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

   1 /* Copyright (C) 2001,02,03 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 #undef  PSEUDO_ERRVAL
 102 #define PSEUDO_ERRVAL(name, syscall_name, args) \
 103   .text;                                                                      \
 104   ENTRY (name)                                                                \
 105     DO_CALL (syscall_name, args);                                             \
 106     negl %rax
 107
 108 #undef  PSEUDO_END_ERRVAL
 109 #define PSEUDO_END_ERRVAL(name) \
 110   END (name)
 111
 112 #define ret_NOERRNO ret
 113
 114 #ifndef PIC
 115 #define SYSCALL_ERROR_HANDLER   /* Nothing here; code in sysdep.S is used.  */
 116 #elif RTLD_PRIVATE_ERRNO
 117 # define SYSCALL_ERROR_HANDLER                  \
 118 0:                                              \
 119   leaq errno(%rip), %rcx;                       \
 120   xorq %rdx, %rdx;                              \
 121   subq %rax, %rdx;                              \
 122   movl %edx, (%rcx);                            \
 123   orq $-1, %rax;                                \
 124   jmp L(pseudo_end);
 125 #elif USE___THREAD
 126 # ifndef NOT_IN_libc
 127 #  define SYSCALL_ERROR_ERRNO __libc_errno
 128 # else
 129 #  define SYSCALL_ERROR_ERRNO errno
 130 # endif
 131 # define SYSCALL_ERROR_HANDLER                  \
 132 0:                                              \
 133   movq SYSCALL_ERROR_ERRNO@GOTTPOFF(%rip), %rcx;\
 134   xorq %rdx, %rdx;                              \
 135   subq %rax, %rdx;                              \
 136   movl %edx, %fs:(%rcx);                        \
 137   orq $-1, %rax;                                \
 138   jmp L(pseudo_end);
 139 #elif defined _LIBC_REENTRANT
 140 /* Store (- %rax) into errno through the GOT.
 141    Note that errno occupies only 4 bytes.  */
 142 # define SYSCALL_ERROR_HANDLER                  \
 143 0:                                              \
 144   xorq %rdx, %rdx;                              \
 145   subq %rax, %rdx;                              \
 146   pushq %rdx;                                   \
 147   cfi_adjust_cfa_offset(8);                     \
 148   PUSH_ERRNO_LOCATION_RETURN;                   \
 149   call BP_SYM (__errno_location)@PLT;           \
 150   POP_ERRNO_LOCATION_RETURN;                    \
 151   popq %rdx;                                    \
 152   cfi_adjust_cfa_offset(-8);                    \
 153   movl %edx, (%rax);                            \
 154   orq $-1, %rax;                                \
 155   jmp L(pseudo_end);
 156
 157 /* A quick note: it is assumed that the call to `__errno_location' does
 158    not modify the stack!  */
 159 #else /* Not _LIBC_REENTRANT.  */
 160 # define SYSCALL_ERROR_HANDLER                  \
 161 0:movq errno@GOTPCREL(%RIP), %rcx;              \
 162   xorq %rdx, %rdx;                              \
 163   subq %rax, %rdx;                              \
 164   movl %edx, (%rcx);                            \
 165   orq $-1, %rax;                                \
 166   jmp L(pseudo_end);
 167 #endif  /* PIC */
 168
 169 /* The Linux/x86-64 kernel expects the system call parameters in
 170    registers according to the following table:
 171
 172     syscall number      rax
 173     arg 1               rdi
 174     arg 2               rsi
 175     arg 3               rdx
 176     arg 4               r10
 177     arg 5               r8
 178     arg 6               r9
 179
 180     The Linux kernel uses and destroys internally these registers:
 181     return address from
 182     syscall             rcx
 183     additionally clobered: r12-r15,rbx,rbp
 184     eflags from syscall r11
 185
 186     Normal function call, including calls to the system call stub
 187     functions in the libc, get the first six parameters passed in
 188     registers and the seventh parameter and later on the stack.  The
 189     register use is as follows:
 190
 191      system call number in the DO_CALL macro
 192      arg 1              rdi
 193      arg 2              rsi
 194      arg 3              rdx
 195      arg 4              rcx
 196      arg 5              r8
 197      arg 6              r9
 198
 199     We have to take care that the stack is aligned to 16 bytes.  When
 200     called the stack is not aligned since the return address has just
 201     been pushed.
