sysdeps/unix/make-syscalls.sh

   1 #! /bin/sh
   2
   3 # Usage: make-syscalls.sh ../sysdeps/unix/common
   4 # Expects $sysdirs in environment.
   5
   6 ##############################################################################
   7 #
   8 # This script is used to process the syscall data encoded in the various
   9 # syscalls.list files to produce thin assembly syscall wrappers around the
  10 # appropriate OS syscall. See syscall-template.s for more details on the
  11 # actual wrapper.
  12 #
  13 # Syscall Signature Prefixes:
  14 #
  15 # C: cancellable (i.e., this syscall is a cancellation point)
  16 # E: errno and return value are not set by the call
  17 # V: errno is not set, but errno or zero (success) is returned from the call
  18 #
  19 # Syscall Signature Key Letters:
  20 #
  21 # a: unchecked address (e.g., 1st arg to mmap)
  22 # b: non-NULL buffer (e.g., 2nd arg to read; return value from mmap)
  23 # B: optionally-NULL buffer (e.g., 4th arg to getsockopt)
  24 # f: buffer of 2 ints (e.g., 4th arg to socketpair)
  25 # F: 3rd arg to fcntl
  26 # i: scalar (any signedness & size: int, long, long long, enum, whatever)
  27 # I: 3rd arg to ioctl
  28 # n: scalar buffer length (e.g., 3rd arg to read)
  29 # N: pointer to value/return scalar buffer length (e.g., 6th arg to recvfrom)
  30 # p: non-NULL pointer to typed object (e.g., any non-void* arg)
  31 # P: optionally-NULL pointer to typed object (e.g., 2nd argument to gettimeofday)
  32 # s: non-NULL string (e.g., 1st arg to open)
  33 # S: optionally-NULL string (e.g., 1st arg to acct)
  34 # v: vararg scalar (e.g., optional 3rd arg to open)
  35 # V: byte-per-page vector (3rd arg to mincore)
  36 # W: wait status, optionally-NULL pointer to int (e.g., 2nd arg of wait4)
  37 #
  38
  39 ##############################################################################
  40
  41 thisdir=$1; shift
  42
  43 echo ''
  44 echo \#### DIRECTORY = $thisdir
  45 # Check each sysdep dir with higher priority than this one,
  46 # and remove from $calls all the functions found in other dirs.
  47 # Punt when we reach the directory defining these syscalls.
  48 sysdirs=`for dir in $sysdirs; do
  49          test $dir = $thisdir && break; echo $dir; done`
  50 echo \#### SYSDIRS = $sysdirs
  51
  52 # Get the list of system calls for this directory.
  53 calls=`sed 's/#.*$//
  54 /^[     ]*$/d' $thisdir/syscalls.list`
  55
  56 calls=`echo "$calls" |
  57 while read file caller rest; do
  58   # Remove each syscall that is implemented by a file in $dir.
  59   # If a syscall specified a "caller", then only compile that syscall
  60   # if the caller function is also implemented in this directory.
  61   srcfile=-;
  62   for dir in $sysdirs; do
  63      { test -f $dir/$file.c && srcfile=$dir/$file.c; } ||
  64      { test -f $dir/$file.S && srcfile=$dir/$file.S; } ||
  65      { test x$caller != x- &&
  66         { { test -f $dir/$caller.c && srcfile=$dir/$caller.c; } ||
  67           { test -f $dir/$caller.S && srcfile=$dir/$caller.S; }; }; } && break;
  68   done;
  69   echo $file $srcfile $caller $rest;
  70 done`
  71
  72 # Any calls left?
  73 test -n "$calls" || exit 0
  74
  75 # This uses variables $weak, $strong, and $any_versioned.
  76 emit_weak_aliases()
  77 {
  78   # A shortcoming in the current gas is that it will only allow one
  79   # version-alias per symbol.  So we create new strong aliases as needed.
  80   vcount=""
  81
  82   # We use the <shlib-compat.h> macros to generate the versioned aliases
  83   # so that the version sets can be mapped to the configuration's
  84   # minimum version set as per shlib-versions DEFAULT lines.  But note
  85   # we don't generate any "#if SHLIB_COMPAT (...)" conditionals.  To do
  86   # that we'd need to change the syscalls.list format so that it can
  87   # list the "obsoleted" version set too.  If it ever arises that we
  88   # have a syscall entry point that is obsoleted by a newer version set,
  89   # we'll have to revamp all this.
