[deliverable/linux.git] / arch / x86 / include / asm / segment.h

#ifndef _ASM_X86_SEGMENT_H
#define _ASM_X86_SEGMENT_H

#include <linux/const.h>

/*
 * Constructor for a conventional segment GDT (or LDT) entry.
 * This is a macro so it can be used in initializers.
 */
#define GDT_ENTRY(flags, base, limit)			\
	((((base)  & _AC(0xff000000,ULL)) << (56-24)) |	\
	 (((flags) & _AC(0x0000f0ff,ULL)) << 40) |	\
	 (((limit) & _AC(0x000f0000,ULL)) << (48-16)) |	\
	 (((base)  & _AC(0x00ffffff,ULL)) << 16) |	\
	 (((limit) & _AC(0x0000ffff,ULL))))

/* Simple and small GDT entries for booting only: */

#define GDT_ENTRY_BOOT_CS	2
#define GDT_ENTRY_BOOT_DS	3
#define GDT_ENTRY_BOOT_TSS	4
#define __BOOT_CS		(GDT_ENTRY_BOOT_CS*8)
#define __BOOT_DS		(GDT_ENTRY_BOOT_DS*8)
#define __BOOT_TSS		(GDT_ENTRY_BOOT_TSS*8)

/*
 * Bottom two bits of selector give the ring
 * privilege level
 */
#define SEGMENT_RPL_MASK	0x3

/* User mode is privilege level 3: */
#define USER_RPL		0x3

/* Bit 2 is Table Indicator (TI): selects between LDT or GDT */
#define SEGMENT_TI_MASK		0x4
/* LDT segment has TI set ... */
#define SEGMENT_LDT		0x4
/* ... GDT has it cleared */
#define SEGMENT_GDT		0x0

#define GDT_ENTRY_INVALID_SEG	0

#ifdef CONFIG_X86_32
/*
 * The layout of the per-CPU GDT under Linux:
 *
 *   0 - null								<=== cacheline #1
 *   1 - reserved
 *   2 - reserved
 *   3 - reserved
 *
 *   4 - unused								<=== cacheline #2
 *   5 - unused
 *
 *  ------- start of TLS (Thread-Local Storage) segments:
 *
 *   6 - TLS segment #1			[ glibc's TLS segment ]
 *   7 - TLS segment #2			[ Wine's %fs Win32 segment ]
 *   8 - TLS segment #3							<=== cacheline #3
 *   9 - reserved
 *  10 - reserved
 *  11 - reserved
 *
 *  ------- start of kernel segments:
 *
 *  12 - kernel code segment						<=== cacheline #4
 *  13 - kernel data segment
 *  14 - default user CS
 *  15 - default user DS
 *  16 - TSS								<=== cacheline #5
 *  17 - LDT
 *  18 - PNPBIOS support (16->32 gate)
 *  19 - PNPBIOS support
 *  20 - PNPBIOS support						<=== cacheline #6
 *  21 - PNPBIOS support
 *  22 - PNPBIOS support
 *  23 - APM BIOS support
 *  24 - APM BIOS support						<=== cacheline #7
 *  25 - APM BIOS support
 *
 *  26 - ESPFIX small SS
 *  27 - per-cpu			[ offset to per-cpu data area ]
 *  28 - stack_canary-20		[ for stack protector ]		<=== cacheline #8
 *  29 - unused
 *  30 - unused
 *  31 - TSS for double fault handler
 */
#define GDT_ENTRY_TLS_MIN		6
#define GDT_ENTRY_TLS_MAX 		(GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1)

#define GDT_ENTRY_KERNEL_CS		12
#define GDT_ENTRY_KERNEL_DS		13
#define GDT_ENTRY_DEFAULT_USER_CS	14
#define GDT_ENTRY_DEFAULT_USER_DS	15
#define GDT_ENTRY_TSS			16
#define GDT_ENTRY_LDT			17
#define GDT_ENTRY_PNPBIOS_CS32		18
#define GDT_ENTRY_PNPBIOS_CS16		19
#define GDT_ENTRY_PNPBIOS_DS		20
#define GDT_ENTRY_PNPBIOS_TS1		21
#define GDT_ENTRY_PNPBIOS_TS2		22
#define GDT_ENTRY_APMBIOS_BASE		23

#define GDT_ENTRY_ESPFIX_SS		26
#define GDT_ENTRY_PERCPU		27
#define GDT_ENTRY_STACK_CANARY		28

