aboutsummaryrefslogtreecommitdiff
path: root/NEWS
AgeCommit message (Collapse)AuthorFilesLines
2025-01-01Update copyright dates with scripts/update-copyrightsPaul Eggert1-1/+1
2024-12-31elf: Add glibc.rtld.execstackAdhemerval Zanella1-0/+5
The new tunable can be used to control whether executable stacks are allowed from either the main program or dependencies. The default is to allow executable stacks. The executable stacks default permission is checked agains the one provided by the PT_GNU_STACK from program headers (if present). The tunable also disables the stack permission change if any dependency requires an executable stack at loading time. Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
2024-12-31elf: Do not change stack permission on dlopen/dlmopenAdhemerval Zanella1-0/+6
If some shared library loaded with dlopen/dlmopen requires an executable stack, either implicitly because of a missing GNU_STACK ELF header (where the ABI default flags implies in the executable bit) or explicitly because of the executable bit from GNU_STACK; the loader will try to set the both the main thread and all thread stacks (from the pthread cache) as executable. Besides the issue where any __nptl_change_stack_perm failure does not undo the previous executable transition (meaning that if the library fails to load, there can be thread stacks with executable stacks), this behavior was used on a CVE [1] as a vector for RCE. This patch changes that if a shared library requires an executable stack, and the current stack is not executable, dlopen fails. The change is done only for dynamically loaded modules, if the program or any dependency requires an executable stack, the loader will still change the main thread before program execution and any thread created with default stack configuration. [1] https://www.qualys.com/2023/07/19/cve-2023-38408/rce-openssh-forwarded-ssh-agent.txt Checked on x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
2024-12-30INSTALL, NEWS: Document requirement of gawk with MPFR supportAndreas K. Hüttel1-0/+3
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-12-30Mention CORE-MATH optimize routines on NEWSAdhemerval Zanella1-0/+5
Reviewed-by: Andreas K. Huettel <dilfridge@gentoo.org>
2024-12-24NEWS: Mention testing glibc build with a different set of compilersH.J. Lu1-0/+11
Also document C and C++ compilers used to test glibc should come from the same set of compilers. Signed-off-by: H.J. Lu <hjl.tools@gmail.com> Reviewed-by: Sam James <sam@gentoo.org>
2024-12-12Implement C23 atan2piJoseph Myers1-1/+2
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the atan2pi functions (atan2(y,x)/pi). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-11Implement C23 atanpiJoseph Myers1-1/+1
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the atanpi functions (atan(x)/pi). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-10Implement C23 asinpiJoseph Myers1-1/+1
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the asinpi functions (asin(x)/pi). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-09Implement C23 acospiJoseph Myers1-1/+1
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the acospi functions (acos(x)/pi). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-05Implement C23 tanpiJoseph Myers1-1/+1
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the tanpi functions (tan(pi*x)). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-04Implement C23 sinpiJoseph Myers1-1/+1
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the sinpi functions (sin(pi*x)). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-04Implement C23 cospiJoseph Myers1-0/+7
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the cospi functions (cos(pi*x)). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-11-28Remove nios2-linux-gnuAdhemerval Zanella1-0/+2
GCC 15 (e876acab6cdd84bb2b32c98fc69fb0ba29c81153) and binutils (e7a16d9fd65098045ef5959bf98d990f12314111) both removed all Nios II support, and the architecture has been EOL'ed by the vendor. The kernel still has support, but without a proper compiler there is no much sense in keep it on glibc. Reviewed-by: Florian Weimer <fweimer@redhat.com>
2024-11-12linux: Add support for getrandom vDSOAdhemerval Zanella1-1/+3
