path: root/include/asm-x86/processor.h

#ifndef __ASM_X86_PROCESSOR_H
#define __ASM_X86_PROCESSOR_H

#include <asm/processor-flags.h>

/* migration helpers, for KVM - will be removed in 2.6.25: */
#include <asm/vm86.h>
#define Xgt_desc_struct	desc_ptr

/* Forward declaration, a strange C thing */
struct task_struct;
struct mm_struct;

#include <asm/vm86.h>
#include <asm/math_emu.h>
#include <asm/segment.h>
#include <asm/types.h>
#include <asm/sigcontext.h>
#include <asm/current.h>
#include <asm/cpufeature.h>
#include <asm/system.h>
#include <asm/page.h>
#include <asm/percpu.h>
#include <asm/msr.h>
#include <asm/desc_defs.h>
#include <asm/nops.h>
#include <linux/personality.h>
#include <linux/cpumask.h>
#include <linux/cache.h>
#include <linux/threads.h>
#include <linux/init.h>

/*
 * Default implementation of macro that returns current
 * instruction pointer ("program counter").
 */
static inline void *current_text_addr(void)
{
	void *pc;
	asm volatile("mov $1f,%0\n1:":"=r" (pc));
	return pc;
}

#ifdef CONFIG_X86_VSMP
#define ARCH_MIN_TASKALIGN	(1 << INTERNODE_CACHE_SHIFT)
#define ARCH_MIN_MMSTRUCT_ALIGN	(1 << INTERNODE_CACHE_SHIFT)
#else
#define ARCH_MIN_TASKALIGN	16
#define ARCH_MIN_MMSTRUCT_ALIGN	0
#endif

/*
 *  CPU type and hardware bug flags. Kept separately for each CPU.
 *  Members of this structure are referenced in head.S, so think twice
 *  before touching them. [mj]
 */

struct cpuinfo_x86 {
	__u8	x86;		/* CPU family */
	__u8	x86_vendor;	/* CPU vendor */
	__u8	x86_model;
	__u8	x86_mask;
#ifdef CONFIG_X86_32
	char	wp_works_ok;	/* It doesn't on 386's */
	char	hlt_works_ok;	/* Problems on some 486Dx4's and old 386's */
	char	hard_math;
	char	rfu;
	char	fdiv_bug;
	char	f00f_bug;
	char	coma_bug;
	char	pad0;
#else
	/* number of 4K pages in DTLB/ITLB combined(in pages)*/
	int     x86_tlbsize;
	__u8    x86_virt_bits, x86_phys_bits;
	/* cpuid returned core id bits */
	__u8    x86_coreid_bits;
	/* Max extended CPUID function supported */
	__u32   extended_cpuid_level;
#endif
	int	cpuid_level;	/* Maximum supported CPUID level, -1=no CPUID */
	__u32	x86_capability[NCAPINTS];
	char	x86_vendor_id[16];
	char	x86_model_id[64];
	int 	x86_cache_size;  /* in KB - valid for CPUS which support this
				    call  */
	int 	x86_cache_alignment;	/* In bytes */
	int	x86_power;
	unsigned long loops_per_jiffy;
#ifdef CONFIG_SMP
	cpumask_t llc_shared_map;	/* cpus sharing the last level cache */
#endif
	u16 x86_max_cores;		/* cpuid returned max cores value */
	u16 apicid;
	u16 x86_clflush_size;
#ifdef CONFIG_SMP
	u16 booted_cores;		/* number of cores as seen by OS */
	u16 phys_proc_id; 		/* Physical processor id. */
	u16 cpu_core_id;  		/* Core id */
	u16 cpu_index;			/* index into per_cpu list */
#endif
} __attribute__((__aligned__(SMP_CACHE_BYTES)));

