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commit 94cd37ebb293321115a36a422b091fdb72d2fb08
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 94cd37ebb293321115a36a422b091fdb72d2fb08.
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>
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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 720480934ab910.
Checked on ia64-linux-gnu.
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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>
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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>
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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>
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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>
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This reverts commit 2682695e5c7acf1e60dd3b5c3a14d4e82416262c.
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.
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Since commit 2682695e5c7a, `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>
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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.
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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>
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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.
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Constify __x86_cacheinfo_p and __x86_cpu_features_p, not their pointer
target types.
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Reviewed-by: DJ Delorie <dj@redhat.com>
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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).
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Search " YYY " and " YYY\n", instead of "YYY", to avoid matching
"XXXYYYZZZ" with "YYY".
Update /proc/cpuinfo CPU feature names:
/proc/cpuinfo glibc
------------------------------------------------
avx512vbmi AVX512_VBMI
dts DS
pni SSE3
tsc_deadline_timer TSC_DEADLINE
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Return EXIT_FAILURE only if the level 2 libx86-64-isa-level.so is used
on x86-64 baseline machine.
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It is not available with the baseline ISA.
Fixes commit 68ab82f56690ada86ac1e0c46bad06ba189a10ef
("powerpc: Runtime selection between sc and scv for syscalls").
Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
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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>
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This reverts commit 20b39d59467b0c1d858e89ded8b0cebe55e22f60 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.
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In commit 863d775c481704baaa41855fc93e5a1ca2dc6bf6, 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>
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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>
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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>
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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>
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All linkers support __ehdr_start that support static PIE linking,
so there is no need to check for its presence via a weak reference.
This avoids a RELATIVE relocation in static PIE startup code on some
targets.
With non-PIE static linking the weak ref check is kept in case the
linker does not support __ehdr_start.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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Add SUPPORT_STATIC_PIE that targets can define if they support
static PIE. This requires PI_STATIC_AND_HIDDEN support and various
linker features as described in
commit 9d7a3741c9e59eba87fb3ca6b9f979befce07826
Add --enable-static-pie configure option to build static PIE [BZ #19574]
Currently defined on x86_64, i386 and aarch64 where static PIE is
known to work.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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With static pie linking pointers in the tunables list need
RELATIVE relocs since the absolute address is not known at link
time. We want to avoid relocations so the static pie self
relocation can be done after tunables are initialized.
This is a simple fix that embeds the tunable strings into the
tunable list instead of using pointers. It is possible to have
a more compact representation of tunables with some additional
complexity in the generator and tunable parser logic. Such
optimization will be useful if the list of tunables grows.
There is still an issue that tunables_strdup allocates and the
failure handling code path is sufficiently complex that it can
easily have RELATIVE relocations. It is possible to avoid the
early allocation and only change environment variables in a
setuid exe after relocations are processed. But that is a
bigger change and early failure is fatal anyway so it is not
as critical to fix right away. This is bug 27181.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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The representation of the tunables including type information and
the tunable list structure are only used in the implementation not
in the tunables api that is exposed to usage within glibc.
This patch moves the representation related definitions into the
existing dl-tunable-types.h and uses that only for implementation.
The tunable callback and related types are moved to dl-tunables.h
because they are part of the tunables api.
This reduces the details exposed in the tunables api so the internals
are easier to change.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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In <sys/platform/x86.h>, define CPU features as enum instead of using
the C preprocessor magic to make it easier to wrap this functionality
in other languages. Move the C preprocessor magic to internal header
for better GCC codegen when more than one features are checked in a
single expression as in x86-64 dl-hwcaps-subdirs.c.
1. Rename COMMON_CPUID_INDEX_XXX to CPUID_INDEX_XXX.
2. Move CPUID_INDEX_MAX to sysdeps/x86/include/cpu-features.h.
3. Remove struct cpu_features and __x86_get_cpu_features from
<sys/platform/x86.h>.
