Joseph Myers [Wed, 22 Nov 2017 22:21:10 +0000 (22:21 +0000)]
Obsolete p_secstodate.
This patch, relative to a tree with
<https://sourceware.org/ml/libc-alpha/2017-11/msg00797.html> (pending
review) applied, obsoletes p_secstodate, making the underlying
function __p_secstodate into a compat symbol not available for new
binaries or ports. The calls in ns_print.c (part of incomplete
handling of TKEY) are changed to use %lu to print times instead of
trying to pretty-print the times any more.
Tested for x86_64.
* resolv/res_debug.c (p_secstodate): Condition definition on
[SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_27)]. Define
directly as __p_secstodate, and as a compat symbol. Do not use
libresolv_hidden_def.
* resolv/resolv.h (p_secstodate): Remove macro and function
declaration.
* resolv/ns_print.c (ns_sprintrrf): Print times with %lu, not
using p_secstodate.
* include/resolv.h (__p_secstodate): Do not use
libresolv_hidden_proto.
* resolv/Makefile (tests): Move tst-p_secstodate to ....
(tests-internal): ... here.
* resolv/tst-p_secstodate.c: Include <shlib-compat.h>. Condition
all contents on [TEST_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_27)]
and declare and use __p_secstodate and use compat_symbol_reference
in that case.
[!TEST_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_27)] (do_test): Add
implementation returning 77.
If __gmtime_r returns NULL (because the year overflows the range of
int), this will dereference a null pointer. Otherwise, if the
computed year does not fit in four characters, this will cause a
buffer overrun of the fixed-size 15-byte buffer. With current GCC
mainline, there is a compilation failure because of the possible
buffer overrun.
I couldn't find a specification for how this function is meant to
behave, but Paul pointed to RFC 4034 as relevant to the cases where
this function is called from within glibc. The function's interface
is inherently problematic when dates beyond Y2038 might be involved,
because of the ambiguity in how to interpret 32-bit timestamps as such
dates (the RFC suggests interpreting times as being within 68 years of
the present date, which would mean some kind of interface whose
behavior depends on the present date).
This patch works on the basis of making a minimal fix in preparation
for obsoleting the function. The function is made to handle times in
the interval [0, 0x7fffffff] only, on all platforms, with <overflow>
used as the output string in other cases (and errno set to EOVERFLOW
in such cases). This seems to be a reasonable state for the function
to be in when made a compat symbol by a future patch, being compatible
with any existing uses for existing timestamps without trying to work
for later timestamps. Results independent of the range of time_t also
simplify the testcase.
I couldn't persuade GCC to recognize the ranges of the struct tm
fields by adding explicit range checks with a call to
__builtin_unreachable if outside the range (this looks similar to
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80776>), so having added
a range check on the input, this patch then disables the
-Wformat-overflow= warning for the sprintf call (I prefer that to the
use of strftime, as being more transparently correct without knowing
what each of %m and %M etc. is).
I do not know why this build failure should be new with mainline GCC
(that is, I don't know what GCC change might have introduced it, when
the basic functionality for such warnings was already in GCC 7).
I do not know if this is a security issue (that is, if there are
plausible ways in which a date before -999 or after 9999 from an
untrusted source might end up in this function). The system clock is
arguably an untrusted source (in that e.g. NTP is insecure), but
probably not to that extent (NTP can't communicate such wild
timestamps), and uses from within glibc are limited to 32-bit inputs.
Tested with build-many-glibcs.py that this restores the build for arm
with yesterday's mainline GCC. Also tested for x86_64 and x86.
[BZ #22463]
* resolv/res_debug.c: Include <libc-diag.h>.
(p_secstodate): Assert time_t at least as wide as u_long. On
overflow, use integer seconds since the epoch as output, or use
"<overflow>" as output and set errno to EOVERFLOW if integer
seconds since the epoch would be 14 or more characters.
(p_secstodate) [__GNUC_PREREQ (7, 0)]: Disable -Wformat-overflow=
for sprintf call.
* resolv/tst-p_secstodate.c: New file.
* resolv/Makefile (tests): Add tst-p_secstodate.
($(objpfx)tst-p_secstodate): Depend on $(objpfx)libresolv.so.
Joseph Myers [Wed, 22 Nov 2017 21:11:00 +0000 (21:11 +0000)]
Remove unused sparc64/soft-fp libm function implementations.
sysdeps/sparc/sparc64/soft-fp has files s_frexpl.c, s_scalblnl.c and
s_scalbnl.c that are never used because the ldbl-128 versions always
come first in the sysdeps directory ordering. This patch removes the
unused files.