#define X86_VENDOR_INTEL 0
#define X86_VENDOR_CYRIX 1
#define X86_VENDOR_AMD 2
#define X86_VENDOR_UMC 3
#define X86_VENDOR_NEXGEN 4
#define X86_VENDOR_CENTAUR 5
#define X86_VENDOR_TRANSMETA 7
#define X86_VENDOR_NSC 8
#define X86_VENDOR_NUM 9
#define X86_VENDOR_UNKNOWN 0xff

/*
 * capabilities of CPUs
 */
extern struct cpuinfo_x86 boot_cpu_data;
extern struct cpuinfo_x86 new_cpu_data;
extern struct tss_struct doublefault_tss;
extern __u32 cleared_cpu_caps[NCAPINTS];

#ifdef CONFIG_SMP
DECLARE_PER_CPU(struct cpuinfo_x86, cpu_info);
#define cpu_data(cpu)		per_cpu(cpu_info, cpu)
#define current_cpu_data	cpu_data(smp_processor_id())
#else
#define cpu_data(cpu)		boot_cpu_data
#define current_cpu_data	boot_cpu_data
#endif

void cpu_detect(struct cpuinfo_x86 *c);

extern void identify_cpu(struct cpuinfo_x86 *);
extern void identify_boot_cpu(void);
extern void identify_secondary_cpu(struct cpuinfo_x86 *);
extern void print_cpu_info(struct cpuinfo_x86 *);
extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c);
extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c);
extern unsigned short num_cache_leaves;

#if defined(CONFIG_X86_HT) || defined(CONFIG_X86_64)
extern void detect_ht(struct cpuinfo_x86 *c);
#else
static inline void detect_ht(struct cpuinfo_x86 *c) {}
#endif

static inline void native_cpuid(unsigned int *eax, unsigned int *ebx,
					 unsigned int *ecx, unsigned int *edx)
{
	/* ecx is often an input as well as an output. */
	__asm__("cpuid"
		: "=a" (*eax),
		  "=b" (*ebx),
		  "=c" (*ecx),
		  "=d" (*edx)
		: "0" (*eax), "2" (*ecx));
}

static inline void load_cr3(pgd_t *pgdir)
{
	write_cr3(__pa(pgdir));
}

#ifdef CONFIG_X86_32
/* This is the TSS defined by the hardware. */
struct x86_hw_tss {
	unsigned short	back_link, __blh;
	unsigned long	sp0;
	unsigned short	ss0, __ss0h;
	unsigned long	sp1;
	unsigned short	ss1, __ss1h;	/* ss1 caches MSR_IA32_SYSENTER_CS */
	unsigned long	sp2;
	unsigned short	ss2, __ss2h;
	unsigned long	__cr3;
	unsigned long	ip;
	unsigned long	flags;
	unsigned long	ax, cx, dx, bx;
	unsigned long	sp, bp, si, di;
	unsigned short	es, __esh;
	unsigned short	cs, __csh;
	unsigned short	ss, __ssh;
	unsigned short	ds, __dsh;
	unsigned short	fs, __fsh;
	unsigned short	gs, __gsh;
	unsigned short	ldt, __ldth;
	unsigned short	trace, io_bitmap_base;
} __attribute__((packed));
#else
struct x86_hw_tss {
	u32 reserved1;
	u64 sp0;
	u64 sp1;
	u64 sp2;
	u64 reserved2;
	u64 ist[7];
	u32 reserved3;
	u32 reserved4;
	u16 reserved5;
	u16 io_bitmap_base;
} __attribute__((packed)) ____cacheline_aligned;
#endif

/*
 * Size of io_bitmap.
 */
#define IO_BITMAP_BITS  65536
#define IO_BITMAP_BYTES (IO_BITMAP_BITS/8)
#define IO_BITMAP_LONGS (IO_BITMAP_BYTES/sizeof(long))
#define IO_BITMAP_OFFSET offsetof(struct tss_struct, io_bitmap)
#define INVALID_IO_BITMAP_OFFSET 0x8000
#define INVALID_IO_BITMAP_OFFSET_LAZY 0x9000

struct tss_struct {
	struct x86_hw_tss x86_tss;

