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https://sourceware.org/git/glibc.git
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de6591238b
When dynamically linking, ifunc resolvers are called before TLS is
initialized, so they cannot be safely stack-protected.
We avoid disabling stack-protection on large numbers of files by
using __attribute__ ((__optimize__ ("-fno-stack-protector")))
to turn it off just for the resolvers themselves. (We provide
the attribute even when statically linking, because we will later
use it elsewhere too.)
322 lines
9.7 KiB
Bash
322 lines
9.7 KiB
Bash
#!/bin/sh
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# Usage: make-syscalls.sh ../sysdeps/unix/common
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# Expects $sysdirs in environment.
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##############################################################################
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#
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# This script is used to process the syscall data encoded in the various
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# syscalls.list files to produce thin assembly syscall wrappers around the
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# appropriate OS syscall. See syscall-template.s for more details on the
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# actual wrapper.
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#
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# Syscall Signature Prefixes:
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#
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# C: cancellable (i.e., this syscall is a cancellation point)
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# E: errno and return value are not set by the call
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# V: errno is not set, but errno or zero (success) is returned from the call
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#
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# Syscall Signature Key Letters:
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#
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# a: unchecked address (e.g., 1st arg to mmap)
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# b: non-NULL buffer (e.g., 2nd arg to read; return value from mmap)
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# B: optionally-NULL buffer (e.g., 4th arg to getsockopt)
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# f: buffer of 2 ints (e.g., 4th arg to socketpair)
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# F: 3rd arg to fcntl
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# i: scalar (any signedness & size: int, long, long long, enum, whatever)
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# I: 3rd arg to ioctl
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# n: scalar buffer length (e.g., 3rd arg to read)
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# N: pointer to value/return scalar buffer length (e.g., 6th arg to recvfrom)
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# p: non-NULL pointer to typed object (e.g., any non-void* arg)
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# P: optionally-NULL pointer to typed object (e.g., 2nd argument to gettimeofday)
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# s: non-NULL string (e.g., 1st arg to open)
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# S: optionally-NULL string (e.g., 1st arg to acct)
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# v: vararg scalar (e.g., optional 3rd arg to open)
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# V: byte-per-page vector (3rd arg to mincore)
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# W: wait status, optionally-NULL pointer to int (e.g., 2nd arg of wait4)
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#
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##############################################################################
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thisdir=$1; shift
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echo ''
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echo \#### DIRECTORY = $thisdir
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# Check each sysdep dir with higher priority than this one,
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# and remove from $calls all the functions found in other dirs.
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# Punt when we reach the directory defining these syscalls.
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sysdirs=`for dir in $sysdirs; do
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test $dir = $thisdir && break; echo $dir; done`
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echo \#### SYSDIRS = $sysdirs
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# Get the list of system calls for this directory.
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calls=`sed 's/#.*$//
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/^[ ]*$/d' $thisdir/syscalls.list`
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calls=`echo "$calls" |
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while read file caller rest; do
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# Remove each syscall that is implemented by a file in $dir.
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# If a syscall specified a "caller", then only compile that syscall
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# if the caller function is also implemented in this directory.
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srcfile=-;
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for dir in $sysdirs; do
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{ test -f $dir/$file.c && srcfile=$dir/$file.c; } ||
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{ test -f $dir/$file.S && srcfile=$dir/$file.S; } ||
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{ test x$caller != x- &&
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{ { test -f $dir/$caller.c && srcfile=$dir/$caller.c; } ||
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{ test -f $dir/$caller.S && srcfile=$dir/$caller.S; }; }; } && break;
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done;
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echo $file $srcfile $caller $rest;
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done`
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# Any calls left?
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test -n "$calls" || exit 0
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# This uses variables $weak, $strong, and $any_versioned.
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emit_weak_aliases()
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{
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# A shortcoming in the current gas is that it will only allow one
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# version-alias per symbol. So we create new strong aliases as needed.
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vcount=""
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# We use the <shlib-compat.h> macros to generate the versioned aliases
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# so that the version sets can be mapped to the configuration's
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# minimum version set as per shlib-versions DEFAULT lines. If an
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# entry point is specified in the form NAME@VERSION:OBSOLETED, a
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# SHLIB_COMPAT conditional is generated.
