Instead of polling the stderr, create two pipes and fork to check
if child timeout as expected similar to tst-pselect.c. Also lower
the timeout value.
Checked on x86_64-linux-gnu.
This is a workaround (hack) for a gcc optimization issue (PR 99551).
Without this the generated code may evaluate the expression in the
cold path which causes performance regression for small allocations
in the memory tagging disabled (common) case.
Reviewed-by: DJ Delorie <dj@redhat.com>
The internal _mid_memalign already returns newly tagged memory.
(__libc_memalign and posix_memalign already relied on this, this
patch fixes the other call sites.)
Reviewed-by: DJ Delorie <dj@redhat.com>
The previous patch ensured that all chunk to mem computations use
chunk2rawmem, so now we can rename it to chunk2mem, and in the few
cases where the tag of mem is relevant chunk2mem_tag can be used.
Replaced tag_at (chunk2rawmem (x)) with chunk2mem_tag (x).
Renamed chunk2rawmem to chunk2mem.
Reviewed-by: DJ Delorie <dj@redhat.com>
The difference between chunk2mem and chunk2rawmem is that the latter
does not get the memory tag for the returned pointer. It turns out
chunk2rawmem almost always works:
The input of chunk2mem is a chunk pointer that is untagged so it can
access the chunk header. All memory that is not user allocated heap
memory is untagged, which in the current implementation means that it
has the 0 tag, but this patch does not rely on the tag value. The
patch relies on that chunk operations are either done on untagged
chunks or without doing memory access to the user owned part.
Internal interface contracts:
sysmalloc: Returns untagged memory.
_int_malloc: Returns untagged memory.
_int_free: Takes untagged memory.
_int_memalign: Returns untagged memory.
_int_realloc: Takes and returns tagged memory.
So only _int_realloc and functions outside this list need care.
Alignment checks do not need the right tag and tcache works with
untagged memory.
tag_at was kept in realloc after an mremap, which is not strictly
necessary, since the pointer is only used to retag the memory, but this
way the tag is guaranteed to be different from the old tag.
Reviewed-by: DJ Delorie <dj@redhat.com>
The comment explained why different tag is used after mremap, but
for that correctly tagged pointer should be passed to tag_new_usable.
Use chunk2mem to get the tag.
Reviewed-by: DJ Delorie <dj@redhat.com>
This is a pure refactoring change that does not affect behaviour.
The CHUNK_AVAILABLE_SIZE name was unclear, the memsize name tries to
follow the existing convention of mem denoting the allocation that is
handed out to the user, while chunk is its internally used container.
The user owned memory for a given chunk starts at chunk2mem(p) and
the size is memsize(p). It is not valid to use on dumped heap chunks.
Moved the definition next to other chunk and mem related macros.
Reviewed-by: DJ Delorie <dj@redhat.com>
This is a target hook for memory tagging, the original was a naive
implementation. Uses the same algorithm as __libc_mtag_tag_region,
but with instructions that also zero the memory. This was not
benchmarked on real cpu, but expected to be faster than the naive
implementation.
This is a target hook for memory tagging, the original was a naive
implementation. The optimized version relies on "dc gva" to tag 64
bytes at a time for large allocations and optimizes small cases without
adding too many branches. This was not benchmarked on real cpu, but
expected to be faster than the naive implementation.
This is a common operation when heap tagging is enabled, so inline the
instruction instead of using an extern call.
The .inst directive is used instead of the name of the instruction (or
acle intrinsics) because malloc.c is not compiled for armv8.5-a+memtag
architecture, runtime cpu support detection is used.
Prototypes are removed from the comments as they were not always
correct.
Use the runtime check where possible: it should not cause slow down in
the !USE_MTAG case since then mtag_enabled is constant false, but it
allows compiling the tagging logic so it's less likely to break or
diverge when developers only test the !USE_MTAG case.
Reviewed-by: DJ Delorie <dj@redhat.com>
The branches may be better optimized since mtag_enabled is widely used.
Granule size larger than a chunk header is not supported since then we
cannot have both the chunk header and user area granule aligned. To
fix that for targets with large granule, the chunk layout has to change.
So code that attempted to handle the granule mask generally was changed.
