Commit Graph

1662 Commits

Author SHA1 Message Date
Stefan Liebler
ad0aa1f549 elf: Remove LD_HWCAP_MASK / tunable glibc.cpu.hwcap_mask
Remove the environment variable LD_HWCAP_MASK and the tunable
glibc.cpu.hwcap_mask as those are not used anymore in common-code
after removal in elf/dl-cache.c:search_cache().

The only remaining user is sparc32 where it is used in
elf_machine_matches_host().  If sparc32 does not need it anymore,
we can get rid of it at all.  Otherwise we could also move
LD_HWCAP_MASK / tunable glibc.cpu.hwcap_mask to be sparc32 specific.
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2024-06-18 10:45:36 +02:00
Andreas K. Hüttel
98ffc1bfeb
Convert to autoconf 2.72 (vanilla release, no distribution patches)
As discussed at the patch review meeting

Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
Reviewed-by: Simon Chopin <simon.chopin@canonical.com>
2024-06-17 21:15:28 +02:00
Joseph Myers
7ec903e028 Implement C23 exp2m1, exp10m1
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.
2024-06-17 16:31:49 +00:00
Joseph Myers
55eb99e9a9 Implement C23 log10p1
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.
2024-06-17 13:48:13 +00:00
Joseph Myers
bb014f50c4 Implement C23 logp1
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.
2024-06-17 13:47:09 +00:00
Paul Eggert
7c1ec1b7d0 Minor code improvement to timespec_subtract example
This saves a few instructions.
BORROW cannot be -1, since NSEC_DIFF is at most 999999999.
Idea taken from Gnulib, here:
https://git.savannah.gnu.org/cgit/gnulib.git/commit/?id=fe33f943054b93af8b965ce6564b8713b0979a21
2024-06-15 08:53:50 -07:00
Paul Eggert
ee768a30fe Modernize and fix doc’s “Date and Time” (BZ 31876)
POSIX.1-2024 (now official) specifies tm_gmtoff and tm_zone.
This is a good time to update the manual’s “Date and Time”
chapter so I went through it, fixed some outdated
stuff that had been in there for decades, and improved it to match
POSIX.1-2024 better and to clarify some implementation-defined
behavior.  Glibc already conforms to POSIX.1-2024 in these matters, so
this is merely a documentation change.

* manual/examples/strftim.c: Use snprintf instead of now-deprecated
  function asctime.  Check for localtime failure.  Simplify by using
  puts instead of fputs.  Prefer ‘buf, sizeof buf’ to less-obvious
  ‘buffer, SIZE’.

* manual/examples/timespec_subtract.c: Modernize to use struct
  timespec not struct timeval, and rename from timeval_subtract.c.
  All uses changed.  Check for overflow.  Do not check for negative
  return value, which ought to be OK since negative time_t is OK.
  Use GNU indenting style.

* manual/time.texi:

  Document CLOCKS_PER_SEC, TIME_UTC, timespec_get, timespec_getres,
  strftime_l.

  Document the storage lifetime of tm_zone and of tzname.

  Caution against use of tzname, timezone and daylight, saying that
  these variables have unspecified values when TZ is geographic.
  This is what glibc actually does (contrary to what the manual said
  before this patch), and POSIX is planned to say the same thing
  <https://austingroupbugs.net/view.php?id=1816>.
  Also say that directly accessing the variables is not thread-safe.

  Say that localtime_r and ctime_r don’t necessarily set time zone
  state.  Similarly, in the tzset documentation, say that it is called
  by ctime, localtime, mktime, strftime, not that it is called by all
  time conversion functions that depend on the time zone.

  Say that tm_isdst is useful mostly just for mktime, and that
  other uses should prefer tm_gmtoff and tm_zone instead.

  Do not say that strftime ignores tm_gmtoff and tm_zone, because
  it doesn’t do that.

  Document what gmtime does to tm_gmtoff and tm_zone.

