summaryrefslogtreecommitdiffstats
path: root/arch/x86/include/asm/desc.h
blob: 68a99d2a5f335d6b6b059624e0e2aa1d38d60a4d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_DESC_H
#define _ASM_X86_DESC_H

#include <asm/desc_defs.h>
#include <asm/ldt.h>
#include <asm/mmu.h>
#include <asm/fixmap.h>
#include <asm/irq_vectors.h>
#include <asm/cpu_entry_area.h>

#include <linux/smp.h>
#include <linux/percpu.h>

static inline void fill_ldt(struct desc_struct *desc, const struct user_desc *info)
{
	desc->limit0		= info->limit & 0x0ffff;

	desc->base0		= (info->base_addr & 0x0000ffff);
	desc->base1		= (info->base_addr & 0x00ff0000) >> 16;

	desc->type		= (info->read_exec_only ^ 1) << 1;
	desc->type	       |= info->contents << 2;
	/* Set the ACCESS bit so it can be mapped RO */
	desc->type	       |= 1;

	desc->s			= 1;
	desc->dpl		= 0x3;
	desc->p			= info->seg_not_present ^ 1;
	desc->limit1		= (info->limit & 0xf0000) >> 16;
	desc->avl		= info->useable;
	desc->d			= info->seg_32bit;
	desc->g			= info->limit_in_pages;

	desc->base2		= (info->base_addr & 0xff000000) >> 24;
	/*
	 * Don't allow setting of the lm bit. It would confuse
	 * user_64bit_mode and would get overridden by sysret anyway.
	 */
	desc->l			= 0;
}

extern struct desc_ptr idt_descr;
extern gate_desc idt_table[];
extern const struct desc_ptr debug_idt_descr;
extern gate_desc debug_idt_table[];

struct gdt_page {
	struct desc_struct gdt[GDT_ENTRIES];
} __attribute__((aligned(PAGE_SIZE)));

DECLARE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page);

/* Provide the original GDT */
static inline struct desc_struct *get_cpu_gdt_rw(unsigned int cpu)
{
	return per_cpu(gdt_page, cpu).gdt;
}

/* Provide the current original GDT */
static inline struct desc_struct *get_current_gdt_rw(void)
{
	return this_cpu_ptr(&gdt_page)->gdt;
}

/* Provide the fixmap address of the remapped GDT */
static inline struct desc_struct *get_cpu_gdt_ro(int cpu)
{
	return (struct desc_struct *)&get_cpu_entry_area(cpu)->gdt;
}

/* Provide the current read-only GDT */
static inline struct desc_struct *get_current_gdt_ro(void)
{
	return get_cpu_gdt_ro(smp_processor_id());
}

/* Provide the physical address of the GDT page. */
static inline phys_addr_t get_cpu_gdt_paddr(unsigned int cpu)
{
	return per_cpu_ptr_to_phys(get_cpu_gdt_rw(cpu));
}

static inline void pack_gate(gate_desc *gate, unsigned type, unsigned long func,
			     unsigned dpl, unsigned ist, unsigned seg)
{
	gate->offset_low	= (u16) func;
	gate->bits.p		= 1;
	gate->bits.dpl		= dpl;
	gate->bits.zero		= 0;
	gate->bits.type		= type;
	gate->offset_middle	= (u16) (func >> 16);
#ifdef CONFIG_X86_64
	gate->segment		= __KERNEL_CS;
	gate->bits.ist		= ist;
	gate->reserved		= 0;
	gate->offset_high	= (u32) (func >> 32);
#else
	gate->segment		= seg;
	gate->bits.ist		= 0;
#endif
}

static inline int desc_empty(const void *ptr)
{
	const u32 *desc = ptr;

	return !(desc[0] | desc[1]);
}

#ifdef CONFIG_PARAVIRT_XXL
#include <asm/paravirt.h>
#else
#define load_TR_desc()				native_load_tr_desc()
#define load_gdt(dtr)				native_load_gdt(dtr)
#define load_idt(dtr)				native_load_idt(dtr)
#define load_tr(tr)				asm volatile("ltr %0"::"m" (tr))
#define load_ldt(ldt)				asm volatile("lldt %0"::"m" (ldt))

#define store_gdt(dtr)				native_store_gdt(dtr)
#define store_tr(tr)				(tr = native_store_tr())

#define load_TLS(t, cpu)			native_load_tls(t, cpu)
#define set_ldt					native_set_ldt

#define write_ldt_entry(dt, entry, desc)	native_write_ldt_entry(dt, entry, desc)
#define write_gdt_entry(dt, entry, desc, type)	native_write_gdt_entry(dt, entry, desc, type)
#define write_idt_entry(dt, entry, g)		native_write_idt_entry(dt, entry, g)

static inline void paravirt_alloc_ldt(struct desc_struct *ldt, unsigned entries)
{
}

static inline void paravirt_free_ldt(struct desc_struct *ldt, unsigned entries)
{
}
#endif	/* CONFIG_PARAVIRT_XXL */

