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1 #ifndef _ASM_X86_SEGMENT_H
2 #define _ASM_X86_SEGMENT_H
3 
4 #include <linux/const.h>
5 
6 /*
7  * Constructor for a conventional segment GDT (or LDT) entry.
8  * This is a macro so it can be used in initializers.
9  */
10 #define GDT_ENTRY(flags, base, limit)			\
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))))
16 
17 /* Simple and small GDT entries for booting only: */
18 
19 #define GDT_ENTRY_BOOT_CS	2
20 #define GDT_ENTRY_BOOT_DS	3
21 #define GDT_ENTRY_BOOT_TSS	4
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
41 
42 #define GDT_ENTRY_INVALID_SEG	0
43 
44 #ifdef CONFIG_X86_32
45 /*
46  * The layout of the per-CPU GDT under Linux:
47  *
48  *   0 - null								<=== cacheline #1
49  *   1 - reserved
50  *   2 - reserved
51  *   3 - reserved
52  *
53  *   4 - unused								<=== cacheline #2
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 ]
60  *   8 - TLS segment #3							<=== cacheline #3
61  *   9 - reserved
62  *  10 - reserved
63  *  11 - reserved
64  *
65  *  ------- start of kernel segments:
66  *
67  *  12 - kernel code segment						<=== cacheline #4
68  *  13 - kernel data segment
69  *  14 - default user CS
70  *  15 - default user DS
71  *  16 - TSS								<=== cacheline #5
72  *  17 - LDT
73  *  18 - PNPBIOS support (16->32 gate)
74  *  19 - PNPBIOS support
75  *  20 - PNPBIOS support						<=== cacheline #6
76  *  21 - PNPBIOS support
77  *  22 - PNPBIOS support
78  *  23 - APM BIOS support
79  *  24 - APM BIOS support						<=== cacheline #7
80  *  25 - APM BIOS support
81  *
82  *  26 - ESPFIX small SS
83  *  27 - per-cpu			[ offset to per-cpu data area ]
84  *  28 - stack_canary-20		[ for stack protector ]		<=== cacheline #8
85  *  29 - unused
86  *  30 - unused
87  *  31 - TSS for double fault handler
88  */
89 #define GDT_ENTRY_TLS_MIN		6
90 #define GDT_ENTRY_TLS_MAX 		(GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1)
91 
92 #define GDT_ENTRY_KERNEL_CS		12
93 #define GDT_ENTRY_KERNEL_DS		13
94 #define GDT_ENTRY_DEFAULT_USER_CS	14
95 #define GDT_ENTRY_DEFAULT_USER_DS	15
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
108 
109 #define GDT_ENTRY_DOUBLEFAULT_TSS	31
110 
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 
120 #define __KERNEL_CS			(GDT_ENTRY_KERNEL_CS*8)
121 #define __KERNEL_DS			(GDT_ENTRY_KERNEL_DS*8)
122 #define __USER_DS			(GDT_ENTRY_DEFAULT_USER_DS*8 + 3)
123 #define __USER_CS			(GDT_ENTRY_DEFAULT_USER_CS*8 + 3)
124 #define __ESPFIX_SS			(GDT_ENTRY_ESPFIX_SS*8)
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 
131 /* "Is this PNP code selector (PNP_CS32 or PNP_CS16)?" */
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 
141 #ifdef CONFIG_SMP
142 # define __KERNEL_PERCPU		(GDT_ENTRY_PERCPU*8)
143 #else
144 # define __KERNEL_PERCPU		0
145 #endif
146 
147 #ifdef CONFIG_CC_STACKPROTECTOR
148 # define __KERNEL_STACK_CANARY		(GDT_ENTRY_STACK_CANARY*8)
149 #else
150 # define __KERNEL_STACK_CANARY		0
151 #endif
152 
153 #else /* 64-bit: */
154 
155 #include <asm/cache.h>
156 
157 #define GDT_ENTRY_KERNEL32_CS		1
158 #define GDT_ENTRY_KERNEL_CS		2
159 #define GDT_ENTRY_KERNEL_DS		3
160 
161 /*
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  *
