sysdeps/unix/sysv/linux/i386/sysdep.h

   1 /* Copyright (C) 1992-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper, <drepper@gnu.org>, August 1995.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _LINUX_I386_SYSDEP_H
  20 #define _LINUX_I386_SYSDEP_H 1
  21
  22 /* There is some commonality.  */
  23 #include <sysdeps/unix/i386/sysdep.h>
  24 /* Defines RTLD_PRIVATE_ERRNO and USE_DL_SYSINFO.  */
  25 #include <dl-sysdep.h>
  26 #include <tls.h>
  27
  28
  29 /* For Linux we can use the system call table in the header file
  30         /usr/include/asm/unistd.h
  31    of the kernel.  But these symbols do not follow the SYS_* syntax
  32    so we have to redefine the `SYS_ify' macro here.  */
  33 #undef SYS_ify
  34 #define SYS_ify(syscall_name)   __NR_##syscall_name
  35
  36 #if defined USE_DL_SYSINFO \
  37     && (!defined NOT_IN_libc || defined IS_IN_libpthread)
  38 # define I386_USE_SYSENTER      1
  39 #else
  40 # undef I386_USE_SYSENTER
  41 #endif
  42
  43 #ifdef __ASSEMBLER__
  44
  45 /* Linux uses a negative return value to indicate syscall errors,
  46    unlike most Unices, which use the condition codes' carry flag.
  47
  48    Since version 2.1 the return value of a system call might be
  49    negative even if the call succeeded.  E.g., the `lseek' system call
  50    might return a large offset.  Therefore we must not anymore test
  51    for < 0, but test for a real error by making sure the value in %eax
  52    is a real error number.  Linus said he will make sure the no syscall
  53    returns a value in -1 .. -4095 as a valid result so we can savely
  54    test with -4095.  */
  55
  56 /* We don't want the label for the error handle to be global when we define
  57    it here.  */
  58 #ifdef PIC
  59 # define SYSCALL_ERROR_LABEL 0f
  60 #else
  61 # define SYSCALL_ERROR_LABEL syscall_error
  62 #endif
  63
  64 #undef  PSEUDO
  65 #define PSEUDO(name, syscall_name, args)                                      \
  66   .text;                                                                      \
  67   ENTRY (name)                                                                \
  68     DO_CALL (syscall_name, args);                                             \
  69     cmpl $-4095, %eax;                                                        \
  70     jae SYSCALL_ERROR_LABEL
  71
  72 #undef  PSEUDO_END
  73 #define PSEUDO_END(name)                                                      \
  74   SYSCALL_ERROR_HANDLER                                                       \
  75   END (name)
  76
  77 #undef  PSEUDO_NOERRNO
  78 #define PSEUDO_NOERRNO(name, syscall_name, args)                              \
  79   .text;                                                                      \
  80   ENTRY (name)                                                                \
  81     DO_CALL (syscall_name, args)
  82
  83 #undef  PSEUDO_END_NOERRNO
  84 #define PSEUDO_END_NOERRNO(name)                                              \
  85   END (name)
  86
  87 #define ret_NOERRNO ret
  88
  89 /* The function has to return the error code.  */
  90 #undef  PSEUDO_ERRVAL
  91 #define PSEUDO_ERRVAL(name, syscall_name, args) \
  92   .text;                                                                      \
  93   ENTRY (name)                                                                \
  94     DO_CALL (syscall_name, args);                                             \
  95     negl %eax
  96
  97 #undef  PSEUDO_END_ERRVAL
  98 #define PSEUDO_END_ERRVAL(name) \
  99   END (name)
 100
 101 #define ret_ERRVAL ret
 102
 103 #ifndef PIC
 104 # define SYSCALL_ERROR_HANDLER  /* Nothing here; code in sysdep.S is used.  */
 105 #else
 106
 107 # if RTLD_PRIVATE_ERRNO
 108 #  define SYSCALL_ERROR_HANDLER                                               \
 109 0:SETUP_PIC_REG(cx);                                                          \
 110   addl $_GLOBAL_OFFSET_TABLE_, %ecx;                                          \
 111   negl %eax;                                                                  \