  Say that the asctime, asctime_r, ctime, and ctime_r are now deprecated
  and/or obsolescent, and that behavior is undefined if the year is <
  1000 or > 9999.  Document strftime before these now-obsolescent
  functions, so that readers see the useful function first.

  Coin the terms “geographical format” and “proleptic format” for the
  two main formats of TZ settings, to simplify exposition.  Use this
  wording consistently.

  Update top-level proleptic syntax to match POSIX.1-2024, which glibc
  already implements.  Document the angle-bracket quoted forms of time
  zone abbreviations in proleptic TZ.  Say that time zone abbreviations
  can contain only ASCII alphanumerics, ‘+’, and ‘-’.

  Document what happens if the proleptic form specifies a DST
  abbreviation and offset but omits the rules.  POSIX says this is
  implementation-defined so we need to document it.  Although this
  documentation mentions ‘posixrules’ tersely, we need to rethink
  ‘posixrules’ since I think it stops working after 2038.

  Clarify wording about TZ settings beginning with ‘;’.

  Say that timegm is in ISO C (as of C23).

  Say that POSIX.1-2024 removed gettimeofday.

  Say that tm_gmtoff and tm_zone are extensions to ISO C, which is
  clearer than saying they are invisible in a struct ISO C enviroment,
  and gives us more wiggle room if we want to make them visible in
  strict ISO C, something that ISO C allows.

  Drop mention of old standards like POSIX.1c and POSIX.2-1992 in the
  text when the history is so old that it’s no longer useful in a
  general-purpose manual.

  Define Coordinated Universal Time (UTC), time zone, time zone ruleset,
  and POSIX Epoch, and use these phrases more consistently.

  Improve TZ examples to show more variety, and to reflect current
  practice and timestamps.  Remove obsolete example about Argentina.
  Add an example for Ireland.

  Don’t rely on GCC extensions when explaining ctime_r.

  Do not say that difftime produces the mathematically correct result,
  since it might be inexact.

  For clock_t don’t say “as in the example above” when there is no
  such example, and don’t say that casting to double works “properly
  and consistently no matter what”, as it suffers from rounding and
  overflow.

  Don’t say broken-down time is not useful for calculations; it’s
  merely painful.

  Say that UTC is not defined before 1960.

  Rename Time Zone Functions to Time Zone State.  All uses changed.

  Update Internet RFC 822 → 5322, 1305 → 5905.  Drop specific years of
  ISO 8601 as they don’t matter.

  Minor style changes: @code{"..."} → @t{"..."} to avoid overquoting in
  info files, @code → @env for environment variables, Daylight Saving
  Time → daylight saving time, white space → whitespace, prime meridian
  → Prime Meridian.
2024-06-15 08:53:50 -07:00
Andreas K. Hüttel
41d6461484
manual: minor language fix (bz 31340)
Resolves: https://sourceware.org/bugzilla/show_bug.cgi?id=31340
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-06-15 15:42:29 +02:00
Paul Eggert
400bdb5c85 Improve doc for time_t range (BZ 31808) 2024-06-04 09:04:04 -07:00
Noah Goldstein
46b5e98ef6 x86: Add seperate non-temporal tunable for memset
The tuning for non-temporal stores for memset vs memcpy is not always
the same. This includes both the exact value and whether non-temporal
stores are profitable at all for a given arch.

This patch add `x86_memset_non_temporal_threshold`. Currently we
disable non-temporal stores for non Intel vendors as the only
benchmarks showing its benefit have been on Intel hardware.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
2024-05-30 12:36:09 -05:00
Andreas Schwab
c35cad016b manual: clarify defintions of floating point exponent bounds (bug 31518)
For decimal exponent bounds the range is inclusive, for binary exponent
bounds the range is exclusive.
2024-05-21 10:25:46 +02:00
Joseph Myers
79c52daf47 Implement C23 log2p1
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.
2024-05-20 13:41:39 +00:00
DJ Delorie
a07e000e82 manual: add dup3
Reviewed-by: Florian Weimer <fweimer@redhat.com>
2024-05-13 17:38:47 -04:00
caiyinyu
095067efdf LoongArch: Add glibc.cpu.hwcap support.
The current IFUNC selection is always using the most recent
features which are available via AT_HWCAP.  But in
some scenarios it is useful to adjust this selection.