Tested with build-many-glibcs.py that installed stripped shared
libraries are unchanged by this patch.
Joseph Myers [Wed, 22 Nov 2017 18:44:23 +0000 (18:44 +0000)]
Avoid use of strlen in getlogin_r (bug 22447).
Building glibc with current mainline GCC fails, among other reasons,
because of an error for use of strlen on the nonstring ut_user field.
This patch changes the problem code in getlogin_r to use __strnlen
instead. It also needs to set the trailing NUL byte of the result
explicitly, because of the case where ut_user does not have such a
trailing NUL byte (but the result should always have one).
Tested for x86_64. Also tested that, in conjunction with
<https://sourceware.org/ml/libc-alpha/2017-11/msg00797.html>, it fixes
the build for arm with mainline GCC.
[BZ #22447]
* sysdeps/unix/getlogin_r.c (__getlogin_r): Use __strnlen not
strlen to compute length of ut_user and set trailing NUL byte of
result explicitly.
Mike FABIAN [Fri, 17 Nov 2017 09:54:52 +0000 (10:54 +0100)]
lv_LV locale: fix collation [BZ #15537]
[BZ #15537]
* localedata/locales/lv_LV (LC_COLLATE): Fix collation by
using “copy "iso14651_t1"” and then implementing the
collation rules for lv from CLDR on top of that.
* Makefile: Add lv_LV.UTF-8 to test-input and to the list
of locales to be built for testing.
* lv_LV.UTF-8.in: New file with test data to test the Latvian
sorting.
Joseph Myers [Tue, 21 Nov 2017 22:21:23 +0000 (22:21 +0000)]
Update hppa bits/mman.h from Linux 4.14.
This patch updates the hppa bits/mman.h based on Linux 4.14. Some
MADV_* macros are removed in Linux 4.14 as unused/unimplemented, so
this patch removes them from glibc, while adding two new macros added
in Linux 4.14.
Tested (compilation only) for hppa with build-many-glibcs.py.
nptl: Add workaround for ASSERT_PTHREAD_INTERNAL_SIZE with GCC 4.9
GCC 4.9 (the minimum current supported) emits an warning for universal
zero initializer ({0}) on ASSERT_PTHREAD_INTERNAL_SIZE:
pthread_attr_init.c: In function ‘__pthread_attr_init_2_1’:
pthread_attr_init.c:37:3: error: missing braces around initializer [-Werror=missing-braces]
ASSERT_PTHREAD_INTERNAL_SIZE (pthread_attr_t, struct pthread_attr);
^
pthread_attr_init.c:37:3: error: (near initialization for ‘(anonymous).__size’) [-Werror=missing-braces]
It is fact GCC BZ#53119 [1] fixed in later version (GCC5+). Since
current branch is closed and there is no indication it will be backports
(comment #20 in same bug report) this patch fixes by using a double
bracket to zero initialize the struct.
Checked on x86_64-linux-gnu with GCC 7 and GCC 4.9.
* nptl/pthreadP.h (ASSERT_PTHREAD_INTERNAL_SIZE): Add workarond for
-Wmissing-braces on GCC 4.9.
Stefan Liebler [Tue, 21 Nov 2017 07:45:28 +0000 (08:45 +0100)]
S390: Add cfi information for start routines in order to stop unwinding.
GDB failed to detect the outermost frame while showing the backtrace
within a thread:
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
Before this patch, the start routines like thread_start had no cfi information.
GDB is then using the prologue unwinder if no cfi information is available.
This unwinder tries to unwind r15 and stops e.g. if r15 was updated or
on some jump-instructions.
On older glibc-versions (before commit "Remove cached PID/TID in clone" c579f48edba88380635ab98cb612030e3ed8691e), the thread_start function used
such a jump-instruction and GDB did not fail with an error.
This patch adds cfi information for _start, thread_start and __makecontext_ret
and marks r14 as undefined which marks the frame as outermost frame and GDB
stops the backtrace. Also tested different gcc versions in order to test
_Unwind_Backtrace() in libgcc as this is used by backtrace() in glibc.
Stefan Liebler [Tue, 21 Nov 2017 07:39:53 +0000 (08:39 +0100)]
Remove attribute_hidden for wchar ifunc symbols.
On s390 (31bit) various debug/tst-*chk* testcases are failing as the tests
are ending with a segmentation fault.
One test is e.g. calling wcsnrtombs in debug/tst-chk1.c:1549.
The function wcsnrtombs itself calls __wcsnlen. This function is called via
PLT! The PLT-stub itself loads the address from GOT (r12 is assumed to be
the GOT-pointer). In this case the loaded address is zero and the following
branch leads to the segmentation fault.
