Neither the <dlfcn.h> entry points, nor lazy symbol resolution, nor
initial shared library load-up, are cancellation points, so ld.so
should exclusively use I/O primitives that are not cancellable. We
currently achieve this by having the cancellation hooks compile as
no-ops when IS_IN(rtld); this patch changes to using exclusively
_nocancel primitives in the source code instead, which makes the
intent clearer and significantly reduces the amount of code compiled
under IS_IN(rtld) as well as IS_IN(libc) -- in particular,
elf/Makefile no longer thinks we require a copy of unwind.c in
rtld-libc.a. (The older mechanism is preserved as a backstop.)
The bulk of the change is splitting up the files that define the
_nocancel I/O functions, so they don't also define the variants that
*are* cancellation points; after which, the existing logic for picking
out the bits of libc that need to be recompiled as part of ld.so Just
Works. I did this for all of the _nocancel functions, not just the
ones used by ld.so, for consistency.
fcntl was a little tricky because it's only a cancellation point for
certain opcodes (F_SETLKW(64), which can block), and the existing
__fcntl_nocancel wasn't applying the FCNTL_ADJUST_CMD hook, which
strikes me as asking for trouble, especially as the only nontrivial
definition of FCNTL_ADJUST_CMD (for powerpc64) changes F_*LK* opcodes.
To fix this, fcntl_common moves to fcntl_nocancel.c along with
__fcntl_nocancel, and changes its name to the extern (but hidden)
symbol __fcntl_nocancel_adjusted, so that regular fcntl can continue
calling it. __fcntl_nocancel now applies FCNTL_ADJUST_CMD; so that
both both fcntl.c and fcntl_nocancel.c can see it, the only nontrivial
definition moves from sysdeps/u/s/l/powerpc/powerpc64/fcntl.c to
.../powerpc64/sysdep.h and becomes entirely a macro, instead of a macro
that calls an inline function.
The nptl version of libpthread also changes a little, because its
"compat-routines" formerly included files that defined all the
_nocancel functions it uses; instead of continuing to duplicate them,
I exported the relevant ones from libc.so as GLIBC_PRIVATE. Since the
Linux fcntl.c calls a function defined by fcntl_nocancel.c, it can no
longer be used from libpthread.so; instead, introduce a custom
forwarder, pt-fcntl.c, and export __libc_fcntl from libc.so as
GLIBC_PRIVATE. The nios2-linux ABI doesn't include a copy of vfork()
in libpthread, and it was handling that by manipulating
libpthread-routines in .../linux/nios2/Makefile; it is cleaner to do
what other such ports do, and have a pt-vfork.S that defines no symbols.
Right now, it appears that Hurd does not implement _nocancel I/O, so
sysdeps/generic/not-cancel.h will forward everything back to the
regular functions. This changed the names of some of the functions
that sysdeps/mach/hurd/dl-sysdep.c needs to interpose.
* elf/dl-load.c, elf/dl-misc.c, elf/dl-profile.c, elf/rtld.c
* sysdeps/unix/sysv/linux/dl-sysdep.c
Include not-cancel.h. Use __close_nocancel instead of __close,
__open64_nocancel instead of __open, __read_nocancel instead of
__libc_read, and __write_nocancel instead of __libc_write.
* csu/check_fds.c (check_one_fd)
* sysdeps/posix/fdopendir.c (__fdopendir)
* sysdeps/posix/opendir.c (__alloc_dir): Use __fcntl_nocancel
instead of __fcntl and/or __libc_fcntl.
* sysdeps/unix/sysv/linux/pthread_setname.c (pthread_setname_np)
* sysdeps/unix/sysv/linux/pthread_getname.c (pthread_getname_np)
* sysdeps/unix/sysv/linux/i386/smp.h (is_smp_system):
Use __open64_nocancel instead of __open_nocancel.
* sysdeps/unix/sysv/linux/not-cancel.h: Move all of the
hidden_proto declarations to the end and issue them if either
IS_IN(libc) or IS_IN(rtld).
* sysdeps/unix/sysv/linux/Makefile [subdir=io] (sysdep_routines):
Add close_nocancel, fcntl_nocancel, nanosleep_nocancel,
open_nocancel, open64_nocancel, openat_nocancel, pause_nocancel,
read_nocancel, waitpid_nocancel, write_nocancel.
* io/Versions [GLIBC_PRIVATE]: Add __libc_fcntl,
__fcntl_nocancel, __open64_nocancel, __write_nocancel.
* posix/Versions: Add __nanosleep_nocancel, __pause_nocancel.
* nptl/pt-fcntl.c: New file.
