Some CORE-MATH routines uses roundeven and most of ISA do not have
an specific instruction for the operation. In this case, the call
will be routed to generic implementation.
However, if the ISA does support round() and ctz() there is a better
alternative (as used by CORE-MATH).
This patch adds such optimization and also enables it on powerpc.
On a power10 it shows the following improvement:
expm1f master patched improvement
latency 9.8574 7.0139 28.85%
reciprocal-throughput 4.3742 2.6592 39.21%
Checked on powerpc64le-linux-gnu and aarch64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
The constants themselves were added to elf.h back in 8754a4133e but the
array in _dl_show_auxv wasn't modified accordingly, resulting in the
following output when running LD_SHOW_AUXV=1 /bin/true on recent Linux:
AT_??? (0x1b): 0x1c
AT_??? (0x1c): 0x20
With this patch:
AT_RSEQ_FEATURE_SIZE: 28
AT_RSEQ_ALIGN: 32
Tested on Linux 6.11 x86_64
Signed-off-by: Yannick Le Pennec <yannick.lepennec@live.fr>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The test was added in commit ac8cc9e300
without all the required Makefile scaffolding. Tweak the test
so that it actually builds (including with dynamic SIGSTKSZ).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
When adding explicit initialization of rseq fields prior to
registration, I glossed over the fact that 'cpu_id_start' is also
documented as initialized by user-space.
While current kernels don't validate the content of this field on
registration, future ones could.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Add ROP protect instructions to strncpy and ppc-mount functions.
Modify FRAME_MIN_SIZE to 48 bytes for ELFv2 to reserve additional
16 bytes for ROP save slot and padding.
Signed-off-by: Sachin Monga <smonga@linux.ibm.com>
Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
The k>>31 in signgam = 1 - (((k&(k>>31))&1)<<1); is not portable:
* The ISO C standard says "If E1 has a signed type and a negative
value, the resulting value is implementation-defined." (this is
still in C23).
* If the int type is larger than 32 bits (e.g. a 64-bit type),
then k = INT_MAX; line 144 will make k>>31 put 1 in bit 0
(thus signgam will be -1) while 0 is expected.
Moreover, instead of the fx >= 0x1p31f condition, testing fx >= 0
is probably better for 2 reasons:
The signgam expression has more or less a condition on the sign
of fx (the goal of k>>31, which can be dropped with this new
condition). Since fx ≥ 0 should be the most common case, one can
get signgam directly in this case (value 1). And this simplifies
the expression for the other case (fx < 0).
This new condition may be easier/faster to test on the processor
(e.g. by avoiding a load of a constant from the memory).
This is commit d41459c731865516318f813cf4c966dafa0eecbf from CORE-MATH.
Checked on x86_64-linux-gnu.
Exercise the case where an exited thread will cause
pthread_getcpuclockid to fail.
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Test coverage of sem_getvalue is fairly limited. Add a test that runs
it on threads on each CPU. For this purpose I adapted
tst-skeleton-thread-affinity.c; it didn't seem very suitable to use
as-is or include directly in a different test doing things per-CPU,
but did seem a suitable starting point (thus sharing
tst-skeleton-affinity.c) for such testing.
Tested for x86_64.
The CORE-MATH implementation is correctly rounded (for any rounding mode)
and shows better performance to the generic tanf.
The code was adapted to glibc style, to use the definition of
math_config.h, to remove errno handling, and to use a generic
128 bit routine for ABIs that do not support it natively.