Linux 6.11 has getrandom() in vDSO. It operates on a thread-local opaque state allocated with mmap using flags specified by the vDSO. Multiple states are allocated at once, as many as fit into a page, and these are held in an array of available states to be doled out to each thread upon first use, and recycled when a thread terminates. As these states run low, more are allocated. To make this procedure async-signal-safe, a simple guard is used in the LSB of the opaque state address, falling back to the syscall if there's reentrancy contention. Also, _Fork() is handled by blocking signals on opaque state allocation (so _Fork() always sees a consistent state even if it interrupts a getrandom() call) and by iterating over the thread stack cache on reclaim_stack. Each opaque state will be in the free states list (grnd_alloc.states) or allocated to a running thread. The cancellation is handled by always using GRND_NONBLOCK flags while calling the vDSO, and falling back to the cancellable syscall if the kernel returns EAGAIN (would block). Since getrandom is not defined by POSIX and cancellation is supported as an extension, the cancellation is handled as 'may occur' instead of 'shall occur' [1], meaning that if vDSO does not block (the expected behavior) getrandom will not act as a cancellation entrypoint. It avoids a pthread_testcancel call on the fast path (different than 'shall occur' functions, like sem_wait()). It is currently enabled for x86_64, which is available in Linux 6.11, and aarch64, powerpc32, powerpc64, loongarch64, and s390x, which are available in Linux 6.12. Link: https://pubs.opengroup.org/onlinepubs/9799919799/nframe.html [1] Co-developed-by: Jason A. Donenfeld <Jason@zx2c4.com> Tested-by: Jason A. Donenfeld <Jason@zx2c4.com> # x86_64 Tested-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> # x86_64, aarch64 Tested-by: Xi Ruoyao <xry111@xry111.site> # x86_64, aarch64, loongarch64 Tested-by: Stefan Liebler <stli@linux.ibm.com> # s390x
2024-11-04Add feature test macro _ISOC2Y_SOURCELenard Mollenkopf1-0/+7
This patch starts preparation for C2Y support in glibc headers by adding a feature test macro _ISOC2Y_SOURCE and corresponding __GLIBC_USE (ISOC2Y). (I mostly copied the work of Joseph Myers for C2X). As with other such macros, C2Y features are also enabled by compiling for a standard newer than C23, or by using _GNU_SOURCE. This patch does not itself enable anything new in the headers for C2Y; that is to be done in followup patches. (For example an implementation of WG14 N3349.) Once C2Y becomes an actual standard we'll presumably move to using the actual year in the feature test macro and __GLIBC_USE, with some period when both macro spellings are accepted, as was done with _ISOC2X_SOURCE. Tested for x86_64. Signed-off-by: Lenard Mollenkopf <glibc@lenardmollenkopf.de>
2024-10-08stdlib: Make abort/_Exit AS-safe (BZ 26275)Adhemerval Zanella1-0/+5
The recursive lock used on abort does not synchronize with a new process creation (either by fork-like interfaces or posix_spawn ones), nor it is reinitialized after fork(). Also, the SIGABRT unblock before raise() shows another race condition, where a fork or posix_spawn() call by another thread, just after the recursive lock release and before the SIGABRT signal, might create programs with a non-expected signal mask. With the default option (without POSIX_SPAWN_SETSIGDEF), the process can see SIG_DFL for SIGABRT, where it should be SIG_IGN. To fix the AS-safe, raise() does not change the process signal mask, and an AS-safe lock is used if a SIGABRT is installed or the process is blocked or ignored. With the signal mask change removal, there is no need to use a recursive loc. The lock is also taken on both _Fork() and posix_spawn(), to avoid the spawn process to see the abort handler as SIG_DFL. A read-write lock is used to avoid serialize _Fork and posix_spawn execution. Both sigaction (SIGABRT) and abort() requires to lock as writer (since both change the disposition). The fallback is also simplified: there is no need to use a loop of ABORT_INSTRUCTION after _exit() (if the syscall does not terminate the process, the system is broken). The proposed fix changes how setjmp works on a SIGABRT handler, where glibc does not save the signal mask. So usage like the below will now always abort. static volatile int chk_fail_ok; static jmp_buf chk_fail_buf; static void handler (int sig) { if (chk_fail_ok) { chk_fail_ok = 0; longjmp (chk_fail_buf, 1); } else _exit (127); } [...] signal (SIGABRT, handler); [....] chk_fail_ok = 1; if (! setjmp (chk_fail_buf)) { // Something that can calls abort, like a failed fortify function. chk_fail_ok = 0; printf ("FAIL\n"); } Such cases will need to use sigsetjmp instead. The _dl_start_profile calls sigaction through _profil, and to avoid pulling abort() on loader the call is replaced with __libc_sigaction. Checked on x86_64-linux-gnu and aarch64-linux-gnu. Reviewed-by: DJ Delorie <dj@redhat.com>
2024-09-25arc: Remove HAVE_ARC_BE macro and disable big-endian portFlorian Weimer1-1/+1
It is no longer needed, now that ARC is always little endian.