Due to the attribute_hidden in commit 44af8a32c341672b5160fdc2839767e9a837ad26
"Mark internal wchar functions with attribute_hidden [BZ #18822]"
for e.g. the __wcsnlen function, r12 is not loaded with the GOT-pointer
in wcsnrtombs.
On s390x (64bit), this __wcsnlen call is also using the PLT-stub. But it is
not failing as the GOT-pointer is setup with larl-instruction by the PLT-stub
itself.
Note: On s390x/s390, __wcsnlen is an IFUNC symbol.
On x86_64, __wcsnlen is also an IFUNC symbol and is called via PLT, too.
Further IFUNC symbols on s390 which were marked as hidden by the mentioned
commit are: __wcscat, __wcsncpy, __wcpncpy, __wcschrnul.
This patch removes the attribute_hidden in wchar.h.
Then the compiler setups e.g. r12 on s390 in order to call __wcsnlen via PLT.
Paul Eggert [Tue, 21 Nov 2017 00:25:49 +0000 (16:25 -0800)]
regex: don't assume uint64_t or uint32_t
This avoids -Werror=overflow errors for 32-bit systems in
the 64-bit case. Problem reported by Joseph Myers in:
https://sourceware.org/ml/libc-alpha/2017-11/msg00694.html
Also, when this code is used in Gnulib it ports to platforms
that lack uint64_t and uint32_t. The C standard doesn't guarantee
them, and on some 32-bit compilers there is no uint64_t.
Problem reported by Gianluigi Tiesi in:
http://lists.gnu.org/archive/html/bug-gnulib/2012-03/msg00154.html
* posix/regcomp.c (init_word_char): Don't assume that the types
uint64_t and uint32_t exist. Adapted from Gnulib patch
2012-05-27T06:40:00!eggert@cs.ucla.edu. See:
https://git.savannah.gnu.org/cgit/gnulib.git/commit/?id=252b52457da7887667c036d18cc5169777615bb0
The generic memset reads dczid_el0 on every memset. This has a
significant impact on falkor for a range of sizes because reading
dczid_el0 is slow.
The DZP bit in the dczid_el0 register does not change dynamically, so
it is safe to read once during program startup. With this patch
dczid_el0 is read once during startup and zva_size is cached. This is
used to invoke the falkor-specific memset; the generic memset routine
remains unchanged.
The gains due to this are significant for falkor, with run time
reductions as high as 48%. Here's a sample from the falkor tests:
* sysdeps/aarch64/memset-reg.h: New file.
* sysdeps/aarch64/memset.S: Use it.
(__memset): Rename to MEMSET macro.
[ZVA_MACRO]: Use zva_macro.
* sysdeps/aarch64/multiarch/Makefile (sysdep_routines):
Add memset_generic and memset_falkor.
* sysdeps/aarch64/multiarch/ifunc-impl-list.c
(__libc_ifunc_impl_list): Add memset ifuncs.
* sysdeps/aarch64/multiarch/init-arch.h (INIT_ARCH): New
local variable zva_size.
* sysdeps/aarch64/multiarch/memset.c: New file.
* sysdeps/aarch64/multiarch/memset_generic.S: New file.
* sysdeps/aarch64/multiarch/memset_falkor.S: New file.
* sysdeps/aarch64/multiarch/rtld-memset.S: New file.
* sysdeps/unix/sysv/linux/aarch64/cpu-features.c
(DCZID_DZP_MASK): New macro.
(DCZID_BS_MASK): Likewise.
(init_cpu_features): Read and set zva_size.
* sysdeps/unix/sysv/linux/aarch64/cpu-features.h
(struct cpu_features): New member zva_size.
benchtests: Fix walking sizes and directions for *-walk benchmarks
Make the walking benchmarks walk only backwards since copying both
ways is biased in favour of implementations that use non-temporal
stores for larger sizes; falkor is one of them. This also fixes up
bugs in computation of the result which ended up multiplying the
length with the timing result unnecessarily.
* benchtests/bench-memcpy-walk.c (do_one_test): Copy only
backwards. Fix timing computation.
* benchtests/bench-memmove-walk.c (do_one_test): Likewise.
* benchtests/bench-memset-walk.c (do_one_test): Walk backwards
on memset by N at a time. Fix timing computation.
Florian Weimer [Sun, 19 Nov 2017 07:58:31 +0000 (08:58 +0100)]
manual: Move preadv/writev variants to Scatter-Gather section
Also remove a comment about performance. fwrite vs writev performance
is a very complex topic and cannot be reduced to a simple advice based
on transfer size.
support_become_root: Don't fail when /proc/<pid/setgroups is missing
The requirement to write "deny" to /proc/<pid>/setgroups for a given user
namespace before being able to write a gid mapping was introduced in Linux
3.19. Before that this requirement including the file did not exist.
So don't fail when errno == ENOENT.