 112   movl %eax, rtld_errno@GOTOFF(%ecx);                                         \
 113   orl $-1, %eax;                                                              \
 114   ret;
 115
 116 # elif defined _LIBC_REENTRANT
 117
 118 #  ifndef NOT_IN_libc
 119 #   define SYSCALL_ERROR_ERRNO __libc_errno
 120 #  else
 121 #   define SYSCALL_ERROR_ERRNO errno
 122 #  endif
 123 #  define SYSCALL_ERROR_HANDLER                                       \
 124 0:SETUP_PIC_REG (cx);                                                         \
 125   addl $_GLOBAL_OFFSET_TABLE_, %ecx;                                          \
 126   movl SYSCALL_ERROR_ERRNO@GOTNTPOFF(%ecx), %ecx;                             \
 127   negl %eax;                                                                  \
 128   SYSCALL_ERROR_HANDLER_TLS_STORE (%eax, %ecx);                               \
 129   orl $-1, %eax;                                                              \
 130   ret;
 131 #  ifndef NO_TLS_DIRECT_SEG_REFS
 132 #   define SYSCALL_ERROR_HANDLER_TLS_STORE(src, destoff)                      \
 133   movl src, %gs:(destoff)
 134 #  else
 135 #   define SYSCALL_ERROR_HANDLER_TLS_STORE(src, destoff)                      \
 136   addl %gs:0, destoff;                                                        \
 137   movl src, (destoff)
 138 #  endif
 139 # else
 140 /* Store (- %eax) into errno through the GOT.  */
 141 #  define SYSCALL_ERROR_HANDLER                                               \
 142 0:SETUP_PIC_REG(cx);                                                          \
 143   addl $_GLOBAL_OFFSET_TABLE_, %ecx;                                          \
 144   negl %eax;                                                                  \
 145   movl errno@GOT(%ecx), %ecx;                                                 \
 146   movl %eax, (%ecx);                                                          \
 147   orl $-1, %eax;                                                              \
 148   ret;
 149 # endif /* _LIBC_REENTRANT */
 150 #endif  /* PIC */
 151
 152
 153 /* The original calling convention for system calls on Linux/i386 is
 154    to use int $0x80.  */
 155 #ifdef I386_USE_SYSENTER
 156 # ifdef SHARED
 157 #  define ENTER_KERNEL call *%gs:SYSINFO_OFFSET
 158 # else
 159 #  define ENTER_KERNEL call *_dl_sysinfo
 160 # endif
 161 #else
 162 # define ENTER_KERNEL int $0x80
 163 #endif
 164
 165 /* Linux takes system call arguments in registers:
 166
 167         syscall number  %eax         call-clobbered
 168         arg 1           %ebx         call-saved
 169         arg 2           %ecx         call-clobbered
 170         arg 3           %edx         call-clobbered
 171         arg 4           %esi         call-saved
 172         arg 5           %edi         call-saved
 173         arg 6           %ebp         call-saved
 174
 175    The stack layout upon entering the function is:
 176
 177         24(%esp)        Arg# 6
 178         20(%esp)        Arg# 5
 179         16(%esp)        Arg# 4
 180         12(%esp)        Arg# 3
 181          8(%esp)        Arg# 2
 182          4(%esp)        Arg# 1
 183           (%esp)        Return address
 184
 185    (Of course a function with say 3 arguments does not have entries for
 186    arguments 4, 5, and 6.)
 187
 188    The following code tries hard to be optimal.  A general assumption
 189    (which is true according to the data books I have) is that
 190
 191         2 * xchg        is more expensive than  pushl + movl + popl
 192
 193    Beside this a neat trick is used.  The calling conventions for Linux
 194    tell that among the registers used for parameters %ecx and %edx need
 195    not be saved.  Beside this we may clobber this registers even when
 196    they are not used for parameter passing.
 197
 198    As a result one can see below that we save the content of the %ebx
 199    register in the %edx register when we have less than 3 arguments
 200    (2 * movl is less expensive than pushl + popl).
 201
 202    Second unlike for the other registers we don't save the content of
 203    %ecx and %edx when we have more than 1 and 2 registers resp.