	/*
	 * The extra 1 is there because the CPU will access an
	 * additional byte beyond the end of the IO permission
	 * bitmap. The extra byte must be all 1 bits, and must
	 * be within the limit.
	 */
	unsigned long	io_bitmap[IO_BITMAP_LONGS + 1];
	/*
	 * Cache the current maximum and the last task that used the bitmap:
	 */
	unsigned long io_bitmap_max;
	struct thread_struct *io_bitmap_owner;
	/*
	 * pads the TSS to be cacheline-aligned (size is 0x100)
	 */
	unsigned long __cacheline_filler[35];
	/*
	 * .. and then another 0x100 bytes for emergency kernel stack
	 */
	unsigned long stack[64];
} __attribute__((packed));

DECLARE_PER_CPU(struct tss_struct, init_tss);

/* Save the original ist values for checking stack pointers during debugging */
struct orig_ist {
	unsigned long ist[7];
};

#define	MXCSR_DEFAULT		0x1f80

struct i387_fsave_struct {
	u32	cwd;
	u32	swd;
	u32	twd;
	u32	fip;
	u32	fcs;
	u32	foo;
	u32	fos;
	u32	st_space[20];	/* 8*10 bytes for each FP-reg = 80 bytes */
	u32	status;		/* software status information */
};

struct i387_fxsave_struct {
	u16	cwd;
	u16	swd;
	u16	twd;
	u16	fop;
	union {
		struct {
			u64	rip;
			u64	rdp;
		};
		struct {
			u32	fip;
			u32	fcs;
			u32	foo;
			u32	fos;
		};
	};
	u32	mxcsr;
	u32	mxcsr_mask;
	u32	st_space[32];	/* 8*16 bytes for each FP-reg = 128 bytes */
	u32	xmm_space[64];	/* 16*16 bytes for each XMM-reg = 256 bytes */
	u32	padding[24];
} __attribute__((aligned(16)));

struct i387_soft_struct {
	u32	cwd;
	u32	swd;
	u32	twd;
	u32	fip;
	u32	fcs;
	u32	foo;
	u32	fos;
	u32	st_space[20];	/* 8*10 bytes for each FP-reg = 80 bytes */
	u8	ftop, changed, lookahead, no_update, rm, alimit;
	struct info	*info;
	u32	entry_eip;
};

union i387_union {
	struct i387_fsave_struct	fsave;
	struct i387_fxsave_struct	fxsave;
	struct i387_soft_struct 	soft;
};

#ifdef CONFIG_X86_32
/*
 * the following now lives in the per cpu area:
 * extern	int cpu_llc_id[NR_CPUS];
 */
DECLARE_PER_CPU(u8, cpu_llc_id);
#else
DECLARE_PER_CPU(struct orig_ist, orig_ist);
#endif

extern void print_cpu_info(struct cpuinfo_x86 *);
extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c);
extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c);
extern unsigned short num_cache_leaves;

struct thread_struct {
/* cached TLS descriptors. */
	struct desc_struct tls_array[GDT_ENTRY_TLS_ENTRIES];
	unsigned long	sp0;
	unsigned long	sp;
#ifdef CONFIG_X86_32
	unsigned long	sysenter_cs;
#else
	unsigned long 	usersp;	/* Copy from PDA */
	unsigned short	es, ds, fsindex, gsindex;
#endif
	unsigned long	ip;
	unsigned long	fs;
	unsigned long	gs;
/* Hardware debugging registers */
	unsigned long	debugreg0;
	unsigned long	debugreg1;
	unsigned long	debugreg2;
	unsigned long	debugreg3;
	unsigned long	debugreg6;
	unsigned long	debugreg7;
/* fault info */
	unsigned long	cr2, trap_no, error_code;
/* floating point info */
	union i387_union	i387 __attribute__((aligned(16)));;
#ifdef CONFIG_X86_32
/* virtual 86 mode info */
	struct vm86_struct __user *vm86_info;
	unsigned long		screen_bitmap;
	unsigned long		v86flags, v86mask, saved_sp0;
	unsigned int		saved_fs, saved_gs;
#endif
/* IO permissions */
	unsigned long	*io_bitmap_ptr;
	unsigned long	iopl;
/* max allowed port in the bitmap, in bytes: */
	unsigned io_bitmap_max;
/* MSR_IA32_DEBUGCTLMSR value to switch in if TIF_DEBUGCTLMSR is set.  */
	unsigned long	debugctlmsr;
/* Debug Store - if not 0 points to a DS Save Area configuration;
 *               goes into MSR_IA32_DS_AREA */
	unsigned long	ds_area_msr;
};

