arch/x86/include/asm/desc.h

Source file repositories/reference/linux-study-clean/arch/x86/include/asm/desc.h

File Facts

System
Linux kernel
Corpus path
arch/x86/include/asm/desc.h
Extension
.h
Size
11618 bytes
Lines
454
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: implementation source
Status
source 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

struct gdt_page {
	struct desc_struct gdt[GDT_ENTRIES];
} __attribute__((aligned(PAGE_SIZE)));

DECLARE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page);

/* Provide the original GDT */
static inline struct desc_struct *get_cpu_gdt_rw(unsigned int cpu)
{
	return per_cpu(gdt_page, cpu).gdt;
}

/* Provide the current original GDT */
static inline struct desc_struct *get_current_gdt_rw(void)
{
	return this_cpu_ptr(&gdt_page)->gdt;
}

/* Provide the fixmap address of the remapped GDT */
static inline struct desc_struct *get_cpu_gdt_ro(int cpu)
{
	return (struct desc_struct *)&get_cpu_entry_area(cpu)->gdt;
}

/* Provide the current read-only GDT */
static inline struct desc_struct *get_current_gdt_ro(void)
{
	return get_cpu_gdt_ro(smp_processor_id());
}

/* Provide the physical address of the GDT page. */
static inline phys_addr_t get_cpu_gdt_paddr(unsigned int cpu)
{
	return per_cpu_ptr_to_phys(get_cpu_gdt_rw(cpu));
}

static inline void pack_gate(gate_desc *gate, unsigned type, unsigned long func,
			     unsigned dpl, unsigned ist, unsigned seg)
{
	gate->offset_low	= (u16) func;
	gate->bits.p		= 1;
	gate->bits.dpl		= dpl;
	gate->bits.zero		= 0;
	gate->bits.type		= type;
	gate->offset_middle	= (u16) (func >> 16);
#ifdef CONFIG_X86_64
	gate->segment		= __KERNEL_CS;
	gate->bits.ist		= ist;
	gate->reserved		= 0;
	gate->offset_high	= (u32) (func >> 32);
#else
	gate->segment		= seg;
	gate->bits.ist		= 0;
#endif
}

static inline int desc_empty(const void *ptr)
{
	const u32 *desc = ptr;

	return !(desc[0] | desc[1]);
}

#ifdef CONFIG_PARAVIRT_XXL
#include <asm/paravirt.h>
#else
#define load_TR_desc()				native_load_tr_desc()
#define load_gdt(dtr)				native_load_gdt(dtr)
#define load_idt(dtr)				native_load_idt(dtr)
#define load_tr(tr)				asm volatile("ltr %0"::"m" (tr))
#define load_ldt(ldt)				asm volatile("lldt %0"::"m" (ldt))

#define store_gdt(dtr)				native_store_gdt(dtr)
#define store_tr(tr)				(tr = native_store_tr())

#define load_TLS(t, cpu)			native_load_tls(t, cpu)
#define set_ldt					native_set_ldt

#define write_ldt_entry(dt, entry, desc)	native_write_ldt_entry(dt, entry, desc)
#define write_gdt_entry(dt, entry, desc, type)	native_write_gdt_entry(dt, entry, desc, type)
#define write_idt_entry(dt, entry, g)		native_write_idt_entry(dt, entry, g)

static inline void paravirt_alloc_ldt(struct desc_struct *ldt, unsigned entries)
{
}

static inline void paravirt_free_ldt(struct desc_struct *ldt, unsigned entries)
{
}
#endif	/* CONFIG_PARAVIRT_XXL */

Annotation

Implementation Notes