  90   if [ $any_versioned = t ]; then
  91     echo "       echo '#include <shlib-compat.h>'; \\"
  92   fi
  93
  94   for name in $weak; do
  95     case $name in
  96       *@@*)
  97         base=`echo $name | sed 's/@@.*//'`
  98         ver=`echo $name | sed 's/.*@@//;s/\./_/g'`
  99         echo "   echo '#if IS_IN (libc)'; \\"
 100         if test -z "$vcount" ; then
 101           source=$strong
 102           vcount=1
 103         else
 104           source="${strong}_${vcount}"
 105           vcount=`expr $vcount + 1`
 106           echo "         echo 'strong_alias ($strong, $source)'; \\"
 107         fi
 108         echo "   echo 'versioned_symbol (libc, $source, $base, $ver)'; \\"
 109         echo "   echo '#else'; \\"
 110         echo "   echo 'strong_alias ($strong, $base)'; \\"
 111         echo "   echo '#endif'; \\"
 112         ;;
 113       *@*)
 114         base=`echo $name | sed 's/@.*//'`
 115         ver=`echo $name | sed 's/.*@//;s/\./_/g'`
 116         echo "   echo '#if defined SHARED && IS_IN (libc)'; \\"
 117         if test -z "$vcount" ; then
 118           source=$strong
 119           vcount=1
 120         else
 121           source="${strong}_${vcount}"
 122           vcount=`expr $vcount + 1`
 123           echo "         echo 'strong_alias ($strong, $source)'; \\"
 124         fi
 125         echo "   echo 'compat_symbol (libc, $source, $base, $ver)'; \\"
 126         echo "   echo '#endif'; \\"
 127         ;;
 128       !*)
 129         name=`echo $name | sed 's/.//'`
 130         echo "   echo 'strong_alias ($strong, $name)'; \\"
 131         echo "   echo 'libc_hidden_def ($name)'; \\"
 132         ;;
 133       *)
 134         echo "   echo 'weak_alias ($strong, $name)'; \\"
 135         echo "   echo 'libc_hidden_weak ($name)'; \\"
 136         ;;
 137     esac
 138   done
 139 }
 140
 141
 142 # Emit rules to compile the syscalls remaining in $calls.
 143 echo "$calls" |
 144 while read file srcfile caller syscall args strong weak; do
 145
 146   vdso_syscall=
 147   case x"$syscall" in
 148   *:*@*)
 149     vdso_syscall="${syscall#*:}"
 150     syscall="${syscall%:*}"
 151     ;;
 152   esac
 153
 154   case x"$syscall" in
 155   x-) callnum=_ ;;
 156   *)
 157   # Figure out if $syscall is defined with a number in syscall.h.
 158   callnum=-
 159   eval `{ echo "#include <sysdep.h>";
 160         echo "callnum=SYS_ify ($syscall)"; } |
 161           $asm_CPP -D__OPTIMIZE__ - |
 162           sed -n -e "/^callnum=.*$syscall/d" \
 163                  -e "/^\(callnum=\)[    ]*\(.*\)/s//\1'\2'/p"`
 164   ;;
 165   esac
 166
 167   cancellable=0
 168   noerrno=0
 169   errval=0
 170   case $args in
 171   C*) cancellable=1; args=`echo $args | sed 's/C:\?//'`;;
 172   E*) noerrno=1; args=`echo $args | sed 's/E:\?//'`;;
 173   V*) errval=1; args=`echo $args | sed 's/V:\?//'`;;
 174   esac
 175
 176   # Derive the number of arguments from the argument signature
 177   case $args in
 178   [0-9]) nargs=$args;;
 179   ?:) nargs=0;;
 180   ?:?) nargs=1;;
 181   ?:??) nargs=2;;
 182   ?:???) nargs=3;;
 183   ?:????) nargs=4;;
 184   ?:?????) nargs=5;;
 185   ?:??????) nargs=6;;
 186   ?:???????) nargs=7;;
 187   ?:????????) nargs=8;;
 188   ?:?????????) nargs=9;;
 189   esac
 190
 191   # Make sure only the first syscall rule is used, if multiple dirs
 192   # define the same syscall.
 193   echo ''
 194   echo "#### CALL=$file NUMBER=$callnum ARGS=$args SOURCE=$srcfile"
 195
 196   # If there are versioned aliases the entry is only generated for the
 197   # shared library, unless it is a default version.
 198   any_versioned=f
 199   shared_only=f
 200   case $weak in
 201     *@@*) any_versioned=t ;;
 202     *@*) any_versioned=t shared_only=t ;;
 203   esac
 204
 205  case x$srcfile"$callnum" in
 206  x--)
 207   # Undefined callnum for an extra syscall.
