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26 results

setup_percpu.c

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    • Thomas Gleixner's avatar
      945fd17a
      x86/cpu_entry_area: Sync cpu_entry_area to initial_page_table · 945fd17a
      Thomas Gleixner authored
      
      The separation of the cpu_entry_area from the fixmap missed the fact that
      on 32bit non-PAE kernels the cpu_entry_area mapping might not be covered in
      initial_page_table by the previous synchronizations.
      
      This results in suspend/resume failures because 32bit utilizes initial page
      table for resume. The absence of the cpu_entry_area mapping results in a
      triple fault, aka. insta reboot.
      
      With PAE enabled this works by chance because the PGD entry which covers
      the fixmap and other parts incindentally provides the cpu_entry_area
      mapping as well.
      
      Synchronize the initial page table after setting up the cpu entry
      area. Instead of adding yet another copy of the same code, move it to a
      function and invoke it from the various places.
      
      It needs to be investigated if the existing calls in setup_arch() and
      setup_per_cpu_areas() can be replaced by the later invocation from
      setup_cpu_entry_areas(), but that's beyond the scope of this fix.
      
      Fixes: 92a0f81d ("x86/cpu_entry_area: Move it out of the fixmap")
      Reported-by: default avatarWoody Suwalski <terraluna977@gmail.com>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Tested-by: default avatarWoody Suwalski <terraluna977@gmail.com>
      Cc: William Grant <william.grant@canonical.com>
      Cc: stable@vger.kernel.org
      Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1802282137290.1392@nanos.tec.linutronix.de
      945fd17a
      History
      x86/cpu_entry_area: Sync cpu_entry_area to initial_page_table
      Thomas Gleixner authored
      
      The separation of the cpu_entry_area from the fixmap missed the fact that
      on 32bit non-PAE kernels the cpu_entry_area mapping might not be covered in
      initial_page_table by the previous synchronizations.
      
      This results in suspend/resume failures because 32bit utilizes initial page
      table for resume. The absence of the cpu_entry_area mapping results in a
      triple fault, aka. insta reboot.
      
      With PAE enabled this works by chance because the PGD entry which covers
      the fixmap and other parts incindentally provides the cpu_entry_area
      mapping as well.
      
      Synchronize the initial page table after setting up the cpu entry
      area. Instead of adding yet another copy of the same code, move it to a
      function and invoke it from the various places.
      
      It needs to be investigated if the existing calls in setup_arch() and
      setup_per_cpu_areas() can be replaced by the later invocation from
      setup_cpu_entry_areas(), but that's beyond the scope of this fix.
      
      Fixes: 92a0f81d ("x86/cpu_entry_area: Move it out of the fixmap")
      Reported-by: default avatarWoody Suwalski <terraluna977@gmail.com>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Tested-by: default avatarWoody Suwalski <terraluna977@gmail.com>
      Cc: William Grant <william.grant@canonical.com>
      Cc: stable@vger.kernel.org
      Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1802282137290.1392@nanos.tec.linutronix.de
    setup_percpu.c 8.47 KiB
    // 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();
    
    	/*
    	 * 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.
    	 *
    	 * FIXME: Can the later sync in setup_cpu_entry_areas() replace
    	 * this call?
    	 */
    	sync_initial_page_table();
    }