The environment variable:

GLIBC_TUNABLES=glibc.cpu.hwcaps=-xxx,yyy,zzz,....

can be used to enable HWCAP feature yyy, disable HWCAP feature xxx,
where the feature name is case-sensitive and has to match the ones
used in sysdeps/loongarch/cpu-tunables.c.

Signed-off-by: caiyinyu <caiyinyu@loongson.cn>
2024-04-24 18:22:38 +08:00
Florian Weimer
f8d8b1b1e6 aarch64: Enhanced CPU diagnostics for ld.so
This prints some information from struct cpu_features, and the midr_el1
and dczid_el0 system register contents on every CPU.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
2024-04-08 16:48:55 +02:00
Florian Weimer
7a430f40c4 x86: Add generic CPUID data dumper to ld.so --list-diagnostics
This is surprisingly difficult to implement if the goal is to produce
reasonably sized output.  With the current approaches to output
compression (suppressing zeros and repeated results between CPUs,
folding ranges of identical subleaves, dealing with the %ecx
reflection issue), the output is less than 600 KiB even for systems
with 256 logical CPUs.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
2024-04-08 16:48:55 +02:00
Paul Eggert
57581acd95 Fix bsearch, qsort doc to match POSIX better
* manual/search.texi (Array Search Function):
Correct the statement about lfind’s mean runtime:
it is proportional to a number (not that number),
and this is true only if random elements are searched for.
Relax the constraint on bsearch’s array argument:
POSIX says it need not be sorted, only partially sorted.
Say that the first arg passed to bsearch’s comparison function
is the key, and the second arg is an array element, as
POSIX requires.  For bsearch and qsort, say that the
comparison function should not alter the array, as POSIX
requires.  For qsort, say that the comparison function
must define a total order, as POSIX requires, that
it should not depend on element addresses, that
the original array index can be used for stable sorts,
and that if qsort still works if memory allocation fails.
Be more consistent in calling the array elements
“elements” rather than “objects”.

Co-authored-by: Zack Weinberg <zack@owlfolio.org>
2024-04-06 10:10:32 -07:00
Stafford Horne
3db9d208dd misc: Add support for Linux uio.h RWF_NOAPPEND flag
In Linux 6.9 a new flag is added to allow for Per-io operations to
disable append mode even if a file was opened with the flag O_APPEND.
This is done with the new RWF_NOAPPEND flag.

This caused two test failures as these tests expected the flag 0x00000020
to be unused.  Adding the flag definition now fixes these tests on Linux
6.9 (v6.9-rc1).

  FAIL: misc/tst-preadvwritev2
  FAIL: misc/tst-preadvwritev64v2

This patch adds the flag, adjusts the test and adds details to
documentation.

Link: https://lore.kernel.org/all/20200831153207.GO3265@brightrain.aerifal.cx/
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2024-04-04 09:41:27 +01:00
Alejandro Colomar
95c70fd0d4 manual: significand() uses FLT_RADIX, not 2
It's implemented using scalb(), which uses FLT_RADIX, AFAIK.