Florian Weimer [Sat, 18 Nov 2017 13:11:09 +0000 (14:11 +0100)]
support_create_temp_directory: Align behavior with create_temp_file
create_temp_file automatically supplies the test directory and the
XXXXXX suffix. support_create_temp_directory required the caller to
specify them, which was confusing.
Linux commit ID cba6ac4869e45cc93ac5497024d1d49576e82666 reserved a new
bit for a scenario where transactional memory is available, but the
suspended state is disabled.
* sysdeps/powerpc/bits/hwcap.h (PPC_FEATURE2_HTM_NO_SUSPEND): New
macro.
* sysdeps/powerpc/dl-procinfo.c (_dl_powerpc_cap_flags): Add
htm-no-suspend.
Signed-off-by: Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>
Joseph Myers [Fri, 17 Nov 2017 23:39:11 +0000 (23:39 +0000)]
Use libm_alias_ldouble in sysdeps/x86_64/fpu.
This patch continues the preparation for additional _FloatN / _FloatNx
function aliases by using libm_alias_ldouble for sysdeps/x86_64/fpu
long double functions, so that they can have _Float64x aliases added
in future.
Tested for x86_64, including build-many-glibcs.py tests that installed
stripped shared libraries are unchanged by the patch.
* sysdeps/x86_64/fpu/e_expl.S: Include <libm-alias-ldouble.h>.
[USE_AS_EXPM1L] (expm1l): Define using libm_alias_ldouble.
* sysdeps/x86_64/fpu/s_ceill.S: Include <libm-alias-ldouble.h>.
(ceill): Define using libm_alias_ldouble.
* sysdeps/x86_64/fpu/s_copysignl.S: Include
<libm-alias-ldouble.h>.
(copysignl): Define using libm_alias_ldouble.
* sysdeps/x86_64/fpu/s_fabsl.S: Include <libm-alias-ldouble.h>.
(fabsl): Define using libm_alias_ldouble.
* sysdeps/x86_64/fpu/s_floorl.S: Include <libm-alias-ldouble.h>.
(floorl): Define using libm_alias_ldouble.
* sysdeps/x86_64/fpu/s_fmaxl.S: Include <libm-alias-ldouble.h>.
(fmaxl): Define using libm_alias_ldouble.
* sysdeps/x86_64/fpu/s_fminl.S: Include <libm-alias-ldouble.h>.
(fminl): Define using libm_alias_ldouble.
* sysdeps/x86_64/fpu/s_llrintl.S: Include <libm-alias-ldouble.h>.
(llrintl): Define using libm_alias_ldouble.
(lrintl): Likewise.
* sysdeps/x86_64/fpu/s_nearbyintl.S: Include
<libm-alias-ldouble.h>.
(nearbyintl): Define using libm_alias_ldouble.
* sysdeps/x86_64/fpu/s_truncl.S: Include <libm-alias-ldouble.h>.
(truncl): Define using libm_alias_ldouble.
* sysdeps/x86_64/x32/fpu/s_lrintl.S: Include
<libm-alias-ldouble.h>.
(lrintl): Define using libm_alias_ldouble.
Joseph Myers [Fri, 17 Nov 2017 22:54:39 +0000 (22:54 +0000)]
Use libm_alias_ldouble in sysdeps/i386/fpu.
This patch continues the preparation for additional _FloatN / _FloatNx
function aliases by using libm_alias_ldouble for sysdeps/i386/fpu long
double functions, so that they can have _Float64x aliases added in
future.
Tested for x86_64 (which includes some of these implementations) and
x86, including build-many-glibcs.py tests that installed stripped
shared libraries are unchanged by the patch.
* sysdeps/i386/fpu/e_expl.S: Include <libm-alias-ldouble.h>.
[USE_AS_EXPM1L] (expm1l): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_asinhl.S: Include <libm-alias-ldouble.h>.
(asinhl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_atanl.c: Include <libm-alias-ldouble.h>.
(atanl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_cbrtl.S: Include <libm-alias-ldouble.h>.
(cbrtl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_ceill.S: Include <libm-alias-ldouble.h>.
(ceill): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_copysignl.S: Include <libm-alias-ldouble.h>.
(copysignl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_fabsl.S: Include <libm-alias-ldouble.h>.
(fabsl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_floorl.S: Include <libm-alias-ldouble.h>.
