aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86/include/uapi/asm/sigcontext.h
blob: 62d4111c1c549a8f1cc70636e708934a83605cde (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
#ifndef _UAPI_ASM_X86_SIGCONTEXT_H
#define _UAPI_ASM_X86_SIGCONTEXT_H

/*
 * Linux signal context definitions. The sigcontext includes a complex
 * hierarchy of CPU and FPU state, available to user-space (on the stack) when
 * a signal handler is executed.
 *
 * As over the years this ABI grew from its very simple roots towards
 * supporting more and more CPU state organically, some of the details (which
 * were rather clever hacks back in the days) became a bit quirky by today.
 *
 * The current ABI includes flexible provisions for future extensions, so we
 * won't have to grow new quirks for quite some time. Promise!
 */

#include <linux/compiler.h>
#include <linux/types.h>

#define FP_XSTATE_MAGIC1		0x46505853U
#define FP_XSTATE_MAGIC2		0x46505845U
#define FP_XSTATE_MAGIC2_SIZE		sizeof(FP_XSTATE_MAGIC2)

/*
 * Bytes 464..511 in the current 512-byte layout of the FXSAVE/FXRSTOR frame
 * are reserved for SW usage. On CPUs supporting XSAVE/XRSTOR, these bytes are
 * used to extend the fpstate pointer in the sigcontext, which now includes the
 * extended state information along with fpstate information.
 *
 * If sw_reserved.magic1 == FP_XSTATE_MAGIC1 then there's a
 * sw_reserved.extended_size bytes large extended context area present. (The
 * last 32-bit word of this extended area (at the
 * fpstate+extended_size-FP_XSTATE_MAGIC2_SIZE address) is set to
 * FP_XSTATE_MAGIC2 so that you can sanity check your size calculations.)
 *
 * This extended area typically grows with newer CPUs that have larger and
 * larger XSAVE areas.
 */
struct _fpx_sw_bytes {
	/*
	 * If set to FP_XSTATE_MAGIC1 then this is an xstate context.
	 * 0 if a legacy frame.
	 */
	__u32				magic1;

	/*
	 * Total size of the fpstate area:
	 *
	 *  - if magic1 == 0 then it's sizeof(struct _fpstate)
	 *  - if magic1 == FP_XSTATE_MAGIC1 then it's sizeof(struct _xstate)
	 *    plus extensions (if any)
	 */
	__u32				extended_size;

	/*
	 * Feature bit mask (including FP/SSE/extended state) that is present
	 * in the memory layout:
	 */
	__u64				xfeatures;

	/*
	 * Actual XSAVE state size, based on the xfeatures saved in the layout.
	 * 'extended_size' is greater than 'xstate_size':
	 */
	__u32				xstate_size;

	/* For future use: */
	__u32				padding[7];
};

/*
 * As documented in the iBCS2 standard:
 *
 * The first part of "struct _fpstate" is just the normal i387 hardware setup,
 * the extra "status" word is used to save the coprocessor status word before
 * entering the handler.
 *
 * The FPU state data structure has had to grow to accommodate the extended FPU
 * state required by the Streaming SIMD Extensions.  There is no documented
 * standard to accomplish this at the moment.
 */

/* 10-byte legacy floating point register: */
struct _fpreg {
	__u16				significand[4];
	__u16				exponent;
};

/* 16-byte floating point register: */
struct _fpxreg {
	__u16				significand[4];
	__u16				exponent;
	__u16				padding[3];
};

/* 16-byte XMM register: */
struct _xmmreg {
	__u32				element[4];
};

#define X86_FXSR_MAGIC			0x0000

/*
 * The 32-bit FPU frame:
 */
struct _fpstate_32 {
	/* Legacy FPU environment: */
	__u32				cw;
	__u32				sw;
	__u32				tag;
	__u32				ipoff;
	__u32				cssel;
	__u32				dataoff;
	__u32				datasel;
	struct _fpreg			_st[8];
	__u16				status;
	__u16				magic;		/* 0xffff: regular FPU data only */
							/* 0x0000: FXSR FPU data */