Link: <https://lore.kernel.org/linux-man/ZeYKUOKYS7G90SaV@debian/T/#mf21ab57e16b92eb6be6c7df79dc0eb43d4454056>
Reported-by: Morten Welinder <mwelinder@gmail.com>
Cc: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: Vincent Lefevre <vincent@vinc17.net>
Cc: DJ Delorie <dj@redhat.com>
Cc: Paul Zimmermann <Paul.Zimmermann@inria.fr>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Reviewed-by: DJ Delorie <dj@redhat.com>
2024-04-03 09:16:22 -03:00
Alejandro Colomar
e01b3b86e8 manual: Clarify return value of cbrt(3)
Link: <https://lore.kernel.org/linux-man/ZeYKUOKYS7G90SaV@debian/T/#mff0ab388000c6afdb5e5162804d4a0073de481de>
Reported-by: Morten Welinder <mwelinder@gmail.com>
Cowritten-by: Morten Welinder <mwelinder@gmail.com>
Cc: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: Vincent Lefevre <vincent@vinc17.net>
Cc: DJ Delorie <dj@redhat.com>
Cc: Paul Zimmermann <Paul.Zimmermann@inria.fr>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Reviewed-by: DJ Delorie <dj@redhat.com>
2024-04-03 09:16:22 -03:00
Alejandro Colomar
077613291b manual: floor(log2(fabs(x))) has rounding errors
Link: <https://inbox.sourceware.org/libc-alpha/20240305150131.GD3653@qaa.vinc17.org/T/#m3ceecda630012995339bcc5448fee451cf277a8b>
Reported-by: Vincent Lefevre <vincent@vinc17.net>
Suggested-by: Vincent Lefevre <vincent@vinc17.net>
Reviewed-by: DJ Delorie <dj@redhat.com>
Cc: Morten Welinder <mwelinder@gmail.com>
Cc: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: Paul Zimmermann <Paul.Zimmermann@inria.fr>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2024-04-03 09:16:22 -03:00
Alejandro Colomar
b7d15bd1f0 manual: logb(x) is floor(log2(fabs(x)))
log2(3) doesn't accept negative input, but it seems logb(3) does accept
it.

Link: <https://lore.kernel.org/linux-man/ZeYKUOKYS7G90SaV@debian/T/#u>
Reported-by: Morten Welinder <mwelinder@gmail.com>
Reviewed-by: DJ Delorie <dj@redhat.com>
Cc: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: Vincent Lefevre <vincent@vinc17.net>
Cc: Paul Zimmermann <Paul.Zimmermann@inria.fr>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2024-04-03 09:16:22 -03:00
Adhemerval Zanella
a4ed0471d7 Always define __USE_TIME_BITS64 when 64 bit time_t is used
It was raised on libc-help [1] that some Linux kernel interfaces expect
the libc to define __USE_TIME_BITS64 to indicate the time_t size for the
kABI.  Different than defined by the initial y2038 design document [2],
the __USE_TIME_BITS64 is only defined for ABIs that support more than
one time_t size (by defining the _TIME_BITS for each module).

The 64 bit time_t redirects are now enabled using a different internal
define (__USE_TIME64_REDIRECTS). There is no expected change in semantic
or code generation.

Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, and
arm-linux-gnueabi

[1] https://sourceware.org/pipermail/libc-help/2024-January/006557.html
[2] https://sourceware.org/glibc/wiki/Y2038ProofnessDesign

Reviewed-by: DJ Delorie <dj@redhat.com>
2024-04-02 15:28:36 -03:00
Joe Talbott
d370155b9a manual/tunables - Add entry for enable_secure tunable. 2024-03-01 17:43:03 +00:00
Askar Safin
dbae3a3940 trivial doc fix: remove weird phrase "syscall takes zero to five arguments"
"number of arguments, from zero to five" is wrong, because on Linux maximal number
of arguments is 6, not 5. Also, maximal number of arguments is kernel-dependent,
so let's not include it here at all.

Moreover, "Each kind of system call has a definite number of arguments" is questionable.
Think about SYS_open on Linux, which takes 2 or 3 arguments. Or SYS_clone on Linux x86_64, which
takes 2 to 5 arguments. So I propose to fully remove this sentence.

