Florian Weimer [Mon, 3 May 2021 06:12:11 +0000 (08:12 +0200)]
nptl: Move call_once into libc
The symbol was moved using scripts/move-symbol-to-libc.py.
This change also turns __pthread_once into a compatibility symbol
because after the call_once move, an internal call to __pthread_once
can be used. This an adjustment to __libc_once: Outside libc (e.g.,
in nscd), it has to call pthread_once. With __pthread_once as a
compatibility symbol, it is no longer to add a new GLIBC_2.34
version after the move from libpthread, and this commit removes
the new __pthread_once@@GLIBC_2.34 version.
Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>
This implementation is based on __memset_power8 and integrates a lot
of suggestions from Anton Blanchard.
The biggest difference is that it makes extensive use of stxvl to
alignment and tail code to avoid branches and small stores. It has
three main execution paths:
a) "Short lengths" for lengths up to 64 bytes, avoiding as many
branches as possible.
b) "General case" for larger lengths, it has an alignment section
using stxvl to avoid branches, a 128 bytes loop and then a tail
code, again using stxvl with few branches.
c) "Zeroing cache blocks" for lengths from 256 bytes upwards and set
value being zero. It is mostly the __memset_power8 code but the
alignment phase was simplified because, at this point, address is
already 16-bytes aligned and also changed to use vector stores.
The tail code was also simplified to reuse the general case tail.
All unaligned stores use stxvl instructions that do not generate
alignment interrupts on POWER10, making it safe to use on
caching-inhibited memory.
On average, this implementation provides something around 30%
improvement when compared to __memset_power8.
Reviewed-by: Matheus Castanho <msc@linux.ibm.com> Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
This implementation is based on __memcpy_power8_cached and integrates
suggestions from Anton Blanchard.
It benefits from loads and stores with length for short lengths and for
tail code, simplifying the code.
All unaligned memory accesses use instructions that do not generate
alignment interrupts on POWER10, making it safe to use on
caching-inhibited memory.
The main loop has also been modified in order to increase instruction
throughput by reducing the dependency on updates from previous iterations.
On average, this implementation provides around 30% improvement when
compared to __memcpy_power7 and 10% improvement in comparison to
__memcpy_power8_cached.
This patch was initially based on the __memmove_power7 with some ideas
from strncpy implementation for Power 9.
Improvements from __memmove_power7:
1. Use lxvl/stxvl for alignment code.
The code for Power 7 uses branches when the input is not naturally
aligned to the width of a vector. The new implementation uses
lxvl/stxvl instead which reduces pressure on GPRs. It also allows
the removal of branch instructions, implicitly removing branch stalls
and mispredictions.
2. Use of lxv/stxv and lxvl/stxvl pair is safe to use on Cache Inhibited
memory.
On Power 10 vector load and stores are safe to use on CI memory for
addresses unaligned to 16B. This code takes advantage of this to
do unaligned loads.
The unaligned loads don't have a significant performance impact by
themselves. However doing so decreases register pressure on GPRs
and interdependence stalls on load/store pairs. This also improved
readability as there are now less code paths for different alignments.
Finally this reduces the overall code size.
3. Improved performance.
This version runs on average about 30% better than memmove_power7
for lengths larger than 8KB. For input lengths shorter than 8KB
the improvement is smaller, it has on average about 17% better
performance.
This version has a degradation of about 50% for input lengths
in the 0 to 31 bytes range when dest is unaligned.
Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
Joseph Myers [Thu, 29 Apr 2021 10:50:11 +0000 (10:50 +0000)]
Update kernel version to 5.12 in tst-mman-consts.py.
This patch updates the kernel version in the test tst-mman-consts.py
to 5.12. (There are no new MAP_* constants covered by this test in
5.12 that need any other header changes.)
Joseph Myers [Wed, 28 Apr 2021 17:19:24 +0000 (17:19 +0000)]
Update syscall lists for Linux 5.12.
Linux 5.12 has one new syscall, mount_setattr. Update
syscall-names.list and regenerate the arch-syscall.h headers with
build-many-glibcs.py update-syscalls.
Martin Sebor [Tue, 27 Apr 2021 19:01:55 +0000 (13:01 -0600)]
Add __attribute_access_none to disable GCC warnings [BZ #27714]
GCC 11 warns when a pointer to an uninitialized object is passed
to a function that takes a const-qualified argument. This is done
on the assumption that most such functions read from the object.
For the rare case of a function that doesn't, GCC 11 extends
attribute access to add a new mode called none.