static inline unsigned long native_get_debugreg(int regno)
{
	unsigned long val = 0; 	/* Damn you, gcc! */

	switch (regno) {
	case 0:
		asm("mov %%db0, %0" :"=r" (val)); break;
	case 1:
		asm("mov %%db1, %0" :"=r" (val)); break;
	case 2:
		asm("mov %%db2, %0" :"=r" (val)); break;
	case 3:
		asm("mov %%db3, %0" :"=r" (val)); break;
	case 6:
		asm("mov %%db6, %0" :"=r" (val)); break;
	case 7:
		asm("mov %%db7, %0" :"=r" (val)); break;
	default:
		BUG();
	}
	return val;
}

static inline void native_set_debugreg(int regno, unsigned long value)
{
	switch (regno) {
	case 0:
		asm("mov %0,%%db0"	: /* no output */ :"r" (value));
		break;
	case 1:
		asm("mov %0,%%db1"	: /* no output */ :"r" (value));
		break;
	case 2:
		asm("mov %0,%%db2"	: /* no output */ :"r" (value));
		break;
	case 3:
		asm("mov %0,%%db3"	: /* no output */ :"r" (value));
		break;
	case 6:
		asm("mov %0,%%db6"	: /* no output */ :"r" (value));
		break;
	case 7:
		asm("mov %0,%%db7"	: /* no output */ :"r" (value));
		break;
	default:
		BUG();
	}
}

/*
 * Set IOPL bits in EFLAGS from given mask
 */
static inline void native_set_iopl_mask(unsigned mask)
{
#ifdef CONFIG_X86_32
	unsigned int reg;
	__asm__ __volatile__ ("pushfl;"
			      "popl %0;"
			      "andl %1, %0;"
			      "orl %2, %0;"
			      "pushl %0;"
			      "popfl"
				: "=&r" (reg)
				: "i" (~X86_EFLAGS_IOPL), "r" (mask));
#endif
}

static inline void native_load_sp0(struct tss_struct *tss,
				   struct thread_struct *thread)
{
	tss->x86_tss.sp0 = thread->sp0;
#ifdef CONFIG_X86_32
	/* Only happens when SEP is enabled, no need to test "SEP"arately */
	if (unlikely(tss->x86_tss.ss1 != thread->sysenter_cs)) {
		tss->x86_tss.ss1 = thread->sysenter_cs;
		wrmsr(MSR_IA32_SYSENTER_CS, thread->sysenter_cs, 0);
	}
#endif
}

static inline void native_swapgs(void)
{
#ifdef CONFIG_X86_64
	asm volatile("swapgs" ::: "memory");
#endif
}

#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#else
#define __cpuid native_cpuid
#define paravirt_enabled() 0

/*
 * These special macros can be used to get or set a debugging register
 */
#define get_debugreg(var, register)				\
	(var) = native_get_debugreg(register)
#define set_debugreg(value, register)				\
	native_set_debugreg(register, value)

static inline void load_sp0(struct tss_struct *tss,
			    struct thread_struct *thread)
{
	native_load_sp0(tss, thread);
}

#define set_iopl_mask native_set_iopl_mask
#define SWAPGS	swapgs
#endif /* CONFIG_PARAVIRT */

