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#ifndef X86_64_PDA_H
#define X86_64_PDA_H
 
#include <linux/cache.h>
 
/* Per processor datastructure. %gs points to it while the kernel runs */ 
/* To use a new field with the *_pda macros it needs to be added to tools/offset.c */
struct x8664_pda {
	unsigned long kernelstack;  /* TOS for current process */ 
	unsigned long oldrsp; 	    /* user rsp for system call */
	unsigned long irqrsp;	    /* Old rsp for interrupts. */ 
	struct task_struct *pcurrent;	/* Current process */
        int irqcount;		    /* Irq nesting counter. Starts with -1 */  	
	int cpunumber;		    /* Logical CPU number */
	/* XXX: could be a single list */
	unsigned long *pgd_quick;
	unsigned long *pmd_quick;
	unsigned long *pte_quick;
	unsigned long pgtable_cache_sz;
	char *irqstackptr;	/* top of irqstack */
	unsigned long volatile *level4_pgt; 
} ____cacheline_aligned;
 
#define PDA_STACKOFFSET (5*8)
 
#define IRQSTACK_ORDER 2
#define IRQSTACKSIZE (PAGE_SIZE << IRQSTACK_ORDER) 
 
extern struct x8664_pda cpu_pda[];
 
/* 
 * There is no fast way to get the base address of the PDA, all the accesses
 * have to mention %fs/%gs.  So it needs to be done this Torvaldian way.
 */ 
#define sizeof_field(type,field)  (sizeof(((type *)0)->field))
#define typeof_field(type,field)  typeof(((type *)0)->field)
 
extern void __bad_pda_field(void);
/* Don't use offsetof because it requires too much infrastructure */
#define pda_offset(field) ((unsigned long)&((struct x8664_pda *)0)->field)
 
#define pda_to_op(op,field,val) do { \
       switch (sizeof_field(struct x8664_pda, field)) { 		\
       case 2: asm volatile(op "w %0,%%gs:%P1" :: "r" (val), "i"(pda_offset(field)):"memory"); break;	\
       case 4: asm volatile(op "l %0,%%gs:%P1" :: "r" (val), "i"(pda_offset(field)):"memory"); break;	\
       case 8: asm volatile(op "q %0,%%gs:%P1" :: "r" (val), "i"(pda_offset(field)):"memory"); break;	\
       default: __bad_pda_field(); 					\
       } \
       } while (0)
 
 
#define pda_from_op(op,field) ({ \
       typedef typeof_field(struct x8664_pda, field) T__; T__ ret__; \
       switch (sizeof_field(struct x8664_pda, field)) { 		\
       case 2: asm volatile(op "w %%gs:%P1,%0":"=r" (ret__): "i" (pda_offset(field)):"memory"); break;	\
       case 4: asm volatile(op "l %%gs:%P1,%0":"=r" (ret__): "i" (pda_offset(field)):"memory"); break;	\
       case 8: asm volatile(op "q %%gs:%P1,%0":"=r" (ret__): "i" (pda_offset(field)):"memory"); break;	\
       default: __bad_pda_field(); 					\
       } \
       ret__; })
 
 
#define read_pda(field) pda_from_op("mov",field)
#define write_pda(field,val) pda_to_op("mov",field,val)
#define add_pda(field,val) pda_to_op("add",field,val)
#define sub_pda(field,val) pda_to_op("sub",field,val)
 
#endif