arch/x86/kernel/setup_percpu.c - arm/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/init.h>
 #include <linux/bootmem.h>
 #include <linux/percpu.h>
 #include <linux/kexec.h>
 #include <linux/crash_dump.h>
 #include <linux/smp.h>
 #include <linux/topology.h>
 #include <linux/pfn.h>
 #include <asm/sections.h>
 #include <asm/processor.h>
 #include <asm/desc.h>
 #include <asm/setup.h>
 #include <asm/mpspec.h>
 #include <asm/apicdef.h>
 #include <asm/highmem.h>
 #include <asm/proto.h>
 #include <asm/cpumask.h>
 #include <asm/cpu.h>
 #include <asm/stackprotector.h>

 DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
 EXPORT_PER_CPU_SYMBOL(cpu_number);

 #ifdef CONFIG_X86_64
 #define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load)
 #else
 #define BOOT_PERCPU_OFFSET 0
 #endif

 DEFINE_PER_CPU_READ_MOSTLY(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET;
 EXPORT_PER_CPU_SYMBOL(this_cpu_off);

 unsigned long __per_cpu_offset[NR_CPUS] __ro_after_init = {
 	[0 ... NR_CPUS-1] = BOOT_PERCPU_OFFSET,
 };
 EXPORT_SYMBOL(__per_cpu_offset);

 /*
  * On x86_64 symbols referenced from code should be reachable using
  * 32bit relocations.  Reserve space for static percpu variables in
  * modules so that they are always served from the first chunk which
  * is located at the percpu segment base.  On x86_32, anything can
  * address anywhere.  No need to reserve space in the first chunk.
  */
 #ifdef CONFIG_X86_64
 #define PERCPU_FIRST_CHUNK_RESERVE	PERCPU_MODULE_RESERVE
 #else
 #define PERCPU_FIRST_CHUNK_RESERVE	0
 #endif

 #ifdef CONFIG_X86_32
 /**
  * pcpu_need_numa - determine percpu allocation needs to consider NUMA
  *
  * If NUMA is not configured or there is only one NUMA node available,
  * there is no reason to consider NUMA.  This function determines
  * whether percpu allocation should consider NUMA or not.
  *
  * RETURNS:
  * true if NUMA should be considered; otherwise, false.
  */
 static bool __init pcpu_need_numa(void)
 {
 #ifdef CONFIG_NEED_MULTIPLE_NODES
 	pg_data_t *last = NULL;
 	unsigned int cpu;

 	for_each_possible_cpu(cpu) {
 		int node = early_cpu_to_node(cpu);

 		if (node_online(node) && NODE_DATA(node) &&
 		    last && last != NODE_DATA(node))
 			return true;

 		last = NODE_DATA(node);
 	}
 #endif
 	return false;
 }
 #endif

 /**
  * pcpu_alloc_bootmem - NUMA friendly alloc_bootmem wrapper for percpu
  * @cpu: cpu to allocate for
  * @size: size allocation in bytes
  * @align: alignment
  *
  * Allocate @size bytes aligned at @align for cpu @cpu.  This wrapper
  * does the right thing for NUMA regardless of the current
  * configuration.
  *
  * RETURNS:
  * Pointer to the allocated area on success, NULL on failure.
  */
 static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
 					unsigned long align)
 {
 	const unsigned long goal = __pa(MAX_DMA_ADDRESS);
 #ifdef CONFIG_NEED_MULTIPLE_NODES
 	int node = early_cpu_to_node(cpu);
 	void *ptr;

 	if (!node_online(node) || !NODE_DATA(node)) {
 		ptr = __alloc_bootmem_nopanic(size, align, goal);
 		pr_info("cpu %d has no node %d or node-local memory\n",
 			cpu, node);
 		pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
 			 cpu, size, __pa(ptr));
 	} else {
 		ptr = __alloc_bootmem_node_nopanic(NODE_DATA(node),
 						   size, align, goal);
 		pr_debug("per cpu data for cpu%d %lu bytes on node%d at %016lx\n",
 			 cpu, size, node, __pa(ptr));
 	}
 	return ptr;
 #else
 	return __alloc_bootmem_nopanic(size, align, goal);
 #endif
 }

