The clone3 system call (since Linux 5.3) provides a superset of the
functionality of clone and clone2. It also provides a number of API
improvements, including the ability to specify the size of the child's
stack area which can be used by kernel to compute the shadow stack size
when allocating the shadow stack. Add:
extern int __clone_internal (struct clone_args *__cl_args,
int (*__func) (void *__arg), void *__arg);
to provide an abstract interface for clone, clone2 and clone3.
1. Simplify stack management for thread creation by passing both stack
base and size to create_thread.
2. Consolidate clone vs clone2 differences into a single file.
3. Call __clone3 if HAVE_CLONE3_WAPPER is defined. If __clone3 returns
-1 with ENOSYS, fall back to clone or clone2.
4. Use only __clone_internal to clone a thread. Since the stack size
argument for create_thread is now unconditional, always pass stack size
to create_thread.
5. Enable the public clone3 wrapper in the future after it has been
added to all targets.
NB: Sandbox will return ENOSYS on clone3 in both Chromium:
The following revision refers to this bug:
218438259d
commit 218438259dd795456f0a48f67cbe5b4e520db88b
Author: Matthew Denton <mpdenton@chromium.org>
Date: Thu Jun 03 20:06:13 2021
Linux sandbox: return ENOSYS for clone3
Because clone3 uses a pointer argument rather than a flags argument, we
cannot examine the contents with seccomp, which is essential to
preventing sandboxed processes from starting other processes. So, we
won't be able to support clone3 in Chromium. This CL modifies the
BPF policy to return ENOSYS for clone3 so glibc always uses the fallback
to clone.
Bug: 1213452
Change-Id: I7c7c585a319e0264eac5b1ebee1a45be2d782303
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2936184
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Matthew Denton <mpdenton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#888980}
[modify] https://crrev.com/218438259dd795456f0a48f67cbe5b4e520db88b/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc
and Firefox:
https://hg.mozilla.org/integration/autoland/rev/ecb4011a0c76
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
<limits.h> used to be a header file with no declarations.
GCC's libgomp includes it in a #pragma GCC visibility hidden block.
Including <unistd.h> from <limits.h> (indirectly) declares everything
in <unistd.h> with hidden visibility, resulting in linker failures.
This commit avoids C declarations in assembler mode and only declares
__sysconf in <limits.h> (and not the entire contents of <unistd.h>).
The __sysconf symbol is already part of the ABI. PTHREAD_STACK_MIN
is no longer defined for __USE_DYNAMIC_STACK_SIZE && __ASSEMBLER__
because there is no possible definition.
Additionally, PTHREAD_STACK_MIN is now defined by <pthread.h> for
__USE_MISC because this is what developers expect based on the macro
name. It also helps to avoid libgomp linker failures in GCC because
libgomp includes <pthread.h> before its visibility hacks.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The constant PTHREAD_STACK_MIN may be too small for some processors.
Rename _SC_SIGSTKSZ_SOURCE to _DYNAMIC_STACK_SIZE_SOURCE. When
_DYNAMIC_STACK_SIZE_SOURCE or _GNU_SOURCE are defined, define
PTHREAD_STACK_MIN to sysconf(_SC_THREAD_STACK_MIN) which is changed
to MIN (PTHREAD_STACK_MIN, sysconf(_SC_MINSIGSTKSZ)).
Consolidate <bits/local_lim.h> with <bits/pthread_stack_min.h> to
provide a constant target specific PTHREAD_STACK_MIN value.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
As a result, is not necessary to specify __attribute__ ((nocommon))
on individual definitions.
GCC 10 defaults to -fno-common on all architectures except ARC,
but this change is compatible with older GCC versions and ARC, too.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This patch adds a way to close a range of file descriptors on
posix_spawn as a new file action. The API is similar to the one
provided by Solaris 11 [1], where the file action causes the all open
file descriptors greater than or equal to input on to be closed when
the new process is spawned.
The function posix_spawn_file_actions_addclosefrom_np is safe to be
implemented by iterating over /proc/self/fd, since the Linux spawni.c
helper process does not use CLONE_FILES, so its has own file descriptor
table and any failure (in /proc operation) aborts the process creation
and returns an error to the caller.
I am aware that this file action might be redundant to the current
approach of POSIX in promoting O_CLOEXEC in more interfaces. However
O_CLOEXEC is still not the default and for some specific usages, the
caller needs to close all possible file descriptors to avoid them
leaking. Some examples are CPython (discussed in BZ#10353) and OpenJDK
jspawnhelper [2] (where OpenJDK spawns a helper process to exactly
closes all file descriptors). Most likely any environment which calls
functions that might open file descriptor under the hood and aim to use
posix_spawn might face the same requirement.
Checked on x86_64-linux-gnu and i686-linux-gnu on kernel 5.11 and 4.15.
[1] https://docs.oracle.com/cd/E36784_01/html/E36874/posix-spawn-file-actions-addclosefrom-np-3c.html
[2] https://github.com/openjdk/jdk/blob/master/src/java.base/unix/native/libjava/childproc.c#L82
The function closes all open file descriptors greater than or equal to
input argument. Negative values are clamped to 0, i.e, it will close
all file descriptors.
