syscalls.list support for vDSO IFUNCs, use it for x32 gettimeofday and time.

This commit is contained in:
Roland McGrath 2012-05-22 16:00:50 -07:00
parent d6c33fda03
commit c14874927b
6 changed files with 128 additions and 48 deletions

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@ -1,5 +1,18 @@
2012-05-24 Roland McGrath <roland@hack.frob.com>
* sysdeps/unix/sysv/linux/x86_64/x32/syscalls.list: New file.
* sysdeps/unix/make-syscalls.sh: Support "syscall:vdso_name@VDSOVER"
in the third column, to generate for the shared library an IFUNC
that uses _dl_vdso_vsym.
* Makerules (COMPILE.c, compile-stdin.c): New variables.
* Makeconfig (object-suffixes-noshared): New variable.
* sysdeps/unix/sysv/linux/dl-vdso.h (PREPARE_VERSION_KNOWN): New macro.
(VDSO_NAME_LINUX_2_6, VDSO_HASH_LINUX_2_6): New macros.
(VDSO_NAME_LINUX_2_6_15, VDSO_HASH_LINUX_2_6_15): New macros.
(VDSO_NAME_LINUX_2_6_29, VDSO_HASH_LINUX_2_6_29): New macros.
[BZ #14132]
* include/sys/time.h (__gettimeofday): Remove macro.
(__gettimeofday, gettimeofday): Add libc_hidden_proto.

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@ -720,6 +720,10 @@ CFLAGS-.op = -pg
libtype.op = lib%_p.a
endif
# Convenience variable for when we want to treat shared-library cases
# differently from the rest.
object-suffixes-noshared := $(filter-out .os,$(object-suffixes))
bppfx = BP-
ifeq (yes,$(build-bounded))
# Under --enable-bounded, we build the library with `-fbounded-pointers -g'

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@ -366,6 +366,7 @@ compile.c = $(CC) $< -c $(CFLAGS) $(CPPFLAGS)
compile.cc = $(CXX) $< -c $(CXXFLAGS) $(CPPFLAGS)
compile.S = $(CC) $< -c $(CPPFLAGS) $(S-CPPFLAGS) \
$(ASFLAGS) $(ASFLAGS-$(suffix $@))
COMPILE.c = $(CC) -c $(CFLAGS) $(CPPFLAGS)
COMPILE.S = $(CC) -c $(CPPFLAGS) $(S-CPPFLAGS) \
$(ASFLAGS) $(ASFLAGS-$(suffix $@))
@ -374,6 +375,9 @@ COMPILE.S = $(CC) -c $(CPPFLAGS) $(S-CPPFLAGS) \
# together. You can't compile the C library with such a compiler.
OUTPUT_OPTION = -o $@
# This is the end of the pipeline for compiling generated C code.
compile-stdin.c = $(COMPILE.c) -o $@ -x c - $(compile-mkdep-flags)
# We need the $(CFLAGS) to be in there to have the right predefines during
# the dependency run for C sources. But having it for assembly sources can
# get the wrong predefines.