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if [ $any_versioned = t ]; then
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echo " echo '#include <shlib-compat.h>'; \\"
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fi
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for name in $weak; do
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case $name in
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*@@*)
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base=`echo $name | sed 's/@@.*//'`
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ver=`echo $name | sed 's/.*@@//;s/\./_/g'`
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echo " echo '#if IS_IN (libc)'; \\"
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if test -z "$vcount" ; then
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source=$strong
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vcount=1
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else
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source="${strong}_${vcount}"
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vcount=`expr $vcount + 1`
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echo " echo 'strong_alias ($strong, $source)'; \\"
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fi
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echo " echo 'versioned_symbol (libc, $source, $base, $ver)'; \\"
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echo " echo '#else'; \\"
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echo " echo 'strong_alias ($strong, $base)'; \\"
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echo " echo '#endif'; \\"
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;;
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*@*)
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base=`echo $name | sed 's/@.*//'`
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ver=`echo $name | sed 's/.*@//;s/\./_/g'`
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case $ver in
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*:*)
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compat_ver=${ver#*:}
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ver=${ver%%:*}
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compat_cond=" && SHLIB_COMPAT (libc, $ver, $compat_ver)"
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;;
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*)
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compat_cond=
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;;
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esac
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echo " echo '#if defined SHARED && IS_IN (libc)$compat_cond'; \\"
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if test -z "$vcount" ; then
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source=$strong
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vcount=1
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else
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source="${strong}_${vcount}"
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vcount=`expr $vcount + 1`
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echo " echo 'strong_alias ($strong, $source)'; \\"
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fi
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echo " echo 'compat_symbol (libc, $source, $base, $ver)'; \\"
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echo " echo '#endif'; \\"
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;;
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!*)
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name=`echo $name | sed 's/.//'`
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echo " echo 'strong_alias ($strong, $name)'; \\"
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echo " echo 'hidden_def ($name)'; \\"
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;;
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*)
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echo " echo 'weak_alias ($strong, $name)'; \\"
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echo " echo 'hidden_weak ($name)'; \\"
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;;
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esac
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done
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}
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# Emit rules to compile the syscalls remaining in $calls.
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echo "$calls" |
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while read file srcfile caller syscall args strong weak; do
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vdso_syscall=
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case x"$syscall" in
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*:*@*)
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vdso_syscall="${syscall#*:}"
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syscall="${syscall%:*}"
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;;
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esac
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case x"$syscall" in
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x-) callnum=_ ;;
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*)
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# Figure out if $syscall is defined with a number in syscall.h.
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callnum=-
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eval `{ echo "#include <sysdep.h>";
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echo "callnum=SYS_ify ($syscall)"; } |
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$asm_CPP -D__OPTIMIZE__ - |
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sed -n -e "/^callnum=.*$syscall/d" \
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-e "/^\(callnum=\)[ ]*\(.*\)/s//\1'\2'/p"`
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;;
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esac
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cancellable=0
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noerrno=0
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errval=0
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case $args in
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C*) cancellable=1; args=`echo $args | sed 's/C:\?//'`;;
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E*) noerrno=1; args=`echo $args | sed 's/E:\?//'`;;
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V*) errval=1; args=`echo $args | sed 's/V:\?//'`;;
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esac
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# Derive the number of arguments from the argument signature
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case $args in
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[0-9]) nargs=$args;;
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?:) nargs=0;;
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?:?) nargs=1;;
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?:??) nargs=2;;
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?:???) nargs=3;;
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?:????) nargs=4;;
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?:?????) nargs=5;;
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?:??????) nargs=6;;
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?:???????) nargs=7;;
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?:????????) nargs=8;;
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?:?????????) nargs=9;;
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esac
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# Make sure only the first syscall rule is used, if multiple dirs
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# define the same syscall.
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echo ''
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echo "#### CALL=$file NUMBER=$callnum ARGS=$args SOURCE=$srcfile"
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# If there are versioned aliases the entry is only generated for the
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# shared library, unless it is a default version.
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any_versioned=f
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shared_only=f
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case $weak in
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*@@*) any_versioned=t ;;
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*@*) any_versioned=t shared_only=t ;;
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esac
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case x$srcfile"$callnum" in
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x--)
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# Undefined callnum for an extra syscall.