#define GDT_ENTRY_DOUBLEFAULT_TSS	31

/*
 * Number of entries in the GDT table:
 */
#define GDT_ENTRIES			32

/*
 * Segment selector values corresponding to the above entries:
 */

#define __KERNEL_CS			(GDT_ENTRY_KERNEL_CS*8)
#define __KERNEL_DS			(GDT_ENTRY_KERNEL_DS*8)
#define __USER_DS			(GDT_ENTRY_DEFAULT_USER_DS*8 + 3)
#define __USER_CS			(GDT_ENTRY_DEFAULT_USER_CS*8 + 3)
#define __ESPFIX_SS			(GDT_ENTRY_ESPFIX_SS*8)

/* segment for calling fn: */
#define PNP_CS32			(GDT_ENTRY_PNPBIOS_CS32*8)
/* code segment for BIOS: */
#define PNP_CS16			(GDT_ENTRY_PNPBIOS_CS16*8)

/* "Is this PNP code selector (PNP_CS32 or PNP_CS16)?" */
#define SEGMENT_IS_PNP_CODE(x)		(((x) & 0xf4) == PNP_CS32)

/* data segment for BIOS: */
#define PNP_DS				(GDT_ENTRY_PNPBIOS_DS*8)
/* transfer data segment: */
#define PNP_TS1				(GDT_ENTRY_PNPBIOS_TS1*8)
/* another data segment: */
#define PNP_TS2				(GDT_ENTRY_PNPBIOS_TS2*8)

#ifdef CONFIG_SMP
# define __KERNEL_PERCPU		(GDT_ENTRY_PERCPU*8)
#else
# define __KERNEL_PERCPU		0
#endif

#ifdef CONFIG_CC_STACKPROTECTOR
# define __KERNEL_STACK_CANARY		(GDT_ENTRY_STACK_CANARY*8)
#else
# define __KERNEL_STACK_CANARY		0
#endif

#else /* 64-bit: */

#include <asm/cache.h>

#define GDT_ENTRY_KERNEL32_CS		1
#define GDT_ENTRY_KERNEL_CS		2
#define GDT_ENTRY_KERNEL_DS		3

/*
 * We cannot use the same code segment descriptor for user and kernel mode,
 * not even in long flat mode, because of different DPL.
 *
 * GDT layout to get 64-bit SYSCALL/SYSRET support right. SYSRET hardcodes
 * selectors:
 *
 *   if returning to 32-bit userspace: cs = STAR.SYSRET_CS,
 *   if returning to 64-bit userspace: cs = STAR.SYSRET_CS+16,
 *
 * ss = STAR.SYSRET_CS+8 (in either case)
 *
 * thus USER_DS should be between 32-bit and 64-bit code selectors:
 */
#define GDT_ENTRY_DEFAULT_USER32_CS	4
#define GDT_ENTRY_DEFAULT_USER_DS	5
#define GDT_ENTRY_DEFAULT_USER_CS	6

/* Needs two entries */
#define GDT_ENTRY_TSS			8
/* Needs two entries */
#define GDT_ENTRY_LDT			10

#define GDT_ENTRY_TLS_MIN		12
#define GDT_ENTRY_TLS_MAX		14

/* Abused to load per CPU data from limit */
#define GDT_ENTRY_PER_CPU		15

/*
 * Number of entries in the GDT table:
 */
#define GDT_ENTRIES			16

/*
 * Segment selector values corresponding to the above entries:
 *
 * Note, selectors also need to have a correct RPL,
 * expressed with the +3 value for user-space selectors:
 */
#define __KERNEL32_CS			(GDT_ENTRY_KERNEL32_CS*8)
#define __KERNEL_CS			(GDT_ENTRY_KERNEL_CS*8)
#define __KERNEL_DS			(GDT_ENTRY_KERNEL_DS*8)
#define __USER32_CS			(GDT_ENTRY_DEFAULT_USER32_CS*8 + 3)
#define __USER_DS			(GDT_ENTRY_DEFAULT_USER_DS*8 + 3)
#define __USER32_DS			__USER_DS
#define __USER_CS			(GDT_ENTRY_DEFAULT_USER_CS*8 + 3)
#define __PER_CPU_SEG			(GDT_ENTRY_PER_CPU*8 + 3)

/* TLS indexes for 64-bit - hardcoded in arch_prctl(): */
#define FS_TLS				0
#define GS_TLS				1

#define GS_TLS_SEL			((GDT_ENTRY_TLS_MIN+GS_TLS)*8 + 3)
#define FS_TLS_SEL			((GDT_ENTRY_TLS_MIN+FS_TLS)*8 + 3)