#define store_ldt(ldt) asm("sldt %0" : "=m"(ldt))

static inline void native_write_idt_entry(gate_desc *idt, int entry, const gate_desc *gate)
{
	memcpy(&idt[entry], gate, sizeof(*gate));
}

static inline void native_write_ldt_entry(struct desc_struct *ldt, int entry, const void *desc)
{
	memcpy(&ldt[entry], desc, 8);
}

static inline void
native_write_gdt_entry(struct desc_struct *gdt, int entry, const void *desc, int type)
{
	unsigned int size;

	switch (type) {
	case DESC_TSS:	size = sizeof(tss_desc);	break;
	case DESC_LDT:	size = sizeof(ldt_desc);	break;
	default:	size = sizeof(*gdt);		break;
	}

	memcpy(&gdt[entry], desc, size);
}

static inline void set_tssldt_descriptor(void *d, unsigned long addr,
					 unsigned type, unsigned size)
{
	struct ldttss_desc *desc = d;

	memset(desc, 0, sizeof(*desc));

	desc->limit0		= (u16) size;
	desc->base0		= (u16) addr;
	desc->base1		= (addr >> 16) & 0xFF;
	desc->type		= type;
	desc->p			= 1;
	desc->limit1		= (size >> 16) & 0xF;
	desc->base2		= (addr >> 24) & 0xFF;
#ifdef CONFIG_X86_64
	desc->base3		= (u32) (addr >> 32);
#endif
}

static inline void __set_tss_desc(unsigned cpu, unsigned int entry, struct x86_hw_tss *addr)
{
	struct desc_struct *d = get_cpu_gdt_rw(cpu);
	tss_desc tss;

	set_tssldt_descriptor(&tss, (unsigned long)addr, DESC_TSS,
			      __KERNEL_TSS_LIMIT);
	write_gdt_entry(d, entry, &tss, DESC_TSS);
}

#define set_tss_desc(cpu, addr) __set_tss_desc(cpu, GDT_ENTRY_TSS, addr)

static inline void native_set_ldt(const void *addr, unsigned int entries)
{
	if (likely(entries == 0))
		asm volatile("lldt %w0"::"q" (0));
	else {
		unsigned cpu = smp_processor_id();
		ldt_desc ldt;

		set_tssldt_descriptor(&ldt, (unsigned long)addr, DESC_LDT,
				      entries * LDT_ENTRY_SIZE - 1);
		write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_LDT,
				&ldt, DESC_LDT);
		asm volatile("lldt %w0"::"q" (GDT_ENTRY_LDT*8));
	}
}

static inline void native_load_gdt(const struct desc_ptr *dtr)
{
	asm volatile("lgdt %0"::"m" (*dtr));
}

static inline void native_load_idt(const struct desc_ptr *dtr)
{
	asm volatile("lidt %0"::"m" (*dtr));
}

static inline void native_store_gdt(struct desc_ptr *dtr)
{
	asm volatile("sgdt %0":"=m" (*dtr));
}

static inline void store_idt(struct desc_ptr *dtr)
{
	asm volatile("sidt %0":"=m" (*dtr));
}

/*
 * The LTR instruction marks the TSS GDT entry as busy. On 64-bit, the GDT is
 * a read-only remapping. To prevent a page fault, the GDT is switched to the
 * original writeable version when needed.
 */
#ifdef CONFIG_X86_64
static inline void native_load_tr_desc(void)
{
	struct desc_ptr gdt;
	int cpu = raw_smp_processor_id();
	bool restore = 0;
	struct desc_struct *fixmap_gdt;

	native_store_gdt(&gdt);
	fixmap_gdt = get_cpu_gdt_ro(cpu);

	/*
	 * If the current GDT is the read-only fixmap, swap to the original
	 * writeable version. Swap back at the end.
	 */
	if (gdt.address == (unsigned long)fixmap_gdt) {
		load_direct_gdt(cpu);
		restore = 1;
	}
	asm volatile("ltr %w0"::"q" (GDT_ENTRY_TSS*8));
	if (restore)
		load_fixmap_gdt(cpu);
}
#else
static inline void native_load_tr_desc(void)
{
	asm volatile("ltr %w0"::"q" (GDT_ENTRY_TSS*8));
}
#endif

static inline unsigned long native_store_tr(void)
{
	unsigned long tr;

	asm volatile("str %0":"=r" (tr));

	return tr;
}

static inline void native_load_tls(struct thread_struct *t, unsigned int cpu)
{
	struct desc_struct *gdt = get_cpu_gdt_rw(cpu);
	unsigned int i;

	for (i = 0; i < GDT_ENTRY_TLS_ENTRIES; i++)
		gdt[GDT_ENTRY_TLS_MIN + i] = t->tls_array[i];
}

DECLARE_PER_CPU(bool, __tss_limit_invalid);

static inline void force_reload_TR(void)
{
	struct desc_struct *d = get_current_gdt_rw();
	tss_desc tss;

	memcpy(&tss, &d[GDT_ENTRY_TSS], sizeof(tss_desc));