(floorl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_fmaxl.S: Include <libm-alias-ldouble.h>.
(fmaxl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_fminl.S: Include <libm-alias-ldouble.h>.
(fminl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_frexpl.S: Include <libm-alias-ldouble.h>.
(frexpl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_llrintl.S: Include <libm-alias-ldouble.h>.
(llrintl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_logbl.c: Include <libm-alias-ldouble.h>.
(logbl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_lrintl.S: Include <libm-alias-ldouble.h>.
(lrintl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_nearbyintl.S: Include <libm-alias-ldouble.h>.
(nearbyintl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_nextafterl.c: Include <libm-alias-ldouble.h>.
(nextafterl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_remquol.S: Include <libm-alias-ldouble.h>.
(remquol): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_rintl.c: Include <libm-alias-ldouble.h>.
(rintl): Define using libm_alias_ldouble.
* sysdeps/i386/fpu/s_truncl.S: Include <libm-alias-ldouble.h>.
(truncl): Define using libm_alias_ldouble.
* sysdeps/i386/i686/fpu/s_fmaxl.S: Include <libm-alias-ldouble.h>.
(fmaxl): Define using libm_alias_ldouble.
* sysdeps/i386/i686/fpu/s_fminl.S: Include <libm-alias-ldouble.h>.
(fminl): Define using libm_alias_ldouble.
Joseph Myers [Fri, 17 Nov 2017 22:01:43 +0000 (22:01 +0000)]
Support bits/floatn.h inclusion from .S files.
Further _FloatN / _FloatNx type alias support will involve making
architecture-specific .S files use the common macros for libm function
aliases. Making them use those macros will also serve to simplify
existing code for aliases / symbol versions in various cases, similar
to such simplifications for ldbl-opt code.
The libm-alias-*.h files sometimes need to include <bits/floatn.h> to
determine which aliases they should define. At present, this does not
work for inclusion from .S files because <bits/floatn.h> can define
typedefs for old compilers. This patch changes all the
<bits/floatn.h> and <bits/floatn-common.h> headers to include
__ASSEMBLER__ conditionals. Those conditionals disable everything
related to C syntax in the __ASSEMBLER__ case, not just the problem
typedefs, as that seemed cleanest. The __HAVE_* definitions remain in
the __ASSEMBLER__ case, as those provide information that is required
to define the correct set of aliases.
Tested with build-many-glibcs.py for a representative set of
configurations (x86_64-linux-gnu i686-linux-gnu ia64-linux-gnu
powerpc64le-linux-gnu mips64-linux-gnu-n64 sparc64-linux-gnu) with GCC
6. Also tested with GCC 6 for i686-linux-gnu in conjunction with
changes to use alias macros in .S files.
* bits/floatn-common.h [!__ASSEMBLER]: Disable everything related
to C syntax instead of availability and properties of types.
* bits/floatn.h [!__ASSEMBLER]: Likewise.
* sysdeps/ia64/bits/floatn.h [!__ASSEMBLER]: Likewise.
* sysdeps/ieee754/ldbl-128/bits/floatn.h [!__ASSEMBLER]: Likewise.
* sysdeps/mips/ieee754/bits/floatn.h [!__ASSEMBLER]: Likewise.
* sysdeps/powerpc/bits/floatn.h [!__ASSEMBLER]: Likewise.
* sysdeps/x86/bits/floatn.h [!__ASSEMBLER]: Likewise.
aarch64: Fix f{max,min}{f} build for GCC 4.9 and 5
GCC 4.9 and 5 do not generate a correct f{max,min}nm instruction for
__builtin_{fmax,fmin}{f} without -ffinite-math-only. It is clear a
compiler issue since the instruction can handle NaN and Inf correctly
and GCC6+ does not show this issue.
We can backport a fix to GCC 5, raise the minimum required GCC version
for aarch64 (since GCC 4.9 branch is now closed [1]) and/or add
configure check to check for this issue. However I think
-ffinite-math-only should be safe for these specific implementations
and it is a simpler solution.
Checked on aarch64-linux-gnu with GCC 5.3.1.
* sysdeps/aarch64/fpu/Makefile (CFLAGS-s_fmax.c, CFLAGS-s_fmaxf.c,
CFLAGS-s_fmin.c, CFLAGS-s_fminf.c): New rule: add -ffinite-math-only.
Update all sourceware links to https. The website redirects
everything to https anyway so let the web server do a bit less work.
The only reference that remains unchanged is the one in the old
ChangeLog, since it didn't seem worth changing it.