 202
 203
 204     Syscalls of more than 6 arguments are not supported.  */
 205
 206 #undef  DO_CALL
 207 #define DO_CALL(syscall_name, args)             \
 208     DOARGS_##args                               \
 209     movq $SYS_ify (syscall_name), %rax;         \
 210     syscall;
 211
 212 #define DOARGS_0 /* nothing */
 213 #define DOARGS_1 /* nothing */
 214 #define DOARGS_2 /* nothing */
 215 #define DOARGS_3 /* nothing */
 216 #define DOARGS_4 movq %rcx, %r10;
 217 #define DOARGS_5 DOARGS_4
 218 #define DOARGS_6 DOARGS_5
 219
 220 #else   /* !__ASSEMBLER__ */
 221 /* Define a macro which expands inline into the wrapper code for a system
 222    call.  */
 223 #undef INLINE_SYSCALL
 224 #define INLINE_SYSCALL(name, nr, args...) \
 225   ({                                                                          \
 226     unsigned long resultvar = INTERNAL_SYSCALL (name, , nr, args);            \
 227     if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (resultvar, ), 0))         \
 228       {                                                                       \
 229         __set_errno (INTERNAL_SYSCALL_ERRNO (resultvar, ));                   \
 230         resultvar = (unsigned long) -1;                                       \
 231       }                                                                       \
 232     (long) resultvar; })
 233
 234 #undef INTERNAL_SYSCALL_DECL
 235 #define INTERNAL_SYSCALL_DECL(err) do { } while (0)
 236
 237 #undef INTERNAL_SYSCALL
 238 #define INTERNAL_SYSCALL(name, err, nr, args...) \
 239   ({                                                                          \
 240     unsigned long resultvar;                                                  \
 241     LOAD_ARGS_##nr (args)                                                     \
 242     asm volatile (                                                            \
 243     "movq %1, %%rax\n\t"                                                      \
 244     "syscall\n\t"                                                             \
 245     : "=a" (resultvar)                                                        \
 246     : "i" (__NR_##name) ASM_ARGS_##nr : "memory", "cc", "r11", "cx");         \
 247     (long) resultvar; })
 248
 249 #undef INTERNAL_SYSCALL_ERROR_P
 250 #define INTERNAL_SYSCALL_ERROR_P(val, err) \
 251   ((unsigned long) (val) >= -4095L)
 252
 253 #undef INTERNAL_SYSCALL_ERRNO
 254 #define INTERNAL_SYSCALL_ERRNO(val, err)        (-(val))
 255
 256 #define LOAD_ARGS_0()
 257 #define ASM_ARGS_0
 258
 259 #define LOAD_ARGS_1(a1)                                 \
 260   register long int _a1 asm ("rdi") = (long) (a1);      \
 261   LOAD_ARGS_0 ()
 262 #define ASM_ARGS_1      ASM_ARGS_0, "r" (_a1)
 263
 264 #define LOAD_ARGS_2(a1, a2)                             \
 265   register long int _a2 asm ("rsi") = (long) (a2);      \
 266   LOAD_ARGS_1 (a1)
 267 #define ASM_ARGS_2      ASM_ARGS_1, "r" (_a2)
 268
 269 #define LOAD_ARGS_3(a1, a2, a3)                         \
 270   register long int _a3 asm ("rdx") = (long) (a3);      \
 271   LOAD_ARGS_2 (a1, a2)
 272 #define ASM_ARGS_3      ASM_ARGS_2, "r" (_a3)
 273
 274 #define LOAD_ARGS_4(a1, a2, a3, a4)                     \
 275   register long int _a4 asm ("r10") = (long) (a4);      \
 276   LOAD_ARGS_3 (a1, a2, a3)
 277 #define ASM_ARGS_4      ASM_ARGS_3, "r" (_a4)
 278
 279 #define LOAD_ARGS_5(a1, a2, a3, a4, a5)                 \
 280   register long int _a5 asm ("r8") = (long) (a5);       \
 281   LOAD_ARGS_4 (a1, a2, a3, a4)
 282 #define ASM_ARGS_5      ASM_ARGS_4, "r" (_a5)
 283
 284 #define LOAD_ARGS_6(a1, a2, a3, a4, a5, a6)             \
 285   register long int _a6 asm ("r9") = (long) (a6);       \
 286   LOAD_ARGS_5 (a1, a2, a3, a4, a5)
 287 #define ASM_ARGS_6      ASM_ARGS_5, "r" (_a6)
 288
 289 #endif  /* __ASSEMBLER__ */
 290
 291 #endif /* linux/x86_64/sysdep.h */