This simplified CHUNK_AVAILABLE_SIZE and the logic in malloc_usable_size.
Reviewed-by: DJ Delorie <dj@redhat.com>
When glibc is built with memory tagging support (USE_MTAG) but it is not
enabled at runtime (mtag_enabled) then unconditional memset was used
even though that can be often avoided.
This is for performance when tagging is supported but not enabled.
The extra check should have no overhead: tag_new_zero_region already
had a runtime check which the compiler can now optimize away.
Reviewed-by: DJ Delorie <dj@redhat.com>
The memset api is suboptimal and does not provide much benefit. Memory
tagging only needs a zeroing memset (and only for memory that's sized
and aligned to multiples of the tag granule), so change the internal
api and the target hooks accordingly. This is to simplify the
implementation of the target hook.
Reviewed-by: DJ Delorie <dj@redhat.com>
A flag check can be faster than function pointers because of how
branch prediction and speculation works and it can also remove a layer
of indirection when there is a mismatch between the malloc internal
tag_* api and __libc_mtag_* target hooks.
Memory tagging wrapper functions are moved to malloc.c from arena.c and
the logic now checks mmap_enabled. The definition of tag_new_usable is
moved after chunk related definitions.
This refactoring also allows using mtag_enabled checks instead of
USE_MTAG ifdefs when memory tagging support only changes code logic
when memory tagging is enabled at runtime. Note: an "if (false)" code
block is optimized away even at -O0 by gcc.
Reviewed-by: DJ Delorie <dj@redhat.com>
This does not change behaviour, just removes one layer of indirection
in the internal memory tagging logic.
Use tag_ and mtag_ prefixes instead of __tag_ and __mtag_ since these
are all symbols with internal linkage, private to malloc.c, so there
is no user namespace pollution issue.
Reviewed-by: DJ Delorie <dj@redhat.com>
Use inline functions instead of macros, because macros can cause unused
variable warnings and type conversion issues. We assume these functions
may appear in the code but only in dead code paths (hidden by a runtime
check), so it's important that they can compile with correct types, but
if they are actually used that should be an error.
Currently the hooks are only used when USE_MTAG is true which only
happens on aarch64 and then the aarch64 specific code is used not this
generic header. However followup refactoring will allow the hooks to
be used with !USE_MTAG.
Note: the const qualifier in the comment was wrong: changing tags is a
write operation.
Reviewed-by: DJ Delorie <dj@redhat.com>
Either the memory belongs to the dumped area, in which case we don't
want to tag (the dumped area has the same tag as malloc internal data
so tagging is unnecessary, but chunks there may not have the right
alignment for the tag granule), or the memory will be unmapped
immediately (and thus tagging is not useful).
Reviewed-by: DJ Delorie <dj@redhat.com>
The chunk cannot be a dumped one here. The only non-obvious cases
are free and realloc which may be called on a dumped area chunk,
but in both cases it can be verified that tagging is already
avoided for dumped area chunks.
Reviewed-by: DJ Delorie <dj@redhat.com>
This is only used internally in malloc.c, the extern declaration
was wrong, __mtag_mmap_flags has internal linkage.
Reviewed-by: DJ Delorie <dj@redhat.com>
At an _int_free call site in realloc the wrong size was used for tag
clearing: the chunk header of the next chunk was also cleared which
in practice may work, but logically wrong.
The tag clearing is moved before the memcpy to save a tag computation,
this avoids a chunk2mem. Another chunk2mem is removed because newmem
does not have to be recomputed. Whitespaces got fixed too.
Reviewed-by: DJ Delorie <dj@redhat.com>
_int_free must be called with a chunk that has its tag reset. This was
missing in a rare case that could crash when heap tagging is enabled:
when in a multi-threaded process the current arena runs out of memory
during realloc, but another arena still has space to finish the realloc
then _int_free was called without clearing the user allocation tags.
Fixes bug 27468.
Reviewed-by: DJ Delorie <dj@redhat.com>
The arch13 memmove variant is currently selected by the ifunc selector
if the Miscellaneous-Instruction-Extensions Facility 3 facility bit
is present, but the function is also using vector instructions.