* nptl/Makefile (pthread-compat-wrappers): Remove fcntl.
(libpthread-routines): Add pt-fcntl.
* include/fcntl.h (__fcntl_nocancel_adjusted): New function.
(__libc_fcntl): Remove attribute_hidden.
* sysdeps/unix/sysv/linux/fcntl.c (__libc_fcntl): Call
__fcntl_nocancel_adjusted, not fcntl_common.
(__fcntl_nocancel): Move to new file fcntl_nocancel.c.
(fcntl_common): Rename to __fcntl_nocancel_adjusted; also move
to fcntl_nocancel.c.
* sysdeps/unix/sysv/linux/fcntl_nocancel.c: New file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/fcntl.c: Remove file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h:
Define FCNTL_ADJUST_CMD here, as a self-contained macro.
* sysdeps/unix/sysv/linux/close.c: Move __close_nocancel to...
* sysdeps/unix/sysv/linux/close_nocancel.c: ...this new file.
* sysdeps/unix/sysv/linux/nanosleep.c: Move __nanosleep_nocancel to...
* sysdeps/unix/sysv/linux/nanosleep_nocancel.c: ...this new file.
* sysdeps/unix/sysv/linux/open.c: Move __open_nocancel to...
* sysdeps/unix/sysv/linux/open_nocancel.c: ...this new file.
* sysdeps/unix/sysv/linux/open64.c: Move __open64_nocancel to...
* sysdeps/unix/sysv/linux/open64_nocancel.c: ...this new file.
* sysdeps/unix/sysv/linux/openat.c: Move __openat_nocancel to...
* sysdeps/unix/sysv/linux/openat_nocancel.c: ...this new file.
* sysdeps/unix/sysv/linux/openat64.c: Move __openat64_nocancel to...
* sysdeps/unix/sysv/linux/openat64_nocancel.c: ...this new file.
* sysdeps/unix/sysv/linux/pause.c: Move __pause_nocancel to...
* sysdeps/unix/sysv/linux/pause_nocancel.c: ...this new file.
* sysdeps/unix/sysv/linux/read.c: Move __read_nocancel to...
* sysdeps/unix/sysv/linux/read_nocancel.c: ...this new file.
* sysdeps/unix/sysv/linux/waitpid.c: Move __waitpid_nocancel to...
* sysdeps/unix/sysv/linux/waitpid_nocancel.c: ...this new file.
* sysdeps/unix/sysv/linux/write.c: Move __write_nocancel to...
* sysdeps/unix/sysv/linux/write_nocancel.c: ...this new file.
* sysdeps/unix/sysv/linux/nios2/Makefile: Don't override
libpthread-routines.
* sysdeps/unix/sysv/linux/nios2/pt-vfork.S: New file which
defines nothing.
* sysdeps/mach/hurd/dl-sysdep.c: Define __read instead of
__libc_read, and __write instead of __libc_write. Define
__open64 in addition to __open.
The NO_CANCELLATION macro is used currently on generic headers to
define non cancellable syscalls and on Linux fcntl to implement the non
cancellable variation. Former should be single-handled by not-cancel.h
header and former could be simplified build both cancellable and non
cancellable for default objects and alias the non-cancellable to default
one for rtld ones (since Linux already support cancellation as default).
This patch thus removes the NO_CANCELLATION macro and its usage. The
generic non cancellable fcntl is route to internal fcntl.
Checked on x86_64-linux-gnu and i686-linux-gnu. Also checked with
a build again major ABIs.
* sysdeps/generic/not-cancel.h (NO_CANCELLATION): Remove macro.
* sysdeps/unix/sysv/linux/aarch64/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/alpha/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/arm/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/hppa/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/i386/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/ia64/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/m68k/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/microblaze/sysdep-cancel.h
(NO_CANCELLATION): Likewise.
* sysdeps/unix/sysv/linux/mips/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/nios2/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/powerpc/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/sysdep-cancel.h
(NO_CANCELLATION): Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/sysdep-cancel.h
(NO_CANCELLATION): Likewise.
* sysdeps/unix/sysv/linux/sh/sysdep-cancel.h (NO_CANCELLATION):
Likewise
* sysdeps/unix/sysv/linux/sparc/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/tile/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/x86_64/sysdep-cancel.h (NO_CANCELLATION):
Likewise.
* sysdeps/unix/sysv/linux/not-cancel.h (__fcntl_nocancel): Add
hidden prototype.
* sysdeps/unix/sysv/linux/fcntl.c (__fcntl_nocancel): Define only
for !IS_IN (rtld) and remove NO_CANCELLATION usage.
This patch removes __ASSUME_F_GETOWN_EX now it can be assumed to be
true unconditionally.