Benchtest on x64_64 (Ryzen 9 5900X, gcc 14.2.1), aarch64 (neoverse1,
gcc 13.2.1), and powerpc (POWER10, gcc 13.2.1):
latency master patched improvement
x86_64 82.3961 54.8052 33.49%
x86_64v2 82.3415 54.8052 33.44%
x86_64v3 69.3661 50.4864 27.22%
i686 219.271 45.5396 79.23%
aarch64 29.2127 19.1951 34.29%
power10 19.5060 16.2760 16.56%
reciprocal-throughput master patched improvement
x86_64 28.3976 19.7334 30.51%
x86_64v2 28.4568 19.7334 30.65%
x86_64v3 21.1815 16.1811 23.61%
i686 105.016 15.1426 85.58%
aarch64 18.1573 10.7681 40.70%
power10 8.7207 8.7097 0.13%
Signed-off-by: Alexei Sibidanov <sibid@uvic.ca>
Signed-off-by: Paul Zimmermann <Paul.Zimmermann@inria.fr>
Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: DJ Delorie <dj@redhat.com>
It is based on binary64 erfc-inputs, with random inputs in
[0,b=0x1.41bbf6p+3] where b in the smallest number such that
erfcf(b) rounds to 0 (to nearest).
Reviewed-by: DJ Delorie <dj@redhat.com>
It is based on binary64 erf-inputs, with random inputs in [0,b=0x1.f5a888p+1]
where b in the smallest number such that erff(b) rounds to 1 (to nearest).
Reviewed-by: DJ Delorie <dj@redhat.com>
For a static PIE with non-zero load address, its PT_DYNAMIC segment
entries contain the relocated values for the load address in static PIE.
Since static PIE usually doesn't have PT_PHDR segment, use p_vaddr of
the PT_LOAD segment with offset == 0 as the load address in static PIE
and adjust the entries of PT_DYNAMIC segment in static PIE by properly
setting the l_addr field for static PIE. This fixes BZ #31799.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
Async-signal-safety is preserved, too. In fact, getenv is fully
reentrant and can be called from the malloc call in setenv
(if a replacement malloc uses getenv during its initialization).
This is relatively easy to implement because even before this change,
setenv, unsetenv, clearenv, putenv do not deallocate the environment
strings themselves as they are removed from the environment.
The main changes are:
* Use release stores for environment array updates, following
the usual pattern for safely publishing immutable data
(in this case, the environment strings).
* Do not deallocate the environment array. Instead, keep older
versions around and adopt an exponential resizing policy. This
results in an amortized constant space leak per active environment
variable, but there already is such a leak for the variable itself
(and that is even length-dependent, and includes no-longer used
values).
* Add a seqlock-like mechanism to retry getenv if a concurrent
unsetenv is observed. Without that, it is possible that
getenv returns NULL for a variable that is never unset. This
is visible on some AArch64 implementations with the newly
added stdlib/tst-getenv-unsetenv test case. The mechanism
is not a pure seqlock because it tolerates one write from
unsetenv. This avoids the need for a second copy of the
environ array that getenv can read from a signal handler
that happens to interrupt an unsetenv call.
No manual updates are included with this patch because environ
usage with execve, posix_spawn, system is still not thread-safe
relative unsetenv. The new process may end up with an environment
that misses entries that were never unset. This is the same issue
described above for getenv.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The hardware architects have a new recommendation not to use
non-temporal load/stores for memset. This patch removes this path.
I found there was no difference in the memset speed with/without
non-temporal load/stores either.
Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The hardware architects have a new recommendation not to use
non-temporal load/stores for memcpy. This patch removes this path.
I found there was no difference in the memcpy speed with/without
non-temporal load/stores either.
Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The ROP instructions were added in ISA 3.1 (ie, Power10), however they
were defined so that if executed on older cpus, they would behave as
nops. This allows us to emit them on older cpus and they'd just be
ignored, but if run on a Power10, then the binary would be ROP protected.
Hash instructions use negative offsets so the default position
of ROP pointer is FRAME_ROP_SAVE from caller's SP.
Modified FRAME_MIN_SIZE_PARM to 112 for ELFv2 to reserve
additional 16 bytes for ROP save slot and padding.
Signed-off-by: Sachin Monga <smonga@linux.ibm.com>
Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
This is an addendum to commit b7b52b9dec ("error, error_at_line: Add
missing va_end calls"), which added the va_end calls in the callers where
they belong.
