arch/x86/include/asm/io_bitmap.h

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

File Facts

System
Linux kernel
Corpus path
arch/x86/include/asm/io_bitmap.h
Extension
.h
Size
1370 bytes
Lines
53
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 io_bitmap {
	u64		sequence;
	refcount_t	refcnt;
	/* The maximum number of bytes to copy so all zero bits are covered */
	unsigned int	max;
	unsigned long	bitmap[IO_BITMAP_LONGS];
};

struct task_struct;

#ifdef CONFIG_X86_IOPL_IOPERM
void io_bitmap_share(struct task_struct *tsk);
void io_bitmap_exit(struct task_struct *tsk);

static inline void native_tss_invalidate_io_bitmap(void)
{
	/*
	 * Invalidate the I/O bitmap by moving io_bitmap_base outside the
	 * TSS limit so any subsequent I/O access from user space will
	 * trigger a #GP.
	 *
	 * This is correct even when VMEXIT rewrites the TSS limit
	 * to 0x67 as the only requirement is that the base points
	 * outside the limit.
	 */
	this_cpu_write(cpu_tss_rw.x86_tss.io_bitmap_base,
		       IO_BITMAP_OFFSET_INVALID);
}

void native_tss_update_io_bitmap(void);

#ifdef CONFIG_PARAVIRT_XXL
#include <asm/paravirt.h>
#else
#define tss_update_io_bitmap native_tss_update_io_bitmap
#define tss_invalidate_io_bitmap native_tss_invalidate_io_bitmap
#endif

#else
static inline void io_bitmap_share(struct task_struct *tsk) { }
static inline void io_bitmap_exit(struct task_struct *tsk) { }
static inline void tss_update_io_bitmap(void) { }
#endif

#endif

Annotation

Implementation Notes