - pfn = __phys_to_pfn(__pa_symbol(vdso_k_arch_data)) + - vmf->pgoff - VDSO_ARCH_PAGES_START; + page = virt_to_page(vdso_k_arch_data) + vmf->pgoff - VDSO_ARCH_PAGES_START; break; default: return VM_FAULT_SIGBUS; } - return vmf_insert_pfn(vma, vmf->address, pfn); + get_page(page); + vmf->page = page; + return 0; } const struct vm_special_mapping vdso_vvar_mapping = { @@ -100,7 +129,7 @@ struct vm_area_struct *vdso_install_vvar_mapping(struct mm_struct *mm, unsigned { return _install_special_mapping(mm, addr, VDSO_NR_PAGES * PAGE_SIZE, VM_READ | VM_MAYREAD | VM_IO | VM_DONTDUMP | - VM_PFNMAP | VM_SEALED_SYSMAP, + VM_MIXEDMAP | VM_SEALED_SYSMAP, &vdso_vvar_mapping); } diff --git a/mm/memblock.c b/mm/memblock.c index b3ddfdec7a80..ae6a5af46bd7 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -959,28 +959,6 @@ __init void memblock_clear_kho_scratch_only(void) { kho_scratch_only = false; } - -__init void memmap_init_kho_scratch_pages(void) -{ - phys_addr_t start, end; - unsigned long pfn; - int nid; - u64 i; - - if (!IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT)) - return; - - /* - * Initialize struct pages for free scratch memory. - * The struct pages for reserved scratch memory will be set up in - * reserve_bootmem_region() - */ - __for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE, - MEMBLOCK_KHO_SCRATCH, &start, &end, &nid) { - for (pfn = PFN_UP(start); pfn < PFN_DOWN(end); pfn++) - init_deferred_page(pfn, nid); - } -} #endif /** diff --git a/mm/mm_init.c b/mm/mm_init.c index df34797691bd..7363b5b0d22a 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -786,7 +786,8 @@ void __meminit reserve_bootmem_region(phys_addr_t start, for_each_valid_pfn(pfn, PFN_DOWN(start), PFN_UP(end)) { struct page *page = pfn_to_page(pfn); - __init_deferred_page(pfn, nid); + if (!pfn_is_kho_scratch(pfn)) + __init_deferred_page(pfn, nid); /* * no need for atomic set_bit because the struct @@ -1996,9 +1997,12 @@ static void __init deferred_free_pages(unsigned long pfn, /* Free a large naturally-aligned chunk if possible */ if (nr_pages == MAX_ORDER_NR_PAGES && IS_MAX_ORDER_ALIGNED(pfn)) { - for (i = 0; i < nr_pages; i += pageblock_nr_pages) + for (i = 0; i < nr_pages; i += pageblock_nr_pages) { + if (pfn_is_kho_scratch(page_to_pfn(page + i))) + continue; init_pageblock_migratetype(page + i, MIGRATE_MOVABLE, false); + } __free_pages_core(page, MAX_PAGE_ORDER, MEMINIT_EARLY); return; } @@ -2007,7 +2011,7 @@ static void __init deferred_free_pages(unsigned long pfn, accept_memory(PFN_PHYS(pfn), nr_pages * PAGE_SIZE); for (i = 0; i < nr_pages; i++, page++, pfn++) { - if (pageblock_aligned(pfn)) + if (pageblock_aligned(pfn) && !pfn_is_kho_scratch(pfn)) init_pageblock_migratetype(page, MIGRATE_MOVABLE, false); __free_pages_core(page, 0, MEMINIT_EARLY); @@ -2078,9 +2082,11 @@ deferred_init_memmap_chunk(unsigned long start_pfn, unsigned long end_pfn, unsigned long mo_pfn = ALIGN(spfn + 1, MAX_ORDER_NR_PAGES); unsigned long chunk_end = min(mo_pfn, epfn); - nr_pages += deferred_init_pages(zone, spfn, chunk_end); - deferred_free_pages(spfn, chunk_end - spfn); + // KHO scratch is MAX_ORDER_NR_PAGES aligned. + if (!pfn_is_kho_scratch(spfn)) + deferred_init_pages(zone, spfn, chunk_end); + deferred_free_pages(spfn, chunk_end - spfn); spfn = chunk_end; if (can_resched) @@ -2088,6 +2094,7 @@ deferred_init_memmap_chunk(unsigned long start_pfn, unsigned long end_pfn, else touch_nmi_watchdog(); } + nr_pages += epfn - spfn; } return nr_pages;