#endif

#ifndef CONFIG_PARAVIRT
# define get_kernel_rpl()		0
#endif

#define IDT_ENTRIES			256
#define NUM_EXCEPTION_VECTORS		32

/* Bitmask of exception vectors which push an error code on the stack: */
#define EXCEPTION_ERRCODE_MASK		0x00027d00

#define GDT_SIZE			(GDT_ENTRIES*8)
#define GDT_ENTRY_TLS_ENTRIES		3
#define TLS_SIZE			(GDT_ENTRY_TLS_ENTRIES* 8)

#ifdef __KERNEL__
#ifndef __ASSEMBLY__

extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][2+2+5];
#ifdef CONFIG_TRACING
# define trace_early_idt_handlers early_idt_handlers
#endif

/*
 * Load a segment. Fall back on loading the zero
 * segment if something goes wrong..
 */
#define loadsegment(seg, value)						\
do {									\
	unsigned short __val = (value);					\
									\
	asm volatile("						\n"	\
		     "1:	movl %k0,%%" #seg "		\n"	\
									\
		     ".section .fixup,\"ax\"			\n"	\
		     "2:	xorl %k0,%k0			\n"	\
		     "		jmp 1b				\n"	\
		     ".previous					\n"	\
									\
		     _ASM_EXTABLE(1b, 2b)				\
									\
		     : "+r" (__val) : : "memory");			\
} while (0)

/*
 * Save a segment register away:
 */
#define savesegment(seg, value)				\
	asm("mov %%" #seg ",%0":"=r" (value) : : "memory")

/*
 * x86-32 user GS accessors:
 */
#ifdef CONFIG_X86_32
# ifdef CONFIG_X86_32_LAZY_GS
#  define get_user_gs(regs)		(u16)({ unsigned long v; savesegment(gs, v); v; })
#  define set_user_gs(regs, v)		loadsegment(gs, (unsigned long)(v))
#  define task_user_gs(tsk)		((tsk)->thread.gs)
#  define lazy_save_gs(v)		savesegment(gs, (v))
#  define lazy_load_gs(v)		loadsegment(gs, (v))
# else	/* X86_32_LAZY_GS */
#  define get_user_gs(regs)		(u16)((regs)->gs)
#  define set_user_gs(regs, v)		do { (regs)->gs = (v); } while (0)
#  define task_user_gs(tsk)		(task_pt_regs(tsk)->gs)
#  define lazy_save_gs(v)		do { } while (0)
#  define lazy_load_gs(v)		do { } while (0)
# endif	/* X86_32_LAZY_GS */
#endif	/* X86_32 */