Tested x86_64 that disassembly of installed shared libraries is
unchanged by this patch.
* sysdeps/unix/sysv/linux/kernel-features.h
(__ASSUME_F_GETOWN_EX): Remove macro.
* sysdeps/unix/sysv/linux/fcntl.c: Do not include
<kernel-features.h>.
(miss_F_GETOWN_EX): Remove variable or macro.
(do_fcntl): Do not check miss_F_GETOWN_EX.
(do_fcntl) [!__ASSUME_F_GETOWN_EX]: Remove conditional code.
The syscall conventions on some Linux archs prevented F_GETOWN from working
correctly in some situations. This can be rectified when using the new
F_GETOWN_EX command.
* sysdeps/unix/sysv/linux/fcntl.c (__fcntl_nocancel): Remove
static inline __attribute ((always_inline)). Don't define if
NO_CANCELLATION.
(__libc_fcntl): Use INLINE_SYSCALL directly instead of
__fcntl_nocancel.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/fcntl.c (__fcntl_nocancel):
Remove static inline __attribute ((always_inline)). Don't define
if NO_CANCELLATION.
(__libc_fcntl): Use INLINE_SYSCALL directly instead of
__fcntl_nocancel.
* sysdeps/unix/sysv/linux/i386/fcntl.c (__fcntl_nocancel): Define to
__libc_fcntl if NO_CANCELLATION and __ASSUME_FCNTL64 == 0.
Don't define at all if NO_CANCELLATION and __ASSUME_FCNTL64 > 0.
(__libc_fcntl): Don't define if __fcntl_nocancel is a macro.
2004-07-09 Ulrich Drepper <drepper@redhat.com>
* sysdeps/unix/sysv/linux/fcntl.c (__fcntl_nocancel): Move attribute
to the front for gcc 3.5+.
* sysdeps/unix/sysv/linux/i386/fcntl.c: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/fcntl.c: Likewise.
* include/fcntl.h: Don't declare __fcntl_nocancel here if
NO_CANCELLATION is defined.
2004-07-05 Ulrich Drepper <drepper@redhat.com>
* elf/dl-init.c: Don't define and use _dl_starting_up if
HAVE_INLINED_SYSCALLS is defined and the variable is not used.
* elf/dl-support.c: Likewise.
* elf/rtld.c: Likewise.
* elf/dl-misc.c (_dl_debug_vdprintf): Use writev syscall directly
if HAVE_INLINED_SYSCALLS is defined.
* sysdeps/powerpc/powerpc64/dl-machine.h: Don't rest _dl_starting_up
here.
* sysdeps/powerpc/powerpc32/dl-start.S: Likewise.
* sysdeps/unix/sysv/linux/configure.in: Define HAVE_INLINED_SYSCALLS.
* config.h.in: Add entry for HAVE_INLINED_SYSCALLS.
* sysdeps/posix/profil.c: If compiled for ld.so, omit code which
is needed to stop profiling.
* elf/dl-open.c (dl_open_worker): If a newly opened object is to be
profile make sure it cannot be unloaded.
* sysdeps/unix/sysv/linux/dl-origin.c: Inline readlink syscall.
* sysdeps/unix/sysv/linux/fcntl.c: If compiled without cancellation
support, make sure the helper function is inlined.
* sysdeps/unix/sysv/linux/pread.c: Likewise.
* sysdeps/unix/sysv/linux/pwrite.c: Likewise.
* sysdeps/unix/sysv/linux/i386/fcntl.c: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/fcntl.c: Likewise.
* sysdeps/generic/utmp_file.c: Use not-cancelable syscalls all
over the place. It would be allowed to have these fucntions as
cancellation points but the cleanup would be ugly and a lot of
work.
* sysdeps/generic/not-cancel.h (fcntl_not_cancel): Define.
* sysdeps/unix/sysv/linux/not-cancel.h (fcntl_not_cancel): Define.
* include/fcntl.h (__fcntl_nocancel): Declare.
* sysdeps/unix/sysv/linux/fcntl.c: New file.
* sysdeps/unix/sysv/linux/i386/fcntl.c (__libc_fcntl): Only enable
cancellation if absolutely needed.
(__fcntl_nocancel): Define.
* posix/unistd.h (gethostid): Remove __THROW. Clarify comment.
* sysdeps/unix/sysv/linux/Makefile (CFLAGS-gethostid.c): Add
-fexceptions.
* sysdeps/unix/sysv/linux/gethostid.c (gethostid): Use
extend_alloca.
* resolv/res_init.c (__res_nclose): Use close_not_cancel_no_status
instead of __close.