 /*
  * Helpers for first chunk memory allocation
  */
 static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size, size_t align)
 {
 	return pcpu_alloc_bootmem(cpu, size, align);
 }

 static void __init pcpu_fc_free(void *ptr, size_t size)
 {
 	free_bootmem(__pa(ptr), size);
 }

 static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
 {
 #ifdef CONFIG_NEED_MULTIPLE_NODES
 	if (early_cpu_to_node(from) == early_cpu_to_node(to))
 		return LOCAL_DISTANCE;
 	else
 		return REMOTE_DISTANCE;
 #else
 	return LOCAL_DISTANCE;
 #endif
 }

 static void __init pcpup_populate_pte(unsigned long addr)
 {
 	populate_extra_pte(addr);
 }

 static inline void setup_percpu_segment(int cpu)
 {
 #ifdef CONFIG_X86_32
 	struct desc_struct d = GDT_ENTRY_INIT(0x8092, per_cpu_offset(cpu),
 					      0xFFFFF);

 	write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PERCPU, &d, DESCTYPE_S);
 #endif
 }

 void __init setup_per_cpu_areas(void)
 {
 	unsigned int cpu;
 	unsigned long delta;
 	int rc;

 	pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%u nr_node_ids:%d\n",
 		NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);

 	/*
 	 * Allocate percpu area.  Embedding allocator is our favorite;
 	 * however, on NUMA configurations, it can result in very
 	 * sparse unit mapping and vmalloc area isn't spacious enough
 	 * on 32bit.  Use page in that case.
 	 */
 #ifdef CONFIG_X86_32
 	if (pcpu_chosen_fc == PCPU_FC_AUTO && pcpu_need_numa())
 		pcpu_chosen_fc = PCPU_FC_PAGE;
 #endif
 	rc = -EINVAL;
 	if (pcpu_chosen_fc != PCPU_FC_PAGE) {
 		const size_t dyn_size = PERCPU_MODULE_RESERVE +
 			PERCPU_DYNAMIC_RESERVE - PERCPU_FIRST_CHUNK_RESERVE;
 		size_t atom_size;

 		/*
 		 * On 64bit, use PMD_SIZE for atom_size so that embedded
 		 * percpu areas are aligned to PMD.  This, in the future,
 		 * can also allow using PMD mappings in vmalloc area.  Use
 		 * PAGE_SIZE on 32bit as vmalloc space is highly contended
 		 * and large vmalloc area allocs can easily fail.
 		 */
 #ifdef CONFIG_X86_64
 		atom_size = PMD_SIZE;
 #else
 		atom_size = PAGE_SIZE;
 #endif
 		rc = pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
 					    dyn_size, atom_size,
 					    pcpu_cpu_distance,
 					    pcpu_fc_alloc, pcpu_fc_free);
 		if (rc < 0)
 			pr_warning("%s allocator failed (%d), falling back to page size\n",
 				   pcpu_fc_names[pcpu_chosen_fc], rc);
 	}
 	if (rc < 0)
 		rc = pcpu_page_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
 					   pcpu_fc_alloc, pcpu_fc_free,
 					   pcpup_populate_pte);
 	if (rc < 0)
 		panic("cannot initialize percpu area (err=%d)", rc);

 	/* alrighty, percpu areas up and running */
 	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
 	for_each_possible_cpu(cpu) {
 		per_cpu_offset(cpu) = delta + pcpu_unit_offsets[cpu];
 		per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
 		per_cpu(cpu_number, cpu) = cpu;
 		setup_percpu_segment(cpu);
 		setup_stack_canary_segment(cpu);
 		/*
 		 * Copy data used in early init routines from the
 		 * initial arrays to the per cpu data areas.  These
 		 * arrays then become expendable and the *_early_ptr's
 		 * are zeroed indicating that the static arrays are
 		 * gone.
 		 */
 #ifdef CONFIG_X86_LOCAL_APIC
 		per_cpu(x86_cpu_to_apicid, cpu) =
 			early_per_cpu_map(x86_cpu_to_apicid, cpu);
 		per_cpu(x86_bios_cpu_apicid, cpu) =
 			early_per_cpu_map(x86_bios_cpu_apicid, cpu);
 		per_cpu(x86_cpu_to_acpiid, cpu) =
 			early_per_cpu_map(x86_cpu_to_acpiid, cpu);
 #endif
 #ifdef CONFIG_X86_32
 		per_cpu(x86_cpu_to_logical_apicid, cpu) =
 			early_per_cpu_map(x86_cpu_to_logical_apicid, cpu);
 #endif
 #ifdef CONFIG_X86_64
 		per_cpu(irq_stack_ptr, cpu) =
 			per_cpu(irq_stack_union.irq_stack, cpu) +
 			IRQ_STACK_SIZE;
 #endif
 #ifdef CONFIG_NUMA
 		per_cpu(x86_cpu_to_node_map, cpu) =
 			early_per_cpu_map(x86_cpu_to_node_map, cpu);
 		/*
 		 * Ensure that the boot cpu numa_node is correct when the boot
 		 * cpu is on a node that doesn't have memory installed.
 		 * Also cpu_up() will call cpu_to_node() for APs when
 		 * MEMORY_HOTPLUG is defined, before per_cpu(numa_node) is set
 		 * up later with c_init aka intel_init/amd_init.
 		 * So set them all (boot cpu and all APs).
 		 */
 		set_cpu_numa_node(cpu, early_cpu_to_node(cpu));
 #endif
 		/*
 		 * Up to this point, the boot CPU has been using .init.data
 		 * area.  Reload any changed state for the boot CPU.
 		 */
 		if (!cpu)
 			switch_to_new_gdt(cpu);
 	}

