arch/x86/mm/cpu_entry_area.c

Source file repositories/reference/linux-study-clean/arch/x86/mm/cpu_entry_area.c

File Facts

System
Linux kernel
Corpus path
arch/x86/mm/cpu_entry_area.c
Extension
.c
Size
7999 bytes
Lines
280
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

for_each_possible_cpu(j) {
			if (cea_offset(j) == cea)
				goto again;

			if (i == j)
				break;
		}

		per_cpu(_cea_offset, i) = cea;
	}
}
#else /* !X86_64 */
DECLARE_PER_CPU_PAGE_ALIGNED(struct doublefault_stack, doublefault_stack);

static __always_inline unsigned int cea_offset(unsigned int cpu)
{
	return cpu;
}
static inline void init_cea_offsets(void) { }
#endif

/* Is called from entry code, so must be noinstr */
noinstr struct cpu_entry_area *get_cpu_entry_area(int cpu)
{
	unsigned long va = CPU_ENTRY_AREA_PER_CPU + cea_offset(cpu) * CPU_ENTRY_AREA_SIZE;
	BUILD_BUG_ON(sizeof(struct cpu_entry_area) % PAGE_SIZE != 0);

	return (struct cpu_entry_area *) va;
}
EXPORT_SYMBOL(get_cpu_entry_area);

void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags)
{
	unsigned long va = (unsigned long) cea_vaddr;
	pte_t pte = pfn_pte(pa >> PAGE_SHIFT, flags);

	/*
	 * The cpu_entry_area is shared between the user and kernel
	 * page tables.  All of its ptes can safely be global.
	 * _PAGE_GLOBAL gets reused to help indicate PROT_NONE for
	 * non-present PTEs, so be careful not to set it in that
	 * case to avoid confusion.
	 */
	if (boot_cpu_has(X86_FEATURE_PGE) &&
	    (pgprot_val(flags) & _PAGE_PRESENT))
		pte = pte_set_flags(pte, _PAGE_GLOBAL);

	set_pte_vaddr(va, pte);
}

static void __init
cea_map_percpu_pages(void *cea_vaddr, void *ptr, int pages, pgprot_t prot)
{
	for ( ; pages; pages--, cea_vaddr+= PAGE_SIZE, ptr += PAGE_SIZE)
		cea_set_pte(cea_vaddr, per_cpu_ptr_to_phys(ptr), prot);
}

static void __init percpu_setup_debug_store(unsigned int cpu)
{
#ifdef CONFIG_CPU_SUP_INTEL
	unsigned int npages;
	void *cea;

	if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
		return;

	cea = &get_cpu_entry_area(cpu)->cpu_debug_store;
	npages = sizeof(struct debug_store) / PAGE_SIZE;
	BUILD_BUG_ON(sizeof(struct debug_store) % PAGE_SIZE != 0);
	cea_map_percpu_pages(cea, &per_cpu(cpu_debug_store, cpu), npages,
			     PAGE_KERNEL);

	cea = &get_cpu_entry_area(cpu)->cpu_debug_buffers;
	/*
	 * Force the population of PMDs for not yet allocated per cpu
	 * memory like debug store buffers.
	 */
	npages = sizeof(struct debug_store_buffers) / PAGE_SIZE;
	for (; npages; npages--, cea += PAGE_SIZE)
		cea_set_pte(cea, 0, PAGE_NONE);
#endif
}

#ifdef CONFIG_X86_64

#define cea_map_stack(name) do {					\
	npages = sizeof(estacks->name## _stack) / PAGE_SIZE;		\
	cea_map_percpu_pages(cea->estacks.name## _stack,		\
			estacks->name## _stack, npages, PAGE_KERNEL);	\
	} while (0)

Annotation

Implementation Notes