POSIX pthread_setspecific() is one such rare function that takes
a const void* argument but that doesn't read from the object it
points to. To suppress the -Wmaybe-uninitialized issued by GCC
11 when the address of an uninitialized object is passed to it
(e.g., the result of malloc()), this change #defines
__attr_access_none in cdefs.h and uses the macro on the function
in sysdeps/htl/pthread.h and sysdeps/nptl/pthread.h.
Hanataka Shinya [Thu, 18 Feb 2021 04:00:48 +0000 (23:00 -0500)]
LC_COLLATE: Fix last character ellipsis handling (Bug 22668)
During ellipsis processing the collation cursor was not correctly
moved to the end of the ellipsis after processing.
The code inserted the new entry after the cursor, but before the
real end of the ellipsis:
[cursor]
... element_t <-> element_t <-> element_t <-> element_t
"<U0000>" "<U0001>" "<U007F>"
startp endp
The cursor should be pointing at endp, the last element in the
doubly-linked list, otherwise when execution returns to the
caller we will start inserting the next line after <U007E>.
Subsequent operations end up unlinking the ellipsis end entry or
just leaving it in the list dangling from the end. This kind of
dangling is immediately visible in C.UTF-8 with the following
sorting from strcoll:
<U0010FFFF>
<U0000FFFF>
<U000007FF>
<U0000007F>
With the cursor correctly adjusted the end entry is correctly given
the right location and thus the right weight.
Retested and no regressions on x86_64 and i686.
Co-authored-by: Carlos O'Donell <carlos@redhat.com>
No bug. This commit optimizes strchr-evex.S. The optimizations are
mostly small things such as save an ALU in the alignment process,
saving a few instructions in the loop return. The one significant
change is saving 2 instructions in the 4x loop. test-strchr,
test-strchrnul, test-wcschr, and test-wcschrnul are all passing.
No bug. This commit optimizes strchr-avx2.S. The optimizations are all
small things such as save an ALU in the alignment process, saving a
few instructions in the loop return, saving some bytes in the main
loop, and increasing the ILP in the return cases. test-strchr,
test-strchrnul, test-wcschr, and test-wcschrnul are all passing.
And pthread_mutexattr_getkind_np as a compatibility symbol.
(There is no declaration in <pthread.h>, so there is no need
to add an alias or a deprecation warning there.)
The symbols were moved using scripts/move-symbol-to-libc.py.
nptl: Move pthread_mutex_trylock, __pthread_mutex_trylock into libc
The symbols were moved using scripts/move-symbol-to-libc.py.
__pthread_mutex_trylock is used to implement mtx_timedlock,
which still resides in libpthread, so add a GLIBC_2.34 version
for it, to match the existing GLIBC_2.0 version.
nptl: Move pthread_mutex_timedlock, pthread_mutex_clocklock to libc
The symbols were moved using scripts/move-symbol-to-libc.py.
The symbol aliasing follows pthread_cond_timedwait et al.
Missing hidden prototypes had to be added to nptl/pthreadP.h
for consistency.
1. Take into account first 16B comparison for aligned strings
The previous version compares the first 16B and increments r4 by the number
of bytes until the address is 16B-aligned, then starts doing aligned loads at
that address. For aligned strings, this causes the first 16B to be compared
twice, because the increment is 0. Here we calculate the next 16B-aligned
address differently, which avoids that issue.
2. Use simple comparisons for the first ~192 bytes
The main loop is good for big strings, but comparing 16B each time is better
for smaller strings. So after aligning the address to 16 Bytes, we check
more 176B in 16B chunks. There may be some overlaps with the main loop for
unaligned strings, but we avoid using the more aggressive strategy too soon,
and also allow the loop to start at a 64B-aligned address. This greatly
benefits smaller strings and avoids overlapping checks if the string is
already aligned at a 64B boundary.
3. Reduce dependencies between load blocks caused by address calculation on loop
Doing a precise time tracing on the code showed many loads in the loop were
stalled waiting for updates to r4 from previous code blocks. This
implementation avoids that as much as possible by using 2 registers (r4 and
r5) to hold addresses to be used by different parts of the code.
Also, the previous code aligned the address to 16B, then to 64B by doing a
few 48B loops (if needed) until the address was aligned. The main loop could
not start until that 48B loop had finished and r4 was updated with the
current address. Here we calculate the address used by the loop very early,
so it can start sooner.