/*
 * Save the cr4 feature set we're using (ie
 * Pentium 4MB enable and PPro Global page
 * enable), so that any CPU's that boot up
 * after us can get the correct flags.
 */
extern unsigned long mmu_cr4_features;

static inline void set_in_cr4(unsigned long mask)
{
	unsigned cr4;
	mmu_cr4_features |= mask;
	cr4 = read_cr4();
	cr4 |= mask;
	write_cr4(cr4);
}

static inline void clear_in_cr4(unsigned long mask)
{
	unsigned cr4;
	mmu_cr4_features &= ~mask;
	cr4 = read_cr4();
	cr4 &= ~mask;
	write_cr4(cr4);
}

struct microcode_header {
	unsigned int hdrver;
	unsigned int rev;
	unsigned int date;
	unsigned int sig;
	unsigned int cksum;
	unsigned int ldrver;
	unsigned int pf;
	unsigned int datasize;
	unsigned int totalsize;
	unsigned int reserved[3];
};

struct microcode {
	struct microcode_header hdr;
	unsigned int bits[0];
};

typedef struct microcode microcode_t;
typedef struct microcode_header microcode_header_t;

/* microcode format is extended from prescott processors */
struct extended_signature {
	unsigned int sig;
	unsigned int pf;
	unsigned int cksum;
};

struct extended_sigtable {
	unsigned int count;
	unsigned int cksum;
	unsigned int reserved[3];
	struct extended_signature sigs[0];
};

typedef struct {
	unsigned long seg;
} mm_segment_t;


/*
 * create a kernel thread without removing it from tasklists
 */
extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);

/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);

/* Prepare to copy thread state - unlazy all lazy status */
extern void prepare_to_copy(struct task_struct *tsk);

unsigned long get_wchan(struct task_struct *p);

/*
 * Generic CPUID function
 * clear %ecx since some cpus (Cyrix MII) do not set or clear %ecx
 * resulting in stale register contents being returned.
 */
static inline void cpuid(unsigned int op,
			 unsigned int *eax, unsigned int *ebx,
			 unsigned int *ecx, unsigned int *edx)
{
	*eax = op;
	*ecx = 0;
	__cpuid(eax, ebx, ecx, edx);
}

/* Some CPUID calls want 'count' to be placed in ecx */
static inline void cpuid_count(unsigned int op, int count,
			       unsigned int *eax, unsigned int *ebx,
			       unsigned int *ecx, unsigned int *edx)
{
	*eax = op;
	*ecx = count;
	__cpuid(eax, ebx, ecx, edx);
}

/*
 * CPUID functions returning a single datum
 */
static inline unsigned int cpuid_eax(unsigned int op)
{
	unsigned int eax, ebx, ecx, edx;

	cpuid(op, &eax, &ebx, &ecx, &edx);
	return eax;
}
static inline unsigned int cpuid_ebx(unsigned int op)
{
	unsigned int eax, ebx, ecx, edx;

	cpuid(op, &eax, &ebx, &ecx, &edx);
	return ebx;
}
static inline unsigned int cpuid_ecx(unsigned int op)
{
	unsigned int eax, ebx, ecx, edx;

	cpuid(op, &eax, &ebx, &ecx, &edx);
	return ecx;
}
static inline unsigned int cpuid_edx(unsigned int op)
{
	unsigned int eax, ebx, ecx, edx;

	cpuid(op, &eax, &ebx, &ecx, &edx);
	return edx;
}

/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
static inline void rep_nop(void)
{
	__asm__ __volatile__("rep;nop": : :"memory");
}

/* Stop speculative execution */
static inline void sync_core(void)
{
	int tmp;
	asm volatile("cpuid" : "=a" (tmp) : "0" (1)
					  : "ebx", "ecx", "edx", "memory");
}