2024-09-20iconv: Support in-place conversions (bug 10460, bug 32033)Florian Weimer1-0/+3
Check if any of the input files overlaps with the output file, and use a temporary file in this case, so that the input is no clobbered before it is read. This fixes bug 10460. It allows to use iconv more easily as a functional replacement for GNU recode. The updated output buffer management truncates the output file if there is no input, fixing bug 32033. Reviewed-by: DJ Delorie <dj@redhat.com>
2024-09-11Linux: Add the sched_setattr and sched_getattr functionsFlorian Weimer1-0/+3
And struct sched_attr. In sysdeps/unix/sysv/linux/bits/sched.h, the hack that defines sched_param around the inclusion of <linux/sched/types.h> is quite ugly, but the definition of struct sched_param has already been dropped by the kernel, so there is nothing else we can do and maintain compatibility of <sched.h> with a wide range of kernel header versions. (An alternative would involve introducing a separate header for this functionality, but this seems unnecessary.) The existing sched_* functions that change scheduler parameters are already incompatible with PTHREAD_PRIO_PROTECT mutexes, so there is no harm in adding more functionality in this area. The documentation mostly defers to the Linux manual pages. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2024-07-24resolv: Implement strict-error stub resolver option (bug 27929)Florian Weimer1-0/+10
For now, do not enable this mode by default due to the potential impact on compatibility with existing deployments. Reviewed-by: DJ Delorie <dj@redhat.com>
2024-07-24resolv: Support clearing option flags with a “-” prefix (bug 14799)Florian Weimer1-1/+5
I think using a “-” prefix is less confusing than introducing double-negation construct (“no-no-tld-query”). Reviewed-by: DJ Delorie <dj@redhat.com>
2024-07-21NEWS: Add new sectionAndreas K. Hüttel1-0/+27
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-07-20NEWS: drop 2.40 section "Changes to build and runtime requirements"Andreas K. Hüttel1-4/+0
Can't find anything that should go here. Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-07-20NEWS: add fixed security advisories listAndreas K. Hüttel1-2/+17
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-07-20NEWS: add resolved bugs listAndreas K. Hüttel1-2/+135
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-07-20NEWS: add more major improvements for 2.40Andreas K. Hüttel1-3/+13
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-07-09Linux: Make __rseq_size useful for feature detection (bug 31965)Florian Weimer1-0/+3
The __rseq_size value is now the active area of struct rseq (so 20 initially), not the full struct size including padding at the end (32 initially). Update misc/tst-rseq to print some additional diagnostics. Reviewed-by: Michael Jeanson <mjeanson@efficios.com> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
2024-06-17Implement C23 exp2m1, exp10m1Joseph Myers1-0/+2
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the exp2m1 and exp10m1 functions (exp2(x)-1 and exp10(x)-1, like expm1). As with other such functions, these use type-generic templates that could be replaced with faster and more accurate type-specific implementations in future. Test inputs are copied from those for expm1, plus some additions close to the overflow threshold (copied from exp2 and exp10) and also some near the underflow threshold. exp2m1 has the unusual property of having an input (M_MAX_EXP) where whether the function overflows (under IEEE semantics) depends on the rounding mode. Although these could reasonably be XFAILed in the testsuite (as we do in some cases for arguments very close to a function's overflow threshold when an error of a few ulps in the implementation can result in the implementation not agreeing with an ideal one on whether overflow takes place - the testsuite isn't smart enough to handle this automatically), since these functions aren't required to be correctly rounding, I made the implementation check for and handle this case specially. The Makefile ordering expected by lint-makefiles for the new functions is a bit peculiar, but I implemented it in this patch so that the test passes; I don't know why log2 also needed moving in one Makefile variable setting when it didn't in my previous patches, but the failure showed a different place was expected for that function as well. The powerpc64le IFUNC setup seems not to be as self-contained as one might hope; it shouldn't be necessary to add IFUNCs for new functions such as these simply to get them building, but without setting up IFUNCs for the new functions, there were undefined references to __GI___expm1f128 (that IFUNC machinery results in no such function being defined, but doesn't stop include/math.h from doing the redirection resulting in the exp2m1f128 and exp10m1f128 implementations expecting to call it). