Address space for heap segments is reserved in a mmap call with
MAP_ANONYMOUS | MAP_PRIVATE and protection flags PROT_NONE. This
reservation does not count against the RSS limit of the process or
system. Backing memory is allocated using mprotect in alloc_new_heap
and grow_heap, and at this point, the allocator expects the kernel
to provide memory (subject to memory overcommit).
The SIGSEGV that might generate due to MAP_NORESERVE (according to
the mmap manual page) does not seem to occur in practice, it's always
SIGKILL from the OOM killer. Even if there is a way that SIGSEGV
could be generated, it is confusing to applications that this only
happens for secondary heaps, not for large mmap-based allocations,
and not for the main arena.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Now that kernel exports linux/mount.h and includes it on linux/fs.h,
its definitions might clash with glibc exports sys/mount.h. To avoid
the need to rearrange the Linux header to be always after glibc one,
the glibc sys/mount.h is changed to:
1. Undefine the macros also used as enum constants. This covers prior
inclusion of <linux/mount.h> (for instance MS_RDONLY).
2. Include <linux/mount.h> based on the usual __has_include check
(needs to use __has_include ("linux/mount.h") to paper over GCC
bugs.
3. Define enum fsconfig_command only if FSOPEN_CLOEXEC is not defined.
(FSOPEN_CLOEXEC should be a very close proxy.)
4. Define struct mount_attr if MOUNT_ATTR_SIZE_VER0 is not defined.
(Added in the same commit on the Linux side.)
This patch also adds some tests to check if including linux/fs.h and
linux/mount.h after and before sys/mount.h does work.
Checked on x86_64-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Improve performance of recursive IO locks by adding a fast path for
the single-threaded case. To reduce the number of memory accesses for
locking/unlocking, only increment the recursion counter if the lock
is already taken.
On Neoverse V1, a microbenchmark with many small freads improved by
2.9x. Multithreaded performance improved by 2%.
Reviewed-by: Cristian Rodríguez <crrodriguez@opensuse.org>
So far this test checks if pidfd_open-syscall is supported,
which was introduced with linux 5.3.
The process_madvise-syscall was introduced with linux 5.10.
Thus you'll get FAILs if you are running a kernel in between.
This patch adds a check if the first process_madvise-syscall
returns ENOSYS and in this case will fail with UNSUPPORTED.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
`#ifndef STPCPY` is incorrect for checking if `STRCPY` is already
defined. It doesn't end up mattering as the whole check is
guarded by `#if IS_IN (libc)` but is incorrect none the less.
GCC normally does this optimization for us in
strlen_pass::handle_builtin_strcpy but only for optimized
build. To avoid needing to include strcpy.S in the rtld build to
support the debug build, just do the optimization by hand.
Add more IEEE half conversion routines:
- Convert 32-bit/64-bit integer to IEEE half.
- Convert IEEE half to 32-bit/64-bit integer.
They are required by RISC-V _Float16 support, tested with RISC-V GCC.
Similar to 6720d36b66 for x86-64.
Clang cannot assemble movzx in the AT&T dialect mode. Change movzx to
movzbl, which follows the AT&T dialect and is used elsewhere in the
file.
The older libc versions are obsolete for over twenty years now.
This patch removes the special flags for libc5 and libc4 and assumes
that all libraries cached are libc6 compatible and use FLAG_ELF_LIBC6.
Checked with a build for all affected architectures.
Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
exit only terminates the current thread, not the whole process, so it
is the wrong fallback system call in this context. All supported
Linux versions implement the exit_group system call anyway.
This patch updates the kernel version in the tests tst-mman-consts.py,
tst-mount-consts.py and tst-pidfd-consts.py to 5.18. (There are no
new constants covered by these tests in 5.19, or in 5.17 or 5.18 in
the case of tst-mount-consts.py that previously used version 5.16,
that need any other header changes.)
