sysdeps/unix/sysv/linux/x86_64/sysdep.h

   1 /* Copyright (C) 2001,02,03,04 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #ifndef _LINUX_X86_64_SYSDEP_H
  20 #define _LINUX_X86_64_SYSDEP_H 1
  21
  22 /* There is some commonality.  */
  23 #include <sysdeps/unix/x86_64/sysdep.h>
  24 #include <bp-sym.h>
  25 #include <bp-asm.h>
  26 #include <tls.h>
  27
  28 #ifdef IS_IN_rtld
  29 # include <dl-sysdep.h>         /* Defines RTLD_PRIVATE_ERRNO.  */
  30 #endif
  31
  32 /* For Linux we can use the system call table in the header file
  33         /usr/include/asm/unistd.h
  34    of the kernel.  But these symbols do not follow the SYS_* syntax
  35    so we have to redefine the `SYS_ify' macro here.  */
  36 #undef SYS_ify
  37 #define SYS_ify(syscall_name)   __NR_##syscall_name
  38
  39 /* This is a kludge to make syscalls.list find these under the names
  40    pread and pwrite, since some kernel headers define those names
  41    and some define the *64 names for the same system calls.  */
  42 #if !defined __NR_pread && defined __NR_pread64
  43 # define __NR_pread __NR_pread64
  44 #endif
  45 #if !defined __NR_pwrite && defined __NR_pwrite64
  46 # define __NR_pwrite __NR_pwrite64
  47 #endif
  48
  49 /* This is to help the old kernel headers where __NR_semtimedop is not
  50    available.  */
  51 #ifndef __NR_semtimedop
  52 # define __NR_semtimedop 220
  53 #endif
  54
  55
  56 #ifdef __ASSEMBLER__
  57
  58 /* Linux uses a negative return value to indicate syscall errors,
  59    unlike most Unices, which use the condition codes' carry flag.
  60
  61    Since version 2.1 the return value of a system call might be
  62    negative even if the call succeeded.  E.g., the `lseek' system call
  63    might return a large offset.  Therefore we must not anymore test
  64    for < 0, but test for a real error by making sure the value in %eax
  65    is a real error number.  Linus said he will make sure the no syscall
  66    returns a value in -1 .. -4095 as a valid result so we can savely
  67    test with -4095.  */
  68
  69 /* We don't want the label for the error handle to be global when we define
  70    it here.  */
  71 #ifdef PIC
  72 # define SYSCALL_ERROR_LABEL 0f
  73 #else
  74 # define SYSCALL_ERROR_LABEL syscall_error
  75 #endif
  76
  77 #undef  PSEUDO
  78 #define PSEUDO(name, syscall_name, args)                                      \
  79   .text;                                                                      \
  80   ENTRY (name)                                                                \
  81     DO_CALL (syscall_name, args);                                             \
  82     cmpq $-4095, %rax;                                                        \
  83     jae SYSCALL_ERROR_LABEL;                                                  \
  84   L(pseudo_end):
  85
  86 #undef  PSEUDO_END
  87 #define PSEUDO_END(name)                                                      \
  88   SYSCALL_ERROR_HANDLER                                                       \
  89   END (name)
  90
  91 #undef  PSEUDO_NOERRNO
  92 #define PSEUDO_NOERRNO(name, syscall_name, args) \
  93   .text;                                                                      \
  94   ENTRY (name)                                                                \
  95     DO_CALL (syscall_name, args)
  96
  97 #undef  PSEUDO_END_NOERRNO
  98 #define PSEUDO_END_NOERRNO(name) \
  99   END (name)
 100
 101 #define ret_NOERRNO ret
 102
 103 #undef  PSEUDO_ERRVAL
 104 #define PSEUDO_ERRVAL(name, syscall_name, args) \
 105   .text;                                                                      \
 106   ENTRY (name)                                                                \
 107     DO_CALL (syscall_name, args);                                             \
 108     negq %rax
 109
 110 #undef  PSEUDO_END_ERRVAL
 111 #define PSEUDO_END_ERRVAL(name) \
 112   END (name)
 113
 114 #define ret_ERRVAL ret
 115
 116 #ifndef PIC
 117 #define SYSCALL_ERROR_HANDLER   /* Nothing here; code in sysdep.S is used.  */
 118 #elif RTLD_PRIVATE_ERRNO
 119 # define SYSCALL_ERROR_HANDLER                  \
 120 0:                                              \
 121   leaq rtld_errno(%rip), %rcx;                  \
 122   xorq %rdx, %rdx;                              \
 123   subq %rax, %rdx;                              \
 124   movl %edx, (%rcx);                            \
 125   orq $-1, %rax;                                \
 126   jmp L(pseudo_end);
 127 #elif USE___THREAD
 128 # ifndef NOT_IN_libc
 129 #  define SYSCALL_ERROR_ERRNO __libc_errno
 130 # else
 131 #  define SYSCALL_ERROR_ERRNO errno
 132 # endif
 133 # define SYSCALL_ERROR_HANDLER                  \
 134 0:                                              \
 135   movq SYSCALL_ERROR_ERRNO@GOTTPOFF(%rip), %rcx;\
 136   xorq %rdx, %rdx;                              \
 137   subq %rax, %rdx;                              \
 138   movl %edx, %fs:(%rcx);                        \
 139   orq $-1, %rax;                                \
 140   jmp L(pseudo_end);
 141 #elif defined _LIBC_REENTRANT
 142 /* Store (- %rax) into errno through the GOT.