 204
 205    The code below might look a bit long but we have to take care for
 206    the pipelined processors (i586).  Here the `pushl' and `popl'
 207    instructions are marked as NP (not pairable) but the exception is
 208    two consecutive of these instruction.  This gives no penalty on
 209    other processors though.  */
 210
 211 #undef  DO_CALL
 212 #define DO_CALL(syscall_name, args)                                           \
 213     PUSHARGS_##args                                                           \
 214     DOARGS_##args                                                             \
 215     movl $SYS_ify (syscall_name), %eax;                                       \
 216     ENTER_KERNEL                                                              \
 217     POPARGS_##args
 218
 219 #define PUSHARGS_0      /* No arguments to push.  */
 220 #define DOARGS_0        /* No arguments to frob.  */
 221 #define POPARGS_0       /* No arguments to pop.  */
 222 #define _PUSHARGS_0     /* No arguments to push.  */
 223 #define _DOARGS_0(n)    /* No arguments to frob.  */
 224 #define _POPARGS_0      /* No arguments to pop.  */
 225
 226 #define PUSHARGS_1      movl %ebx, %edx; L(SAVEBX1): PUSHARGS_0
 227 #define DOARGS_1        _DOARGS_1 (4)
 228 #define POPARGS_1       POPARGS_0; movl %edx, %ebx; L(RESTBX1):
 229 #define _PUSHARGS_1     pushl %ebx; cfi_adjust_cfa_offset (4); \
 230                         cfi_rel_offset (ebx, 0); L(PUSHBX1): _PUSHARGS_0
 231 #define _DOARGS_1(n)    movl n(%esp), %ebx; _DOARGS_0(n-4)
 232 #define _POPARGS_1      _POPARGS_0; popl %ebx; cfi_adjust_cfa_offset (-4); \
 233                         cfi_restore (ebx); L(POPBX1):
 234
 235 #define PUSHARGS_2      PUSHARGS_1
 236 #define DOARGS_2        _DOARGS_2 (8)
 237 #define POPARGS_2       POPARGS_1
 238 #define _PUSHARGS_2     _PUSHARGS_1
 239 #define _DOARGS_2(n)    movl n(%esp), %ecx; _DOARGS_1 (n-4)
 240 #define _POPARGS_2      _POPARGS_1
 241
 242 #define PUSHARGS_3      _PUSHARGS_2
 243 #define DOARGS_3        _DOARGS_3 (16)
 244 #define POPARGS_3       _POPARGS_3
 245 #define _PUSHARGS_3     _PUSHARGS_2
 246 #define _DOARGS_3(n)    movl n(%esp), %edx; _DOARGS_2 (n-4)
 247 #define _POPARGS_3      _POPARGS_2
 248
 249 #define PUSHARGS_4      _PUSHARGS_4
 250 #define DOARGS_4        _DOARGS_4 (24)
 251 #define POPARGS_4       _POPARGS_4
 252 #define _PUSHARGS_4     pushl %esi; cfi_adjust_cfa_offset (4); \
 253                         cfi_rel_offset (esi, 0); L(PUSHSI1): _PUSHARGS_3
 254 #define _DOARGS_4(n)    movl n(%esp), %esi; _DOARGS_3 (n-4)
 255 #define _POPARGS_4      _POPARGS_3; popl %esi; cfi_adjust_cfa_offset (-4); \
 256                         cfi_restore (esi); L(POPSI1):
 257
 258 #define PUSHARGS_5      _PUSHARGS_5
 259 #define DOARGS_5        _DOARGS_5 (32)
 260 #define POPARGS_5       _POPARGS_5
 261 #define _PUSHARGS_5     pushl %edi; cfi_adjust_cfa_offset (4); \
 262                         cfi_rel_offset (edi, 0); L(PUSHDI1): _PUSHARGS_4
 263 #define _DOARGS_5(n)    movl n(%esp), %edi; _DOARGS_4 (n-4)
 264 #define _POPARGS_5      _POPARGS_4; popl %edi; cfi_adjust_cfa_offset (-4); \
 265                         cfi_restore (edi); L(POPDI1):
 266
 267 #define PUSHARGS_6      _PUSHARGS_6
 268 #define DOARGS_6        _DOARGS_6 (40)
 269 #define POPARGS_6       _POPARGS_6
 270 #define _PUSHARGS_6     pushl %ebp; cfi_adjust_cfa_offset (4); \
 271                         cfi_rel_offset (ebp, 0); L(PUSHBP1): _PUSHARGS_5
 272 #define _DOARGS_6(n)    movl n(%esp), %ebp; _DOARGS_5 (n-4)
 273 #define _POPARGS_6      _POPARGS_5; popl %ebp; cfi_adjust_cfa_offset (-4); \
 274                         cfi_restore (ebp); L(POPBP1):
 275
 276 #else   /* !__ASSEMBLER__ */
 277
 278 /* We need some help from the assembler to generate optimal code.  We
 279    define some macros here which later will be used.  */
 280 asm (".L__X'%ebx = 1\n\t"
 281      ".L__X'%ecx = 2\n\t"
 282      ".L__X'%edx = 2\n\t"
 283      ".L__X'%eax = 3\n\t"
 284      ".L__X'%esi = 3\n\t"
 285      ".L__X'%edi = 3\n\t"
 286      ".L__X'%ebp = 3\n\t"
 287      ".L__X'%esp = 3\n\t"
 288      ".macro bpushl name reg\n\t"
 289      ".if 1 - \\name\n\t"
 290      ".if 2 - \\name\n\t"
 291      "error\n\t"
 292      ".else\n\t"
 293      "xchgl \\reg, %ebx\n\t"
 294      ".endif\n\t"
