The function was tuned around 64-byte entry alignment and performs
better for all sizes with it.
As well different code boths where explicitly written to touch the
minimum number of cache line i.e sizes <= 32 touch only the entry
cache line.
In GNU ld, -d assigns space to common symbols for -r (i.e. change common
symbols to STB_GLOBAL definitions). This option was added in commit
da2d1bc5ad (1998) perhaps because ld at
that time had a bug that common symbols did not override shared object
definitions. -d has been long unneeded and more so since -fno-common
was added to +cflags.
By adding an internal alias to avoid the GOT indirection.
On some architecture, __libc_single_thread may be accessed through
copy relocations and thus it requires to update also the copies
default copy.
This is done by adding a new internal macro,
libc_hidden_data_{proto,def}, which has an addition argument that
specifies the alias name (instead of default __GI_ one).
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Fangrui Song <maskray@google.com>
It was added on Linux 5.2 (2db154b3ea8e14b04fee23e3fdfd5e9d17fbc6ae)
as way t move a mount from one place to another and, in the next
commit, allow to attach an unattached mount tree.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
It was added on 5.2 (93766fbd2696c2c4453dd8e1070977e9cd4e6b6d) to
provide a way by which a filesystem opened with fsopen and configured
by a series of fsconfig calls can have a detached mount object
created for it.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.2 (24dcb3d90a1f67fe08c68a004af37df059d74005)
to start the process of preparing to create a superblock that will
then be mountable, using an fd as a context handle.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This avoids a compilation error:
tst-resolv-noaaaa.c: In function 'response':
tst-resolv-noaaaa.c:74:11: error: a label can only be part of a statement and a declaration is not a statement
char ipv4[4] = {192, 0, 2, i + 1};
^~~~
tst-resolv-noaaaa.c:79:11: error: a label can only be part of a statement and a declaration is not a statement
char *name = xasprintf ("ptr-%d", i);
^~~~
It makes sense to include the owner name (LHS) and record type in the
output, so that they can be checked for correctness.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Minor clean-up, we need to change this part in following patch, clean this up
to prevent we duplicated the change twice.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The sanity tests where meant to ensure that the default implementation
was only being built without multiarch with the exception of the
multiarch/rtld-*.S files.
The code used IS_IN (rtld) to check if the build for was for an
multiarch/rtld-*.S file which is incorrect as IS_IN (rtld) is set for
the non-multiarch build as well.
commit 464d189b96 (origin/master, origin/HEAD)
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Wed Jun 22 08:24:21 2022 -0700
stdlib: Remove attr_write from mbstows if dst is NULL [BZ: 29265]
Incorrectly called `__mbstowcs_chk` in the NULL __dst case which is
incorrect as in the NULL __dst case we are explicitly skipping
the objsize checks.
As well, remove the `__always_inline` attribute which exists in
`__fortify_function`.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Most of these don't really matter as there was no dirty upper state
but we should generally avoid stray sse when its not needed.
The one case that really matters is in svml_d_tanh4_core_avx2.S:
blendvps %xmm0, %xmm8, %xmm7
When there was a dirty upper state.
Tested on x86_64-linux
1. Refactor files so that all implementations for in the multiarch
directory.
- Essentially moved sse2 {raw|w}memchr.S implementation to
multiarch/{raw|w}memchr-sse2.S
- The non-multiarch {raw|w}memchr.S file now only includes one of
the implementations in the multiarch directory based on the
compiled ISA level (only used for non-multiarch builds.
Otherwise we go through the ifunc selector).
2. Add ISA level build guards to different implementations.
- I.e memchr-avx2.S which is ISA level 3 will only build if
compiled ISA level <= 3. Otherwise there is no reason to include
it as we will always use one of the ISA level 4
implementations (memchr-evex{-rtm}.S).
3. Add new multiarch/rtld-{raw}memchr.S that just include the
non-multiarch {raw}memchr.S which will in turn select the best
implementation based on the compiled ISA level.