 143    Note that errno occupies only 4 bytes.  */
 144 # define SYSCALL_ERROR_HANDLER                  \
 145 0:                                              \
 146   xorq %rdx, %rdx;                              \
 147   subq %rax, %rdx;                              \
 148   pushq %rdx;                                   \
 149   cfi_adjust_cfa_offset(8);                     \
 150   PUSH_ERRNO_LOCATION_RETURN;                   \
 151   call BP_SYM (__errno_location)@PLT;           \
 152   POP_ERRNO_LOCATION_RETURN;                    \
 153   popq %rdx;                                    \
 154   cfi_adjust_cfa_offset(-8);                    \
 155   movl %edx, (%rax);                            \
 156   orq $-1, %rax;                                \
 157   jmp L(pseudo_end);
 158
 159 /* A quick note: it is assumed that the call to `__errno_location' does
 160    not modify the stack!  */
 161 #else /* Not _LIBC_REENTRANT.  */
 162 # define SYSCALL_ERROR_HANDLER                  \
 163 0:movq errno@GOTPCREL(%RIP), %rcx;              \
 164   xorq %rdx, %rdx;                              \
 165   subq %rax, %rdx;                              \
 166   movl %edx, (%rcx);                            \
 167   orq $-1, %rax;                                \
 168   jmp L(pseudo_end);
 169 #endif  /* PIC */
 170
 171 /* The Linux/x86-64 kernel expects the system call parameters in
 172    registers according to the following table:
 173
 174     syscall number      rax
 175     arg 1               rdi
 176     arg 2               rsi
 177     arg 3               rdx
 178     arg 4               r10
 179     arg 5               r8
 180     arg 6               r9
 181
 182     The Linux kernel uses and destroys internally these registers:
 183     return address from
 184     syscall             rcx
 185     additionally clobered: r12-r15,rbx,rbp
 186     eflags from syscall r11
 187
 188     Normal function call, including calls to the system call stub
 189     functions in the libc, get the first six parameters passed in
 190     registers and the seventh parameter and later on the stack.  The
 191     register use is as follows:
 192
 193      system call number in the DO_CALL macro
 194      arg 1              rdi
 195      arg 2              rsi
 196      arg 3              rdx
 197      arg 4              rcx
 198      arg 5              r8
 199      arg 6              r9
 200
 201     We have to take care that the stack is aligned to 16 bytes.  When
 202     called the stack is not aligned since the return address has just
 203     been pushed.