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-06-17Implement C23 log10p1Joseph Myers1-1/+1
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the log10p1 functions (log10(1+x): like log1p, but for base-10 logarithms). This is directly analogous to the log2p1 implementation (except that whereas log2p1 has a smaller underflow range than log1p, log10p1 has a larger underflow range). The test inputs are copied from those for log1p and log2p1, plus a few more inputs in that wider underflow range. Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-06-17Implement C23 logp1Joseph Myers1-1/+1
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the logp1 functions (aliases for log1p functions - the name is intended to be more consistent with the new log2p1 and log10p1, where clearly it would have been very confusing to name those functions log21p and log101p). As aliases rather than new functions, the content of this patch is somewhat different from those actually adding new functions. Tests are shared with log1p, so this patch *does* mechanically update all affected libm-test-ulps files to expect the same errors for both functions. The vector versions of log1p on aarch64 and x86_64 are *not* updated to have logp1 aliases (and thus there are no corresponding header, tests, abilist or ulps changes for vector functions either). It would be reasonable for such vector aliases and corresponding changes to other files to be made separately. For now, the log1p tests instead avoid testing logp1 in the vector case (a Makefile change is needed to avoid problems with grep, used in generating the .c files for vector function tests, matching more than one ALL_RM_TEST line in a file testing multiple functions with the same inputs, when it assumes that the .inc file only has a single such line). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-06-04Linux: Add epoll ioctlsJoe Damato1-0/+3
As of Linux kernel 6.9, some ioctls and a parameters structure have been introduced which allow user programs to control whether a particular epoll context will busy poll. Update the headers to include these for the convenience of user apps. The ioctls were added in Linux kernel 6.9 commit 18e2bf0edf4dd ("eventpoll: Add epoll ioctl for epoll_params") [1] to include/uapi/linux/eventpoll.h. [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/diff/?h=v6.9&id=18e2bf0edf4dd Signed-off-by: Joe Damato <jdamato@fastly.com> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2024-05-20Implement C23 log2p1Joseph Myers1-0/+7
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the log2p1 functions (log2(1+x): like log1p, but for base-2 logarithms). This illustrates the intended structure of implementations of all these function families: define them initially with a type-generic template implementation. If someone wishes to add type-specific implementations, it is likely such implementations can be both faster and more accurate than the type-generic one and can then override it for types for which they are implemented (adding benchmarks would be desirable in such cases to demonstrate that a new implementation is indeed faster). The test inputs are copied from those for log1p. Note that these changes make gen-auto-libm-tests depend on MPFR 4.2 (or later). The bulk of the changes are fairly generic for any such new function. (sysdeps/powerpc/nofpu/Makefile only needs changing for those type-generic templates that use fabs.) Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-05-06NEWS: Add advisories.Carlos O'Donell1-0/+19