#endif /* !__ASSEMBLY__ */
#endif /* __KERNEL__ */

#endif /* _ASM_X86_SEGMENT_H */
Commit	Line	Data
1965aae3 PA	1	#ifndef _ASM_X86_SEGMENT_H
1965aae3 PA	2	#define _ASM_X86_SEGMENT_H
cef18950	3
014eea51 PA	4	#include <linux/const.h>
014eea51 PA	5
72d64cc7 IM	6	/*
	7	* Constructor for a conventional segment GDT (or LDT) entry.
	8	* This is a macro so it can be used in initializers.
	9	*/
4fdf08b5	10	#define GDT_ENTRY(flags, base, limit) \
014eea51 PA	11	((((base) & _AC(0xff000000,ULL)) << (56-24)) \| \
	12	(((flags) & _AC(0x0000f0ff,ULL)) << 40) \| \
	13	(((limit) & _AC(0x000f0000,ULL)) << (48-16)) \| \
	14	(((base) & _AC(0x00ffffff,ULL)) << 16) \| \
	15	(((limit) & _AC(0x0000ffff,ULL))))
4fdf08b5	16
72d64cc7	17	/* Simple and small GDT entries for booting only: */
2a6648e6 PA	18
2a6648e6 PA	19	#define GDT_ENTRY_BOOT_CS 2
84f53788 DV	20	#define GDT_ENTRY_BOOT_DS 3
84f53788 DV	21	#define GDT_ENTRY_BOOT_TSS 4
72d64cc7 IM	22	#define __BOOT_CS (GDT_ENTRY_BOOT_CS*8)
	23	#define __BOOT_DS (GDT_ENTRY_BOOT_DS*8)
	24	#define __BOOT_TSS (GDT_ENTRY_BOOT_TSS*8)
	25
	26	/*
	27	* Bottom two bits of selector give the ring
	28	* privilege level
	29	*/
	30	#define SEGMENT_RPL_MASK 0x3
	31
	32	/* User mode is privilege level 3: */
	33	#define USER_RPL 0x3
	34
	35	/* Bit 2 is Table Indicator (TI): selects between LDT or GDT */
	36	#define SEGMENT_TI_MASK 0x4
	37	/* LDT segment has TI set ... */
	38	#define SEGMENT_LDT 0x4
	39	/* ... GDT has it cleared */
	40	#define SEGMENT_GDT 0x0
be9d1738	41
6b51311c BP	42	#define GDT_ENTRY_INVALID_SEG 0
6b51311c BP	43
96a388de	44	#ifdef CONFIG_X86_32
b23be399 GOC	45	/*
	46	* The layout of the per-CPU GDT under Linux:
	47	*
72d64cc7	48	* 0 - null <=== cacheline #1
b23be399 GOC	49	* 1 - reserved
	50	* 2 - reserved
	51	* 3 - reserved
	52	*
72d64cc7	53	* 4 - unused <=== cacheline #2
b23be399 GOC	54	* 5 - unused
	55	*
	56	* ------- start of TLS (Thread-Local Storage) segments:
	57	*
	58	* 6 - TLS segment #1 [ glibc's TLS segment ]
	59	* 7 - TLS segment #2 [ Wine's %fs Win32 segment ]
72d64cc7	60	* 8 - TLS segment #3 <=== cacheline #3
b23be399 GOC	61	* 9 - reserved
	62	* 10 - reserved
	63	* 11 - reserved
	64	*
	65	* ------- start of kernel segments:
	66	*
72d64cc7	67	* 12 - kernel code segment <=== cacheline #4
b23be399 GOC	68	* 13 - kernel data segment
	69	* 14 - default user CS
	70	* 15 - default user DS
72d64cc7	71	* 16 - TSS <=== cacheline #5
b23be399 GOC	72	* 17 - LDT
	73	* 18 - PNPBIOS support (16->32 gate)
	74	* 19 - PNPBIOS support
72d64cc7	75	* 20 - PNPBIOS support <=== cacheline #6
b23be399 GOC	76	* 21 - PNPBIOS support
	77	* 22 - PNPBIOS support
	78	* 23 - APM BIOS support
72d64cc7	79	* 24 - APM BIOS support <=== cacheline #7
b23be399 GOC	80	* 25 - APM BIOS support
	81	*
	82	* 26 - ESPFIX small SS
	83	* 27 - per-cpu [ offset to per-cpu data area ]
72d64cc7	84	* 28 - stack_canary-20 [ for stack protector ] <=== cacheline #8
b23be399 GOC	85	* 29 - unused
	86	* 30 - unused
	87	* 31 - TSS for double fault handler
	88	*/
72d64cc7 IM	89	#define GDT_ENTRY_TLS_MIN 6
72d64cc7 IM	90	#define GDT_ENTRY_TLS_MAX (GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1)
b23be399	91
84f53788 DV	92	#define GDT_ENTRY_KERNEL_CS 12
84f53788 DV	93	#define GDT_ENTRY_KERNEL_DS 13
b23be399	94	#define GDT_ENTRY_DEFAULT_USER_CS 14
b23be399	95	#define GDT_ENTRY_DEFAULT_USER_DS 15
84f53788 DV	96	#define GDT_ENTRY_TSS 16
	97	#define GDT_ENTRY_LDT 17