4. Add __x86_get_cpuid_feature_leaf to <sys/platform/x86.h> and put it
in libc.
5. Make __get_cpu_features() private to glibc.
6. Replace __x86_get_cpu_features(N) with __get_cpu_features().
7. Add _dl_x86_get_cpu_features to GLIBC_PRIVATE.
8. Use a single enum index for each CPU feature detection.
9. Pass the CPUID feature leaf to __x86_get_cpuid_feature_leaf.
10. Return zero struct cpuid_feature for the older glibc binary with a
smaller CPUID_INDEX_MAX [BZ #27104].
11. Inside glibc, use the C preprocessor magic so that cpu_features data
can be loaded just once leading to more compact code for glibc.
256 bits are used for each CPUID leaf. Some leaves only contain a few
features. We can add exceptions to such leaves. But it will increase
code sizes and it is harder to provide backward/forward compatibilities
when new features are added to such leaves in the future.
When new leaves are added, _rtld_global_ro offsets will change which
leads to race condition during in-place updates. We may avoid in-place
updates by
1. Rename the old glibc.
2. Install the new glibc.
3. Remove the old glibc.
NB: A function, __x86_get_cpuid_feature_leaf , is used to avoid the copy
relocation issue with IFUNC resolver as shown in IFUNC resolver tests.
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Only define FALLTHROUGH for _LIBC and do not check __clang_major__
value.
It partially syncs with gnulib 5c52f00c69f39fe.
Checked with build-many-glibcs.py for aarch64-linux-gnu.
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Old implementation of realpath allocates a PATH_MAX using alloca for
each symlink in the path, leading to MAXSYMLINKS times PATH_MAX
maximum stack usage.
The test create a symlink with __eloop_threshold() loops and creates
a thread with minimum stack size (obtained through
support_small_stack_thread_attribute). The thread issues a stack
allocations that fill the thread allocated stack minus some slack
plus and the realpath usage (which assumes a bounded stack usage).
If realpath uses more than about 2 * PATH_MAX plus some slack it
triggers a stackoverflow.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
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Only define FALLTHROUGH for _LIBC and do not check __clang_major__
value.
It partially syncs with gnulib 5c52f00c69f39fe.
Checked with build-many-glibcs.py for aarch64-linux-gnu,
x86_64-linux-gnu, and s390x-linux-gnu.
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Since __libc_init_secure is called before ARCH_SETUP_TLS, it must use
"int $0x80" for system calls in i386 static PIE. Add startup_getuid,
startup_geteuid, startup_getgid and startup_getegid to <startup.h>.
Update __libc_init_secure to use them.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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Set the default _dl_sysinfo in _dl_aux_init to avoid RELATIVE relocation
in static PIE.
This is needed for fixing bug 27072 on x86.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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Add extra-test-objs to test-extras so that they are compiled with
-DMODULE_NAME=testsuite instead of -DMODULE_NAME=libc.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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All IFUNC functions which are used in ld.so must have a rtld version if
the IFUNC version isn't safe to use in ld.so.
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Pass --list-tunables to ld.so to print tunables with min and max values.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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I have been testing with GCC trunk and GLIBC master while working on the
OpenRISC port. This test has been failing with fabs not being called,
This is caused as my architecture is configure with no long double
meaning the two calls are the same:
TEST (fabs (Vdouble1), double, fabs);
TEST (fabs (Vldouble1), ldouble, fabs);
Instead of the tgmath calls resolving to fabs and fabsl both calls are
fabs. Next, do to compiler optimiations the second call is eliminated.
Fix this by invoking the failing TEST with Vldouble2.
Note, I also updated the FAIL message to more clearly show where the
failure happened, so I see:
FAIL: math/test-tgmath2
original exit status 1
wrong function called, fabs (ldouble) failure on line 174
Cc: Joseph Myers <joseph@codesourcery.com>
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