#define cpu_relax()   rep_nop()

static inline void __monitor(const void *eax, unsigned long ecx,
		unsigned long edx)
{
	/* "monitor %eax,%ecx,%edx;" */
	asm volatile(
		".byte 0x0f,0x01,0xc8;"
		: :"a" (eax), "c" (ecx), "d"(edx));
}

static inline void __mwait(unsigned long eax, unsigned long ecx)
{
	/* "mwait %eax,%ecx;" */
	asm volatile(
		".byte 0x0f,0x01,0xc9;"
		: :"a" (eax), "c" (ecx));
}

static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
{
	/* "mwait %eax,%ecx;" */
	asm volatile(
		"sti; .byte 0x0f,0x01,0xc9;"
		: :"a" (eax), "c" (ecx));
}

extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);

extern int force_mwait;

extern void select_idle_routine(const struct cpuinfo_x86 *c);

extern unsigned long boot_option_idle_override;

extern void enable_sep_cpu(void);
extern int sysenter_setup(void);

/* Defined in head.S */
extern struct desc_ptr early_gdt_descr;

extern void cpu_set_gdt(int);
extern void switch_to_new_gdt(void);
extern void cpu_init(void);
extern void init_gdt(int cpu);

/* from system description table in BIOS.  Mostly for MCA use, but
 * others may find it useful. */
extern unsigned int machine_id;
extern unsigned int machine_submodel_id;
extern unsigned int BIOS_revision;
extern unsigned int mca_pentium_flag;

/* Boot loader type from the setup header */
extern int bootloader_type;

extern char ignore_fpu_irq;
#define cache_line_size() (boot_cpu_data.x86_cache_alignment)

#define HAVE_ARCH_PICK_MMAP_LAYOUT 1
#define ARCH_HAS_PREFETCHW
#define ARCH_HAS_SPINLOCK_PREFETCH

#ifdef CONFIG_X86_32
#define BASE_PREFETCH	ASM_NOP4
#define ARCH_HAS_PREFETCH
#else
#define BASE_PREFETCH	"prefetcht0 (%1)"
#endif

/* Prefetch instructions for Pentium III and AMD Athlon */
/* It's not worth to care about 3dnow! prefetches for the K6
   because they are microcoded there and very slow.
   However we don't do prefetches for pre XP Athlons currently
   That should be fixed. */
static inline void prefetch(const void *x)
{
	alternative_input(BASE_PREFETCH,
			  "prefetchnta (%1)",
			  X86_FEATURE_XMM,
			  "r" (x));
}

/* 3dnow! prefetch to get an exclusive cache line. Useful for
   spinlocks to avoid one state transition in the cache coherency protocol. */
static inline void prefetchw(const void *x)
{
	alternative_input(BASE_PREFETCH,
			  "prefetchw (%1)",
			  X86_FEATURE_3DNOW,
			  "r" (x));
}

#define spin_lock_prefetch(x)	prefetchw(x)
#ifdef CONFIG_X86_32
/*
 * User space process size: 3GB (default).
 */
#define TASK_SIZE	(PAGE_OFFSET)
#define STACK_TOP	TASK_SIZE
#define STACK_TOP_MAX	STACK_TOP

#define INIT_THREAD  {							\
	.sp0 = sizeof(init_stack) + (long)&init_stack,			\
	.vm86_info = NULL,						\
	.sysenter_cs = __KERNEL_CS,					\
	.io_bitmap_ptr = NULL,						\
	.fs = __KERNEL_PERCPU,						\
}

/*
 * Note that the .io_bitmap member must be extra-big. This is because
 * the CPU will access an additional byte beyond the end of the IO
 * permission bitmap. The extra byte must be all 1 bits, and must
 * be within the limit.
 */
#define INIT_TSS  {							\
	.x86_tss = {							\
		.sp0		= sizeof(init_stack) + (long)&init_stack, \
		.ss0		= __KERNEL_DS,				\
		.ss1		= __KERNEL_CS,				\
		.io_bitmap_base	= INVALID_IO_BITMAP_OFFSET,		\
	 },								\
	.io_bitmap	= { [0 ... IO_BITMAP_LONGS] = ~0 },		\
}

