The shmmax expected value is tricky to check because kernel clamps it
to INT_MAX in two cases:
1. Compat symbols with IPC_64, i.e, 32-bit binaries running on 64-bit
kernels.
2. Default symbol without IPC_64 (defined as IPC_OLD within Linux) and
glibc always use IPC_64 for 32-bit ABIs (to support 64-bit time_t).
It means that 32-bit binaries running on 32-bit kernels will not see
shmmax being clamped.
And finding out whether the compat symbol is used would require checking
the underlying kernel against the current ABI. The shmall and shmmni
already provided enough coverage.
Checked on x86_64-linux-gnu and i686-linux-gnu. It should fix the
tst-sysvshm-linux failures on 32-bit kernels.
In the process of optimizing memcpy for AMD machines, we have found the
vector move operations are outperforming enhanced REP MOVSB for data
transfers above the L2 cache size on Zen3 architectures.
To handle this use case, we are adding an upper bound parameter on
enhanced REP MOVSB:'__x86_rep_movsb_stop_threshold'.
As per large-bench results, we are configuring this parameter to the
L2 cache size for AMD machines and applicable from Zen3 architecture
supporting the ERMS feature.
For architectures other than AMD, it is the computed value of
non-temporal threshold parameter.
Reviewed-by: Premachandra Mallappa <premachandra.mallappa@amd.com>
Signal number is written into the tail of buf, but printed from the
beginning, outputting garbage on the screen. Fix this by printing
from the correct position.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Dmitry V. Levin <ldv@altlinux.org>
Add _SC_MINSIGSTKSZ for the minimum signal stack size derived from
AT_MINSIGSTKSZ, which is the minimum number of bytes of free stack
space required in order to gurantee successful, non-nested handling
of a single signal whose handler is an empty function, and _SC_SIGSTKSZ
which is the suggested minimum number of bytes of stack space required
for a signal stack.
If AT_MINSIGSTKSZ isn't available, sysconf (_SC_MINSIGSTKSZ) returns
MINSIGSTKSZ. On Linux/x86 with XSAVE, the signal frame used by kernel
is composed of the following areas and laid out as:
------------------------------
| alignment padding |
------------------------------
| xsave buffer |
------------------------------
| fsave header (32-bit only) |
------------------------------
| siginfo + ucontext |
------------------------------
Compute AT_MINSIGSTKSZ value as size of xsave buffer + size of fsave
header (32-bit only) + size of siginfo and ucontext + alignment padding.
If _SC_SIGSTKSZ_SOURCE or _GNU_SOURCE are defined, MINSIGSTKSZ and SIGSTKSZ
are redefined as
/* Default stack size for a signal handler: sysconf (SC_SIGSTKSZ). */
# undef SIGSTKSZ
# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
/* Minimum stack size for a signal handler: SIGSTKSZ. */
# undef MINSIGSTKSZ
# define MINSIGSTKSZ SIGSTKSZ
Compilation will fail if the source assumes constant MINSIGSTKSZ or
SIGSTKSZ.
The reason for not simply increasing the kernel's MINSIGSTKSZ #define
(apart from the fact that it is rarely used, due to glibc's shadowing
definitions) was that userspace binaries will have baked in the old
value of the constant and may be making assumptions about it.
For example, the type (char [MINSIGSTKSZ]) changes if this #define
changes. This could be a problem if an newly built library tries to
memcpy() or dump such an object defined by and old binary.
Bounds-checking and the stack sizes passed to things like sigaltstack()
and makecontext() could similarly go wrong.
BSD 4.1 did not have an argument for TIOCFLUSH, BSD 4.2 added it. There
are still a lot of applications out there that pass a NULL argument to
TIOCFLUSH, so we should rather cope with it.