	/*
	 * LTR requires an available TSS, and the TSS is currently
	 * busy.  Make it be available so that LTR will work.
	 */
	tss.type = DESC_TSS;
	write_gdt_entry(d, GDT_ENTRY_TSS, &tss, DESC_TSS);

	load_TR_desc();
	this_cpu_write(__tss_limit_invalid, false);
}

/*
 * Call this if you need the TSS limit to be correct, which should be the case
 * if and only if you have TIF_IO_BITMAP set or you're switching to a task
 * with TIF_IO_BITMAP set.
 */
static inline void refresh_tss_limit(void)
{
	DEBUG_LOCKS_WARN_ON(preemptible());

	if (unlikely(this_cpu_read(__tss_limit_invalid)))
		force_reload_TR();
}

/*
 * If you do something evil that corrupts the cached TSS limit (I'm looking
 * at you, VMX exits), call this function.
 *
 * The optimization here is that the TSS limit only matters for Linux if the
 * IO bitmap is in use.  If the TSS limit gets forced to its minimum value,
 * everything works except that IO bitmap will be ignored and all CPL 3 IO
 * instructions will #GP, which is exactly what we want for normal tasks.
 */
static inline void invalidate_tss_limit(void)
{
	DEBUG_LOCKS_WARN_ON(preemptible());

	if (unlikely(test_thread_flag(TIF_IO_BITMAP)))
		force_reload_TR();
	else
		this_cpu_write(__tss_limit_invalid, true);
}

/* This intentionally ignores lm, since 32-bit apps don't have that field. */
#define LDT_empty(info)					\
	((info)->base_addr		== 0	&&	\
	 (info)->limit			== 0	&&	\
	 (info)->contents		== 0	&&	\
	 (info)->read_exec_only		== 1	&&	\
	 (info)->seg_32bit		== 0	&&	\
	 (info)->limit_in_pages		== 0	&&	\
	 (info)->seg_not_present	== 1	&&	\
	 (info)->useable		== 0)

/* Lots of programs expect an all-zero user_desc to mean "no segment at all". */
static inline bool LDT_zero(const struct user_desc *info)
{
	return (info->base_addr		== 0 &&
		info->limit		== 0 &&
		info->contents		== 0 &&
		info->read_exec_only	== 0 &&
		info->seg_32bit		== 0 &&
		info->limit_in_pages	== 0 &&
		info->seg_not_present	== 0 &&
		info->useable		== 0);
}

static inline void clear_LDT(void)
{
	set_ldt(NULL, 0);
}

static inline unsigned long get_desc_base(const struct desc_struct *desc)
{
	return (unsigned)(desc->base0 | ((desc->base1) << 16) | ((desc->base2) << 24));
}

static inline void set_desc_base(struct desc_struct *desc, unsigned long base)
{
	desc->base0 = base & 0xffff;
	desc->base1 = (base >> 16) & 0xff;
	desc->base2 = (base >> 24) & 0xff;
}

static inline unsigned long get_desc_limit(const struct desc_struct *desc)
{
	return desc->limit0 | (desc->limit1 << 16);
}

static inline void set_desc_limit(struct desc_struct *desc, unsigned long limit)
{
	desc->limit0 = limit & 0xffff;
	desc->limit1 = (limit >> 16) & 0xf;
}

void update_intr_gate(unsigned int n, const void *addr);
void alloc_intr_gate(unsigned int n, const void *addr);

extern unsigned long system_vectors[];

#ifdef CONFIG_X86_64
DECLARE_PER_CPU(u32, debug_idt_ctr);
static inline bool is_debug_idt_enabled(void)
{
	if (this_cpu_read(debug_idt_ctr))
		return true;

	return false;
}

static inline void load_debug_idt(void)
{
	load_idt((const struct desc_ptr *)&debug_idt_descr);
}
#else
static inline bool is_debug_idt_enabled(void)
{
	return false;
}

static inline void load_debug_idt(void)
{
}
#endif

/*
 * The load_current_idt() must be called with interrupts disabled
 * to avoid races. That way the IDT will always be set back to the expected
 * descriptor. It's also called when a CPU is being initialized, and
 * that doesn't need to disable interrupts, as nothing should be
 * bothering the CPU then.
 */
static inline void load_current_idt(void)
{
	if (is_debug_idt_enabled())
		load_debug_idt();
	else
		load_idt((const struct desc_ptr *)&idt_descr);
}

extern void idt_setup_early_handler(void);
extern void idt_setup_early_traps(void);
extern void idt_setup_traps(void);
extern void idt_setup_apic_and_irq_gates(void);

#ifdef CONFIG_X86_64
extern void idt_setup_early_pf(void);
extern void idt_setup_ist_traps(void);
extern void idt_setup_debugidt_traps(void);
#else
static inline void idt_setup_early_pf(void) { }
static inline void idt_setup_ist_traps(void) { }
static inline void idt_setup_debugidt_traps(void) { }
#endif

extern void idt_invalidate(void *addr);

#endif /* _ASM_X86_DESC_H */