about summary refs log tree commit diff
path: root/sysdeps/unix/sysv/linux/i386/sysdep.h
blob: 87de7d640fa1a9972674adbe5c35a35b91e86c56 (plain) (blame)
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
452
453
454
/* Copyright (C) 1992-2023 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifndef _LINUX_I386_SYSDEP_H
#define _LINUX_I386_SYSDEP_H 1

/* There is some commonality.  */
#include <sysdeps/unix/sysv/linux/sysdep.h>
#include <sysdeps/unix/i386/sysdep.h>
/* Defines RTLD_PRIVATE_ERRNO and USE_DL_SYSINFO.  */
#include <dl-sysdep.h>
#include <tls.h>


/* For Linux we can use the system call table in the header file
	/usr/include/asm/unistd.h
   of the kernel.  But these symbols do not follow the SYS_* syntax
   so we have to redefine the `SYS_ify' macro here.  */
#undef SYS_ify
#define SYS_ify(syscall_name)	__NR_##syscall_name

#ifndef I386_USE_SYSENTER
# if defined USE_DL_SYSINFO \
     && (IS_IN (libc) || IS_IN (libpthread))
#  define I386_USE_SYSENTER	1
# else
#  define I386_USE_SYSENTER	0
# endif
#endif

#if !I386_USE_SYSENTER && IS_IN (libc) && !defined SHARED
/* Inside static libc, we have two versions.  For compilation units
   with !I386_USE_SYSENTER, the vDSO entry mechanism cannot be
   used. */
# define I386_DO_SYSCALL_STRING "__libc_do_syscall_int80"
#else
# define I386_DO_SYSCALL_STRING "__libc_do_syscall"
#endif

#ifdef __ASSEMBLER__

/* Linux uses a negative return value to indicate syscall errors,
   unlike most Unices, which use the condition codes' carry flag.

   Since version 2.1 the return value of a system call might be
   negative even if the call succeeded.  E.g., the `lseek' system call
   might return a large offset.  Therefore we must not anymore test
   for < 0, but test for a real error by making sure the value in %eax
   is a real error number.  Linus said he will make sure the no syscall
   returns a value in -1 .. -4095 as a valid result so we can safely
   test with -4095.  */

/* We don't want the label for the error handle to be global when we define
   it here.  */
#undef SYSCALL_ERROR_LABEL
#define SYSCALL_ERROR_LABEL __syscall_error

#undef	PSEUDO
#define	PSEUDO(name, syscall_name, args)				      \
  .text;								      \
  ENTRY (name)								      \
    DO_CALL (syscall_name, args);					      \
    cmpl $-4095, %eax;							      \
    jae SYSCALL_ERROR_LABEL

#undef	PSEUDO_END
#define	PSEUDO_END(name)						      \
  SYSCALL_ERROR_HANDLER							      \
  END (name)

#undef	PSEUDO_NOERRNO
#define	PSEUDO_NOERRNO(name, syscall_name, args)			      \
  .text;								      \
  ENTRY (name)								      \
    DO_CALL (syscall_name, args)

#undef	PSEUDO_END_NOERRNO
#define	PSEUDO_END_NOERRNO(name)					      \
  END (name)

#define ret_NOERRNO ret

/* The function has to return the error code.  */
#undef	PSEUDO_ERRVAL
#define	PSEUDO_ERRVAL(name, syscall_name, args) \
  .text;								      \
  ENTRY (name)								      \
    DO_CALL (syscall_name, args);					      \
    negl %eax

#undef	PSEUDO_END_ERRVAL
#define	PSEUDO_END_ERRVAL(name) \
  END (name)

#define ret_ERRVAL ret

#define SYSCALL_ERROR_HANDLER	/* Nothing here; code in sysdep.c is used.  */

/* The original calling convention for system calls on Linux/i386 is
   to use int $0x80.  */
#if I386_USE_SYSENTER
# ifdef PIC
#  define ENTER_KERNEL call *%gs:SYSINFO_OFFSET
# else
#  define ENTER_KERNEL call *_dl_sysinfo
# endif
#else
# define ENTER_KERNEL int $0x80
#endif