The main loop now uses 2 pointers 128B apart to make pointer updates less
frequent, and also unrolls 1 iteration to guarantee there is enough time
between iterations to update the pointers, reducing stalled cycles.
4. Use new P10 instructions
lxvp is used to load 32B with a single instruction, reducing contention in
the load queue.
vextractbm allows simplifying the tail code for the loop, replacing
vbpermq and avoiding having to generate a permute control vector.
Reviewed-by: Paul E Murphy <murphyp@linux.ibm.com> Reviewed-by: Raphael M Zinsly <rzinsly@linux.ibm.com> Reviewed-by: Lucas A. M. Magalhaes <lamm@linux.ibm.com>
nptl: Move setxid broadcast implementation into libc
The signal handler is exported as __nptl_setxid_sighandler, so
that the libpthread initialization code can install it. This
is sufficient for now because it is guarantueed to happen before
the first pthread_create call.
nptl: Move core condition variable functions into libc
Onl pthread_cond_clockwait did not have a forwarder, so it needs
a new symbol version.
Some complications arise due to the need to supply hidden aliases,
GLIBC_PRIVATE exports (for the C11 condition variable implementation
that still remains in libpthread) and 64-bit time_t stubs.
pthread_cond_broadcast, pthread_cond_signal, pthread_cond_timedwait,
pthread_cond_wait, pthread_cond_clockwait have been moved using
scripts/move-symbol-to-libc.py.
This is complicated because of a second compilation of
nptl/pthread_mutex_lock.c via nptl/pthread_mutex_cond_lock.c.
PTHREAD_MUTEX_VERSIONS is introduced to suppress symbol versions
in that case.
The symbols __pthread_mutex_lock, __pthread_mutex_unlock,
__pthread_mutex_init, __pthread_mutex_destroy, pthread_mutex_lock,
pthread_mutex_unlock, pthread_mutex_init, pthread_mutex_destroy
have been moved using scripts/move-symbol-to-libc.py.
The current approach is to do this optimizations at a higher level,
in generic code, so that single-threaded cases can be specifically
targeted.
Furthermore, using IS_IN (libc) as a compile-time indicator that
all locks are private is no longer correct once process-shared lock
implementations are moved into libc.
The generic <lowlevellock.h> is not compatible with assembler code
(obviously), so it's necessary to remove two long-unused #includes.
This is optimization is similar in spirit to the SINGLE_THREAD_P check
in the malloc implementation. Doing this in generic code allows us
to prioritize those cases which are likely to occur in single-threaded
programs (normal and recursive mutexes).
nptl: Move rwlock functions with forwarders into libc
The forwarders were only used internally, so new symbol versions
are needed. All symbols are moved at once because the forwarders
are no-ops if libpthread is not loaded, leading to inconsistencies
in case of a partial migration.
The symbols __pthread_rwlock_rdlock, __pthread_rwlock_unlock,
__pthread_rwlock_wrlock, pthread_rwlock_rdlock,
pthread_rwlock_unlock, pthread_rwlock_wrlock have been moved using
scripts/move-symbol-to-libc.py.
The __ symbol variants are turned into compat symbols, which is why they
do not receive a GLIBC_2.34 version.
nptl: Move part of TCB initialization from libpthread to __tls_init_tp
This initalization should only happen once for the main thread's TCB.
At present, auditors can achieve this by not linking against
libpthread. If libpthread becomes part of libc, doing this
initialization in libc would happen for every audit namespace,
or too late (if it happens from the main libc only). That's why
moving this code into ld.so seems the right thing to do, right after
the TCB initialization.
For !__ASSUME_SET_ROBUST_LIST ports, this also moves the symbol
__set_robust_list_avail into ld.so, as __nptl_set_robust_list_avail.
It also turned into a proper boolean flag.
Inline the __pthread_initialize_pids function because it seems no
longer useful as a separate function.
elf: Introduce __tls_init_tp for second-phase TCB initialization
TLS_INIT_TP is processor-specific, so it is not a good place to
put thread library initialization code (it would have to be repeated
for all CPUs). Introduce __tls_init_tp as a separate function,
to be called immediately after TLS_INIT_TP. Move the existing
stack list setup code for NPTL to this function.
dlfcn: dlerror needs to call free from the base namespace [BZ #24773]
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).
dlfcn: Failures after dlmopen should not terminate process [BZ #24772]
Commit 9e78f6f6e7134a5f299cc8de77370218f8019237 ("Implement
_dl_catch_error, _dl_signal_error in libc.so [BZ #16628]") has the
side effect that distinct namespaces, as created by dlmopen, now have
separate implementations of the rtld exception mechanism. This means
that the call to _dl_catch_error from libdl in a secondary namespace
does not actually install an exception handler because the
thread-local variable catch_hook in the libc.so copy in the secondary
namespace is distinct from that of the base namepace. As a result, a
dlsym/dlopen/... failure in a secondary namespace terminates the process
with a dynamic linker error because it looks to the exception handler
mechanism as if no handler has been installed.