	/* FXSR FPU environment */
	__u32				_fxsr_env[6];	/* FXSR FPU env is ignored */
	__u32				mxcsr;
	__u32				reserved;
	struct _fpxreg			_fxsr_st[8];	/* FXSR FPU reg data is ignored */
	struct _xmmreg			_xmm[8];	/* First 8 XMM registers */
	union {
		__u32			padding1[44];	/* Second 8 XMM registers plus padding */
		__u32			padding[44];	/* Alias name for old user-space */
	};

	union {
		__u32			padding2[12];
		struct _fpx_sw_bytes	sw_reserved;	/* Potential extended state is encoded here */
	};
};

/*
 * The 64-bit FPU frame. (FXSAVE format and later)
 *
 * Note1: If sw_reserved.magic1 == FP_XSTATE_MAGIC1 then the structure is
 *        larger: 'struct _xstate'. Note that 'struct _xstate' embedds
 *        'struct _fpstate' so that you can always assume the _fpstate portion
 *        exists so that you can check the magic value.
 *
 * Note2: Reserved fields may someday contain valuable data. Always
 *	  save/restore them when you change signal frames.
 */
struct _fpstate_64 {
	__u16				cwd;
	__u16				swd;
	/* Note this is not the same as the 32-bit/x87/FSAVE twd: */
	__u16				twd;
	__u16				fop;
	__u64				rip;
	__u64				rdp;
	__u32				mxcsr;
	__u32				mxcsr_mask;
	__u32				st_space[32];	/*  8x  FP registers, 16 bytes each */
	__u32				xmm_space[64];	/* 16x XMM registers, 16 bytes each */
	__u32				reserved2[12];
	union {
		__u32			reserved3[12];
		struct _fpx_sw_bytes	sw_reserved;	/* Potential extended state is encoded here */
	};
};

#ifdef __i386__
# define _fpstate _fpstate_32
#else
# define _fpstate _fpstate_64
#endif

struct _header {
	__u64				xfeatures;
	__u64				reserved1[2];
	__u64				reserved2[5];
};

struct _ymmh_state {
	/* 16x YMM registers, 16 bytes each: */
	__u32				ymmh_space[64];
};

/*
 * Extended state pointed to by sigcontext::fpstate.
 *
 * In addition to the fpstate, information encoded in _xstate::xstate_hdr
 * indicates the presence of other extended state information supported
 * by the CPU and kernel:
 */
struct _xstate {
	struct _fpstate			fpstate;
	struct _header			xstate_hdr;
	struct _ymmh_state		ymmh;
	/* New processor state extensions go here: */
};

/*
 * The 32-bit signal frame:
 */
struct sigcontext_32 {
	__u16				gs, __gsh;
	__u16				fs, __fsh;
	__u16				es, __esh;
	__u16				ds, __dsh;
	__u32				di;
	__u32				si;
	__u32				bp;
	__u32				sp;
	__u32				bx;
	__u32				dx;
	__u32				cx;
	__u32				ax;
	__u32				trapno;
	__u32				err;
	__u32				ip;
	__u16				cs, __csh;
	__u32				flags;
	__u32				sp_at_signal;
	__u16				ss, __ssh;

	/*
	 * fpstate is really (struct _fpstate *) or (struct _xstate *)
	 * depending on the FP_XSTATE_MAGIC1 encoded in the SW reserved
	 * bytes of (struct _fpstate) and FP_XSTATE_MAGIC2 present at the end
	 * of extended memory layout. See comments at the definition of
	 * (struct _fpx_sw_bytes)
	 */
	__u32				fpstate; /* Zero when no FPU/extended context */
	__u32				oldmask;
	__u32				cr2;
};

/*
 * The 64-bit signal frame:
 */
struct sigcontext_64 {
	__u64				r8;
	__u64				r9;
	__u64				r10;
	__u64				r11;
	__u64				r12;
	__u64				r13;
	__u64				r14;
	__u64				r15;
	__u64				di;
	__u64				si;
	__u64				bp;
	__u64				bx;
	__u64				dx;
	__u64				ax;
	__u64				cx;
	__u64				sp;
	__u64				ip;
	__u64				flags;
	__u16				cs;
	__u16				gs;
	__u16				fs;
	__u16				ss;
	__u64				err;
	__u64				trapno;
	__u64				oldmask;
	__u64				cr2;