The existing code specifies -Wl,--defsym=malloc=0 and other malloc.os
definitions before libc_pic.a so that libc_pic.a(malloc.os) is not
fetched. This trick is used to avoid multiple definition errors which
would happen as a chain result:
dl-allobjs.os has an undefined __libc_scratch_buffer_set_array_size
__libc_scratch_buffer_set_array_size fetches libc_pic.a(scratch_buffer_set_array_size.os)
libc_pic.a(scratch_buffer_set_array_size.os) has an undefined free
free fetches libc_pic.a(malloc.os)
libc_pic.a(malloc.os) has an undefined __libc_message
__libc_message fetches libc_pic.a(libc_fatal.os)
libc_fatal.os will cause a multiple definition error (__GI___libc_fatal)
>>> defined at dl-fxstatat64.c
>>> /tmp/p/glibc/Release/elf/dl-allobjs.os:(__GI___libc_fatal)
>>> defined at libc_fatal.c
>>> libc_fatal.os:(.text+0x240) in archive /tmp/p/glibc/Release/libc_pic.a
LLD processes --defsym after all input files, so this trick does not
suppress multiple definition errors with LLD. Split the step into two
and use an object file to make the intention more obvious and make LLD
work.
This is conceptually more appropriate because --defsym defines a SHN_ABS
symbol while a normal definition is relative to the image base.
See https://sourceware.org/pipermail/libc-alpha/2020-March/111910.html
for discussions about the --defsym semantics.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
For configurations with cross-compiling equal to 'maybe' or 'no',
ldconfig will not run and thus the ld.so.cache will not be created
on the container testroot.pristine.
This lead to failures on both tst-glibc-hwcaps-prepend-cache and
tst-ldconfig-ld_so_conf-update on environments where the same
compiler can be used to build different ABIs (powerpc and x86 for
instance).
This patch addas a new test-container hook, ldconfig.run, that
triggers a ldconfig execution prior the test execution.
Checked on x86_64-linux-gnu and i686-linux-gnu.
commit 94cd37ebb2
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Wed Sep 16 05:27:32 2020 -0700
x86: Use HAS_CPU_FEATURE with IBT and SHSTK [BZ #26625]
broke
GLIBC_TUNABLES=glibc.cpu.hwcaps=-IBT,-SHSTK
since it can no longer disable IBT nor SHSTK. Handle IBT and SHSTK with:
1. Revert commit 94cd37ebb2.
2. Clears the usable CET feature bits if kernel doesn't support CET.
3. Add GLIBC_TUNABLES tests without dlopen.
4. Add tests to verify that CPU_FEATURE_USABLE on IBT and SHSTK matches
_get_ssp.
5. Update GLIBC_TUNABLES tests with dlopen to verify that CET is disabled
with GLIBC_TUNABLES.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
brk used by statup before TCB is properly set, so we can't use
IA64_USE_NEW_STUB.
This patch fixes a regression introduced by 720480934a.
Checked on ia64-linux-gnu.
A not so recent kernel change[1] changed how the trampoline
`__kernel_sigtramp_rt64` is used to call signal handlers.
This was exposed on the test misc/tst-sigcontext-get_pc
Before kernel 5.9, the kernel set LR to the trampoline address and
jumped directly to the signal handler, and at the end the signal
handler, as any other function, would `blr` to the address set. In
other words, the trampoline was executed just at the end of the signal
handler and the only thing it did was call sigreturn. But since
kernel 5.9 the kernel set CTRL to the signal handler and calls to the
trampoline code, the trampoline then `bctrl` to the address in CTRL,
setting the LR to the next instruction in the middle of the
trampoline, when the signal handler returns, the rest of the
trampoline code executes the same code as before.
Here is the full trampoline code as of kernel 5.11.0-rc5 for
reference:
V_FUNCTION_BEGIN(__kernel_sigtramp_rt64)
.Lsigrt_start:
bctrl /* call the handler */
addi r1, r1, __SIGNAL_FRAMESIZE
li r0,__NR_rt_sigreturn
sc
.Lsigrt_end:
V_FUNCTION_END(__kernel_sigtramp_rt64)
This new behavior breaks how `backtrace()` uses to detect the
trampoline frame to correctly reconstruct the stack frame when it is
called from inside a signal handling.
This workaround rely on the fact that the trampoline code is at very
least two (maybe 3?) instructions in size (as it is in the 32 bits
version, only on `li` and `sc`), so it is safe to check the return
address be in the range __kernel_sigtramp_rt64 .. + 4.