 	/* indicate the early static arrays will soon be gone */
 #ifdef CONFIG_X86_LOCAL_APIC
 	early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
 	early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
 	early_per_cpu_ptr(x86_cpu_to_acpiid) = NULL;
 #endif
 #ifdef CONFIG_X86_32
 	early_per_cpu_ptr(x86_cpu_to_logical_apicid) = NULL;
 #endif
 #ifdef CONFIG_NUMA
 	early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
 #endif

 	/* Setup node to cpumask map */
 	setup_node_to_cpumask_map();

 	/* Setup cpu initialized, callin, callout masks */
 	setup_cpu_local_masks();

 #ifdef CONFIG_X86_32
 	/*
 	 * Sync back kernel address range again.  We already did this in
 	 * setup_arch(), but percpu data also needs to be available in
 	 * the smpboot asm.  We can't reliably pick up percpu mappings
 	 * using vmalloc_fault(), because exception dispatch needs
 	 * percpu data.
 	 */
 	clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,
 			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
 			KERNEL_PGD_PTRS);

 	/*
 	 * sync back low identity map too.  It is used for example
 	 * in the 32-bit EFI stub.
 	 */
 	clone_pgd_range(initial_page_table,
 			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
 			min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
 #endif
 }
	// SPDX-License-Identifier: GPL-2.0
	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/kernel.h>
	#include <linux/export.h>
	#include <linux/init.h>
	#include <linux/bootmem.h>
	#include <linux/percpu.h>
	#include <linux/kexec.h>
	#include <linux/crash_dump.h>
	#include <linux/smp.h>
	#include <linux/topology.h>
	#include <linux/pfn.h>
	#include <asm/sections.h>
	#include <asm/processor.h>
	#include <asm/desc.h>
	#include <asm/setup.h>
	#include <asm/mpspec.h>
	#include <asm/apicdef.h>
	#include <asm/highmem.h>
	#include <asm/proto.h>
	#include <asm/cpumask.h>
	#include <asm/cpu.h>
	#include <asm/stackprotector.h>

	DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
	EXPORT_PER_CPU_SYMBOL(cpu_number);

	#ifdef CONFIG_X86_64
	#define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load)
	#else
	#define BOOT_PERCPU_OFFSET 0
	#endif

	DEFINE_PER_CPU_READ_MOSTLY(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET;
	EXPORT_PER_CPU_SYMBOL(this_cpu_off);

	unsigned long __per_cpu_offset[NR_CPUS] __ro_after_init = {
	[0 ... NR_CPUS-1] = BOOT_PERCPU_OFFSET,
	};
	EXPORT_SYMBOL(__per_cpu_offset);

	/*
	* On x86_64 symbols referenced from code should be reachable using
	* 32bit relocations. Reserve space for static percpu variables in
	* modules so that they are always served from the first chunk which
	* is located at the percpu segment base. On x86_32, anything can
	* address anywhere. No need to reserve space in the first chunk.
	*/
	#ifdef CONFIG_X86_64
	#define PERCPU_FIRST_CHUNK_RESERVE PERCPU_MODULE_RESERVE
	#else
	#define PERCPU_FIRST_CHUNK_RESERVE 0
	#endif