GLIBC-SA-2024-0004: ISO-2022-CN-EXT: fix out-of-bound writes when writing escape sequence (CVE-2024-2961) GLIBC-SA-2024-0005: nscd: Stack-based buffer overflow in netgroup cache (CVE-2024-33599) GLIBC-SA-2024-0006: nscd: Null pointer crashes after notfound response (CVE-2024-33600) GLIBC-SA-2024-0007: nscd: netgroup cache may terminate daemon on memory allocation failure (CVE-2024-33601) GLIBC-SA-2024-0008: nscd: netgroup cache assumes NSS callback uses in-buffer strings (CVE-2024-33602) Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2024-04-19login: Use unsigned 32-bit types for seconds-since-epochFlorian Weimer1-1/+8
These fields store timestamps when the system was running. No Linux systems existed before 1970, so these values are unused. Switching to unsigned types allows continued use of the existing struct layouts beyond the year 2038. The intent is to give distributions more time to switch to improved interfaces that also avoid locking/data corruption issues. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2024-03-01NEWS: Move enable_secure_tunable from 2.39 to 2.40.Joe Talbott1-5/+5
2024-02-29rtld: Add glibc.rtld.enable_secure tunable.Joe Simmons-Talbott1-0/+5
Add a tunable for setting __libc_enable_secure to 1. Do not set __libc_enable_secure to 0 if the tunable is set to 0. Ignore all tunables if glib.rtld.enable_secure is set. One use-case for this addition is to enable testing code paths that depend on __libc_enable_secure being set without the need to use setxid binaries. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2024-02-01Refer to C23 in place of C2X in glibcJoseph Myers1-0/+7
WG14 decided to use the name C23 as the informal name of the next revision of the C standard (notwithstanding the publication date in 2024). Update references to C2X in glibc to use the C23 name. This is intended to update everything *except* where it involves renaming files (the changes involving renaming tests are intended to be done separately). In the case of the _ISOC2X_SOURCE feature test macro - the only user-visible interface involved - support for that macro is kept for backwards compatibility, while adding _ISOC23_SOURCE. Tested for x86_64.
2024-01-31Use gcc __builtin_stdc_* builtins in stdbit.h if possibleJakub Jelinek1-1/+4
The following patch uses the GCC 14 __builtin_stdc_* builtins in stdbit.h for the type-generic macros, so that when compiled with GCC 14 or later, it supports not just 8/16/32/64-bit unsigned integers, but also 128-bit (if target supports them) and unsigned _BitInt (any supported precision). And so that the macros don't expand arguments multiple times and can be evaluated in constant expressions. The new testcase is gcc's gcc/testsuite/gcc.dg/builtin-stdc-bit-1.c adjusted to test stdbit.h and the type-generic macros in there instead of the builtins and adjusted to use glibc test framework rather than gcc style tests with __builtin_abort (). Signed-off-by: Jakub Jelinek <jakub@redhat.com> Reviewed-by: Joseph Myers <josmyers@redhat.com>
2024-01-31Open master branch for glibc 2.40 developmentglibc-2.39.9000Andreas K. Hüttel1-0/+27
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-01-30NEWS: insert advisories and fixed bugs for 2.39Andreas K. Hüttel1-4/+133
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-01-30Fix typoAndreas K. Hüttel1-1/+1
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-01-24manual, NEWS: Document malloc side effect of dynamic TLS changesFlorian Weimer1-0/+6
The increased malloc subsystem usage is a side effect of commit d2123d68275acc0f061e73d5f86ca504e0d5a344 ("elf: Fix slow tls access after dlopen [BZ #19924]"). Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
2024-01-24NEWS: Update temporary files ignored by ldconfigFlorian Weimer1-2/+2
Fixes commit 2aa0974d2573441bffd596b07bff8698b1f2f18c ("elf: ldconfig should skip temporary files created by package managers") and commit cfb5a97a93ea656e3b2263e42142a4032986d9ba ("ldconfig: Fixes for skipping temporary files."). Reported-by: Guillem Jover <guillem@debian.org> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2024-01-16NEWS: Mention PLT rewrite on x86-64H.J. Lu1-0/+4
Mention PLT rewrite on x86-64 for glibc 2.39.
2024-01-15aarch64: Add NEWS entry about libmvec for 2.39Szabolcs Nagy1-0/+7
Auto-vectorizing scalar calls is now supported. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2024-01-09i386: Fail if configured with --enable-cetAdhemerval Zanella1-2/+2
Since it is only supported for x86_64. Checked on i686-linux-gnu.