	98	#define GDT_ENTRY_PNPBIOS_CS32 18
	99	#define GDT_ENTRY_PNPBIOS_CS16 19
	100	#define GDT_ENTRY_PNPBIOS_DS 20
	101	#define GDT_ENTRY_PNPBIOS_TS1 21
	102	#define GDT_ENTRY_PNPBIOS_TS2 22
	103	#define GDT_ENTRY_APMBIOS_BASE 23
	104
	105	#define GDT_ENTRY_ESPFIX_SS 26
	106	#define GDT_ENTRY_PERCPU 27
	107	#define GDT_ENTRY_STACK_CANARY 28
b23be399	108
84f53788	109	#define GDT_ENTRY_DOUBLEFAULT_TSS 31
b23be399	110
72d64cc7 IM	111	/*
	112	* Number of entries in the GDT table:
	113	*/
	114	#define GDT_ENTRIES 32
	115
	116	/*
	117	* Segment selector values corresponding to the above entries:
	118	*/
	119
84f53788 DV	120	#define __KERNEL_CS (GDT_ENTRY_KERNEL_CS*8)
84f53788 DV	121	#define __KERNEL_DS (GDT_ENTRY_KERNEL_DS*8)
72d64cc7 IM	122	#define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS*8 + 3)
72d64cc7 IM	123	#define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3)
3234282f	124	#define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS*8)
72d64cc7 IM	125
	126	/* segment for calling fn: */
	127	#define PNP_CS32 (GDT_ENTRY_PNPBIOS_CS32*8)
	128	/* code segment for BIOS: */
	129	#define PNP_CS16 (GDT_ENTRY_PNPBIOS_CS16*8)
	130
84f53788	131	/* "Is this PNP code selector (PNP_CS32 or PNP_CS16)?" */
72d64cc7 IM	132	#define SEGMENT_IS_PNP_CODE(x) (((x) & 0xf4) == PNP_CS32)
	133
	134	/* data segment for BIOS: */
	135	#define PNP_DS (GDT_ENTRY_PNPBIOS_DS*8)
	136	/* transfer data segment: */
	137	#define PNP_TS1 (GDT_ENTRY_PNPBIOS_TS1*8)
	138	/* another data segment: */
	139	#define PNP_TS2 (GDT_ENTRY_PNPBIOS_TS2*8)
	140
b23be399	141	#ifdef CONFIG_SMP
72d64cc7	142	# define __KERNEL_PERCPU (GDT_ENTRY_PERCPU*8)
b23be399	143	#else
72d64cc7	144	# define __KERNEL_PERCPU 0
b23be399	145	#endif
72d64cc7	146
60a5317f	147	#ifdef CONFIG_CC_STACKPROTECTOR
72d64cc7	148	# define __KERNEL_STACK_CANARY (GDT_ENTRY_STACK_CANARY*8)
60a5317f	149	#else
72d64cc7	150	# define __KERNEL_STACK_CANARY 0
60a5317f TH	151	#endif
60a5317f TH	152
84f53788	153	#else /* 64-bit: */
b23be399	154
b23be399 GOC	155	#include <asm/cache.h>
b23be399 GOC	156
72d64cc7 IM	157	#define GDT_ENTRY_KERNEL32_CS 1
	158	#define GDT_ENTRY_KERNEL_CS 2
	159	#define GDT_ENTRY_KERNEL_DS 3
	160
b23be399	161	/*
72d64cc7 IM	162	* We cannot use the same code segment descriptor for user and kernel mode,
	163	* not even in long flat mode, because of different DPL.
	164	*
	165	* GDT layout to get 64-bit SYSCALL/SYSRET support right. SYSRET hardcodes
	166	* selectors:
	167	*
	168	* if returning to 32-bit userspace: cs = STAR.SYSRET_CS,
	169	* if returning to 64-bit userspace: cs = STAR.SYSRET_CS+16,
	170	*
84f53788	171	* ss = STAR.SYSRET_CS+8 (in either case)
72d64cc7	172	*
84f53788	173	* thus USER_DS should be between 32-bit and 64-bit code selectors:
b23be399	174	*/
72d64cc7 IM	175	#define GDT_ENTRY_DEFAULT_USER32_CS 4
	176	#define GDT_ENTRY_DEFAULT_USER_DS 5
	177	#define GDT_ENTRY_DEFAULT_USER_CS 6
	178
	179	/* Needs two entries */
	180	#define GDT_ENTRY_TSS 8
	181	/* Needs two entries */
	182	#define GDT_ENTRY_LDT 10
b23be399	183
72d64cc7 IM	184	#define GDT_ENTRY_TLS_MIN 12
72d64cc7 IM	185	#define GDT_ENTRY_TLS_MAX 14
b23be399	186
72d64cc7 IM	187	/* Abused to load per CPU data from limit */
72d64cc7 IM	188	#define GDT_ENTRY_PER_CPU 15
84f53788	189
72d64cc7 IM	190	/*
	191	* Number of entries in the GDT table:
	192	*/
	193	#define GDT_ENTRIES 16
b23be399	194
72d64cc7 IM	195	/*