	#ifdef CONFIG_X86_32
	/**
	* pcpu_need_numa - determine percpu allocation needs to consider NUMA
	*
	* If NUMA is not configured or there is only one NUMA node available,
	* there is no reason to consider NUMA. This function determines
	* whether percpu allocation should consider NUMA or not.
	*
	* RETURNS:
	* true if NUMA should be considered; otherwise, false.
	*/
	static bool __init pcpu_need_numa(void)
	{
	#ifdef CONFIG_NEED_MULTIPLE_NODES
	pg_data_t *last = NULL;
	unsigned int cpu;

	for_each_possible_cpu(cpu) {
	int node = early_cpu_to_node(cpu);

	if (node_online(node) && NODE_DATA(node) &&
	last && last != NODE_DATA(node))
	return true;

	last = NODE_DATA(node);
	}
	#endif
	return false;
	}
	#endif

	/**
	* pcpu_alloc_bootmem - NUMA friendly alloc_bootmem wrapper for percpu
	* @cpu: cpu to allocate for
	* @size: size allocation in bytes
	* @align: alignment
	*
	* Allocate @size bytes aligned at @align for cpu @cpu. This wrapper
	* does the right thing for NUMA regardless of the current
	* configuration.
	*
	* RETURNS:
	* Pointer to the allocated area on success, NULL on failure.
	*/
	static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
	unsigned long align)
	{
	const unsigned long goal = __pa(MAX_DMA_ADDRESS);
	#ifdef CONFIG_NEED_MULTIPLE_NODES
	int node = early_cpu_to_node(cpu);
	void *ptr;

	if (!node_online(node) \|\| !NODE_DATA(node)) {
	ptr = __alloc_bootmem_nopanic(size, align, goal);
	pr_info("cpu %d has no node %d or node-local memory\n",
	cpu, node);
	pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
	cpu, size, __pa(ptr));
	} else {
	ptr = __alloc_bootmem_node_nopanic(NODE_DATA(node),
	size, align, goal);
	pr_debug("per cpu data for cpu%d %lu bytes on node%d at %016lx\n",
	cpu, size, node, __pa(ptr));
	}
	return ptr;
	#else
	return __alloc_bootmem_nopanic(size, align, goal);
	#endif
	}

	/*
	* Helpers for first chunk memory allocation
	*/
	static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size, size_t align)
	{
	return pcpu_alloc_bootmem(cpu, size, align);
	}

	static void __init pcpu_fc_free(void *ptr, size_t size)
	{
	free_bootmem(__pa(ptr), size);
	}

	static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
	{
	#ifdef CONFIG_NEED_MULTIPLE_NODES
	if (early_cpu_to_node(from) == early_cpu_to_node(to))
	return LOCAL_DISTANCE;
	else
	return REMOTE_DISTANCE;
	#else
	return LOCAL_DISTANCE;
	#endif
	}

	static void __init pcpup_populate_pte(unsigned long addr)
	{
	populate_extra_pte(addr);
	}

	static inline void setup_percpu_segment(int cpu)
	{
	#ifdef CONFIG_X86_32
	struct desc_struct d = GDT_ENTRY_INIT(0x8092, per_cpu_offset(cpu),
	0xFFFFF);

	write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PERCPU, &d, DESCTYPE_S);
	#endif
	}

	void __init setup_per_cpu_areas(void)
	{
	unsigned int cpu;
	unsigned long delta;
	int rc;

	pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%u nr_node_ids:%d\n",
	NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);

	/*
	* Allocate percpu area. Embedding allocator is our favorite;
	* however, on NUMA configurations, it can result in very
	* sparse unit mapping and vmalloc area isn't spacious enough
	* on 32bit. Use page in that case.
	*/
	#ifdef CONFIG_X86_32
	if (pcpu_chosen_fc == PCPU_FC_AUTO && pcpu_need_numa())
	pcpu_chosen_fc = PCPU_FC_PAGE;
	#endif
	rc = -EINVAL;
	if (pcpu_chosen_fc != PCPU_FC_PAGE) {
	const size_t dyn_size = PERCPU_MODULE_RESERVE +
	PERCPU_DYNAMIC_RESERVE - PERCPU_FIRST_CHUNK_RESERVE;
	size_t atom_size;