As indicated by the bug report, this is a common symbol provided by
different systems (Solaris, OpenBSD, NetBSD, FreeBSD) and, although
its has inherent issues with not taking in consideration internal libc
file descriptors (such as syslog), this is also a common feature used
in multiple projects [1][2][3][4][5].
The Linux fallback implementation iterates over /proc and close all
file descriptors sequentially. Although it was raised the questioning
whether getdents on /proc/self/fd might return disjointed entries
when file descriptor are closed; it does not seems the case on my
testing on multiple kernel (v4.18, v5.4, v5.9) and the same strategy
is used on different projects [1][2][3][5].
Also, the interface is set a fail-safe meaning that a failure in the
fallback results in a process abort.
Checked on x86_64-linux-gnu and i686-linux-gnu on kernel 5.11 and 4.15.
[1] 5238e95759/src/basic/fd-util.c (L217)
[2] ddf4b77e11/src/lxc/start.c (L236)
[3] 9e4f2f3a6b/Modules/_posixsubprocess.c (L220)
[4] 5f47c0613e/src/libstd/sys/unix/process2.rs (L303-L308)
[5] https://github.com/openjdk/jdk/blob/master/src/java.base/unix/native/libjava/childproc.c#L82
It was added on Linux 5.9 (278a5fbaed89) with CLOSE_RANGE_CLOEXEC
added on 5.11 (582f1fb6b721f). Although FreeBSD has added the same
syscall, this only adds the symbol on Linux ports. This syscall is
required to provided a fail-safe way to implement the closefrom
symbol (BZ #10353).
Checked on x86_64-linux-gnu and i686-linux-gnu on kernel 5.11 and 4.15.
This partially fixes static-only NSS support (bug 27959): The files
module no longer needs dlopen. Support for the dns module remains
to be added, and also support for disabling dlopen altogether.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
They are no longer needed after everything has been moved into
libc. The _dl_vsym test has to be removed because the symbol
cannot be used outside libc anymore.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbols gai_cancel, gai_error, gai_suspend, getaddrinfo_a,
__gai_suspend_time64 were moved using scripts/move-symbol-to-libc.py.
For Hurd (which remains !PTHREAD_IN_LIBC), a few #define redirects
had to be added because several pthread functions are not available
under __. (Linux uses __ prefixes for most hidden aliases, and has
to in some cases to avoid linknamespace issues.)
Starting with recent commit 84f7ce8447
"posix: Add glob64 with 64-bit time_t support", elf/check-localplt
fails due to extra PLT reference __glob64_time64 in __glob64_time64
itself.
This is observable with gcc 7.5 on x86_64 with -m32 or s390x with
-m31. E.g. if build with gcc 10, gcc is generating a call to
__glob64_time64.localalias.
This patch is adding a hidden version of __glob64_time64 in the
same way as for __globfree64_time64.
The symbols forkpty, login, login_tty, logout, logwtmp, openpty
were moved using scripts/move-symbol-to-libc.py.
This is a single commit because most of the symbols are tied together
via forkpty, for example.
Several changes to use hidden prototypes are needed. This commit
also updates pseudoterminal terminology on modified lines.
For 390 (31-bit), this commit follows the existing style for the
compat symbol version creation.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Replace attribute_hidden with a regular combination of
libc_hidden_proto and libc_hidden_def.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbols were moved using scripts/move-symbol-to-libc.py.
The way the ABI intransition is implemented is changed with this
commit: the implementation is now consolidated in one file with a
TIMER_T_WAS_INT_COMPAT check.
The shared librt is now empty, so this commit adds a placeholder
symbol at the base version, GLIBC_2.2, and potentially at the
GLIBC_2.3.3 version as well (the leftover from the int/timer_t ABI
transition).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbols were moved using scripts/move-symbol-to-libc.py.
The way the ABI intransition is implemented is changed with this
commit: the implementation is now consolidated in one file with a
TIMER_T_WAS_INT_COMPAT check.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This patch redirect roundeven function for futhermore changes.
Signed-off-by: Shen-Ta Hsieh <ibmibmibm.tw@gmail.com>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
The symbol was moved using scripts/move-symbol-to-libc.py.
An explicit call from fork into the mq_notify implementation replaces
the previous use of pthread_atfork.
Reviewed-by: Adhemerva Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
To introduce the proper symbol versioning, the implementation of
the system call wrapper us moved to a C file.
Reviewed-by: Adhemerva Zanella <adhemerval.zanella@linaro.org>
The symbols were moved using scripts/move-symbol-to-libc.py.
There is a minor oddity here: This is generic code shared with Hurd,
and Hurd does not have time64 support. This is why the
versioned_symbol export for __aio_suspend_time64 is restricted to
the PTHREAD_IN_LIBC code.