 295      ".endif\n\t"
 296      ".endm\n\t"
 297      ".macro bpopl name reg\n\t"
 298      ".if 1 - \\name\n\t"
 299      ".if 2 - \\name\n\t"
 300      "error\n\t"
 301      ".else\n\t"
 302      "xchgl \\reg, %ebx\n\t"
 303      ".endif\n\t"
 304      ".endif\n\t"
 305      ".endm\n\t");
 306
 307 /* Define a macro which expands inline into the wrapper code for a system
 308    call.  */
 309 #undef INLINE_SYSCALL
 310 #define INLINE_SYSCALL(name, nr, args...) \
 311   ({                                                                          \
 312     unsigned int resultvar = INTERNAL_SYSCALL (name, , nr, args);             \
 313     if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (resultvar, ), 0))         \
 314       {                                                                       \
 315         __set_errno (INTERNAL_SYSCALL_ERRNO (resultvar, ));                   \
 316         resultvar = 0xffffffff;                                               \
 317       }                                                                       \
 318     (int) resultvar; })
 319
 320 /* Define a macro which expands inline into the wrapper code for a system
 321    call.  This use is for internal calls that do not need to handle errors
 322    normally.  It will never touch errno.  This returns just what the kernel
 323    gave back.
 324
 325    The _NCS variant allows non-constant syscall numbers but it is not
 326    possible to use more than four parameters.  */
 327 #undef INTERNAL_SYSCALL
 328 #ifdef I386_USE_SYSENTER
 329 # ifdef SHARED
 330 #  define INTERNAL_SYSCALL(name, err, nr, args...) \
 331   ({                                                                          \
 332     register unsigned int resultvar;                                          \
 333     EXTRAVAR_##nr                                                             \
 334     asm volatile (                                                            \
 335     LOADARGS_##nr                                                             \
 336     "movl %1, %%eax\n\t"                                                      \
 337     "call *%%gs:%P2\n\t"                                                      \
 338     RESTOREARGS_##nr                                                          \
 339     : "=a" (resultvar)                                                        \
 340     : "i" (__NR_##name), "i" (offsetof (tcbhead_t, sysinfo))                  \
 341       ASMFMT_##nr(args) : "memory", "cc");                                    \
 342     (int) resultvar; })
 343 #  define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
 344   ({                                                                          \
 345     register unsigned int resultvar;                                          \
 346     EXTRAVAR_##nr                                                             \
 347     asm volatile (                                                            \
 348     LOADARGS_##nr                                                             \
 349     "call *%%gs:%P2\n\t"                                                      \
 350     RESTOREARGS_##nr                                                          \
 351     : "=a" (resultvar)                                                        \
 352     : "0" (name), "i" (offsetof (tcbhead_t, sysinfo))                         \
 353       ASMFMT_##nr(args) : "memory", "cc");                                    \
 354     (int) resultvar; })
 355 # else
 356 #  define INTERNAL_SYSCALL(name, err, nr, args...) \
 357   ({                                                                          \
 358     register unsigned int resultvar;                                          \
 359     EXTRAVAR_##nr                                                             \
 360     asm volatile (                                                            \
 361     LOADARGS_##nr                                                             \
 362     "movl %1, %%eax\n\t"                                                      \
 363     "call *_dl_sysinfo\n\t"                                                   \
 364     RESTOREARGS_##nr                                                          \