	196	* Segment selector values corresponding to the above entries:
	197	*
	198	* Note, selectors also need to have a correct RPL,
	199	* expressed with the +3 value for user-space selectors:
	200	*/
	201	#define __KERNEL32_CS (GDT_ENTRY_KERNEL32_CS*8)
	202	#define __KERNEL_CS (GDT_ENTRY_KERNEL_CS*8)
	203	#define __KERNEL_DS (GDT_ENTRY_KERNEL_DS*8)
	204	#define __USER32_CS (GDT_ENTRY_DEFAULT_USER32_CS*8 + 3)
	205	#define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS*8 + 3)
	206	#define __USER32_DS __USER_DS
	207	#define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3)
	208	#define __PER_CPU_SEG (GDT_ENTRY_PER_CPU*8 + 3)
b23be399	209
72d64cc7 IM	210	/* TLS indexes for 64-bit - hardcoded in arch_prctl(): */
	211	#define FS_TLS 0
	212	#define GS_TLS 1
b23be399	213
72d64cc7 IM	214	#define GS_TLS_SEL ((GDT_ENTRY_TLS_MIN+GS_TLS)*8 + 3)
72d64cc7 IM	215	#define FS_TLS_SEL ((GDT_ENTRY_TLS_MIN+FS_TLS)*8 + 3)
b23be399	216
96a388de	217	#endif
cef18950 GOC	218
cef18950 GOC	219	#ifndef CONFIG_PARAVIRT
72d64cc7	220	# define get_kernel_rpl() 0
cef18950 GOC	221	#endif
cef18950 GOC	222
72d64cc7 IM	223	#define IDT_ENTRIES 256
	224	#define NUM_EXCEPTION_VECTORS 32
	225
	226	/* Bitmask of exception vectors which push an error code on the stack: */
	227	#define EXCEPTION_ERRCODE_MASK 0x00027d00
	228
	229	#define GDT_SIZE (GDT_ENTRIES*8)
	230	#define GDT_ENTRY_TLS_ENTRIES 3
	231	#define TLS_SIZE (GDT_ENTRY_TLS_ENTRIES* 8)
15ee09b4	232
8866cd9d RM	233	#ifdef __KERNEL__
8866cd9d RM	234	#ifndef __ASSEMBLY__
72d64cc7	235
9900aa2f	236	extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][2+2+5];
25c74b10	237	#ifdef CONFIG_TRACING
72d64cc7	238	# define trace_early_idt_handlers early_idt_handlers
25c74b10	239	#endif
f05e798a DH	240
	241	/*
	242	* Load a segment. Fall back on loading the zero
	243	* segment if something goes wrong..
	244	*/
	245	#define loadsegment(seg, value) \
	246	do { \
	247	unsigned short __val = (value); \
	248	\
	249	asm volatile(" \n" \
	250	"1: movl %k0,%%" #seg " \n" \
	251	\
	252	".section .fixup,\"ax\" \n" \
	253	"2: xorl %k0,%k0 \n" \
	254	" jmp 1b \n" \
	255	".previous \n" \
	256	\
	257	_ASM_EXTABLE(1b, 2b) \
	258	\
	259	: "+r" (__val) : : "memory"); \
	260	} while (0)
	261
	262	/*
72d64cc7	263	* Save a segment register away:
f05e798a DH	264	*/
	265	#define savesegment(seg, value) \
	266	asm("mov %%" #seg ",%0":"=r" (value) : : "memory")
	267
	268	/*
72d64cc7	269	* x86-32 user GS accessors:
f05e798a DH	270	*/
f05e798a DH	271	#ifdef CONFIG_X86_32
72d64cc7 IM	272	# ifdef CONFIG_X86_32_LAZY_GS
	273	# define get_user_gs(regs) (u16)({ unsigned long v; savesegment(gs, v); v; })
	274	# define set_user_gs(regs, v) loadsegment(gs, (unsigned long)(v))
	275	# define task_user_gs(tsk) ((tsk)->thread.gs)
	276	# define lazy_save_gs(v) savesegment(gs, (v))
	277	# define lazy_load_gs(v) loadsegment(gs, (v))
	278	# else /* X86_32_LAZY_GS */
	279	# define get_user_gs(regs) (u16)((regs)->gs)
	280	# define set_user_gs(regs, v) do { (regs)->gs = (v); } while (0)
	281	# define task_user_gs(tsk) (task_pt_regs(tsk)->gs)
	282	# define lazy_save_gs(v) do { } while (0)
	283	# define lazy_load_gs(v) do { } while (0)
	284	# endif /* X86_32_LAZY_GS */
f05e798a DH	285	#endif /* X86_32 */
f05e798a DH	286
f05e798a DH	287	#endif /* !__ASSEMBLY__ */
f05e798a DH	288	#endif /* __KERNEL__ */
8866cd9d	289
1965aae3	290	#endif /* _ASM_X86_SEGMENT_H */