Reviewed-by: Adhemerva Zanella <adhemerval.zanella@linaro.org>
The Linux nptl implementation is used as base for generic fork
implementation to handle the internal locks and mutexes. The
system specific bits are moved a new internal _Fork symbol.
(This new implementation will be used to provide a async-signal-safe
_Fork now that POSIX has clarified that fork might not be
async-signal-safe [1]).
For Hurd it means that the __nss_database_fork_prepare_parent and
__nss_database_fork_subprocess will be run in a slight different
order.
[1] https://austingroupbugs.net/view.php?id=62
For !__ASSUME_TIME64_SYSCALLS there is no need to issue a 64-bit syscall
if the provided timeout fits in a 32-bit one. The 64-bit usage should
be rare since the timeout is a relative one. This also avoids the need
to use supports_time64() (which breaks the usage case of live migration
like CRIU or similar).
It also fixes an issue on 32-bit select call for !__ASSUME_PSELECT
(microblase with older kernels only) where the expected timeout
is a 'struct timeval' instead of 'struct timespec'.
Checked on i686-linux-gnu on a 4.15 kernel and on a 5.11 kernel
(with and without --enable-kernel=5.1) and on x86_64-linux-gnu.
Reviewed-by: Lukasz Majewski <lukma@denx.de>
For the legacy ABI with supports 32-bit time_t it calls the 64-bit
time directly, since the LFS symbols calls the 64-bit time_t ones
internally.
Checked on i686-linux-gnu and x86_64-linux-gnu.
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Similar to fts, ftw routines passes a stat pointer that might
differ of size and layout when 64-bit time API is used.
Checked on i686-linux-gnu and x86_64-linux-gnu.
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Similar to glob, fts routines passes a stat pointer that might
differ of size and layout when 64-bit time API is used.
Checked on i686-linux-gnu and x86_64-linux-gnu.
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The glob might pass a different stat struct for gl_stat and gl_lstat
when GLOB_ALTDIRFUNC is used. This requires add a new 64-bit time
version that also uses 64-bit time stat functions.
Checked on i686-linux-gnu and x86_64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
A new build flag, _TIME_BITS, enables the usage of the newer 64-bit
time symbols for legacy ABI (where 32-bit time_t is default). The 64
bit time support is only enabled if LFS (_FILE_OFFSET_BITS=64) is
also used.
Different than LFS support, the y2038 symbols are added only for the
required ABIs (armhf, csky, hppa, i386, m68k, microblaze, mips32,
mips64-n32, nios2, powerpc32, sparc32, s390-32, and sh). The ABIs with
64-bit time support are unchanged, both for symbol and types
redirection.
On Linux the full 64-bit time support requires a minimum of kernel
version v5.1. Otherwise, the 32-bit fallbacks are used and might
results in error with overflow return code (EOVERFLOW).
The i686-gnu does not yet support 64-bit time.
This patch exports following rediretions to support 64-bit time:
* libc:
adjtime
adjtimex
clock_adjtime
clock_getres
clock_gettime
clock_nanosleep
clock_settime
cnd_timedwait
ctime
ctime_r
difftime
fstat
fstatat
futimens
futimes
futimesat
getitimer
getrusage
gettimeofday
gmtime
gmtime_r
localtime
localtime_r
lstat_time
lutimes
mktime
msgctl
mtx_timedlock
nanosleep
nanosleep
ntp_gettime
ntp_gettimex
ppoll
pselec
pselect
pthread_clockjoin_np
pthread_cond_clockwait
pthread_cond_timedwait
pthread_mutex_clocklock
pthread_mutex_timedlock
pthread_rwlock_clockrdlock
pthread_rwlock_clockwrlock
pthread_rwlock_timedrdlock
pthread_rwlock_timedwrlock
pthread_timedjoin_np
recvmmsg
sched_rr_get_interval
select
sem_clockwait
semctl
semtimedop
sem_timedwait
setitimer
settimeofday
shmctl
sigtimedwait
stat
thrd_sleep
time
timegm
timerfd_gettime
timerfd_settime
timespec_get
utime
utimensat
utimes
utimes
wait3
wait4
* librt:
aio_suspend
mq_timedreceive
mq_timedsend
timer_gettime
timer_settime
* libanl:
gai_suspend
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The getdate is basically a wrapper localtime and mktime. The 64-bit
time support is done calling the 64-bit internal functions, there is
no need to add a new symbol version.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The recvmsg handling is more complicated because it requires check the
returned kernel control message and make some convertions. For
!__ASSUME_TIME64_SYSCALLS it converts the first 32-bit time SO_TIMESTAMP
or SO_TIMESTAMPNS and appends it to the control buffer if has extra
space or returns MSG_CTRUNC otherwise. The 32-bit time field is kept
as-is.
Calls with __TIMESIZE=32 will see the converted 64-bit time control
messages as spurious control message of unknown type. Calls with
__TIMESIZE=64 running on pre-time64 kernels will see the original
message as a spurious control ones of unknown typ while running on
kernel with native 64-bit time support will only see the time64 version
of the control message.