Martin Sebor [Thu, 16 Nov 2017 00:39:59 +0000 (17:39 -0700)]
The -Wstringop-truncation option new in GCC 8 detects common misuses
of the strncat and strncpy function that may result in truncating
the copied string before the terminating NUL. To avoid false positive
warnings for correct code that intentionally creates sequences of
characters that aren't guaranteed to be NUL-terminated, arrays that
are intended to store such sequences should be decorated with a new
nonstring attribute. This change add this attribute to Glibc and
uses it to suppress such false positives.
ChangeLog:
* misc/sys/cdefs.h (__attribute_nonstring__): New macro.
* sysdeps/gnu/bits/utmp.h (struct utmp): Use it.
* sysdeps/unix/sysv/linux/s390/bits/utmp.h (struct utmp): Same.
Luke Shumaker [Wed, 15 Nov 2017 19:39:22 +0000 (20:39 +0100)]
linux ttyname{_r}: Add tests
Add a new tst-ttyname test that includes several named sub-testcases.
This patch is ordered after the patches with the fixes that it tests for (to
avoid breaking `git bisect`), but for reference, here's how each relevant change
so far affected the testcases in this commit, starting with 15e9a4f378c8607c2ae1aa465436af4321db0e23:
[1]: 15e9a4f introduced a semantic that, under certain failure
conditions, ttyname sets errno=ENODEV, where previously it didn't
set errno; it's not quite fair to hold "before 15e9a4f" ttyname to
those new semantics. This testcase actually fails, but would have
passed if we tested for the old the semantics.
Each of the failing tests before 15e9a4f are all essentially the same bug: that
it returns a PTY slave with the correct minor device number, but from the wrong
devpts filesystem instance.
15e9a4f sought to fix this, but missed several of the cases that can cause this
to happen, and also broke the case where both the erroneous PTY and the correct
PTY exist.
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Luke Shumaker [Wed, 15 Nov 2017 19:36:44 +0000 (20:36 +0100)]
linux ttyname{_r}: Don't bail prematurely [BZ #22145]
Commit 15e9a4f378c8607c2ae1aa465436af4321db0e23 introduced logic for ttyname()
sending back ENODEV to signal that we can't get a name for the TTY because we
inherited it from a different mount namespace.
However, just because we inherited it from a different mount namespace and it
isn't available at its original path, doesn't mean that its name is unknowable;
we can still try to find it by allowing the normal fall back on iterating
through devices.
An example scenario where this happens is with "/dev/console" in containers.
It's a common practice among container managers to allocate a PTY master/slave
pair in the host's mount namespace (the slave having a path like "/dev/pty/$X"),
bind mount the slave to "/dev/console" in the container's mount namespace, and
send the slave FD to a process in the container. Inside of the
container, the slave-end isn't available at its original path ("/dev/pts/$X"),
since the container mount namespace has a separate devpts instance from the host
(that path may or may not exist in the container; if it does exist, it's not the
same PTY slave device). Currently ttyname{_r} sees that the file at the
original "/dev/pts/$X" path doesn't match the FD passed to it, and fails early
and gives up, even though if it kept searching it would find the TTY at
"/dev/console". Fix that; don't have the ENODEV path force an early return
inhibiting the fall-back search.
This change is based on the previous patch that adds use of is_mytty in
getttyname and getttyname_r. Without that change, this effectively reverts 15e9a4f, which made us disregard the false similarity of file pointed to by
"/proc/self/fd/$Y", because if it doesn't bail prematurely then that file
("/dev/pts/$X") will just come up again anyway in the fall-back search.
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Luke Shumaker [Wed, 15 Nov 2017 19:34:30 +0000 (20:34 +0100)]
linux ttyname{_r}: Make tty checks consistent
In the ttyname and ttyname_r routines on Linux, at several points it needs to
check if a given TTY is the TTY we are looking for. It used to be that this
check was (to see if `maybe` is `mytty`):
That is, it made the st_ino and st_dev parts of the check happen even if we have
the st_rdev member. This is an important change, because the kernel allows
multiple devpts filesystem instances to be created; a device file in one devpts
instance may share the same st_rdev with a file in another devpts instance, but
they aren't the same file.
This check appears twice in each file (ttyname.c and ttyname_r.c), once (in
ttyname and __ttyname_r) to check if a candidate file found by inspecting /proc
is the desired TTY, and once (in getttyname and getttyname_r) to check if a
candidate file found by searching /dev is the desired TTY. However, 15e9a4f
only updated the checks for files found via /proc; but the concern about
collisions between devpts instances is just as valid for files found via /dev.
So, update all 4 occurrences the check to be consistent with the version of the
check introduced in 15e9a4f. Make it easy to keep all 4 occurrences of the
check consistent by pulling it in to a static inline function, is_mytty.