Describe AArch64 specific flags PKEY_DISABLE_READ and PKEY_DISABLE_EXECUTE that
are available on AArch64 systems with enabled Stage 1 permission overlays
feature introduced in Armv8.9 / 9.4 (FEAT_S1POE).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This patch adds support for memory protection keys on AArch64 systems with
enabled Stage 1 permission overlays feature introduced in Armv8.9 / 9.4
(FEAT_S1POE) [1].
1. Internal functions "pkey_read" and "pkey_write" to access data
associated with memory protection keys.
2. Implementation of API functions "pkey_get" and "pkey_set" for
the AArch64 target.
3. AArch64-specific PKEY flags for READ and EXECUTE (see below).
4. New target-specific test that checks behaviour of pkeys on
AArch64 targets.
5. This patch also extends existing generic test for pkeys.
6. HWCAP constant for Permission Overlay Extension feature.
To support more accurate mapping of underlying permissions to the
PKEY flags, we introduce additional AArch64-specific flags. The full
list of flags is:
- PKEY_UNRESTRICTED: 0x0 (for completeness)
- PKEY_DISABLE_ACCESS: 0x1 (existing flag)
- PKEY_DISABLE_WRITE: 0x2 (existing flag)
- PKEY_DISABLE_EXECUTE: 0x4 (new flag, AArch64 specific)
- PKEY_DISABLE_READ: 0x8 (new flag, AArch64 specific)
The problem here is that PKEY_DISABLE_ACCESS has unusual semantics as
it overlaps with existing PKEY_DISABLE_WRITE and new PKEY_DISABLE_READ.
For this reason mapping between permission bits RWX and "restrictions"
bits awxr (a for disable access, etc) becomes complicated:
- PKEY_DISABLE_ACCESS disables both R and W
- PKEY_DISABLE_{WRITE,READ} disables W and R respectively
- PKEY_DISABLE_EXECUTE disables X
Combinations like the one below are accepted although they are redundant:
- PKEY_DISABLE_ACCESS | PKEY_DISABLE_READ | PKEY_DISABLE_WRITE
Reverse mapping tries to retain backward compatibility and ORs
PKEY_DISABLE_ACCESS whenever both flags PKEY_DISABLE_READ and
PKEY_DISABLE_WRITE would be present.
This will break code that compares pkey_get output with == instead
of using bitwise operations. The latter is more correct since PKEY_*
constants are essentially bit flags.
It should be noted that PKEY_DISABLE_ACCESS does not prevent execution.
[1] https://developer.arm.com/documentation/ddi0487/ka/ section D8.4.1.4
Co-authored-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
ThunderX1 and ThunderX2 have been retired for a few years now.
So let's remove the thunderx{,2} specific versions of memcpy.
The performance gain or them was for medium and large sizes
while the generic (aarch64) memcpy will handle just slightly worse.
Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Two of the architecture bits/fenv.h headers define femode_t if
__GLIBC_USE (IEC_60559_BFP_EXT), instead of the correct condition
__GLIBC_USE (IEC_60559_BFP_EXT_C23) (both were added after commit
0175c9e9be, but were probably first
developed before it and then not updated to take account of its
changes). This results in failures of the installed headers check for
fenv.h when building with GCC 15 (defaults to -std=gnu23 - we don't
yet have an installed-headers test specifically for C23 mode and don't
yet require a compiler with such a mode for building glibc) together
with a combination of options leaving C23 features enabled, since the
declarations of functions using femode_t use the correct conditions;
see
<https://sourceware.org/pipermail/libc-testresults/2024q4/013163.html>.
Fix the conditionals to get <fenv.h> to work correctly in C23 mode
again.
Tested with build-many-glibcs.py (arc-linux-gnu, arch-linux-gnuhf,
or1k-linux-gnu-hard, or1k-linux-gnu-soft).
Update the inline asm syscall wrappers to match the newer register constraint
usage in INTERNAL_VSYSCALL_CALL_TYPE. Use the faster mfocrf instruction when
available, rather than the slower mfcr microcoded instruction.