Checked on x86_64-linux-gnu and i686-linux-gnu (on 5.4 and on 4.15
kernel).
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Now that pthread_kill is provided by libc.so it is possible to
implement the generic POSIX implementation as
'pthread_kill(pthread_self(), sig)'.
For Linux implementation, pthread_kill read the targeting TID from
the TCB. For raise, this it not possible because it would make raise
fail when issue after vfork (where creates the resulting process
has a different TID from the parent, but its TCB is not updated as
for pthread_create). To make raise use pthread_kill, it is make
usable from vfork by getting the target thread id through gettid
syscall.
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Consolidate all hooks structures into a single one. There are
no static dlopen ABI concerns because glibc 2.34 already comes
with substantial ABI-incompatible changes in this area. (Static
dlopen requires the exact same dynamic glibc version that was used
for static linking.)
The new approach uses a pointer to the hooks structure into
_rtld_global_ro and initalizes it in __rtld_static_init. This avoids
a back-and-forth with various callback functions.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This commit removes the ELF constructor and internal variables from
dlfcn/dlfcn.c. The file now serves the same purpose as
nptl/libpthread-compat.c, so it is renamed to dlfcn/libdl-compat.c.
The use of libdl-shared-only-routines ensures that libdl.a is empty.
This commit adjusts the test suite not to use $(libdl). The libdl.so
symbolic link is no longer installed.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
In elf/Makefile, remove the $(libdl) dependency from testobj1.so
because it the unused libdl DSO now causes elf/tst-unused-deps to
fail.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
There is a minor functionality enhancement: dlerror now sets
errno if it was set as part of the exception. (This is the result
of using %m in asprintf, to avoid the strerror PLT call.) The
previous errno value upon function return was unpredictable.
Documenting this as a feature is premature; we need to make sure
that the error codes are meaningful when they are set by the dynamic
loader.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
ISO C2X has made some changes to the handling of feature test macros
related to features from the floating-point TSes, and to exactly what
such features are present in what headers, that require corresponding
changes in glibc.
* For the few features that were controlled by
__STDC_WANT_IEC_60559_BFP_EXT__ (and the corresponding DFP macro) in
C2X, there is now instead a new feature test macro
__STDC_WANT_IEC_60559_EXT__ covering both binary and decimal FP.
This controls CR_DECIMAL_DIG in <float.h> (provided by GCC; I
implemented support for the new feature test macro for GCC 11) and
the totalorder and payload functions in <math.h>. C2X no longer
says anything about __STDC_WANT_IEC_60559_BFP_EXT__ (so it's
appropriate for that macro to continue to enable exactly the
features from TS 18661-1).
* The SNAN macros for each floating-point type have moved to <float.h>
(and been renamed in the process). Thus, the copies in <math.h>
should only be defined for __STDC_WANT_IEC_60559_BFP_EXT__, not for
C2X.
* The fmaxmag and fminmag functions have been removed (replaced by new
functions for the new min/max operations in IEEE 754-2019). Thus
those should also only be declared for
__STDC_WANT_IEC_60559_BFP_EXT__.
* The _FloatN / _FloatNx handling for the last two points in glibc is
trickier, since __STDC_WANT_IEC_60559_TYPES_EXT__ is still in C2X
(the integration of TS 18661-3 as an Annex, that is, which hasn't
yet been merged into the C standard git repository but has been
accepted by WG14), so C2X with that macro should not declare some
things that are declared for older standards with that macro. The
approach taken here is to provide the declarations (when
__STDC_WANT_IEC_60559_TYPES_EXT__ is enabled) only when (defined
__USE_GNU || !__GLIBC_USE (ISOC2X)), so if C2X features are enabled
then those declarations (that are only in TS 18661-3 and not in C2X)
will only be provided if _GNU_SOURCE is defined as well. Thus
_GNU_SOURCE remains a superset of the TS features as well as of C2X.
Some other somewhat related changes in C2X are not addressed here.
There's an open proposal not to include the fmin and fmax functions
for the _FloatN / _FloatNx types, given the new min/max operations,
which could be handled like the previous point if adopted. And the
fromfp functions have been changed to return a result in floating type
rather than intmax_t / uintmax_t; my inclination there is to treat
that like that change of totalorder type (new symbol versions etc. for
the ABI change; old versions become compat symbols and are no longer
supported as an API).
Tested for x86_64 and x86.
The symbols were moved using scripts/move-symbol-to-libc.py.
The libpthread placeholder symbols need some changes because some
symbol versions have gone away completely. But
__errno_location@@GLIBC_2.0 still exists, so the GLIBC_2.0 version
is still there.
The internal __pthread_create symbol now points to the correct
function, so the sysdeps/nptl/thrd_create.c override is no longer
necessary.
There was an issue how the hidden alias of pthread_getattr_default_np
was defined, so this commit cleans up that aspects and removes the
GLIBC_PRIVATE export altogether.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
ISO C2X adds a timespec_getres function alongside the C11
timespec_get, with functionality similar to that of POSIX clock_getres
(including allowing a NULL pointer to be passed to the function).