/* Linux takes system call arguments in registers:

	syscall number	%eax	     call-clobbered
	arg 1		%ebx	     call-saved
	arg 2		%ecx	     call-clobbered
	arg 3		%edx	     call-clobbered
	arg 4		%esi	     call-saved
	arg 5		%edi	     call-saved
	arg 6		%ebp	     call-saved

   The stack layout upon entering the function is:

	24(%esp)	Arg# 6
	20(%esp)	Arg# 5
	16(%esp)	Arg# 4
	12(%esp)	Arg# 3
	 8(%esp)	Arg# 2
	 4(%esp)	Arg# 1
	  (%esp)	Return address

   (Of course a function with say 3 arguments does not have entries for
   arguments 4, 5, and 6.)

   The following code tries hard to be optimal.  A general assumption
   (which is true according to the data books I have) is that

	2 * xchg	is more expensive than	pushl + movl + popl

   Beside this a neat trick is used.  The calling conventions for Linux
   tell that among the registers used for parameters %ecx and %edx need
   not be saved.  Beside this we may clobber this registers even when
   they are not used for parameter passing.

   As a result one can see below that we save the content of the %ebx
   register in the %edx register when we have less than 3 arguments
   (2 * movl is less expensive than pushl + popl).

   Second unlike for the other registers we don't save the content of
   %ecx and %edx when we have more than 1 and 2 registers resp.

   The code below might look a bit long but we have to take care for
   the pipelined processors (i586).  Here the `pushl' and `popl'
   instructions are marked as NP (not pairable) but the exception is
   two consecutive of these instruction.  This gives no penalty on
   other processors though.  */

#undef	DO_CALL
#define DO_CALL(syscall_name, args)			      		      \
    PUSHARGS_##args							      \
    DOARGS_##args							      \
    movl $SYS_ify (syscall_name), %eax;					      \
    ENTER_KERNEL							      \
    POPARGS_##args

#define PUSHARGS_0	/* No arguments to push.  */
#define	DOARGS_0	/* No arguments to frob.  */
#define	POPARGS_0	/* No arguments to pop.  */
#define	_PUSHARGS_0	/* No arguments to push.  */
#define _DOARGS_0(n)	/* No arguments to frob.  */
#define	_POPARGS_0	/* No arguments to pop.  */

#define PUSHARGS_1	movl %ebx, %edx; L(SAVEBX1): PUSHARGS_0
#define	DOARGS_1	_DOARGS_1 (4)
#define	POPARGS_1	POPARGS_0; movl %edx, %ebx; L(RESTBX1):
#define	_PUSHARGS_1	pushl %ebx; cfi_adjust_cfa_offset (4); \
			cfi_rel_offset (ebx, 0); L(PUSHBX1): _PUSHARGS_0
#define _DOARGS_1(n)	movl n(%esp), %ebx; _DOARGS_0(n-4)
#define	_POPARGS_1	_POPARGS_0; popl %ebx; cfi_adjust_cfa_offset (-4); \
			cfi_restore (ebx); L(POPBX1):

#define PUSHARGS_2	PUSHARGS_1
#define	DOARGS_2	_DOARGS_2 (8)
#define	POPARGS_2	POPARGS_1
#define _PUSHARGS_2	_PUSHARGS_1
#define	_DOARGS_2(n)	movl n(%esp), %ecx; _DOARGS_1 (n-4)
#define	_POPARGS_2	_POPARGS_1

#define PUSHARGS_3	_PUSHARGS_2
#define DOARGS_3	_DOARGS_3 (16)
#define POPARGS_3	_POPARGS_3
#define _PUSHARGS_3	_PUSHARGS_2
#define _DOARGS_3(n)	movl n(%esp), %edx; _DOARGS_2 (n-4)
#define _POPARGS_3	_POPARGS_2

#define PUSHARGS_4	_PUSHARGS_4
#define DOARGS_4	_DOARGS_4 (24)
#define POPARGS_4	_POPARGS_4
#define _PUSHARGS_4	pushl %esi; cfi_adjust_cfa_offset (4); \
			cfi_rel_offset (esi, 0); L(PUSHSI1): _PUSHARGS_3
#define _DOARGS_4(n)	movl n(%esp), %esi; _DOARGS_3 (n-4)
#define _POPARGS_4	_POPARGS_3; popl %esi; cfi_adjust_cfa_offset (-4); \
			cfi_restore (esi); L(POPSI1):