Tested with build-many-glibcs.py.
Redirect internal assertion failures to __libc_assert_fail, based on
based on __libc_message, which writes directly to STDERR_FILENO
and calls abort. Also disable message translation and reword the
error message slightly (adjusting stdlib/tst-bz20544 accordingly).
As a result of these changes, malloc no longer needs its own
redefinition of __assert_fail.
__libc_assert_fail needs to be stubbed out during rtld dependency
analysis because the rtld rebuilds turn __libc_assert_fail into
__assert_fail, which is unconditionally provided by elf/dl-minimal.c.
This change is not possible for the public assert macro and its
__assert_fail function because POSIX requires that the diagnostic
is written to stderr.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
__pthread_sigmask cannot actually fail with valid pointer arguments
(it would need a really broken seccomp filter), and we do not check
for errors elsewhere.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Since commit ec2c1fcefb ("malloc:
Abort on heap corruption, without a backtrace [BZ #21754]"),
__libc_message always terminates the process. Since commit
a289ea09ea ("Do not print backtraces
on fatal glibc errors"), the backtrace facility has been removed.
Therefore, remove enum __libc_message_action and the action
argument of __libc_message, and mark __libc_message as _No_return.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Linux 5.19 has no new syscalls, but enables memfd_secret in the uapi
headers for RISC-V. Update the version number in syscall-names.list
to reflect that it is still current for 5.19 and regenerate the
arch-syscall.h headers with build-many-glibcs.py update-syscalls.
Tested with build-many-glibcs.py.
The inline and library functions that the CMSG_NXTHDR macro may expand
to increment the pointer to the header before checking the stride of
the increment against available space. Since C only allows incrementing
pointers to one past the end of an array, the increment must be done
after a length check. This commit fixes that and includes a regression
test for CMSG_FIRSTHDR and CMSG_NXTHDR.
The Linux, Hurd, and generic headers are all changed.
Tested on Linux on armv7hl, i686, x86_64, aarch64, ppc64le, and s390x.
[BZ #28846]
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
When applications redirect some functions they might get called before
libpthread is fully initialized. They may still expected pthread_self
and cancellable functions to work, so cope with such calls in that
situation.
It uses the bitmask with rejection [1], which calculates a mask
being the lowest power of two bounding the request upper bound,
successively queries new random values, and rejects values
outside the requested range.
Performance-wise, there is no much gain in trying to conserve
bits since arc4random is wrapper on getrandom syscall. It should
be cheaper to just query a uint32_t value. The algorithm also
avoids modulo and divide operations, which might be costly
depending of the architecture.
[1] https://www.pcg-random.org/posts/bounded-rands.html
Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
Cancellation currently cannot happen at this point because dlopen
as used by the unwind link always performs additional allocations
for libgcc_s.so.1, even if it has been loaded already as a dependency
of the main executable. But it seems prudent not to rely on this
quirk.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Make test-c8rtomb.out and test-mbrtoc8.out depend on $(gen-locales) for
xsetlocale (LC_ALL, "de_DE.UTF-8");
xsetlocale (LC_ALL, "zh_HK.BIG5-HKSCS");
Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
gcc 13 issues the following diagnostic for the uchar.h header when the
-Wc++20-compat option is enabled in C++ modes that do not enable char8_t
as a builtin type (C++17 and earlier by default; subject to _GNU_SOURCE
and the gcc -f[no-]char8_t option).
warning: identifier ‘char8_t’ is a keyword in C++20 [-Wc++20-compat]
This change modifies the uchar.h header to suppress the diagnostic through
the use of '#pragma GCC diagnostic' directives for gcc 10 and later (the
-Wc++20-compat option was added in gcc version 10). Unfortunately, a bug
in gcc currently prevents those directives from having the intended effect
as reported at https://gcc.gnu.org/PR106423. A patch for that issue has
been submitted and is available in the email thread archive linked below.
https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598736.html