Implement this function for glibc, similarly to the implementation of
timespec_get.
This includes a basic test like that of timespec_get, but no
documentation in the manual, given that TIME_UTC and timespec_get
aren't documented in the manual at all. The handling of 64-bit time
follows that in timespec_get; people maintaining patch series for
64-bit time will need to update them accordingly (to export
__timespec_getres64, redirect calls in time.h and run the test for
_TIME_BITS=64).
Tested for x86_64 and x86, and (previous version; only testcase
differs) with build-many-glibcs.py.
To help detect common kinds of memory (and other resource) management
bugs, GCC 11 adds support for the detection of mismatched calls to
allocation and deallocation functions. At each call site to a known
deallocation function GCC checks the set of allocation functions
the former can be paired with and, if the two don't match, issues
a -Wmismatched-dealloc warning (something similar happens in C++
for mismatched calls to new and delete). GCC also uses the same
mechanism to detect attempts to deallocate objects not allocated
by any allocation function (or pointers past the first byte into
allocated objects) by -Wfree-nonheap-object.
This support is enabled for built-in functions like malloc and free.
To extend it beyond those, GCC extends attribute malloc to designate
a deallocation function to which pointers returned from the allocation
function may be passed to deallocate the allocated objects. Another,
optional argument designates the positional argument to which
the pointer must be passed.
This change is the first step in enabling this extended support for
Glibc.
Big win in binary size and avoids duplicating the logic in multiple
places.
On x86_64, dropped from 1883206 to 1881790, a 1416 byte decrease.
Also changed logic to track if ttyname_buf has been allocated by
checking if it's NULL instead of tracking buflen as an additional
variable.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Both the sysfs and procfs parsing (through GET_NPROCS_PARSER) are
removed in favor the syscall. The initial scratch buffer should
fit to most of the common usage (1024 bytes with maps to 8192 CPUs).
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
The symbols were moved using move-symbol-to-libc.py.
Both functions are moved at the same time because they depend
on internal functions in sysdeps/pthread/sem_routines.c, which
are moved in this commit as well. Additional hidden prototypes
are required to avoid check-localplt failures.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Calling free directly may end up freeing a pointer allocated by the
dynamic loader using malloc from libc.so in the base namespace using
the allocator from libc.so in a secondary namespace, which results in
crashes.
This commit redirects the free call through GLRO and the dynamic
linker, to reach the correct namespace. It also cleans up the dlerror
handling along the way, so that pthread_setspecific is no longer
needed (which avoids triggering bug 24774).
It's necessary to stub out __libc_disable_asynccancel and
__libc_enable_asynccancel via rtld-stubbed-symbols because the new
direct references to the unwinder result in symbol conflicts when the
rtld exception handling from libc is linked in during the construction
of librtld.map.
unwind-forcedunwind.c is merged into unwind-resume.c. libc now needs
the functions that were previously only used in libpthread.
The GLIBC_PRIVATE exports of __libc_longjmp and __libc_siglongjmp are
no longer needed, so switch them to hidden symbols.
The symbol __pthread_unwind_next has been moved using
scripts/move-symbol-to-libc.py.
Reviewed-by: Adhemerva Zanella <adhemerval.zanella@linaro.org>
So that text_set_element/data_set_element/bss_set_element defined
variables will be retained by the linker.
Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable
will not be optimized out; 'retain' prevents section garbage collection
if the linker support SHF_GNU_RETAIN.
GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C
identifier name sections to be GCed even if there are live
__start_/__stop_ references.
Without the change, there are some static linking problems, e.g.
_IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so
stdout is not flushed on exit.
Note: GCC may warning 'retain' attribute ignored while __has_attribute(retain)
is 1 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587).
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
The commit 2433d39b69, which added time64 support to select, changed
the function to use __NR_pselect6 (or __NR_pelect6_time64) on all
architectures. However, on architectures where the symbol was
implemented with __NR_select the kernel normalizes the passed timeout
instead of return EINVAL. For instance, the input timeval
{ 0, 5000000 } is interpreted as { 5, 0 }.
And as indicated by BZ #27651, this semantic seems to be expected
and changing it results in some performance issues (most likely
the program does not check the return code and keeps issuing
select with unormalized tv_usec argument).
To avoid a different semantic depending whether which syscall the
architecture used to issue, select now always normalize the timeout
input. This is a slight change for some ABIs (for instance aarch64).
Checked on x86_64-linux-gnu and i686-linux-gnu.
The libc version is identical and built with same flags. The libc
version is set as the default version.
The libpthread compat symbol requires to mask it when building the
loader object otherwise ld might complain about a missing
versioned symbol (as for alpha).
Checked on x86_64-linux-gnu.
This is only used internally in malloc.c, the extern declaration
was wrong, __mtag_mmap_flags has internal linkage.
Reviewed-by: DJ Delorie <dj@redhat.com>
This essentially folds compat_symbol_unique functionality into
compat_symbol.
This change eliminates the need for intermediate aliases for defining
multiple symbol versions, for both compat_symbol and versioned_symbol.