	/*
	* On 64bit, use PMD_SIZE for atom_size so that embedded
	* percpu areas are aligned to PMD. This, in the future,
	* can also allow using PMD mappings in vmalloc area. Use
	* PAGE_SIZE on 32bit as vmalloc space is highly contended
	* and large vmalloc area allocs can easily fail.
	*/
	#ifdef CONFIG_X86_64
	atom_size = PMD_SIZE;
	#else
	atom_size = PAGE_SIZE;
	#endif
	rc = pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
	dyn_size, atom_size,
	pcpu_cpu_distance,
	pcpu_fc_alloc, pcpu_fc_free);
	if (rc < 0)
	pr_warning("%s allocator failed (%d), falling back to page size\n",
	pcpu_fc_names[pcpu_chosen_fc], rc);
	}
	if (rc < 0)
	rc = pcpu_page_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
	pcpu_fc_alloc, pcpu_fc_free,
	pcpup_populate_pte);
	if (rc < 0)
	panic("cannot initialize percpu area (err=%d)", rc);

	/* alrighty, percpu areas up and running */
	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
	for_each_possible_cpu(cpu) {
	per_cpu_offset(cpu) = delta + pcpu_unit_offsets[cpu];
	per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
	per_cpu(cpu_number, cpu) = cpu;
	setup_percpu_segment(cpu);
	setup_stack_canary_segment(cpu);
	/*
	* Copy data used in early init routines from the
	* initial arrays to the per cpu data areas. These
	* arrays then become expendable and the *_early_ptr's
	* are zeroed indicating that the static arrays are
	* gone.
	*/
	#ifdef CONFIG_X86_LOCAL_APIC
	per_cpu(x86_cpu_to_apicid, cpu) =
	early_per_cpu_map(x86_cpu_to_apicid, cpu);
	per_cpu(x86_bios_cpu_apicid, cpu) =
	early_per_cpu_map(x86_bios_cpu_apicid, cpu);
	per_cpu(x86_cpu_to_acpiid, cpu) =
	early_per_cpu_map(x86_cpu_to_acpiid, cpu);
	#endif
	#ifdef CONFIG_X86_32
	per_cpu(x86_cpu_to_logical_apicid, cpu) =
	early_per_cpu_map(x86_cpu_to_logical_apicid, cpu);
	#endif
	#ifdef CONFIG_X86_64
	per_cpu(irq_stack_ptr, cpu) =
	per_cpu(irq_stack_union.irq_stack, cpu) +
	IRQ_STACK_SIZE;
	#endif
	#ifdef CONFIG_NUMA
	per_cpu(x86_cpu_to_node_map, cpu) =
	early_per_cpu_map(x86_cpu_to_node_map, cpu);
	/*
	* Ensure that the boot cpu numa_node is correct when the boot
	* cpu is on a node that doesn't have memory installed.
	* Also cpu_up() will call cpu_to_node() for APs when
	* MEMORY_HOTPLUG is defined, before per_cpu(numa_node) is set
	* up later with c_init aka intel_init/amd_init.
	* So set them all (boot cpu and all APs).
	*/
	set_cpu_numa_node(cpu, early_cpu_to_node(cpu));
	#endif
	/*
	* Up to this point, the boot CPU has been using .init.data
	* area. Reload any changed state for the boot CPU.
	*/
	if (!cpu)
	switch_to_new_gdt(cpu);
	}

	/* indicate the early static arrays will soon be gone */
	#ifdef CONFIG_X86_LOCAL_APIC
	early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
	early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
	early_per_cpu_ptr(x86_cpu_to_acpiid) = NULL;
	#endif
	#ifdef CONFIG_X86_32
	early_per_cpu_ptr(x86_cpu_to_logical_apicid) = NULL;
	#endif
	#ifdef CONFIG_NUMA
	early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
	#endif

	/* Setup node to cpumask map */
	setup_node_to_cpumask_map();

	/* Setup cpu initialized, callin, callout masks */
	setup_cpu_local_masks();

	#ifdef CONFIG_X86_32
	/*
	* Sync back kernel address range again. We already did this in
	* setup_arch(), but percpu data also needs to be available in
	* the smpboot asm. We can't reliably pick up percpu mappings
	* using vmalloc_fault(), because exception dispatch needs
	* percpu data.
	*/
	clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,
	swapper_pg_dir + KERNEL_PGD_BOUNDARY,
	KERNEL_PGD_PTRS);

	/*
	* sync back low identity map too. It is used for example
	* in the 32-bit EFI stub.
	*/
	clone_pgd_range(initial_page_table,
	swapper_pg_dir + KERNEL_PGD_BOUNDARY,
	min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
	#endif
	}