#define PUSHARGS_5	_PUSHARGS_5
#define DOARGS_5	_DOARGS_5 (32)
#define POPARGS_5	_POPARGS_5
#define _PUSHARGS_5	pushl %edi; cfi_adjust_cfa_offset (4); \
			cfi_rel_offset (edi, 0); L(PUSHDI1): _PUSHARGS_4
#define _DOARGS_5(n)	movl n(%esp), %edi; _DOARGS_4 (n-4)
#define _POPARGS_5	_POPARGS_4; popl %edi; cfi_adjust_cfa_offset (-4); \
			cfi_restore (edi); L(POPDI1):

#define PUSHARGS_6	_PUSHARGS_6
#define DOARGS_6	_DOARGS_6 (40)
#define POPARGS_6	_POPARGS_6
#define _PUSHARGS_6	pushl %ebp; cfi_adjust_cfa_offset (4); \
			cfi_rel_offset (ebp, 0); L(PUSHBP1): _PUSHARGS_5
#define _DOARGS_6(n)	movl n(%esp), %ebp; _DOARGS_5 (n-4)
#define _POPARGS_6	_POPARGS_5; popl %ebp; cfi_adjust_cfa_offset (-4); \
			cfi_restore (ebp); L(POPBP1):

#else	/* !__ASSEMBLER__ */

extern int __syscall_error (int)
  attribute_hidden __attribute__ ((__regparm__ (1)));

/* Six-argument syscalls use an out-of-line helper, because an inline
   asm using all registers apart from %esp cannot work reliably and
   the assembler does not support describing an asm that saves and
   restores %ebp itself as a separate stack frame.  This structure
   stores the arguments not passed in registers; %edi is passed with a
   pointer to this structure.  */
struct libc_do_syscall_args
{
  int ebx, edi, ebp;
};

# define VDSO_NAME  "LINUX_2.6"
# define VDSO_HASH  61765110

/* List of system calls which are supported as vsyscalls.  */
# define HAVE_CLOCK_GETTIME_VSYSCALL    "__vdso_clock_gettime"
# define HAVE_CLOCK_GETTIME64_VSYSCALL  "__vdso_clock_gettime64"
# define HAVE_GETTIMEOFDAY_VSYSCALL     "__vdso_gettimeofday"
# define HAVE_TIME_VSYSCALL             "__vdso_time"
# define HAVE_CLOCK_GETRES_VSYSCALL     "__vdso_clock_getres"

# define HAVE_CLONE3_WRAPPER		1

# undef HAVE_INTERNAL_BRK_ADDR_SYMBOL
# define HAVE_INTERNAL_BRK_ADDR_SYMBOL 1

/* Define a macro which expands inline into the wrapper code for a system
   call.  This use is for internal calls that do not need to handle errors
   normally.  It will never touch errno.  This returns just what the kernel
   gave back.

   The _NCS variant allows non-constant syscall numbers but it is not
   possible to use more than four parameters.  */
#undef INTERNAL_SYSCALL
#define INTERNAL_SYSCALL_MAIN_0(name, args...) \
    INTERNAL_SYSCALL_MAIN_INLINE(name, 0, args)
#define INTERNAL_SYSCALL_MAIN_1(name, args...) \
    INTERNAL_SYSCALL_MAIN_INLINE(name, 1, args)
#define INTERNAL_SYSCALL_MAIN_2(name, args...) \
    INTERNAL_SYSCALL_MAIN_INLINE(name, 2, args)
#define INTERNAL_SYSCALL_MAIN_3(name, args...) \
    INTERNAL_SYSCALL_MAIN_INLINE(name, 3, args)
#define INTERNAL_SYSCALL_MAIN_4(name, args...) \
    INTERNAL_SYSCALL_MAIN_INLINE(name, 4, args)
#define INTERNAL_SYSCALL_MAIN_5(name, args...) \
    INTERNAL_SYSCALL_MAIN_INLINE(name, 5, args)