If the vector support is not present, one is receiving an operation
exception.
Therefore this patch also checks for vector support in the ifunc
selector and in ifunc-impl-list.c.
Just to be sure, the configure check is now also testing an arch13
vector instruction and an arch13 Miscellaneous-Instruction-Extensions
Facility 3 instruction.
Both new tests io/tst-stat and io/tst-stat-lfs (_FILE_OFFSET_BITS=64)
are comparing the nanosecond fields with the statx result. Unfortunately
on s390(31bit) those fields are always zero if old KABI with non-LFS
support is used. With _FILE_OFFSET_BITS=64 stat is using statx internally.
As suggested by Adhemerval this patch disables the nanosecond check for
s390(31bit).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This essentially folds compat_symbol_unique functionality into
compat_symbol.
This change eliminates the need for intermediate aliases for defining
multiple symbol versions, for both compat_symbol and versioned_symbol.
Some binutils versions do not suport multiple versions per symbol on
some targets, so aliases are automatically introduced, similar to what
compat_symbol_unique did. To reduce symbol table sizes, a configure
check is added to avoid these aliases if they are not needed.
The new mechanism works with data symbols as well as function symbols,
due to the way an assembler-level redirect is used. It is not
compatible with weak symbols for old binutils versions, which is why
the definition of __malloc_initialize_hook had to be changed. This
is not a loss of functionality because weak symbols do not matter
to dynamic linking.
The placeholder symbol needs repeating in nptl/libpthread-compat.c
now that compat_symbol is used, but that seems more obvious than
introducing yet another macro.
A subtle difference was that compat_symbol_unique made the symbol
global automatically. compat_symbol does not do this, so static
had to be removed from the definition of
__libpthread_version_placeholder.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
These symbol usages are not definitions, so compat_symbol_reference is
more appropriate than compat_symbol. compat_symbol_reference is also
safe to emit multiple times (in case the inline assembly is
duplicated; this is possible because it is nested in a function).
compat_symbol does not necessarily have this property because it is
intended to provide a symbol definition.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
A subsequent change will require including <config.h> for defining
symbol_version_reference. <libc-symbol.h> should not include
<config.h> for _ISOMAC, so it cannot define symbol_version_reference
anymore, but symbol_version_reference is needed <shlib-compat.h> even
for _ISOMAC. Moving the definition of symbol_version_reference to a
separate file <libc-symver.h> makes it possible to use a single
definition for both cases.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
GNU/Hurd's readlink system call is partly implemented in userspace, which
also allocates a buffer on the stack for the result, and thus needs one
more path.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2b47727c68 ("posix: Consolidate register-atfork") introduced a fork.h
header to declare the atfork unregister hook, but was missing adding it
for htl.
This fixes tst-atfork2.
During critical sections, signal handling is deferred and thus RPCs return
EINTR, even if SA_RESTART is set. We thus have to restart the whole critical
section in that case.
This also adds HURD_CRITICAL_UNLOCK in the cases where one wants to
break the section in the middle.
This change adds new test to assess sigtimedwait's timeout related
functionality - the sigset_t is configured for SIGUSR1, which will
not be triggered, so sigtimedwait just waits for timeout.
To be more specific - two use cases are checked:
- if sigtimedwait times out immediately when passed struct timespec has
zero values of tv_nsec and tv_sec.
- if sigtimedwait times out after timeout specified in passed argument
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This change adds new test to assess select()'s timeout related
functionality (the rdfs set provides valid fd - stderr - but during
normal program operation there is no data to be read, so one just
waits for timeout).
To be more specific - two use cases are checked:
- if select() times out immediately when passed struct timeval has
zero values of tv_usec and tv_sec.
- if select() times out after timeout specified in passed argument
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This code provides test to check if time on target machine is properly
read via ntp_gettime syscall.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
After this patch applied the ntp_gettimex function is always declared
in the sys/timex.h header. Currently it is not when __REDIRECT_NTH is
defined (i.e. in ARM 32 bit port).
The generic implementation basically handle the system agnostic logic
(filtering out the invalid signals) while the __libc_sigaction is
the function with implements the system and architecture bits.
Checked on x86_64-linux-gnu and i686-linux-gnu.