Some binutils versions do not suport multiple versions per symbol on
some targets, so aliases are automatically introduced, similar to what
compat_symbol_unique did. To reduce symbol table sizes, a configure
check is added to avoid these aliases if they are not needed.
The new mechanism works with data symbols as well as function symbols,
due to the way an assembler-level redirect is used. It is not
compatible with weak symbols for old binutils versions, which is why
the definition of __malloc_initialize_hook had to be changed. This
is not a loss of functionality because weak symbols do not matter
to dynamic linking.
The placeholder symbol needs repeating in nptl/libpthread-compat.c
now that compat_symbol is used, but that seems more obvious than
introducing yet another macro.
A subtle difference was that compat_symbol_unique made the symbol
global automatically. compat_symbol does not do this, so static
had to be removed from the definition of
__libpthread_version_placeholder.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
A subsequent change will require including <config.h> for defining
symbol_version_reference. <libc-symbol.h> should not include
<config.h> for _ISOMAC, so it cannot define symbol_version_reference
anymore, but symbol_version_reference is needed <shlib-compat.h> even
for _ISOMAC. Moving the definition of symbol_version_reference to a
separate file <libc-symver.h> makes it possible to use a single
definition for both cases.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Both htl and nptl uses a different data structure to implement atfork
handlers. The nptl one was refactored by 27761a1042 to use a dynarray
which simplifies the code.
This patch moves the nptl one to be the generic implementation and
replace Hurd linked one. Different than previous NPTL, Hurd also uses
a global lock, so performance should be similar.
Checked on x86_64-linux-gnu, i686-linux-gnu, and with a build for
i686-gnu.
This is helpful for testing compat symbols in cases where _ISOMAC
is activated implicitly due to -DMODULE_NAME=testsuite and cannot
be disabled easily.
There is no need to handle ENOSYS on fstatfs64 call, required only
for alpha (where is already fallbacks to fstatfs).
Checked on x86_64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The __NR_fstatfs64 syscall is supported on all architectures but
aarch64, mips64, riscv64, and x86_64. And newer ABIs also uses
the new fstatfs64 interface (where the struct size is used as
first argument).
So the default implementation now uses:
1. __NR_fstatfs64 for non-LFS call and handle overflow directly
There is no need to handle __NR_fstatfs since all architectures
that only support are LFS only.
2. __NR_fstatfs if defined or __NR_fstatfs64 otherwise for LFS
call.
Alpha is the only outlier, it is a 64-bit architecture which
provides non-LFS interface and only provides __NR_fstatfs64 on
newer kernels (5.1+).
Checked on x86_64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Add __nonnull((2)) to the setrlimit()/getrlimit() function declaration
to avoid null pointer access.
-----
v2
According to the suggestions of the Adhemerval Zanella and Zack Weinberg:
use __nonnull() to check null pointers in the compilation phase.
do not add pointer check code to setrlimit()/getrlimit().
The validity of the "resource" parameter is checked in the syscall.
v1
https://public-inbox.org/libc-alpha/20201230114131.47589-1-nixiaoming@huawei.com/
-----
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Previously, glibc would pick an arbitrary tmpfs file system from
/proc/mounts if /dev/shm was not available. This could lead to
an unsuitable file system being picked for the backing storage for
shm_open, sem_open, and related functions.
This patch introduces a new function, __shm_get_name, which builds
the file name under the appropriate (now hard-coded) directory. It is
called from the various shm_* and sem_* function. Unlike the
SHM_GET_NAME macro it replaces, the callers handle the return values
and errno updates. shm-directory.c is moved directly into the posix
subdirectory because it can be implemented directly using POSIX
functionality. It resides in libc because it is needed by both
librt and nptl/htl.
In the sem_open implementation, tmpfname is initialized directly
from a string constant. This happens to remove one alloca call.
Checked on x86_64-linux-gnu.
Add _SC_MINSIGSTKSZ for the minimum signal stack size derived from
AT_MINSIGSTKSZ, which is the minimum number of bytes of free stack
space required in order to gurantee successful, non-nested handling
of a single signal whose handler is an empty function, and _SC_SIGSTKSZ
which is the suggested minimum number of bytes of stack space required
for a signal stack.
If AT_MINSIGSTKSZ isn't available, sysconf (_SC_MINSIGSTKSZ) returns
MINSIGSTKSZ. On Linux/x86 with XSAVE, the signal frame used by kernel
is composed of the following areas and laid out as:
------------------------------
| alignment padding |
------------------------------
| xsave buffer |
------------------------------
| fsave header (32-bit only) |
------------------------------
| siginfo + ucontext |
------------------------------
Compute AT_MINSIGSTKSZ value as size of xsave buffer + size of fsave
header (32-bit only) + size of siginfo and ucontext + alignment padding.