#define INTERNAL_SYSCALL_MAIN_NCS_0(name, args...) \
    INTERNAL_SYSCALL_MAIN_NCS(name, 0, args)
#define INTERNAL_SYSCALL_MAIN_NCS_1(name, args...) \
    INTERNAL_SYSCALL_MAIN_NCS(name, 1, args)
#define INTERNAL_SYSCALL_MAIN_NCS_2(name, args...) \
    INTERNAL_SYSCALL_MAIN_NCS(name, 2, args)
#define INTERNAL_SYSCALL_MAIN_NCS_3(name, args...) \
    INTERNAL_SYSCALL_MAIN_NCS(name, 3, args)
#define INTERNAL_SYSCALL_MAIN_NCS_4(name, args...) \
    INTERNAL_SYSCALL_MAIN_NCS(name, 4, args)
#define INTERNAL_SYSCALL_MAIN_NCS_5(name, args...) \
    INTERNAL_SYSCALL_MAIN_NCS(name, 5, args)

/* Each object using 6-argument inline syscalls must include a
   definition of __libc_do_syscall.  */
#define INTERNAL_SYSCALL_MAIN_6(name, arg1, arg2, arg3,			\
				arg4, arg5, arg6)			\
  struct libc_do_syscall_args _xv =					\
    {									\
      (int) (arg1),							\
      (int) (arg5),							\
      (int) (arg6)							\
    };									\
    asm volatile (							\
    "movl %1, %%eax\n\t"						\
    "call " I386_DO_SYSCALL_STRING					\
    : "=a" (resultvar)							\
    : "i" (__NR_##name), "c" (arg2), "d" (arg3), "S" (arg4), "D" (&_xv) \
    : "memory", "cc")
#define INTERNAL_SYSCALL_MAIN_NCS_6(name, arg1, arg2, arg3,		\
				    arg4, arg5, arg6)			\
  struct libc_do_syscall_args _xv =					\
    {									\
      (int) (arg1),							\
      (int) (arg5),							\
      (int) (arg6)							\
    };									\
    asm volatile (							\
    "movl %1, %%eax\n\t"						\
    "call " I386_DO_SYSCALL_STRING					\
    : "=a" (resultvar)							\
    : "a" (name), "c" (arg2), "d" (arg3), "S" (arg4), "D" (&_xv)	\
    : "memory", "cc")

#define INTERNAL_SYSCALL(name, nr, args...) \
  ({									      \
    register unsigned int resultvar;					      \
    INTERNAL_SYSCALL_MAIN_##nr (name, args);			      	      \
    (int) resultvar; })
#define INTERNAL_SYSCALL_NCS(name, nr, args...) \
  ({									      \
    register unsigned int resultvar;					      \
    INTERNAL_SYSCALL_MAIN_NCS_##nr (name, args);		      	      \
    (int) resultvar; })

#if I386_USE_SYSENTER
# ifdef PIC
#  define INTERNAL_SYSCALL_MAIN_INLINE(name, nr, args...) \
    LOADREGS_##nr(args)							\
    asm volatile (							\
    "call *%%gs:%P2"							\
    : "=a" (resultvar)							\
    : "a" (__NR_##name), "i" (offsetof (tcbhead_t, sysinfo))		\
      ASMARGS_##nr(args) : "memory", "cc")
#  define INTERNAL_SYSCALL_MAIN_NCS(name, nr, args...) \
    LOADREGS_##nr(args)							\
    asm volatile (							\
    "call *%%gs:%P2"							\
    : "=a" (resultvar)							\
    : "a" (name), "i" (offsetof (tcbhead_t, sysinfo))			\
      ASMARGS_##nr(args) : "memory", "cc")
# else /* I386_USE_SYSENTER && !PIC */
#  define INTERNAL_SYSCALL_MAIN_INLINE(name, nr, args...) \
    LOADREGS_##nr(args)							\
    asm volatile (							\
    "call *_dl_sysinfo"							\
    : "=a" (resultvar)							\
    : "a" (__NR_##name) ASMARGS_##nr(args) : "memory", "cc")
#  define INTERNAL_SYSCALL_MAIN_NCS(name, nr, args...) \
    LOADREGS_##nr(args)							\
    asm volatile (							\
    "call *_dl_sysinfo"							\
    : "=a" (resultvar)							\
    : "a" (name) ASMARGS_##nr(args) : "memory", "cc")
# endif /* I386_USE_SYSENTER && !PIC */
#else /* !I386_USE_SYSENTER */
# define INTERNAL_SYSCALL_MAIN_INLINE(name, nr, args...) \
    LOADREGS_##nr(args)							\
    asm volatile (							\
    "int $0x80"								\
    : "=a" (resultvar)							\
    : "a" (__NR_##name) ASMARGS_##nr(args) : "memory", "cc")
# define INTERNAL_SYSCALL_MAIN_NCS(name, nr, args...) \
    LOADREGS_##nr(args)							\
    asm volatile (							\
    "int $0x80"								\
    : "=a" (resultvar)							\
    : "a" (name) ASMARGS_##nr(args) : "memory", "cc")
#endif /* !I386_USE_SYSENTER */