4. Refactor the ifunc selector and ifunc implementation list to use
the ISA level aware wrapper macros that allow functions below the
compiled ISA level (with a guranteed replacement) to be skipped.
- Guranteed replacement essentially means that for any ISA level
build there must be a function that the baseline of the ISA
supports. So for {raw|w}memchr.S since there is not ISA level 2
function, the ISA level 2 build still includes the ISA level
1 (sse2) function. Once we reach the ISA level 3 build, however,
{raw|w}memchr-avx2{-rtm}.S will always be sufficient so the ISA
level 1 implementation ({raw|w}memchr-sse2.S) will not be built.
Tested with and without multiarch on x86_64 for ISA levels:
{generic, x86-64-v2, x86-64-v3, x86-64-v4}
And m32 with and without multiarch.
1. Factor out some of the ISA level defines in isa-level.c to
standalone header isa-level.h
2. Add new headers with ISA level dependent macros for handling
ifuncs.
Note, this file does not change any code.
Tested with and without multiarch on x86_64 for ISA levels:
{generic, x86-64-v2, x86-64-v3, x86-64-v4}
And m32 with and without multiarch.
mbstows is defined if dst is NULL and is defined to special cased if
dst is NULL so the fortify objsize check if incorrect in that case.
Tested on x86-64 linux.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Let's use LC_ALL=C as we do elsewhere for consistency.
Tested on s390x-ibm-linux-gnu.
See: 72bd208846
Signed-off-by: Sam James <sam@gentoo.org>
Reviewed-by: Stefan Liebler <stli@linux.ibm.com>
We already check for it in root configure.ac with AC_CHECK_TOOL. Let's
use the result.
Tested on s390x-ibm-linux-gnu.
Signed-off-by: Sam James <sam@gentoo.org>
Reviewed-by: Stefan Liebler <stli@linux.ibm.com>
commit c22eb807b0
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Thu Jun 16 15:07:12 2022 -0700
x86: Rename generic functions with unique postfix for clarity
Changed the names of the strspn-c, strcspn-c, and strpbrk-c files
in a general refactor. It didn't change the include paths for the
i386 files breaking the i386 build. This commit fixes that.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
No functions are changed. It just renames generic implementations from
'{func}_sse2' to '{func}_generic'. This is just because the postfix
"_sse2" was overloaded and was used for files that had hand-optimized
sse2 assembly implementations and files that just redirected back
to the generic implementation.
Full xcheck passed on x86_64.
The RTLD_BOOTSTRAP branch is used to relocate ld.so itself. It only
needs to handle RELATIVE, GLOB_DAT, and JUMP_SLOT. RELATIVE has been
handled (by _ELF_DYNAMIC_DO_RELOC due to DT_RELACOUNT, or RELR), so the
switch statement only needs to handle GLOB_DAT and JUMP_SLOT.
We can drop these `#if[n]def RTLD_BOOTSTRAP` and add a large
`# ifndef RTLD_BOOTSTRAP` instead.
The RTLD_BOOTSTRAP branch is used to relocate ld.so itself. It only
needs to handle RELATIVE, GLOB_DAT, and JUMP_SLOT.
TLSDESC/TLS_DTPMOD/TLS_DTPREL handling can be removed. Remove
`case AARCH64_R(RELATIVE)` as well as elf_machine_rela has checked it.
Tested on aarch64-linux-gnu.
The RTLD_BOOTSTRAP branch is used to relocate ld.so itself. It only
needs to handle RELATIVE, GLOB_DAT, and the symbolic relocation type
(R_RISCV_{32,64}). NONE and IRELATIVE can be removed.
The code relies on ld.so having DT_RELACOUNT so that the RTLD_BOOTSTRAP
branch does not need handle RELATIVE. Drop this minor size
optimization for clarity.
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
1. Fix incorrect lower-bound threshold in L(large_memcpy_2x).
Previously was using `__x86_rep_movsb_threshold` and should
have been using `__x86_shared_non_temporal_threshold`.