Signed-off-by: Askar Safin <safinaskar@zohomail.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2024-02-14 12:21:03 -03:00
Paul Eggert
e7b90e6e60 stdlib: fix qsort example in manual
* manual/search.texi (Comparison Functions, Array Sort Function):
Sort an array of long ints, not doubles, to avoid hassles
with NaNs.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2024-02-01 17:54:21 -08:00
Jakub Jelinek
c62b6265a6 manual: Fix up stdbit.texi
My recent change broke make pdf and in other documentation formats
results in weird rendering and invalid URL, all because of a forgotten
comma to separate @uref arguments.
2024-02-01 16:36:55 +01:00
Joseph Myers
42cc619dfb Refer to C23 in place of C2X in glibc
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.
2024-02-01 11:02:01 +00:00
Jakub Jelinek
da89496337 Use gcc __builtin_stdc_* builtins in stdbit.h if possible
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>
2024-01-31 19:17:27 +01:00
Andreas K. Hüttel
068b04eaed
INSTALL, install.texi: minor updates, regenerate
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-01-31 00:13:43 +01:00
Andreas K. Hüttel
1eed32f366
contrib.texi: update
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-01-30 23:48:12 +01:00
Joe Simmons-Talbott
7765034db2
manual/io: Fix swapped reading and writing phrase.
Reviewed-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-01-30 20:10:38 +01:00
Dennis Brendel
c06c8aeb61 manual: fix order of arguments of memalign and aligned_alloc (Bug 27547)
On the summary page the order of the function arguments was reversed, but it is
in correct order in the other places of the manual.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2024-01-24 12:10:38 -05:00
Florian Weimer
486452affb manual, NEWS: Document malloc side effect of dynamic TLS changes
The increased malloc subsystem usage is a side effect of
commit d2123d6827 ("elf: Fix slow tls
access after dlopen [BZ #19924]").

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
2024-01-24 09:34:15 +01:00
Adhemerval Zanella
709fbd3ec3 stdlib: Reinstate stable mergesort implementation on qsort
The mergesort removal from qsort implementation (commit 03bf8357e8)
had the side-effect of making sorting nonstable.  Although neither
POSIX nor C standard specify that qsort should be stable, it seems
that it has become an instance of Hyrum's law where multiple programs
expect it.

Also, the resulting introsort implementation is not faster than
the previous mergesort (which makes the change even less appealing).

This patch restores the previous mergesort implementation, with the
exception of machinery that checks the resulting allocation against
the _SC_PHYS_PAGES (it only adds complexity and the heuristic not
always make sense depending on the system configuration and load).
The alloca usage was replaced with a fixed-size buffer.

For the fallback mechanism, the implementation uses heapsort.  It is
simpler than quicksort, and it does not suffer from adversarial
inputs.  With memory overcommit, it should be rarely triggered.

The drawback is mergesort requires O(n) extra space, and since it is
allocated with malloc the function is AS-signal-unsafe.  It should be
feasible to change it to use mmap, although I am not sure how urgent
it is.  The heapsort is also nonstable, so programs that require a
stable sort would still be subject to this latent issue.

The tst-qsort5 is removed since it will not create quicksort adversarial
inputs with the current qsort_r implementation.

Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
2024-01-15 15:58:35 -03:00
Adhemerval Zanella
a0cfc48e8a i386: Fail if configured with --enable-cet
Since it is only supported for x86_64.

Checked on i686-linux-gnu.
2024-01-09 13:55:51 -03:00
Adhemerval Zanella
460860f457 Remove ia64-linux-gnu
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>
2024-01-08 17:09:36 -03:00
H.J. Lu
848746e88e elf: Add ELF_DYNAMIC_AFTER_RELOC to rewrite PLT
Add ELF_DYNAMIC_AFTER_RELOC to allow target specific processing after
relocation.