 204
 205
 206     Syscalls of more than 6 arguments are not supported.  */
 207
 208 #undef  DO_CALL
 209 #define DO_CALL(syscall_name, args)             \
 210     DOARGS_##args                               \
 211     movq $SYS_ify (syscall_name), %rax;         \
 212     syscall;
 213
 214 #define DOARGS_0 /* nothing */
 215 #define DOARGS_1 /* nothing */
 216 #define DOARGS_2 /* nothing */
 217 #define DOARGS_3 /* nothing */
 218 #define DOARGS_4 movq %rcx, %r10;
 219 #define DOARGS_5 DOARGS_4
 220 #define DOARGS_6 DOARGS_5
 221
 222 #else   /* !__ASSEMBLER__ */
 223 /* Define a macro which expands inline into the wrapper code for a system
 224    call.  */
 225 #undef INLINE_SYSCALL
 226 #define INLINE_SYSCALL(name, nr, args...) \
 227   ({                                                                          \
 228     unsigned long resultvar = INTERNAL_SYSCALL (name, , nr, args);            \
 229     if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (resultvar, ), 0))         \
 230       {                                                                       \
 231         __set_errno (INTERNAL_SYSCALL_ERRNO (resultvar, ));                   \
 232         resultvar = (unsigned long) -1;                                       \
 233       }                                                                       \
 234     (long) resultvar; })
 235
 236 #undef INTERNAL_SYSCALL_DECL
 237 #define INTERNAL_SYSCALL_DECL(err) do { } while (0)
 238
 239 #define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \
 240   ({                                                                          \
 241     unsigned long resultvar;                                                  \
 242     LOAD_ARGS_##nr (args)                                                     \
 243     LOAD_REGS_##nr                                                            \
 244     asm volatile (                                                            \
 245     "syscall\n\t"                                                             \
 246     : "=a" (resultvar)                                                        \
 247     : "0" (name) ASM_ARGS_##nr : "memory", "cc", "r11", "cx");                \
 248     (long) resultvar; })
 249 #undef INTERNAL_SYSCALL
 250 #define INTERNAL_SYSCALL(name, err, nr, args...) \
 251   INTERNAL_SYSCALL_NCS (__NR_##name, err, nr, ##args)
 252
 253 #undef INTERNAL_SYSCALL_ERROR_P
 254 #define INTERNAL_SYSCALL_ERROR_P(val, err) \
 255   ((unsigned long) (val) >= -4095L)
 256
 257 #undef INTERNAL_SYSCALL_ERRNO
 258 #define INTERNAL_SYSCALL_ERRNO(val, err)        (-(val))
 259
 260 #define LOAD_ARGS_0()
 261 #define LOAD_REGS_0
 262 #define ASM_ARGS_0
 263
 264 #define LOAD_ARGS_1(a1)                                 \
 265   long int __arg1 = (long) (a1);                        \
 266   LOAD_ARGS_0 ()
 267 #define LOAD_REGS_1                                     \
 268   register long int _a1 asm ("rdi") = __arg1;           \
 269   LOAD_REGS_0
 270 #define ASM_ARGS_1      ASM_ARGS_0, "r" (_a1)
 271
 272 #define LOAD_ARGS_2(a1, a2)                             \
 273   long int __arg2 = (long) (a2);                        \
 274   LOAD_ARGS_1 (a1)
 275 #define LOAD_REGS_2                                     \
 276   register long int _a2 asm ("rsi") = __arg2;           \
 277   LOAD_REGS_1
 278 #define ASM_ARGS_2      ASM_ARGS_1, "r" (_a2)
 279
 280 #define LOAD_ARGS_3(a1, a2, a3)                         \
 281   long int __arg3 = (long) (a3);                        \
 282   LOAD_ARGS_2 (a1, a2)
 283 #define LOAD_REGS_3                                     \
 284   register long int _a3 asm ("rdx") = __arg3;           \
 285   LOAD_REGS_2
 286 #define ASM_ARGS_3      ASM_ARGS_2, "r" (_a3)
 287
 288 #define LOAD_ARGS_4(a1, a2, a3, a4)                     \
 289   long int __arg4 = (long) (a4);                        \
 290   LOAD_ARGS_3 (a1, a2, a3)
 291 #define LOAD_REGS_4                                     \
 292   register long int _a4 asm ("r10") = __arg4;           \
 293   LOAD_REGS_3
 294 #define ASM_ARGS_4      ASM_ARGS_3, "r" (_a4)
 295
 296 #define LOAD_ARGS_5(a1, a2, a3, a4, a5)                 \
 297   long int __arg5 = (long) (a5);                        \
 298   LOAD_ARGS_4 (a1, a2, a3, a4)
 299 #define LOAD_REGS_5                                     \
 300   register long int _a5 asm ("r8") = __arg5;            \
 301   LOAD_REGS_4
 302 #define ASM_ARGS_5      ASM_ARGS_4, "r" (_a5)
 303
 304 #define LOAD_ARGS_6(a1, a2, a3, a4, a5, a6)             \
 305   long int __arg6 = (long) (a6);                        \
 306   LOAD_ARGS_5 (a1, a2, a3, a4, a5)
 307 #define LOAD_REGS_6                                     \
 308   register long int _a6 asm ("r9") = __arg6;            \
 309   LOAD_REGS_5
 310 #define ASM_ARGS_6      ASM_ARGS_5, "r" (_a6)
 311
 312 #endif  /* __ASSEMBLER__ */
 313
 314 #endif /* linux/x86_64/sysdep.h */