segment.h 7.71 KB
Newer Older
1 2
#ifndef _ASM_X86_SEGMENT_H
#define _ASM_X86_SEGMENT_H
3

4 5
#include <linux/const.h>

6 7 8 9
/*
 * Constructor for a conventional segment GDT (or LDT) entry.
 * This is a macro so it can be used in initializers.
 */
10
#define GDT_ENTRY(flags, base, limit)			\
11 12 13 14 15
	((((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))))
16

17
/* Simple and small GDT entries for booting only: */
18 19

#define GDT_ENTRY_BOOT_CS	2
20 21
#define GDT_ENTRY_BOOT_DS	3
#define GDT_ENTRY_BOOT_TSS	4
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
#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
41

42
#ifdef CONFIG_X86_32
43 44 45
/*
 * The layout of the per-CPU GDT under Linux:
 *
46
 *   0 - null								<=== cacheline #1
47 48 49 50
 *   1 - reserved
 *   2 - reserved
 *   3 - reserved
 *
51
 *   4 - unused								<=== cacheline #2
52 53 54 55 56 57
 *   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 ]
58
 *   8 - TLS segment #3							<=== cacheline #3
59 60 61 62 63 64
 *   9 - reserved
 *  10 - reserved
 *  11 - reserved
 *
 *  ------- start of kernel segments:
 *
65
 *  12 - kernel code segment						<=== cacheline #4
66 67 68
 *  13 - kernel data segment
 *  14 - default user CS
 *  15 - default user DS
69
 *  16 - TSS								<=== cacheline #5
70 71 72
 *  17 - LDT
 *  18 - PNPBIOS support (16->32 gate)
 *  19 - PNPBIOS support
73
 *  20 - PNPBIOS support						<=== cacheline #6
74 75 76
 *  21 - PNPBIOS support
 *  22 - PNPBIOS support
 *  23 - APM BIOS support
77
 *  24 - APM BIOS support						<=== cacheline #7
78 79 80 81
 *  25 - APM BIOS support
 *
 *  26 - ESPFIX small SS
 *  27 - per-cpu			[ offset to per-cpu data area ]
82
 *  28 - stack_canary-20		[ for stack protector ]		<=== cacheline #8
83 84 85 86
 *  29 - unused
 *  30 - unused
 *  31 - TSS for double fault handler
 */
87 88
#define GDT_ENTRY_TLS_MIN		6
#define GDT_ENTRY_TLS_MAX 		(GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1)
89

90 91
#define GDT_ENTRY_KERNEL_CS		12
#define GDT_ENTRY_KERNEL_DS		13
92 93
#define GDT_ENTRY_DEFAULT_USER_CS	14
#define GDT_ENTRY_DEFAULT_USER_DS	15
94 95 96 97 98 99 100 101 102 103 104 105
#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
106

107
#define GDT_ENTRY_DOUBLEFAULT_TSS	31
108

109 110 111 112 113 114 115 116 117
/*
 * Number of entries in the GDT table:
 */
#define GDT_ENTRIES			32

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

118 119
#define __KERNEL_CS			(GDT_ENTRY_KERNEL_CS*8)
#define __KERNEL_DS			(GDT_ENTRY_KERNEL_DS*8)
120 121
#define __USER_DS			(GDT_ENTRY_DEFAULT_USER_DS*8 + 3)
#define __USER_CS			(GDT_ENTRY_DEFAULT_USER_CS*8 + 3)
122
#define __ESPFIX_SS			(GDT_ENTRY_ESPFIX_SS*8)
123 124 125 126 127 128

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

129
/* "Is this PNP code selector (PNP_CS32 or PNP_CS16)?" */
130 131 132 133 134 135 136 137 138
#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)

139
#ifdef CONFIG_SMP
140
# define __KERNEL_PERCPU		(GDT_ENTRY_PERCPU*8)
141
#else
142
# define __KERNEL_PERCPU		0
143
#endif
144

145
#ifdef CONFIG_CC_STACKPROTECTOR
146
# define __KERNEL_STACK_CANARY		(GDT_ENTRY_STACK_CANARY*8)
147
#else
148
# define __KERNEL_STACK_CANARY		0
149 150
#endif

151
#else /* 64-bit: */
152 153 154

#include <asm/cache.h>

155 156 157 158
#define GDT_ENTRY_KERNEL32_CS		1
#define GDT_ENTRY_KERNEL_CS		2
#define GDT_ENTRY_KERNEL_DS		3

159
/*
160 161 162 163 164 165 166 167 168
 * 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,
 *
169
 * ss = STAR.SYSRET_CS+8 (in either case)
170
 *
171
 * thus USER_DS should be between 32-bit and 64-bit code selectors:
172
 */
173 174 175 176 177 178 179 180
#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
181

182 183
#define GDT_ENTRY_TLS_MIN		12
#define GDT_ENTRY_TLS_MAX		14
184

185 186
/* Abused to load per CPU data from limit */
#define GDT_ENTRY_PER_CPU		15
187

188 189 190 191
/*
 * Number of entries in the GDT table:
 */
#define GDT_ENTRIES			16
192

193 194 195 196 197 198 199 200 201 202 203 204 205 206
/*
 * 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)
207

208 209 210
/* TLS indexes for 64-bit - hardcoded in arch_prctl(): */
#define FS_TLS				0
#define GS_TLS				1
211

212 213
#define GS_TLS_SEL			((GDT_ENTRY_TLS_MIN+GS_TLS)*8 + 3)
#define FS_TLS_SEL			((GDT_ENTRY_TLS_MIN+FS_TLS)*8 + 3)
214

215
#endif
216 217

#ifndef CONFIG_PARAVIRT
218
# define get_kernel_rpl()		0
219 220
#endif

221 222 223 224 225 226 227 228 229
#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)
230

231 232
#ifdef __KERNEL__
#ifndef __ASSEMBLY__
233

234
extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][2+2+5];
235
#ifdef CONFIG_TRACING
236
# define trace_early_idt_handlers early_idt_handlers
237
#endif
238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260

/*
 * 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)

/*
261
 * Save a segment register away:
262 263 264 265 266
 */
#define savesegment(seg, value)				\
	asm("mov %%" #seg ",%0":"=r" (value) : : "memory")

/*
267
 * x86-32 user GS accessors:
268 269
 */
#ifdef CONFIG_X86_32
270 271 272 273 274 275 276 277 278 279 280 281 282
# 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 */
283 284 285 286
#endif	/* X86_32 */

#endif /* !__ASSEMBLY__ */
#endif /* __KERNEL__ */
287

288
#endif /* _ASM_X86_SEGMENT_H */