	/*
	 * fpstate is really (struct _fpstate *) or (struct _xstate *)
	 * depending on the FP_XSTATE_MAGIC1 encoded in the SW reserved
	 * bytes of (struct _fpstate) and FP_XSTATE_MAGIC2 present at the end
	 * of extended memory layout. See comments at the definition of
	 * (struct _fpx_sw_bytes)
	 */
	__u64				fpstate; /* Zero when no FPU/extended context */
	__u64				reserved1[8];
};

/*
 * Create the real 'struct sigcontext' type:
 */
#ifdef __KERNEL__
# ifdef __i386__
#  define sigcontext sigcontext_32
# else
#  define sigcontext sigcontext_64
# endif
#endif

/*
 * The old user-space sigcontext definition, just in case user-space still
 * relies on it. The kernel definition (in asm/sigcontext.h) has unified
 * field names but otherwise the same layout.
 */
#ifndef __KERNEL__

#define _fpstate_ia32			_fpstate_32
#define sigcontext_ia32			sigcontext_32


# ifdef __i386__
struct sigcontext {
	__u16				gs, __gsh;
	__u16				fs, __fsh;
	__u16				es, __esh;
	__u16				ds, __dsh;
	__u32				edi;
	__u32				esi;
	__u32				ebp;
	__u32				esp;
	__u32				ebx;
	__u32				edx;
	__u32				ecx;
	__u32				eax;
	__u32				trapno;
	__u32				err;
	__u32				eip;
	__u16				cs, __csh;
	__u32				eflags;
	__u32				esp_at_signal;
	__u16				ss, __ssh;
	struct _fpstate __user		*fpstate;
	__u32				oldmask;
	__u32				cr2;
};
# else /* __x86_64__: */
struct sigcontext {
	__u64				r8;
	__u64				r9;
	__u64				r10;
	__u64				r11;
	__u64				r12;
	__u64				r13;
	__u64				r14;
	__u64				r15;
	__u64				rdi;
	__u64				rsi;
	__u64				rbp;
	__u64				rbx;
	__u64				rdx;
	__u64				rax;
	__u64				rcx;
	__u64				rsp;
	__u64				rip;
	__u64				eflags;		/* RFLAGS */
	__u16				cs;

	/*
	 * Prior to 2.5.64 ("[PATCH] x86-64 updates for 2.5.64-bk3"),
	 * Linux saved and restored fs and gs in these slots.  This
	 * was counterproductive, as fsbase and gsbase were never
	 * saved, so arch_prctl was presumably unreliable.
	 *
	 * These slots should never be reused without extreme caution:
	 *
	 *  - Some DOSEMU versions stash fs and gs in these slots manually,
	 *    thus overwriting anything the kernel expects to be preserved
	 *    in these slots.
	 *
	 *  - If these slots are ever needed for any other purpose,
	 *    there is some risk that very old 64-bit binaries could get
	 *    confused.  I doubt that many such binaries still work,
	 *    though, since the same patch in 2.5.64 also removed the
	 *    64-bit set_thread_area syscall, so it appears that there
	 *    is no TLS API beyond modify_ldt that works in both pre-
	 *    and post-2.5.64 kernels.
	 *
	 * If the kernel ever adds explicit fs, gs, fsbase, and gsbase
	 * save/restore, it will most likely need to be opt-in and use
	 * different context slots.
	 */
	__u16				gs;
	__u16				fs;
	union {
		__u16			ss;	/* If UC_SIGCONTEXT_SS */
		__u16			__pad0;	/* Alias name for old (!UC_SIGCONTEXT_SS) user-space */
	};
	__u64				err;
	__u64				trapno;
	__u64				oldmask;
	__u64				cr2;
	struct _fpstate __user		*fpstate;	/* Zero when no FPU context */
#  ifdef __ILP32__
	__u32				__fpstate_pad;
#  endif
	__u64				reserved1[8];
};
# endif /* __x86_64__ */
#endif /* !__KERNEL__ */

#endif /* _UAPI_ASM_X86_SIGCONTEXT_H */

Privacy Policy