[1] subject: powerpc/64/signal: Balance return predictor stack in signal trampoline
commit: 0138ba5783ae0dcc799ad401a1e8ac8333790df9
url: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0138ba5783ae0dcc799ad401a1e8ac8333790df9
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
https://sourceware.org/bugzilla/show_bug.cgi?id=27077
Before reloading nsswitch.conf, verify that the root directory
hasn't changed - if it has, it's likely that we've entered a
container and should not trust the nsswitch inside the container
nor load any shared objects therein.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
elf/tst-prelink-cmp was initially added for x86 (commit fe534fe898) to validate
the fix for Bug 19178, and later applied to all architectures that use GLOB_DAT
relocations (commit 89569c8bb6). However, that bug only affected targets that
handle GLOB_DAT relocations as ELF_TYPE_CLASS_EXTERN_PROTECTED_DATA, so the test
should only apply to targets defining DL_EXTERN_PROTECTED_DATA, which gates the
usage of the elf type class above. For all other targets not meeting that
criteria, the test now returns with UNSUPPORTED status.
Fixes the test on POWER10 processors, which started using R_PPC64_GLOB_DAT.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The conversion loop to the internal encoding does not follow
the interface contract that __GCONV_FULL_OUTPUT is only returned
after the internal wchar_t buffer has been filled completely. This
is enforced by the first of the two asserts in iconv/skeleton.c:
/* We must run out of output buffer space in this
rerun. */
assert (outbuf == outerr);
assert (nstatus == __GCONV_FULL_OUTPUT);
This commit solves this issue by queuing a second wide character
which cannot be written immediately in the state variable, like
other converters already do (e.g., BIG5-HKSCS or TSCII).
Reported-by: Tavis Ormandy <taviso@gmail.com>
This reverts commit 2682695e5c.
Fixes bug 27237.
That commit turned out to be too intrusive affecting crt files, test
system and benchmark files. They should not be affected, but the
build system does not set the MODULE_NAME and LIBC_NONSHARED reliably.
Since commit 2682695e5c, `make bench-build' with `--enable-static-pie'
fails due to bench-timing-type being incorrectly built with MODULE_NAME
set to `libc'. This commit sets MODULE_NAME to nonlib, thus fixing the
build failure.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Some IFUNC variants are not compatible with BTI and MTE so don't
set them as usable for testing and benchmarking on a BTI or MTE
enabled system.
As far as IFUNC selectors are concerned a system is BTI enabled if
the cpu supports it and glibc was built with BTI branch protection.
Most IFUNC variants are BTI compatible, but thunderx2 memcpy and
memmove use a jump table with indirect jump, without a BTI j.
Fixes bug 26818.
Most packages have been tested with their latest releases, except for
Python, whose latest version is 3.9.1.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The hwcap value is now in linux 5.10 and in glibc bits/hwcap.h, so use
that definition.
Move the definition to init-arch.h so all ifunc selectors can use it
and expose an "mte" shorthand for mte enabled runtime.
For now we allow user code to enable tag checks and use PROT_MTE
mappings without libc involvment, this is not guaranteed ABI, but
can be useful for testing and debugging with MTE.
GCC mainline shows the following error:
../sysdeps/unix/sysv/linux/mips/mips64/getdents64.c: In function '__getdents64':
../sysdeps/unix/sysv/linux/mips/mips64/getdents64.c:121:7: error: 'memcpy' forming offset [4, 7] is out of the bounds [0, 4] [-Werror=array-bounds]
121 | memcpy (((char *) dp + offsetof (struct dirent64, d_ino)),
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
122 | KDP_MEMBER (kdp, d_ino), sizeof ((struct dirent64){0}.d_ino));
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../sysdeps/unix/sysv/linux/mips/mips64/getdents64.c:123:7: error: 'memcpy' forming offset [4, 7] is out of the bounds [0, 4] [-Werror=array-bounds]
123 | memcpy (((char *) dp + offsetof (struct dirent64, d_off)),
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
124 | KDP_MEMBER (kdp, d_off), sizeof ((struct dirent64){0}.d_off));
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The issue is due both d_ino and d_off fields for mips64-n32
kernel_dirent are 32-bits, while this is using memcpy to copy 64 bits
from it into the glibc dirent64.
The fix is to use a temporary buffer to read the correct type
from kernel_dirent.
Checked with a build-many-glibcs.py for mips64el-linux-gnu and I
also checked the tst-getdents64 on mips64el 4.1.4 kernel with
and without fallback enabled (by manually setting the
getdents64_supported).
It is not available with the baseline ISA.
Fixes commit 68ab82f566
("powerpc: Runtime selection between sc and scv for syscalls").
Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
Check ifunc resolver with CPU_FEATURE_USABLE and tunables in dynamic and
static executables to verify that CPUID features are initialized early in
static PIE.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This reverts commit 20b39d5946 for static
library. This avoids the need to rebuild the world for the case where
libstdc++ (and potentially other libraries) are linked to a old glibc.
To avoid requering to provide xstat symbols for newer ABIs (such as
riscv32) a new LIB_COMPAT macro is added. It is similar to SHLIB_COMPAT
but also works for static case (thus evaluating similar to SHLIB_COMPAT
for both shared and static case).
Checked with a check-abi on all affected ABIs. I also check if the
static library does contains the xstat symbols.
In commit 863d775c48, kunpeng920 is added to default memcpy version,
however, there is performance degradation when the copy size is some large bytes, eg: 100k.
This is the result, tested in glibc-2.28:
before backport after backport Performance improvement
memcpy_1k 0.005 0.005 0.00%
memcpy_10k 0.032 0.029 10.34%
memcpy_100k 0.356 0.429 -17.02%
memcpy_1m 7.470 11.153 -33.02%
This is the demo
#include "stdio.h"
#include "string.h"
#include "stdlib.h"
char a[1024*1024] = {12};
char b[1024*1024] = {13};
int main(int argc, char *argv[])
{
int i = atoi(argv[1]);
int j;
int size = atoi(argv[2]);
for (j = 0; j < i; j++)
memcpy(b, a, size*1024);
return 0;
}
# gcc -g -O0 memcpy.c -o memcpy
# time taskset -c 10 ./memcpy 100000 1024
Co-authored-by: liqingqing <liqingqing3@huawei.com>
Hidden visibility can avoid indirections and RELATIVE relocs in
static PIE libc.
The check should use IS_IN_LIB instead of IS_IN(libc) since all
symbols are defined locally in static PIE and the optimization is
useful in all libraries not just libc. However the test system
links objects from libcrypt.a into dynamic linked test binaries
where hidden visibility does not work. I think mixing static and
shared libc components in the same binary should not be supported
usage, but to be safe only use hidden in libc.a.
On some targets (i386) this optimization cannot be applied because
hidden visibility PIE ifunc functions don't work, so it is gated by
NO_HIDDEN_EXTERN_FUNC_IN_PIE.
From -static-pie linked 'int main(){}' this shaves off 71 relative
relocs on aarch64 and reduces code size by about 2k.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
IFUNC resolvers may depend on tunables and cpu feature setup so
move static pie self relocation after those.
It is hard to guarantee that the ealy startup code does not rely
on relocations so this is a bit fragile. It would be more robust
to handle RELATIVE relocs early and only IRELATIVE relocs later,
but the current relocation processing code cannot do that.
The early startup code up to relocation processing includes
_dl_aux_init (auxvec);
__libc_init_secure ();
__tunables_init (__environ);
ARCH_INIT_CPU_FEATURES ();
_dl_relocate_static_pie ();
These are simple enough that RELATIVE relocs can be avoided.
The following steps include
ARCH_SETUP_IREL ();
ARCH_SETUP_TLS ();
ARCH_APPLY_IREL ();
On some targets IRELATIVE processing relies on TLS setup on
others TLS setup relies on IRELATIVE relocs, so the right
position for _dl_relocate_static_pie is target dependent.
For now move self relocation as early as possible on targets
that support static PIE.
Fixes bug 27072.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Extern symbol access in position independent code usually involves GOT
indirection which needs RELATIVE reloc in a static linked PIE. (On
some targets this is avoided e.g. because the linker can relax a GOT
access to a pc-relative access, but this is not generally true.) Code
that runs before static PIE self relocation must avoid relying on
dynamic relocations which can be ensured by using hidden visibility.
However we cannot just make all symbols hidden:
On i386, all calls to IFUNC functions must go through PLT and calls to
hidden functions CANNOT go through PLT in PIE since EBX used in PIE PLT
may not be set up for local calls to hidden IFUNC functions.
This patch aims to make symbol references hidden in code that is used
before and by _dl_relocate_static_pie when building a static PIE libc.
Note: for an object that is used in the startup code, its references
and definition may not have consistent visibility: it is only forced
hidden in the startup code.
This is needed for fixing bug 27072.
Co-authored-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