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Luke Shumaker [Wed, 15 Nov 2017 19:31:32 +0000 (20:31 +0100)]
linux ttyname: Update a reference to kernel docs for kernel 4.10
Linux 4.10 moved many of the documentation files around.
4.10 came out between the time the patch adding the comment (commit 15e9a4f378c8607c2ae1aa465436af4321db0e23) was submitted and the time
it was applied (in February, January, and March 2017; respectively).
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Luke Shumaker [Wed, 15 Nov 2017 19:28:40 +0000 (20:28 +0100)]
manual: Update to mention ENODEV for ttyname and ttyname_r
Commit 15e9a4f378c8607c2ae1aa465436af4321db0e23 introduced ENODEV as a possible
error condition for ttyname and ttyname_r. Update the manual to mention this GNU
extension.
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Joseph Myers [Wed, 15 Nov 2017 18:40:29 +0000 (18:40 +0000)]
Add MADV_WIPEONFORK, MADV_KEEPONFORK from Linux 4.14.
This patch adds the new MADV_WIPEONFORK and MADV_KEEPONFORK from Linux
4.14 to bits/mman-linux.h (and bits/mman.h in the hppa case). Note
there are further hppa MADV_* changes in 4.14; I plan a separate glibc
patch for those.
This patch simplify sigpause by remobing the single thread optimization
since it will be handled already by the __sigsuspend call.
Checked on x86_64-linux-gnu.
* sysdeps/posix/sigpause.c (do_sigpause): Remove.
(__sigpause): Rely on __sigsuspend to implement single thread
optimization. Add LIBC_CANCEL_HANDLED for cancellation marking.
Luke Shumaker [Wed, 15 Nov 2017 16:36:25 +0000 (14:36 -0200)]
linux: Include <sysdep-cancel.h> for epoll_wait
The epoll_wait wrapper uses the raw syscall if __NR_epoll_wait is defined,
and falls back to calling epoll_pwait(..., NULL) if it isn't defined.
However, it didn't include the appropriate headers for __NR_epoll_wait to
be defined, so it was *always* falling back to calling epoll_pwait!
Joseph Myers [Wed, 15 Nov 2017 02:08:56 +0000 (02:08 +0000)]
Use __builtin_tgmath in tgmath.h with GCC 8 (bug 21660).
GCC mainline now supports __builtin_tgmath to allow <tgmath.h> macro
implementations that expand their arguments only once, so avoiding
exponential blowup in the size of macro expansions when calls to those
macros are nested in arguments to those macros.
This patch makes glibc's tgmath.h support using __builtin_tgmath, as a
much simpler and more efficient alternative to the existing
implementation. (As a side effect, the new feature would make it much
more practical to support decimal floating point in <tgmath.h> with
new compilers; currently, libdfp does not provide a <tgmath.h>
implementation, and making decimal arguments cause integer arguments
to be considered of type _Decimal64 instead of double would have been
very problematic in the old implementation.)
Joseph Myers [Tue, 14 Nov 2017 17:52:26 +0000 (17:52 +0000)]
Fix string/tester.c build with GCC 8.
GCC 8 warns about more cases of string functions truncating their
output or not copying a trailing NUL byte.
This patch fixes testsuite build failures caused by such warnings in
string/tester.c. In general, the warnings are disabled around the
relevant calls using DIAG_* macros, since the relevant cases are being
deliberately tested. In one case, the warning is with
-Wstringop-overflow= instead of -Wstringop-truncation; in that case,
the conditional is __GNUC_PREREQ (7, 0) (being the version where
-Wstringop-overflow= was introduced), to allow the conditional to be
removed sooner, since it's harmless to disable the warning for a
GCC version where it doesn't actually occur. In the case of warnings
for strncpy calls in test_memcmp, the calls in question are changed to
use memcpy, as they don't copy a trailing NUL and the point of that
code is to test memcmp rather than strncpy.
Tested (compilation) with GCC 8 for x86_64-linux-gnu with
build-many-glibcs.py (in conjunction with Martin's patch to allow
glibc to build).
* string/tester.c (test_stpncpy): Disable -Wstringop-truncation
for stpncpy calls for GCC 8.
(test_strncat): Disable -Wstringop-truncation warning for strncat
calls for GCC 8. Disable -Wstringop-overflow= warning for one
strncat call for GCC 7.
(test_strncpy): Disable -Wstringop-truncation warning for strncpy
calls for GCC 8.
(test_memcmp): Use memcpy instead of strncpy for calls not copying
trailing NUL.