 365     : "=a" (resultvar)                                                        \
 366     : "i" (__NR_##name) ASMFMT_##nr(args) : "memory", "cc");                  \
 367     (int) resultvar; })
 368 #  define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
 369   ({                                                                          \
 370     register unsigned int resultvar;                                          \
 371     EXTRAVAR_##nr                                                             \
 372     asm volatile (                                                            \
 373     LOADARGS_##nr                                                             \
 374     "call *_dl_sysinfo\n\t"                                                   \
 375     RESTOREARGS_##nr                                                          \
 376     : "=a" (resultvar)                                                        \
 377     : "0" (name) ASMFMT_##nr(args) : "memory", "cc");                         \
 378     (int) resultvar; })
 379 # endif
 380 #else
 381 # define INTERNAL_SYSCALL(name, err, nr, args...) \
 382   ({                                                                          \
 383     register unsigned int resultvar;                                          \
 384     EXTRAVAR_##nr                                                             \
 385     asm volatile (                                                            \
 386     LOADARGS_##nr                                                             \
 387     "movl %1, %%eax\n\t"                                                      \
 388     "int $0x80\n\t"                                                           \
 389     RESTOREARGS_##nr                                                          \
 390     : "=a" (resultvar)                                                        \
 391     : "i" (__NR_##name) ASMFMT_##nr(args) : "memory", "cc");                  \
 392     (int) resultvar; })
 393 # define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
 394   ({                                                                          \
 395     register unsigned int resultvar;                                          \
 396     EXTRAVAR_##nr                                                             \
 397     asm volatile (                                                            \
 398     LOADARGS_##nr                                                             \
 399     "int $0x80\n\t"                                                           \
 400     RESTOREARGS_##nr                                                          \
 401     : "=a" (resultvar)                                                        \
 402     : "0" (name) ASMFMT_##nr(args) : "memory", "cc");                         \
 403     (int) resultvar; })
 404 #endif
 405
 406 #undef INTERNAL_SYSCALL_DECL
 407 #define INTERNAL_SYSCALL_DECL(err) do { } while (0)
 408
 409 #undef INTERNAL_SYSCALL_ERROR_P
 410 #define INTERNAL_SYSCALL_ERROR_P(val, err) \
 411   ((unsigned int) (val) >= 0xfffff001u)
 412
 413 #undef INTERNAL_SYSCALL_ERRNO
 414 #define INTERNAL_SYSCALL_ERRNO(val, err)        (-(val))
 415
 416 #define LOADARGS_0
 417 #ifdef __PIC__
 418 # if defined I386_USE_SYSENTER && defined SHARED
 419 #  define LOADARGS_1 \
 420     "bpushl .L__X'%k3, %k3\n\t"
 421 #  define LOADARGS_5 \
 422     "movl %%ebx, %4\n\t"                                                      \
 423     "movl %3, %%ebx\n\t"
 424 # else
 425 #  define LOADARGS_1 \
 426     "bpushl .L__X'%k2, %k2\n\t"
 427 #  define LOADARGS_5 \
 428     "movl %%ebx, %3\n\t"                                                      \
 429     "movl %2, %%ebx\n\t"
 430 # endif
 431 # define LOADARGS_2     LOADARGS_1
 432 # define LOADARGS_3 \
 433     "xchgl %%ebx, %%edi\n\t"
 434 # define LOADARGS_4     LOADARGS_3
 435 #else
 436 # define LOADARGS_1
 437 # define LOADARGS_2
 438 # define LOADARGS_3
 439 # define LOADARGS_4
 440 # define LOADARGS_5
 441 #endif
 442
 443 #define RESTOREARGS_0
 444 #ifdef __PIC__
 445 # if defined I386_USE_SYSENTER && defined SHARED
 446 #  define RESTOREARGS_1 \
 447     "bpopl .L__X'%k3, %k3\n\t"
 448 #  define RESTOREARGS_5 \
 449     "movl %4, %%ebx"
 450 # else
 451 #  define RESTOREARGS_1 \