2. Avoid reloading __x86_shared_non_temporal_threshold before
the L(large_memcpy_4x) bounds check.
3. Document the second bounds check for L(large_memcpy_4x)
more clearly.
The lower-bound (16448) and upper-bound (SIZE_MAX / 16) are assumed
by memmove-vec-unaligned-erms.
The lower-bound is needed because memmove-vec-unaligned-erms unrolls
the loop aggressively in the L(large_memset_4x) case.
The upper-bound is needed because memmove-vec-unaligned-erms
right-shifts the value of `x86_non_temporal_threshold` by
LOG_4X_MEMCPY_THRESH (4) which without a bound may overflow.
The lack of lower-bound can be a correctness issue. The lack of
upper-bound cannot.
If an executable has copy relocations for extern protected data, that
can only work if the library containing the definition is built with
assumptions (a) the compiler emits GOT-generating relocations (b) the
linker produces R_*_GLOB_DAT instead of R_*_RELATIVE. Otherwise the
library uses its own definition directly and the executable accesses a
stale copy. Note: the GOT relocations defeat the purpose of protected
visibility as an optimization, but allow rtld to make the executable and
library use the same copy when copy relocations are present, but it
turns out this never worked perfectly.
ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA has strange semantics when both
a.so and b.so define protected var and the executable copy relocates
var: b.so accesses its own copy even with GLOB_DAT. The behavior change
is from commit 62da1e3b00 (x86) and then
copied to nios2 (ae5eae7cfc) and arc
(0e7d930c4c).
Without ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA, b.so accesses the copy
relocated data like a.so.
There is now a warning for copy relocation on protected symbol since
commit 7374c02b68. It's extremely
unlikely anyone relies on the ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA
behavior, so let's remove it: this removes a check in the symbol lookup
code.
This has been missing since the the ifuncs where added.
The performance of SSE4.2 is preferable to to SSE2.
Measured on Tigerlake with N = 20 runs.
Geometric Mean of all benchmarks SSE4.2 / SSE2: 0.906
Move the setting of `rep_movsb_stop_threshold` to after the tunables
have been collected so that the `rep_movsb_stop_threshold` (which
is used to redirect control flow to the non_temporal case) will
use any user value for `non_temporal_threshold` (set using
glibc.cpu.x86_non_temporal_threshold)
Refine commit 349b0441da:
1. Copy relocations for extern protected data do not work properly,
regardless whether GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS is used.
It makes sense to produce a warning unconditionally.
2. Non-zero value of an undefined function symbol may break pointer
equality, but may be benign in many cases (many programs don't take the
address in the shared object then compare it with the address in the
executable). Reword the diagnostic to be clearer.
3. Remove the unneeded condition !(undef_map->l_1_needed &
GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS). If the executable does
not not have GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS (can only
occur in error cases), the diagnostic should be emitted as well.
When the defining shared object has
GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS, report an error to apply
the intended enforcement.
On s390x when compiling with GCC 12, I get this warning:
utf8-utf16-z9.c:
../iconv/loop.c: In function ‘__from_utf8_loop_etf3eh_single’:
../iconv/loop.c:445:22: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
445 | bytebuf[inlen++] = *inptr++;
| ~~~~~~~~~~~~~~~~~^~~~~~~~~~
../iconv/loop.c:381:17: note: at offset 4 into destination object ‘bytebuf’ of size 4
381 | unsigned char bytebuf[MAX_NEEDED_INPUT];
| ^~~~~~~
../iconv/loop.c:445:22: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
445 | bytebuf[inlen++] = *inptr++;
| ~~~~~~~~~~~~~~~~~^~~~~~~~~~
../iconv/loop.c:381:17: note: at offset 5 into destination object ‘bytebuf’ of size 4
381 | unsigned char bytebuf[MAX_NEEDED_INPUT];
| ^~~~~~~
This patch tells the compiler that inend is always behind inptr which
avoids the warning. Note that the SINGLE function is only used to
implement the mb*towc*() or wc*tomb*() functions. Those functions use
inptr and inend pointing to a variable on stack, compute the inend pointer
or explicitly check the arguments which always leads to inptr < inend.