If _SC_SIGSTKSZ_SOURCE or _GNU_SOURCE are defined, MINSIGSTKSZ and SIGSTKSZ
are redefined as
/* Default stack size for a signal handler: sysconf (SC_SIGSTKSZ). */
# undef SIGSTKSZ
# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
/* Minimum stack size for a signal handler: SIGSTKSZ. */
# undef MINSIGSTKSZ
# define MINSIGSTKSZ SIGSTKSZ
Compilation will fail if the source assumes constant MINSIGSTKSZ or
SIGSTKSZ.
The reason for not simply increasing the kernel's MINSIGSTKSZ #define
(apart from the fact that it is rarely used, due to glibc's shadowing
definitions) was that userspace binaries will have baked in the old
value of the constant and may be making assumptions about it.
For example, the type (char [MINSIGSTKSZ]) changes if this #define
changes. This could be a problem if an newly built library tries to
memcpy() or dump such an object defined by and old binary.
Bounds-checking and the stack sizes passed to things like sigaltstack()
and makecontext() could similarly go wrong.
This reverts commit 2682695e5c.
Fixes bug 27237.
That commit turned out to be too intrusive affecting crt files, test
system and benchmark files. They should not be affected, but the
build system does not set the MODULE_NAME and LIBC_NONSHARED reliably.
This reverts commit 20b39d5946 for static
library. This avoids the need to rebuild the world for the case where
libstdc++ (and potentially other libraries) are linked to a old glibc.
To avoid requering to provide xstat symbols for newer ABIs (such as
riscv32) a new LIB_COMPAT macro is added. It is similar to SHLIB_COMPAT
but also works for static case (thus evaluating similar to SHLIB_COMPAT
for both shared and static case).
Checked with a check-abi on all affected ABIs. I also check if the
static library does contains the xstat symbols.
Hidden visibility can avoid indirections and RELATIVE relocs in
static PIE libc.
The check should use IS_IN_LIB instead of IS_IN(libc) since all
symbols are defined locally in static PIE and the optimization is
useful in all libraries not just libc. However the test system
links objects from libcrypt.a into dynamic linked test binaries
where hidden visibility does not work. I think mixing static and
shared libc components in the same binary should not be supported
usage, but to be safe only use hidden in libc.a.
On some targets (i386) this optimization cannot be applied because
hidden visibility PIE ifunc functions don't work, so it is gated by
NO_HIDDEN_EXTERN_FUNC_IN_PIE.
From -static-pie linked 'int main(){}' this shaves off 71 relative
relocs on aarch64 and reduces code size by about 2k.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
Introduce a new _FORTIFY_SOURCE level of 3 to enable additional
fortifications that may have a noticeable performance impact, allowing
more fortification coverage at the cost of some performance.
With llvm 9.0 or later, this will replace the use of
__builtin_object_size with __builtin_dynamic_object_size.
__builtin_dynamic_object_size
-----------------------------
__builtin_dynamic_object_size is an LLVM builtin that is similar to
__builtin_object_size. In addition to what __builtin_object_size
does, i.e. replace the builtin call with a constant object size,
__builtin_dynamic_object_size will replace the call site with an
expression that evaluates to the object size, thus expanding its
applicability. In practice, __builtin_dynamic_object_size evaluates
these expressions through malloc/calloc calls that it can associate
with the object being evaluated.
A simple motivating example is below; -D_FORTIFY_SOURCE=2 would miss
this and emit memcpy, but -D_FORTIFY_SOURCE=3 with the help of
__builtin_dynamic_object_size is able to emit __memcpy_chk with the
allocation size expression passed into the function:
void *copy_obj (const void *src, size_t alloc, size_t copysize)
{
void *obj = malloc (alloc);
memcpy (obj, src, copysize);
return obj;
}
Limitations
-----------
If the object was allocated elsewhere that the compiler cannot see, or
if it was allocated in the function with a function that the compiler
does not recognize as an allocator then __builtin_dynamic_object_size
also returns -1.
Further, the expression used to compute object size may be non-trivial
and may potentially incur a noticeable performance impact. These
fortifications are hence enabled at a new _FORTIFY_SOURCE level to
allow developers to make a choice on the tradeoff according to their
environment.
Make the _FORTIFY_SOURCE macro soup in features.h warn about
unsupported fortification levels. For example, it will warn about
_FORTIFY_SOURCE=3 and over with an indication of which level has been
selected.
Co-authored-by: Paul Eggert <eggert@cs.ucla.edu>
This patch adds the basic support for memory tagging.
Various flavours are supported, particularly being able to turn on
tagged memory at run-time: this allows the same code to be used on
systems where memory tagging support is not present without neededing
a separate build of glibc. Also, depending on whether the kernel
supports it, the code will use mmap for the default arena if morecore
does not, or cannot support tagged memory (on AArch64 it is not
available).
All the hooks use function pointers to allow this to work without
needing ifuncs.
Reviewed-by: DJ Delorie <dj@redhat.com>
Change sbrk to fail for !__libc_initial (in the generic
implementation). As a result, sbrk is (relatively) safe to use
for the __libc_initial case (from the main libc). It is therefore
no longer necessary to avoid using it in that case (or updating the
brk cache), and the __libc_initial flag does not need to be updated
as part of dlmopen or static dlopen.
