pda.h
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#ifndef X86_64_PDA_H
#define X86_64_PDA_H
#ifndef __ASSEMBLY__
#include <linux/stddef.h>
#include <linux/types.h>
#include <linux/cache.h>
/* Per processor datastructure. %gs points to it while the kernel runs */
struct x8664_pda {
struct task_struct *pcurrent; /* Current process */
unsigned long data_offset; /* Per cpu data offset from linker address */
struct x8664_pda *me; /* Pointer to itself */
unsigned long kernelstack; /* top of kernel stack for current */
unsigned long oldrsp; /* user rsp for system call */
unsigned long irqrsp; /* Old rsp for interrupts. */
int irqcount; /* Irq nesting counter. Starts with -1 */
int cpunumber; /* Logical CPU number */
char *irqstackptr; /* top of irqstack */
unsigned int __softirq_pending;
unsigned int __nmi_count; /* number of NMI on this CPUs */
struct mm_struct *active_mm;
int mmu_state;
unsigned apic_timer_irqs;
} ____cacheline_aligned;
#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);
#define pda_offset(field) offsetof(struct x8664_pda, 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)
/*
* AK: PDA read accesses should be neither volatile nor have an memory clobber.
* Unfortunately removing them causes all hell to break lose currently.
*/
#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
#define PDA_STACKOFFSET (5*8)
#endif