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if [ x$caller != x- ]; then
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if [ $noerrno != 0 ]; then
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echo >&2 "$0: no number for $fileno, no-error syscall ($strong $weak)"
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exit 2
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fi
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echo "unix-stub-syscalls += $strong $weak"
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fi
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;;
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x*-) ;; ### Do nothing for undefined callnum
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x-*)
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echo "ifeq (,\$(filter $file,\$(unix-syscalls)))"
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if test $shared_only = t; then
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# The versioned symbols are only in the shared library.
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echo "ifneq (,\$(filter .os,\$(object-suffixes)))"
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fi
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# Accumulate the list of syscall files for this directory.
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echo "unix-syscalls += $file"
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test x$caller = x- || echo "unix-extra-syscalls += $file"
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# Emit a compilation rule for this syscall.
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if test $shared_only = t; then
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# The versioned symbols are only in the shared library.
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echo "shared-only-routines += $file"
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test -n "$vdso_syscall" || echo "\$(objpfx)${file}.os: \\"
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else
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object_suffixes='$(object-suffixes)'
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test -z "$vdso_syscall" || object_suffixes='$(object-suffixes-noshared)'
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echo "\
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\$(foreach p,\$(sysd-rules-targets),\
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\$(foreach o,${object_suffixes},\$(objpfx)\$(patsubst %,\$p,$file)\$o)): \\"
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fi
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echo " \$(..)sysdeps/unix/make-syscalls.sh"
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case x"$callnum" in
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x_)
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echo "\
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\$(make-target-directory)
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(echo '/* Dummy module requested by syscalls.list */'; \\"
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;;
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x*)
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echo "\
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\$(make-target-directory)
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(echo '#define SYSCALL_NAME $syscall'; \\
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echo '#define SYSCALL_NARGS $nargs'; \\
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echo '#define SYSCALL_SYMBOL $strong'; \\
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echo '#define SYSCALL_CANCELLABLE $cancellable'; \\
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echo '#define SYSCALL_NOERRNO $noerrno'; \\
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echo '#define SYSCALL_ERRVAL $errval'; \\
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echo '#include <syscall-template.S>'; \\"
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;;
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esac
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# Append any weak aliases or versions defined for this syscall function.
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emit_weak_aliases
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# And finally, pipe this all into the compiler.
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echo ' ) | $(compile-syscall) '"\
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\$(foreach p,\$(patsubst %$file,%,\$(basename \$(@F))),\$(\$(p)CPPFLAGS))"
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if test -n "$vdso_syscall"; then
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# In the shared library, we're going to emit an IFUNC using a vDSO function.
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# $vdso_syscall looks like "name@KERNEL_X.Y" where "name" is the symbol
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# name in the vDSO and KERNEL_X.Y is its symbol version.
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vdso_symbol="${vdso_syscall%@*}"
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vdso_symver="${vdso_syscall#*@}"
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vdso_symver=`echo "$vdso_symver" | sed 's/\./_/g'`
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cat <<EOF
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\$(foreach p,\$(sysd-rules-targets),\$(objpfx)\$(patsubst %,\$p,$file).os): \\
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\$(..)sysdeps/unix/make-syscalls.sh
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\$(make-target-directory)
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(echo '#include <dl-vdso.h>'; \\
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echo 'extern void *${strong}_ifunc (void) __asm ("${strong}");'; \\
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echo 'void *'; \\
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echo 'inhibit_stack_protector'; \\
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echo '${strong}_ifunc (void)'; \\
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echo '{'; \\
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echo ' PREPARE_VERSION_KNOWN (symver, ${vdso_symver});'; \\
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echo ' return _dl_vdso_vsym ("${vdso_symbol}", &symver);'; \\
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echo '}'; \\
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echo 'asm (".type ${strong}, %gnu_indirect_function");'; \\
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EOF
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# This is doing "hidden_def (${strong})", but the compiler
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# doesn't know that we've defined ${strong} in the same file, so
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# we can't do it the normal way.
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cat <<EOF
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echo 'asm (".globl __GI_${strong}");'; \\
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echo 'asm ("__GI_${strong} = ${strong}");'; \\
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EOF
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emit_weak_aliases
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cat <<EOF
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) | \$(compile-stdin.c) \
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\$(foreach p,\$(patsubst %$file,%,\$(basename \$(@F))),\$(\$(p)CPPFLAGS))
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EOF
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fi
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if test $shared_only = t; then
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# The versioned symbols are only in the shared library.
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echo endif
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fi
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echo endif
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;;
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esac
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done
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