As before, direct brk system calls on Linux may lead to memory
corruption.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
GCC 11 with
commit 6fbec038f7a7ddf29f074943611b53210d17c40c
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Mon Feb 3 11:55:43 2020 -0800
Use SHF_GNU_RETAIN to preserve symbol definitions
places used symbols in SECTION_RETAIN sections if assembler supports it.
Mark __libc_freeres_fn as used to avoid
gconv_dl.c: In function 'free_mem':
gconv_dl.c:191:1: error: 'do_release_all' without 'used' attribute and 'free_mem' with 'used' attribute are placed in a section with the same name [-Werror=attributes]
191 | do_release_all (void *nodep)
| ^~~~~~~~~~~~~~
In file included from <command-line>:
gconv_dl.c:202:18: note: 'free_mem' was declared here
202 | libc_freeres_fn (free_mem)
| ^~~~~~~~
./../include/libc-symbols.h:316:15: note: in definition of macro 'libc_freeres_fn'
316 | static void name (void)
| ^~~~
cc1: all warnings being treated as errors
If glibc is build with -O3 on at least 390 (-m31) or x86 (-m32),
gcc 11 dumps this warning:
svc_tcp.c: In function 'rendezvous_request':
svc_tcp.c:274:3: error: 'memcpy' offset [0, 15] is out of the bounds [0, 0] [-Werror=array-bounds]
274 | memcpy (&xprt->xp_raddr, &addr, sizeof (addr));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
In out-of-memory case, if one of the mallocs in makefd_xprt function
returns NULL, a message is dumped, makefd_xprt returns NULL
and the subsequent memcpy would copy to NULL.
Instead of a segfaulting, we delay a bit (see also __svc_accept_failed
and Bug 14889 (CVE-2011-4609) - svc_run() produces high cpu usage when
accept() fails with EMFILE (CVE-2011-4609).
The same applies to svc_unix.c.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The functions strtoimax, strtoumax, wcstoimax, wcstoumax currently
have three implementations each (wordsize-32, wordsize-64 and dummy
implementation in stdlib/ using #error), defining the functions as
thin wrappers round corresponding *_internal functions. Simplify the
code by changing them into aliases of functions such as strtol and
wcstoull. This is more consistent with how e.g. imaxdiv is handled.
Tested for x86_64 and x86.
This change uses (in gai_misc.h):
- __futex_abstimed_wait64 (instead of futex_reltimed_wait)
- __futex_abstimed_wait_cancellable64
(instead of futex_reltimed_wait_cancellable)
from ./sysdeps/nptl/futex-helpers.h
The gai_suspend() accepts relative timeout, which then is converted to
absolute one.
The i686-gnu port (HURD) do not define DONT_NEED_GAI_MISC_COND and as it
doesn't (yet) support 64 bit time it uses not converted
pthread_cond_timedwait().
The __gai_suspend() is supposed to be run on ports with __TIMESIZE !=64 and
__WORDSIZE==32. It internally utilizes __gai_suspend_time64() and hence the
conversion from 32 bit struct timespec to 64 bit one is required.
For ports supporting 64 bit time the __gai_suspend_time64() will be used
either via alias (to __gai_suspend when __TIMESIZE==64) or redirection
(when -D_TIME_BITS=64 is passed).
Build tests:
./src/scripts/build-many-glibcs.py glibcs
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
The __gai_suspend_time64, which supports 64 bit time on ports with
__WORDSIZE == 32 && __TIMESIZE != 64, shall be exported from libanl
(the same library from which original gai_suspend is exported).
Up till now there were no defines for this library. This commit adds
them.
The aio_suspend function has been converted to support 64 bit time.
This change uses (in aio_misc.h):
- __futex_abstimed_wait64 (instead of futex_reltimed_wait)
- __futex_abstimed_wait_cancellable64
(instead of futex_reltimed_wait_cancellable)
from ./sysdeps/nptl/futex-helpers.h
The aio_suspend() accepts relative timeout, which then is converted to
absolute one.
The i686-gnu port (HURD) do not define DONT_NEED_AIO_MISC_COND and as it
doesn't (yet) support 64 bit time it uses not converted
pthread_cond_timedwait().
The __aio_suspend() is supposed to be run on ports with __TIMESIZE !=64 and
__WORDSIZE==32. It internally utilizes __aio_suspend_time64() and hence the
conversion from 32 bit struct timespec to 64 bit one is required.
For ports supporting 64 bit time the __aio_suspend_time64() will be used
either via alias (to __aio_suspend when __TIMESIZE==64) or redirection
(when -D_TIME_BITS=64 is passed).
Build tests:
./src/scripts/build-many-glibcs.py glibcs
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The tls.h inclusion is not really required and limits possible
definition on more arch specific headers.
This is a cleanup to allow inline functions on sysdep.h, more
specifically on i386 and ia64 which requires to access some tls
definitions its own.
No semantic changes expected, checked with a build against all
affected ABIs.