171  * ss = STAR.SYSRET_CS+8 (in either case)
172  *
173  * thus USER_DS should be between 32-bit and 64-bit code selectors:
174  */
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
183 
184 #define GDT_ENTRY_TLS_MIN		12
185 #define GDT_ENTRY_TLS_MAX		14
186 
187 /* Abused to load per CPU data from limit */
188 #define GDT_ENTRY_PER_CPU		15
189 
190 /*
191  * Number of entries in the GDT table:
192  */
193 #define GDT_ENTRIES			16
194 
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)
209 
210 /* TLS indexes for 64-bit - hardcoded in arch_prctl(): */
211 #define FS_TLS				0
212 #define GS_TLS				1
213 
214 #define GS_TLS_SEL			((GDT_ENTRY_TLS_MIN+GS_TLS)*8 + 3)
215 #define FS_TLS_SEL			((GDT_ENTRY_TLS_MIN+FS_TLS)*8 + 3)
216 
217 #endif
218 
219 #ifndef CONFIG_PARAVIRT
220 # define get_kernel_rpl()		0
221 #endif
222 
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)
232 
233 #ifdef __KERNEL__
234 
235 /*
236  * early_idt_handler_array is an array of entry points referenced in the
237  * early IDT.  For simplicity, it's a real array with one entry point
238  * every nine bytes.  That leaves room for an optional 'push $0' if the
239  * vector has no error code (two bytes), a 'push $vector_number' (two
240  * bytes), and a jump to the common entry code (up to five bytes).
241  */
242 #define EARLY_IDT_HANDLER_SIZE 9
243 
244 #ifndef __ASSEMBLY__
245 
246 extern const char early_idt_handler_array[NUM_EXCEPTION_VECTORS][EARLY_IDT_HANDLER_SIZE];
247 #ifdef CONFIG_TRACING
248 # define trace_early_idt_handler_array early_idt_handler_array
249 #endif
250 
251 /*
252  * Load a segment. Fall back on loading the zero
253  * segment if something goes wrong..
254  */
255 #define loadsegment(seg, value)						\
256 do {									\
257 	unsigned short __val = (value);					\
258 									\
259 	asm volatile("						\n"	\
260 		     "1:	movl %k0,%%" #seg "		\n"	\
261 									\
262 		     ".section .fixup,\"ax\"			\n"	\
263 		     "2:	xorl %k0,%k0			\n"	\
264 		     "		jmp 1b				\n"	\
265 		     ".previous					\n"	\
266 									\
267 		     _ASM_EXTABLE(1b, 2b)				\
268 									\
269 		     : "+r" (__val) : : "memory");			\
270 } while (0)
271 
272 /*
273  * Save a segment register away:
274  */
275 #define savesegment(seg, value)				\
276 	asm("mov %%" #seg ",%0":"=r" (value) : : "memory")
277 
278 /*
279  * x86-32 user GS accessors:
280  */
281 #ifdef CONFIG_X86_32
282 # ifdef CONFIG_X86_32_LAZY_GS
283 #  define get_user_gs(regs)		(u16)({ unsigned long v; savesegment(gs, v); v; })
284 #  define set_user_gs(regs, v)		loadsegment(gs, (unsigned long)(v))
285 #  define task_user_gs(tsk)		((tsk)->thread.gs)
286 #  define lazy_save_gs(v)		savesegment(gs, (v))
287 #  define lazy_load_gs(v)		loadsegment(gs, (v))
288 # else	/* X86_32_LAZY_GS */
289 #  define get_user_gs(regs)		(u16)((regs)->gs)
290 #  define set_user_gs(regs, v)		do { (regs)->gs = (v); } while (0)
291 #  define task_user_gs(tsk)		(task_pt_regs(tsk)->gs)
292 #  define lazy_save_gs(v)		do { } while (0)
293 #  define lazy_load_gs(v)		do { } while (0)
294 # endif	/* X86_32_LAZY_GS */
295 #endif	/* X86_32 */
296 
297 #endif /* !__ASSEMBLY__ */
298 #endif /* __KERNEL__ */
299 
300 #endif /* _ASM_X86_SEGMENT_H */
301