2024-01-08Remove ia64-linux-gnuAdhemerval Zanella1-0/+2
Linux 6.7 removed ia64 from the official tree [1], following the general principle that a glibc port needs upstream support for the architecture in all the components it depends on (binutils, GCC, and the Linux kernel). Apart from the removal of sysdeps/ia64 and sysdeps/unix/sysv/linux/ia64, there are updates to various comments referencing ia64 for which removal of those references seemed appropriate. The configuration is removed from README and build-many-glibcs.py. The CONTRIBUTED-BY, elf/elf.h, manual/contrib.texi (the porting mention), *.po files, config.guess, and longlong.h are not changed. For Linux it allows cleanup some clone2 support on multiple files. The following bug can be closed as WONTFIX: BZ 22634 [2], BZ 14250 [3], BZ 21634 [4], BZ 10163 [5], BZ 16401 [6], and BZ 11585 [7]. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=43ff221426d33db909f7159fdf620c3b052e2d1c [2] https://sourceware.org/bugzilla/show_bug.cgi?id=22634 [3] https://sourceware.org/bugzilla/show_bug.cgi?id=14250 [4] https://sourceware.org/bugzilla/show_bug.cgi?id=21634 [5] https://sourceware.org/bugzilla/show_bug.cgi?id=10163 [6] https://sourceware.org/bugzilla/show_bug.cgi?id=16401 [7] https://sourceware.org/bugzilla/show_bug.cgi?id=11585 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2024-01-04i386: Ignore --enable-cetH.J. Lu1-0/+3
Since shadow stack is only supported for x86-64, ignore --enable-cet for i386. Always setting $(enable-cet) for i386 to "no" to support ifneq ($(enable-cet),no) in x86 Makefiles. We can't use ifeq ($(enable-cet),yes) since $(enable-cet) can be "yes", "no" or "permissive". Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2024-01-03Implement C23 <stdbit.h>Joseph Myers1-0/+9
C23 adds a header <stdbit.h> with various functions and type-generic macros for bit-manipulation of unsigned integers (plus macro defines related to endianness). Implement this header for glibc. The functions have both inline definitions in the header (referenced by macros defined in the header) and copies with external linkage in the library (which are implemented in terms of those macros to avoid duplication). They are documented in the glibc manual. Tests, as well as verifying results for various inputs (of both the macros and the out-of-line functions), verify the types of those results (which showed up a bug in an earlier version with the type-generic macro stdc_has_single_bit wrongly returning a promoted type), that the macros can be used at top level in a source file (so don't use ({})), that they evaluate their arguments exactly once, and that the macros for the type-specific functions have the expected implicit conversions to the relevant argument type. Jakub previously referred to -Wconversion warnings in type-generic macros, so I've included a test with -Wconversion (but the only warnings I saw and fixed from that test were actually in inline functions in the <stdbit.h> header - not anything coming from use of the type-generic macros themselves). This implementation of the type-generic macros does not handle unsigned __int128, or unsigned _BitInt types with a width other than that of a standard integer type (and C23 doesn't require the header to handle such types either). Support for those types, using the new type-generic built-in functions Jakub's added for GCC 14, can reasonably be added in a followup (along of course with associated tests). This implementation doesn't do anything special to handle C++, or have any tests of functionality in C++ beyond the existing tests that all headers can be compiled in C++ code; it's not clear exactly what form this header should take in C++, but probably not one using macros. DIS ballot comment AT-107 asks for the word "count" to be added to the names of the stdc_leading_zeros, stdc_leading_ones, stdc_trailing_zeros and stdc_trailing_ones functions and macros. I don't think it's likely to be accepted (accepting any technical comments would mean having an FDIS ballot), but if it is accepted at the WG14 meeting (22-26 January in Strasbourg, starting with DIS ballot comment handling) then there would still be time to update glibc for the renaming before the 2.39 release. The new functions and header are placed in the stdlib/ directory in glibc, rather than creating a new toplevel stdbit/ or putting them in string/ alongside ffs. Tested for x86_64 and x86.