 452     "bpopl .L__X'%k2, %k2\n\t"
 453 #  define RESTOREARGS_5 \
 454     "movl %3, %%ebx"
 455 # endif
 456 # define RESTOREARGS_2  RESTOREARGS_1
 457 # define RESTOREARGS_3 \
 458     "xchgl %%edi, %%ebx\n\t"
 459 # define RESTOREARGS_4  RESTOREARGS_3
 460 #else
 461 # define RESTOREARGS_1
 462 # define RESTOREARGS_2
 463 # define RESTOREARGS_3
 464 # define RESTOREARGS_4
 465 # define RESTOREARGS_5
 466 #endif
 467
 468 #define ASMFMT_0()
 469 #ifdef __PIC__
 470 # define ASMFMT_1(arg1) \
 471         , "cd" (arg1)
 472 # define ASMFMT_2(arg1, arg2) \
 473         , "d" (arg1), "c" (arg2)
 474 # define ASMFMT_3(arg1, arg2, arg3) \
 475         , "D" (arg1), "c" (arg2), "d" (arg3)
 476 # define ASMFMT_4(arg1, arg2, arg3, arg4) \
 477         , "D" (arg1), "c" (arg2), "d" (arg3), "S" (arg4)
 478 # define ASMFMT_5(arg1, arg2, arg3, arg4, arg5) \
 479         , "0" (arg1), "m" (_xv), "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5)
 480 #else
 481 # define ASMFMT_1(arg1) \
 482         , "b" (arg1)
 483 # define ASMFMT_2(arg1, arg2) \
 484         , "b" (arg1), "c" (arg2)
 485 # define ASMFMT_3(arg1, arg2, arg3) \
 486         , "b" (arg1), "c" (arg2), "d" (arg3)
 487 # define ASMFMT_4(arg1, arg2, arg3, arg4) \
 488         , "b" (arg1), "c" (arg2), "d" (arg3), "S" (arg4)
 489 # define ASMFMT_5(arg1, arg2, arg3, arg4, arg5) \
 490         , "b" (arg1), "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5)
 491 #endif
 492
 493 #define EXTRAVAR_0
 494 #define EXTRAVAR_1
 495 #define EXTRAVAR_2
 496 #define EXTRAVAR_3
 497 #define EXTRAVAR_4
 498 #ifdef __PIC__
 499 # define EXTRAVAR_5 int _xv;
 500 #else
 501 # define EXTRAVAR_5
 502 #endif
 503
 504 /* Consistency check for position-independent code.  */
 505 #ifdef __PIC__
 506 # define check_consistency()                                                  \
 507   ({ int __res;                                                               \
 508      __asm__ __volatile__                                                     \
 509        (LOAD_PIC_REG_STR (cx) ";"                                             \
 510         "subl %%ebx, %%ecx;"                                                  \
 511         "je 1f;"                                                              \
 512         "ud2;"                                                                \
 513         "1:\n"                                                                \
 514         : "=c" (__res));                                                      \
 515      __res; })
 516 #endif
 517
 518 #endif  /* __ASSEMBLER__ */
 519
 520
 521 /* Pointer mangling support.  */
 522 #if defined NOT_IN_libc && defined IS_IN_rtld
 523 /* We cannot use the thread descriptor because in ld.so we use setjmp
 524    earlier than the descriptor is initialized.  Using a global variable
 525    is too complicated here since we have no PC-relative addressing mode.  */
 526 #else
 527 # ifdef __ASSEMBLER__
 528 #  define PTR_MANGLE(reg)       xorl %gs:POINTER_GUARD, reg;                  \
 529                                 roll $9, reg
 530 #  define PTR_DEMANGLE(reg)     rorl $9, reg;                                 \
 531                                 xorl %gs:POINTER_GUARD, reg
 532 # else
 533 #  define PTR_MANGLE(var)       asm ("xorl %%gs:%c2, %0\n"                    \
 534                                      "roll $9, %0"                            \
 535                                      : "=r" (var)                             \
 536                                      : "0" (var),                             \
 537                                        "i" (offsetof (tcbhead_t,              \
 538                                                       pointer_guard)))
 539 #  define PTR_DEMANGLE(var)     asm ("rorl $9, %0\n"                          \
 540                                      "xorl %%gs:%c2, %0"                      \
 541                                      : "=r" (var)                             \
 542                                      : "0" (var),                             \
 543                                        "i" (offsetof (tcbhead_t,              \
 544                                                       pointer_guard)))
 545 # endif
 546 #endif
 547
 548 #endif /* linux/i386/sysdep.h */