 208   if [ x$caller != x- ]; then
 209     if [ $noerrno != 0 ]; then
 210       echo >&2 "$0: no number for $fileno, no-error syscall ($strong $weak)"
 211       exit 2
 212     fi
 213     echo "unix-stub-syscalls += $strong $weak"
 214   fi
 215   ;;
 216  x*-) ;; ### Do nothing for undefined callnum
 217  x-*)
 218   echo "ifeq (,\$(filter $file,\$(unix-syscalls)))"
 219
 220   if test $shared_only = t; then
 221     # The versioned symbols are only in the shared library.
 222     echo "ifneq (,\$(filter .os,\$(object-suffixes)))"
 223   fi
 224   # Accumulate the list of syscall files for this directory.
 225   echo "unix-syscalls += $file"
 226   test x$caller = x- || echo "unix-extra-syscalls += $file"
 227
 228   # Emit a compilation rule for this syscall.
 229   if test $shared_only = t; then
 230     # The versioned symbols are only in the shared library.
 231     echo "shared-only-routines += $file"
 232     test -n "$vdso_syscall" || echo "\$(objpfx)${file}.os: \\"
 233   else
 234     object_suffixes='$(object-suffixes)'
 235     test -z "$vdso_syscall" || object_suffixes='$(object-suffixes-noshared)'
 236     echo "\
 237 \$(foreach p,\$(sysd-rules-targets),\
 238 \$(foreach o,${object_suffixes},\$(objpfx)\$(patsubst %,\$p,$file)\$o)): \\"
 239   fi
 240
 241   echo "                \$(..)sysdeps/unix/make-syscalls.sh"
 242   case x"$callnum" in
 243   x_)
 244   echo "\
 245         \$(make-target-directory)
 246         (echo '/* Dummy module requested by syscalls.list */'; \\"
 247   ;;
 248   x*)
 249   echo "\
 250         \$(make-target-directory)
 251         (echo '#define SYSCALL_NAME $syscall'; \\
 252          echo '#define SYSCALL_NARGS $nargs'; \\
 253          echo '#define SYSCALL_SYMBOL $strong'; \\
 254          echo '#define SYSCALL_CANCELLABLE $cancellable'; \\
 255          echo '#define SYSCALL_NOERRNO $noerrno'; \\
 256          echo '#define SYSCALL_ERRVAL $errval'; \\
 257          echo '#include <syscall-template.S>'; \\"
 258   ;;
 259   esac
 260
 261   # Append any weak aliases or versions defined for this syscall function.
 262   emit_weak_aliases
 263
 264   # And finally, pipe this all into the compiler.
 265   echo '        ) | $(compile-syscall) '"\
 266 \$(foreach p,\$(patsubst %$file,%,\$(basename \$(@F))),\$(\$(p)CPPFLAGS))"
 267
 268   if test -n "$vdso_syscall"; then
 269     # In the shared library, we're going to emit an IFUNC using a vDSO function.
 270     # $vdso_syscall looks like "name@KERNEL_X.Y" where "name" is the symbol
 271     # name in the vDSO and KERNEL_X.Y is its symbol version.
 272     vdso_symbol="${vdso_syscall%@*}"
 273     vdso_symver="${vdso_syscall#*@}"
 274     vdso_symver=`echo "$vdso_symver" | sed 's/\./_/g'`
 275     echo "\
 276 \$(foreach p,\$(sysd-rules-targets),\$(objpfx)\$(patsubst %,\$p,$file).os): \\
 277                 \$(..)sysdeps/unix/make-syscalls.sh
 278         \$(make-target-directory)
 279         (echo '#include <dl-vdso.h>'; \\
 280          echo 'extern void *${strong}_ifunc (void) __asm (\"${strong}\");'; \\
 281          echo 'void *'; \\
 282          echo '${strong}_ifunc (void)'; \\
 283          echo '{'; \\
 284          echo '  PREPARE_VERSION_KNOWN (symver, ${vdso_symver});'; \\
 285          echo '  return _dl_vdso_vsym (\"${vdso_symbol}\", &symver);'; \\
 286          echo '}'; \\
 287          echo 'asm (\".type ${strong}, %gnu_indirect_function\");'; \\"
 288     # This is doing "libc_hidden_def (${strong})", but the compiler
 289     # doesn't know that we've defined ${strong} in the same file, so
 290     # we can't do it the normal way.
 291     echo "\
 292          echo 'asm (\".globl __GI_${strong}\\n\"'; \\
 293          echo '     \"__GI_${strong} = ${strong}\");'; \\"
 294     emit_weak_aliases
 295     echo '      ) | $(compile-stdin.c) '"\
 296 \$(foreach p,\$(patsubst %$file,%,\$(basename \$(@F))),\$(\$(p)CPPFLAGS))"
 297   fi
 298
 299   if test $shared_only = t; then
 300     # The versioned symbols are only in the shared library.
 301     echo endif
 302   fi
 303
 304   echo endif
 305  ;;
 306  esac
 307
 308 done