Special notes for backporters (according to Siddhesh Poyarekar):
If someone wants to backport this patch to release branches, they should
also backport the following wcrtomb change. Otherwise the assumptions
assumed by this patch are not true.
commit 9bcd12d223
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Fri May 13 19:10:15 2022 +0530
wcrtomb: Make behavior POSIX compliant
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Add a proper bounds check to __libc_ifunc_impl_list. This makes MAX_IFUNC
redundant and fixes several targets that will write outside the array.
To avoid unnecessary large diffs, pass the maximum in the argument 'i' to
IFUNC_IMPL_ADD - 'max' can be used in new ifunc definitions and existing
ones can be updated if desired.
Passes buildmanyglibc.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Remove an unconditional RMW on flags2 in flockfile - we don't need to change
_IO_FLAGS2_NEED_LOCK since it isn't used in flockfile or funlockfile.
This fixes BZ #27842.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Optimizations are:
1. Reduce code size (-112 bytes).
2. Remove redundant move instructions.
3. Slightly improve instruction selection/scheduling where
possible.
4. Prefer registers which get short instruction encoding.
5. Reduce rodata size (-4k+ rodata is shared with avx2).
Result is roughly a 15-16% speedup:
Function, New Time, Old Time, New / Old
_ZGVbN4v_tanhf, 3.158, 3.749, 0.842
Optimizations are:
1. Reduce code size (-81 bytes).
2. Remove redundant move instructions.
3. Slightly improve instruction selection/scheduling where
possible.
4. Prefer registers which get short instruction encoding.
5. Reduce rodata size (-32 bytes).
Result is roughly a 17-18% speedup:
Function, New Time, Old Time, New / Old
_ZGVdN8v_tanhf, 1.977, 2.402, 0.823
tanhf-avx2 and tanhf-sse4 use the same data tables so we can save
over 4kb using a shared datatable. This does increase the memory
footprint of the sse4 version (as now all the targets are 32 bytes
instead of 16), generally it seems worth the code size save.
NB: This patch doesn't do anything itself, it is setup for future
patches.
Optimizations are:
1. Reduce code size (-67 bytes).
2. Remove redundant move instructions.
3. Slightly improve instruction selection/scheduling where
possible.
4. Reduce rodata usage (-448 bytes).
Result is roughly a 14% speedup:
Function, New Time, Old Time, New / Old
_ZGVeN16v_tanhf, 0.649, 0.752, 0.863
Improvements are:
1. Reduce code size (-62 bytes).
2. Remove redundant move instructions.
3. Slightly improve instruction selection/scheduling where
possible.
4. Prefer registers which get short instruction encoding.
5. Reduce rodata usage (-16 bytes).
The throughput improvement is not significant as the port 0 bottleneck
is unavoidable.
Function, New Time, Old Time, New / Old
_ZGVbN4v_atanhf, 8.821, 8.903, 0.991
Improvements are:
1. Reduce code size (-60 bytes).
2. Remove redundant move instructions.
3. Slightly improve instruction selection/scheduling where
possible.
4. Prefer registers which get short instruction encoding.
5. Shrink rodata usage (-32 bytes).
The throughput improvement is not that significant (3-5%) as the
port 0 bottleneck is unavoidable.
Function, New Time, Old Time, New / Old
_ZGVdN8v_atanhf, 2.799, 2.923, 0.958
Improvements are:
1. Reduce code size (-64 bytes).
2. Remove redundant move instructions.
3. Slightly improve instruction selection/scheduling where
possible.
4. Reduce rodata size ([-128, -188] bytes).
The throughput improvement is not significant as the port 0 bottleneck
is unavoidable.
Function, New Time, Old Time, New / Old
_ZGVeN16v_atanhf, 1.39, 1.408, 0.987