For x86-64, add

 #define DT_X86_64_PLT     (DT_LOPROC + 0)
 #define DT_X86_64_PLTSZ   (DT_LOPROC + 1)
 #define DT_X86_64_PLTENT  (DT_LOPROC + 3)

1. DT_X86_64_PLT: The address of the procedure linkage table.
2. DT_X86_64_PLTSZ: The total size, in bytes, of the procedure linkage
table.
3. DT_X86_64_PLTENT: The size, in bytes, of a procedure linkage table
entry.

With the r_addend field of the R_X86_64_JUMP_SLOT relocation set to the
memory offset of the indirect branch instruction.

Define ELF_DYNAMIC_AFTER_RELOC for x86-64 to rewrite the PLT section
with direct branch after relocation when the lazy binding is disabled.

PLT rewrite is disabled by default since SELinux may disallow modifying
code pages and ld.so can't detect it in all cases.  Use

$ export GLIBC_TUNABLES=glibc.cpu.plt_rewrite=1

to enable PLT rewrite with 32-bit direct jump at run-time or

$ export GLIBC_TUNABLES=glibc.cpu.plt_rewrite=2

to enable PLT rewrite with 32-bit direct jump and on APX processors with
64-bit absolute jump at run-time.

Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
2024-01-05 05:49:49 -08:00
H.J. Lu
bbfb54930c i386: Ignore --enable-cet
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>
2024-01-04 06:08:55 -08:00
Joseph Myers
b34b46b880 Implement C23 <stdbit.h>
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.
2024-01-03 12:07:14 +00:00
Paul Eggert
dff8da6b3e Update copyright dates with scripts/update-copyrights 2024-01-01 10:53:40 -08:00
Bruno Haible
e55599e028 manual: Clarify undefined behavior of feenableexcept (BZ 31019)
Explain undefined behavior of feenableexcept in a special case.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2023-12-19 15:12:38 -03:00
Adhemerval Zanella
9c96c87d60 elf: Ignore GLIBC_TUNABLES for setuid/setgid binaries
The tunable privilege levels were a retrofit to try and keep the malloc
tunable environment variables' behavior unchanged across security
boundaries.  However, CVE-2023-4911 shows how tricky can be
tunable parsing in a security-sensitive environment.

Not only parsing, but the malloc tunable essentially changes some
semantics on setuid/setgid processes.  Although it is not a direct
security issue, allowing users to change setuid/setgid semantics is not
a good security practice, and requires extra code and analysis to check
if each tunable is safe to use on all security boundaries.

It also means that security opt-in features, like aarch64 MTE, would
need to be explicit enabled by an administrator with a wrapper script
or with a possible future system-wide tunable setting.

Co-authored-by: Siddhesh Poyarekar  <siddhesh@sourceware.org>
Reviewed-by: DJ Delorie <dj@redhat.com>
2023-11-21 16:15:42 -03:00
Adhemerval Zanella
6c6fce572f elf: Remove /etc/suid-debug support
Since malloc debug support moved to a different library
(libc_malloc_debug.so), the glibc.malloc.check requires preloading the
debug library to enable it.  It means that suid-debug support has not
been working since 2.34.

To restore its support, it would require to add additional information
and parsing to where to find libc_malloc_debug.so.

It is one thing less that might change AT_SECURE binaries' behavior
due to environment configurations.

Checked on x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2023-11-21 16:15:42 -03:00
Carlos O'Donell
3cbaacdfd2 manual: Fix termios.c example. (Bug 31078)
Remove the unused 'char *name;' from the example.

Use write instead of putchar to write input as it is read.

Example tested on x86_64 by compiling and running the example.

Tested by building the manual pdf and reviewing the results.

Reviewed-by: Florian Weimer <fweimer@redhat.com>
2023-11-20 16:42:23 -05:00
Wilco Dijkstra
2f5524cc53 AArch64: Remove Falkor memcpy
The latest implementations of memcpy are actually faster than the Falkor
implementations [1], so remove the falkor/phecda ifuncs for memcpy and
the now unused IS_FALKOR/IS_PHECDA defines.