This commit restores GLRO (dl_catch_error) and uses it to set the
handler in the base namespace.
The pthread_exit symbol was moved using
scripts/move-symbol-to-libc.py. No new symbol version is needed
because there was a forwarder.
The new tests nptl/tst-pthread_exit-nothreads and
nptl/tst-pthread_exit-nothreads-static exercise the scenario
that pthread_exit is called without libpthread having been linked in.
This is not possible for the generic code, so these tests do not
live in sysdeps/pthread for now.
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.
This internal symbol is used as part of the longjmp implementation.
Rename the file from nptl/pt-cleanup.c to nptl/pthread_cleanup_upto.c
so that the pt-* files remain restricted to libpthread.
The definitions in libc are sufficient, the forwarders are no longer
needed.
The symbols have been moved using scripts/move-symbol-to-libc.py.
s390-linux-gnu and s390x-linux-gnu need a new version placeholder
to keep the GLIBC_2.19 symbol version in libpthread.
Tested on i386-linux-gnu, powerpc64le-linux-gnu, s390x-linux-gnu,
x86_64-linux-gnu. Built with build-many-glibcs.py.
nptl: Move legacy cancelation handling into libc as compat symbols
This affects _pthread_cleanup_pop, _pthread_cleanup_pop_restore,
_pthread_cleanup_push, _pthread_cleanup_push_defer. The symbols
have been moved using scripts/move-symbol-to-libc.py.
No new symbol versions are added because the symbols are turned into
compatibility symbols at the same time.
__pthread_cleanup_pop and __pthread_cleanup_push are added as
GLIBC_PRIVATE symbols because they are also used internally, for
glibc's own cancellation handling.
nptl: Move legacy unwinding implementation into libc
It is still used internally. Since unwinding is now available
unconditionally, avoid indirect calls through function pointers loaded
from the stack by inlining the non-cancellation cleanup code. This
avoids a regression in security hardening.
The out-of-line __libc_cleanup_routine implementation is no longer
needed because the inline definition is now static __always_inline.
Szabolcs Nagy [Thu, 11 Feb 2021 13:24:47 +0000 (13:24 +0000)]
elf: Remove lazy tlsdesc relocation related code
Remove generic tlsdesc code related to lazy tlsdesc processing since
lazy tlsdesc relocation is no longer supported. This includes removing
GL(dl_load_lock) from _dl_make_tlsdesc_dynamic which is only called at
load time when that lock is already held.
nptl_db: Support different libpthread/ld.so load orders (bug 27744)
libthread_db is loaded once GDB encounters libpthread, and at this
point, ld.so may not have been processed by GDB yet. As a result,
_rtld_global cannot be accessed by regular means from libthread_db.
To make this work until GDB can be fixed, acess _rtld_global through
a pointer stored in libpthread.
The new test does not reproduce bug 27744 with
--disable-hardcoded-path-in-tests, but is still a valid smoke test.
With --enable-hardcoded-path-in-tests, it is necessary to avoid
add-symbol-file because this can tickle a GDB bug.
No bug. This commit optimizes strlen-avx2.S. The optimizations are
mostly small things but they add up to roughly 10-30% performance
improvement for strlen. The results for strnlen are bit more
ambiguous. test-strlen, test-strnlen, test-wcslen, and test-wcsnlen
are all passing.
No bug. This commit optimizes strlen-evex.S. The
optimizations are mostly small things but they add up to roughly
10-30% performance improvement for strlen. The results for strnlen are
bit more ambiguous. test-strlen, test-strnlen, test-wcslen, and
test-wcsnlen are all passing.
No bug. This commit adds tests cases and benchmarks for page cross and
for memset to the end of the page without crossing. As well in
test-memset.c this commit adds sentinel on start/end of tstbuf to test
for overwrites
x86: Optimize less_vec evex and avx512 memset-vec-unaligned-erms.S
No bug. This commit adds optimized cased for less_vec memset case that
uses the avx512vl/avx512bw mask store avoiding the excessive
branches. test-memset and test-wmemset are passing.