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@ -64,10 +64,67 @@ done`
# Any calls left?
test -n "$calls" || exit 0
# This uses variables $weak and $strong.
emit_weak_aliases()
{
# A shortcoming in the current gas is that it will only allow one
# version-alias per symbol. So we create new strong aliases as needed.
vcount=""
for name in $weak; do
case $name in
*@@*)
base=`echo $name | sed 's/@@.*//'`
ver=`echo $name | sed 's/.*@@//'`
if test -z "$vcount" ; then
source=$strong
vcount=1
else
source="${strong}_${vcount}"
vcount=`expr $vcount + 1`
echo " echo 'strong_alias ($strong, $source)'; \\"
fi
echo " echo 'default_symbol_version($source, $base, $ver)'; \\"
;;
*@*)
base=`echo $name | sed 's/@.*//'`
ver=`echo $name | sed 's/.*@//'`
if test -z "$vcount" ; then
source=$strong
vcount=1
else
source="${strong}_${vcount}"
vcount=`expr $vcount + 1`
echo " echo 'strong_alias ($strong, $source)'; \\"
fi
echo " echo 'symbol_version ($source, $base, $ver)'; \\"
;;
!*)
name=`echo $name | sed 's/.//'`
echo " echo 'strong_alias ($strong, $name)'; \\"
echo " echo 'libc_hidden_def ($name)'; \\"
;;
*)
echo " echo 'weak_alias ($strong, $name)'; \\"
echo " echo 'libc_hidden_weak ($name)'; \\"
;;
esac
done
}
# Emit rules to compile the syscalls remaining in $calls.
echo "$calls" |
while read file srcfile caller syscall args strong weak; do
vdso_syscall=
case x"$syscall" in
*:*@*)
vdso_syscall="${syscall#*:}"
syscall="${syscall%:*}"
;;
esac
case x"$syscall" in
x-) callnum=_ ;;
*)
@ -144,13 +201,14 @@ while read file srcfile caller syscall args strong weak; do
# Emit a compilation rule for this syscall.
if test $shared_only = t; then
# The versioned symbols are only in the shared library.
echo "\
shared-only-routines += $file
\$(objpfx)${file}.os: \\"
echo "shared-only-routines += $file"
test -n "$vdso_syscall" || echo "\$(objpfx)${file}.os: \\"
else
object_suffixes='$(object-suffixes)'
test -z "$vdso_syscall" || object_suffixes='$(object-suffixes-noshared)'
echo "\
\$(foreach p,\$(sysd-rules-targets),\
\$(foreach o,\$(object-suffixes),\$(objpfx)\$(patsubst %,\$p,$file)\$o)): \\"
\$(foreach o,${object_suffixes},\$(objpfx)\$(patsubst %,\$p,$file)\$o)): \\"
fi
echo " \$(..)sysdeps/unix/make-syscalls.sh"
@ -178,55 +236,43 @@ shared-only-routines += $file
esac
# Append any weak aliases or versions defined for this syscall function.
# A shortcoming in the current gas is that it will only allow one
# version-alias per symbol. So we create new strong aliases as needed.
vcount=""
for name in $weak; do
case $name in
*@@*)
base=`echo $name | sed 's/@@.*//'`
ver=`echo $name | sed 's/.*@@//'`
if test -z "$vcount" ; then
source=$strong
vcount=1
else
source="${strong}_${vcount}"
vcount=`expr $vcount + 1`
echo " echo 'strong_alias ($strong, $source)'; \\"
fi
echo " echo 'default_symbol_version($source, $base, $ver)'; \\"
;;
*@*)
base=`echo $name | sed 's/@.*//'`
ver=`echo $name | sed 's/.*@//'`
if test -z "$vcount" ; then
source=$strong
vcount=1
else
source="${strong}_${vcount}"
vcount=`expr $vcount + 1`
echo " echo 'strong_alias ($strong, $source)'; \\"
fi
echo " echo 'symbol_version ($source, $base, $ver)'; \\"
;;
!*)
name=`echo $name | sed 's/.//'`
echo " echo 'strong_alias ($strong, $name)'; \\"
echo " echo 'libc_hidden_def ($name)'; \\"
;;
*)
echo " echo 'weak_alias ($strong, $name)'; \\"
echo " echo 'libc_hidden_weak ($name)'; \\"
;;
esac
done
emit_weak_aliases
# And finally, pipe this all into the compiler.
echo ' ) | $(compile-syscall) '"\
\$(foreach p,\$(patsubst %$file,%,\$(basename \$(@F))),\$(\$(p)CPPFLAGS))"
if test -n "$vdso_syscall"; then
# In the shared library, we're going to emit an IFUNC using a vDSO function.
# $vdso_syscall looks like "name@KERNEL_X.Y" where "name" is the symbol
# name in the vDSO and KERNEL_X.Y is its symbol version.
vdso_symbol="${vdso_syscall%@*}"
vdso_symver="${vdso_syscall#*@}"
vdso_symver="${vdso_symver//./_}"
echo "\
\$(foreach p,\$(sysd-rules-targets),\$(objpfx)\$(patsubst %,\$p,$file).os): \\
\$(..)sysdeps/unix/make-syscalls.sh\
\$(make-target-directory)
(echo '#include <dl-vdso.h>'; \\
echo 'extern void *${strong}_ifunc (void) __asm (\"${strong}\");'; \\
echo 'void *'; \\
echo '${strong}_ifunc (void)'; \\
echo '{'; \\
echo ' PREPARE_VERSION_KNOWN (symver, ${vdso_symver});'; \\
echo ' return _dl_vdso_vsym (\"${vdso_symbol}\", &symver);'; \\
echo '}'; \\
echo 'asm (\".type ${strong}, %gnu_indirect_function\");'; \\"
# This is doing "libc_hidden_def (${strong})", but the compiler
# doesn't know that we've defined ${strong} in the same file, so
# we can't do it the normal way.
echo "\
echo 'asm (\".globl __GI_${strong}\\n\"'; \\
echo ' \"__GI_${strong} = ${strong}\");'; \\"
emit_weak_aliases
echo ' ) | $(compile-stdin.c) '"\
\$(foreach p,\$(patsubst %$file,%,\$(basename \$(@F))),\$(\$(p)CPPFLAGS))"
fi
if test $shared_only = t; then
# The versioned symbols are only in the shared library.
echo endif

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@ -33,6 +33,17 @@
/* We don't have a specific file where the symbol can be found. */ \
var.filename = NULL
/* Use this for the known version sets defined below, where we
record their precomputed hash values only once, in this file. */
#define PREPARE_VERSION_KNOWN(var, vname) \
PREPARE_VERSION (var, VDSO_NAME_##vname, VDSO_HASH_##vname)
#define VDSO_NAME_LINUX_2_6 "LINUX_2.6"
#define VDSO_HASH_LINUX_2_6 61765110
#define VDSO_NAME_LINUX_2_6_15 "LINUX_2.6.15"
#define VDSO_HASH_LINUX_2_6_15 123718565
#define VDSO_NAME_LINUX_2_6_29 "LINUX_2.6.29"
#define VDSO_HASH_LINUX_2_6_29 123718585
/* Functions for resolving symbols in the VDSO link map. */
extern void *_dl_vdso_vsym (const char *name,

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@ -1,6 +1,8 @@
# File name Caller Syscall name # args Strong name Weak names
fallocate - fallocate Ci:iiii fallocate fallocate64
gettimeofday - gettimeofday:__vdso_gettimeofday@LINUX_2.6 i:pP __gettimeofday gettimeofday
posix_fadvise - fadvise64 Vi:iiii posix_fadvise posix_fadvise64
preadv - preadv Ci:ipii preadv preadv64
pwritev - pwritev Ci:ipii pwritev pwritev64
time - time:__vdso_time@LINUX_2.6 Ei:P time