[1] https://sourceware.org/pipermail/libc-alpha/2022-December/144227.html

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2023-11-13 16:52:50 +00:00
Paul Eggert
d1dcb565a1 Fix type typo in “String/Array Conventions” doc
* manual/string.texi (String/Array Conventions):
Fix typo reported by Alejandro Colomar <alx@kernel.org> in:
https://sourceware.org/pipermail/libc-alpha/2023-November/152646.html
2023-11-08 18:20:09 -08:00
Adhemerval Zanella
bf033c0072 elf: Add glibc.mem.decorate_maps tunable
The PR_SET_VMA_ANON_NAME support is only enabled through a configurable
kernel switch, mainly because assigning a name to a
anonymous virtual memory area might prevent that area from being
merged with adjacent virtual memory areas.

For instance, with the following code:

   void *p1 = mmap (NULL,
                    1024 * 4096,
                    PROT_READ | PROT_WRITE,
                    MAP_PRIVATE | MAP_ANONYMOUS,
                    -1,
                    0);

   void *p2 = mmap (p1 + (1024 * 4096),
                    1024 * 4096,
                    PROT_READ | PROT_WRITE,
                    MAP_PRIVATE | MAP_ANONYMOUS,
                    -1,
                    0);

The kernel will potentially merge both mappings resulting in only one
segment of size 0x800000.  If the segment is names with
PR_SET_VMA_ANON_NAME with different names, it results in two mappings.

Although this will unlikely be an issue for pthread stacks and malloc
arenas (since for pthread stacks the guard page will result in
a PROT_NONE segment, similar to the alignment requirement for the arena
block), it still might prevent the mmap memory allocated for detail
malloc.

There is also another potential scalability issue, where the prctl
requires
to take the mmap global lock which is still not fully fixed in Linux
[1] (for pthread stacks and arenas, it is mitigated by the stack
cached and the arena reuse).

So this patch disables anonymous mapping annotations as default and
add a new tunable, glibc.mem.decorate_maps, can be used to enable
it.

[1] https://lwn.net/Articles/906852/

Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
2023-11-07 10:27:57 -03:00
Adhemerval Zanella
03bf8357e8 stdlib: Remove use of mergesort on qsort (BZ 21719)
This patch removes the mergesort optimization on qsort implementation
and uses the introsort instead.  The mergesort implementation has some
issues:

  - It is as-safe only for certain types sizes (if total size is less
    than 1 KB with large element sizes also forcing memory allocation)
    which contradicts the function documentation.  Although not required
    by the C standard, it is preferable and doable to have an O(1) space
    implementation.

  - The malloc for certain element size and element number adds
    arbitrary latency (might even be worse if malloc is interposed).

  - To avoid trigger swap from memory allocation the implementation
    relies on system information that might be virtualized (for instance
    VMs with overcommit memory) which might lead to potentially use of
    swap even if system advertise more memory than actually has.  The
    check also have the downside of issuing syscalls where none is
    expected (although only once per execution).

  - The mergesort is suboptimal on an already sorted array (BZ#21719).

The introsort implementation is already optimized to use constant extra
space (due to the limit of total number of elements from maximum VM
size) and thus can be used to avoid the malloc usage issues.

Resulting performance is slower due the usage of qsort, specially in the
worst-case scenario (partialy or sorted arrays) and due the fact
mergesort uses a slight improved swap operations.

This change also renders the BZ#21719 fix unrequired (since it is meant
to fix the sorted input performance degradation for mergesort).  The
manual is also updated to indicate the function is now async-cancel
safe.

Checked on x86_64-linux-gnu.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
2023-10-31 14:18:05 -03:00
Adhemerval Zanella
e3397cae92 crypt: Remove manul entry for --enable-crypt 2023-10-31 10:59:04 -03:00