#define LOADREGS_0()
#define ASMARGS_0()
#define LOADREGS_1(arg1) \
	LOADREGS_0 ()
#define ASMARGS_1(arg1) \
	ASMARGS_0 (), "b" ((unsigned int) (arg1))
#define LOADREGS_2(arg1, arg2) \
	LOADREGS_1 (arg1)
#define ASMARGS_2(arg1, arg2) \
	ASMARGS_1 (arg1), "c" ((unsigned int) (arg2))
#define LOADREGS_3(arg1, arg2, arg3) \
	LOADREGS_2 (arg1, arg2)
#define ASMARGS_3(arg1, arg2, arg3) \
	ASMARGS_2 (arg1, arg2), "d" ((unsigned int) (arg3))
#define LOADREGS_4(arg1, arg2, arg3, arg4) \
	LOADREGS_3 (arg1, arg2, arg3)
#define ASMARGS_4(arg1, arg2, arg3, arg4) \
	ASMARGS_3 (arg1, arg2, arg3), "S" ((unsigned int) (arg4))
#define LOADREGS_5(arg1, arg2, arg3, arg4, arg5) \
	LOADREGS_4 (arg1, arg2, arg3, arg4)
#define ASMARGS_5(arg1, arg2, arg3, arg4, arg5) \
	ASMARGS_4 (arg1, arg2, arg3, arg4), "D" ((unsigned int) (arg5))

#define ASMFMT_0()
#ifdef __PIC__
# define ASMFMT_1(arg1) \
	, "cd" (arg1)
# define ASMFMT_2(arg1, arg2) \
	, "d" (arg1), "c" (arg2)
# define ASMFMT_3(arg1, arg2, arg3) \
	, "D" (arg1), "c" (arg2), "d" (arg3)
# define ASMFMT_4(arg1, arg2, arg3, arg4) \
	, "D" (arg1), "c" (arg2), "d" (arg3), "S" (arg4)
# define ASMFMT_5(arg1, arg2, arg3, arg4, arg5) \
	, "0" (arg1), "m" (_xv), "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5)
#else
# define ASMFMT_1(arg1) \
	, "b" (arg1)
# define ASMFMT_2(arg1, arg2) \
	, "b" (arg1), "c" (arg2)
# define ASMFMT_3(arg1, arg2, arg3) \
	, "b" (arg1), "c" (arg2), "d" (arg3)
# define ASMFMT_4(arg1, arg2, arg3, arg4) \
	, "b" (arg1), "c" (arg2), "d" (arg3), "S" (arg4)
# define ASMFMT_5(arg1, arg2, arg3, arg4, arg5) \
	, "b" (arg1), "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5)
#endif

#define EXTRAVAR_0
#define EXTRAVAR_1
#define EXTRAVAR_2
#define EXTRAVAR_3
#define EXTRAVAR_4
#ifdef __PIC__
# define EXTRAVAR_5 int _xv;
#else
# define EXTRAVAR_5
#endif

#endif	/* __ASSEMBLER__ */

/* Each shadow stack slot takes 4 bytes.  Assuming that each stack
   frame takes 128 bytes, this is used to compute shadow stack size
   from stack size.  */
#define STACK_SIZE_TO_SHADOW_STACK_SIZE_SHIFT 5

#endif /* linux/i386/sysdep.h */