#define start_thread(regs, new_eip, new_esp) do {		\
	__asm__("movl %0,%%gs": :"r" (0));			\
	regs->fs = 0;						\
	set_fs(USER_DS);					\
	regs->ds = __USER_DS;					\
	regs->es = __USER_DS;					\
	regs->ss = __USER_DS;					\
	regs->cs = __USER_CS;					\
	regs->ip = new_eip;					\
	regs->sp = new_esp;					\
} while (0)


extern unsigned long thread_saved_pc(struct task_struct *tsk);

#define THREAD_SIZE_LONGS      (THREAD_SIZE/sizeof(unsigned long))
#define KSTK_TOP(info)                                                 \
({                                                                     \
       unsigned long *__ptr = (unsigned long *)(info);                 \
       (unsigned long)(&__ptr[THREAD_SIZE_LONGS]);                     \
})

/*
 * The below -8 is to reserve 8 bytes on top of the ring0 stack.
 * This is necessary to guarantee that the entire "struct pt_regs"
 * is accessable even if the CPU haven't stored the SS/ESP registers
 * on the stack (interrupt gate does not save these registers
 * when switching to the same priv ring).
 * Therefore beware: accessing the ss/esp fields of the
 * "struct pt_regs" is possible, but they may contain the
 * completely wrong values.
 */
#define task_pt_regs(task)                                             \
({                                                                     \
       struct pt_regs *__regs__;                                       \
       __regs__ = (struct pt_regs *)(KSTK_TOP(task_stack_page(task))-8); \
       __regs__ - 1;                                                   \
})

#define KSTK_ESP(task) (task_pt_regs(task)->sp)

#else
/*
 * User space process size. 47bits minus one guard page.
 */
#define TASK_SIZE64	(0x800000000000UL - 4096)

/* This decides where the kernel will search for a free chunk of vm
 * space during mmap's.
 */
#define IA32_PAGE_OFFSET ((current->personality & ADDR_LIMIT_3GB) ? \
			   0xc0000000 : 0xFFFFe000)

#define TASK_SIZE 		(test_thread_flag(TIF_IA32) ? \
				 IA32_PAGE_OFFSET : TASK_SIZE64)
#define TASK_SIZE_OF(child) 	((test_tsk_thread_flag(child, TIF_IA32)) ? \
				  IA32_PAGE_OFFSET : TASK_SIZE64)

#define STACK_TOP		TASK_SIZE
#define STACK_TOP_MAX		TASK_SIZE64

#define INIT_THREAD  { \
	.sp0 = (unsigned long)&init_stack + sizeof(init_stack) \
}

#define INIT_TSS  { \
	.x86_tss.sp0 = (unsigned long)&init_stack + sizeof(init_stack) \
}

#define start_thread(regs, new_rip, new_rsp) do { 			     \
	asm volatile("movl %0,%%fs; movl %0,%%es; movl %0,%%ds": :"r" (0));  \
	load_gs_index(0);						     \
	(regs)->ip = (new_rip);						     \
	(regs)->sp = (new_rsp);						     \
	write_pda(oldrsp, (new_rsp));					     \
	(regs)->cs = __USER_CS;						     \
	(regs)->ss = __USER_DS;						     \
	(regs)->flags = 0x200;						     \
	set_fs(USER_DS);						     \
} while (0)

/*
 * Return saved PC of a blocked thread.
 * What is this good for? it will be always the scheduler or ret_from_fork.
 */
#define thread_saved_pc(t) (*(unsigned long *)((t)->thread.sp - 8))

#define task_pt_regs(tsk) ((struct pt_regs *)(tsk)->thread.sp0 - 1)
#define KSTK_ESP(tsk) -1 /* sorry. doesn't work for syscall. */
#endif /* CONFIG_X86_64 */

/* This decides where the kernel will search for a free chunk of vm
 * space during mmap's.
 */
#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE / 3))

#define KSTK_EIP(task) (task_pt_regs(task)->ip)

#endif