H.J. Lu [Mon, 13 Nov 2017 16:02:39 +0000 (08:02 -0800)]
ld.so: Add architecture specific fields
To support Intel Control-flow Enforcement Technology (CET) run-time
control:
1. An architecture specific field in the writable ld.so namespace is
needed to indicate if CET features are enabled at run-time.
2. An architecture specific field in struct link_map is needed if
CET features are enabled in an ELF module.
This patch adds dl-procruntime.c to the writable ld.so namespace and
link_map.h to struct link_map.
Tested with build-many-glibcs.py.
* elf/dl-support.c: Include <dl-procruntime.c>.
* include/link.h: Include <link_map.h>.
* sysdeps/generic/dl-procruntime.c: New file.
* sysdeps/generic/link_map.h: Likewise.
* sysdeps/generic/ldsodefs.h: Include <dl-procruntime.c> in
the writable ld.so namespace.
Florian Weimer [Sat, 11 Nov 2017 10:51:08 +0000 (11:51 +0100)]
resolv: More precise checks in res_hnok, res_dnok [BZ #22409] [BZ #22412]
res_hnok rejected some host names used on the Internet, such as
www-.example.com. res_hnok and res_dnok failed to perform basic syntax
checking on DNS domain names.
H.J. Lu [Thu, 9 Nov 2017 13:09:49 +0000 (05:09 -0800)]
Add jmp_buf-macros.h
Verify that sizes, alignments and field offsets of jmp_buf as well as
sigjmp_buf are unchanged regardless how struct __jmp_buf_tag is defined.
Since jmp_buf is target specific, jmp_buf-macros.h is added for each
Linux target. A new target must provides its own jmp_buf-macros.h.
Joseph Myers [Tue, 7 Nov 2017 23:47:53 +0000 (23:47 +0000)]
Handle more _FloatN, _FloatNx types in include/float.h.
Continuing the preparation for additional _FloatN / _FloatNx type
support, this patch adds support in include/float.h. This header
defines macros for _Float128 properties when using compilers before
GCC 7 that lack those macros in <float.h>. For testing _Float32 /
_Float64 / _Float32x / _Float64x functions with older compilers, such
macros need to be defined for those types as well; for the older
compilers, those types will always be typedefs for another type, so
the definitions can be in terms of the macros for that other type.
Joseph Myers [Tue, 7 Nov 2017 18:08:44 +0000 (18:08 +0000)]
Handle more _FloatN, _FloatNx types in type-generic strtod tests.
Continuing the preparation for additional _FloatN / _FloatNx type
support, this patch adds support to type-generic strtod tests.
GEN_STRTOD_TEST_FOREACH and STRTOD_TEST_FOREACH are made to handle the
full set of such types. tst-strtod-round-skeleton.c is updated for
those types it can handle without needing changes to the generator
(i.e. those types that have already-handled formats).
This patch adds two new internal defines to set the internal
pthread_mutex_t layout required by the supported ABIS:
1. __PTHREAD_MUTEX_NUSERS_AFTER_KIND which control whether to define
__nusers fields before or after __kind. The preferred value for
is 0 for new ports and it sets __nusers before __kind.
2. __PTHREAD_MUTEX_USE_UNION which control whether internal __spins and
__list members will be place inside an union for linuxthreads
compatibility. The preferred value is 0 for ports and it sets
to not use an union to define both fields.
It fixes the wrong offsets value for __kind value on x86_64-linux-gnu-x32.
Checked with a make check run-built-tests=no on all afected ABIs.
[BZ #22298]
* nptl/allocatestack.c (allocate_stack): Check if
__PTHREAD_MUTEX_HAVE_PREV is non-zero, instead if
__PTHREAD_MUTEX_HAVE_PREV is defined.
* nptl/descr.h (pthread): Likewise.
* nptl/nptl-init.c (__pthread_initialize_minimal_internal):
Likewise.
* nptl/pthread_create.c (START_THREAD_DEFN): Likewise.
* sysdeps/nptl/fork.c (__libc_fork): Likewise.
* sysdeps/nptl/pthread.h (PTHREAD_MUTEX_INITIALIZER): Likewise.
* sysdeps/nptl/bits/thread-shared-types.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION): New
defines.
(__pthread_internal_list): Check __PTHREAD_MUTEX_USE_UNION instead
of __WORDSIZE for internal layout.
(__pthread_mutex_s): Check __PTHREAD_MUTEX_NUSERS_AFTER_KIND instead
of __WORDSIZE for internal __nusers layout and __PTHREAD_MUTEX_USE_UNION
instead of __WORDSIZE whether to use an union for __spins and __list
fields.
(__PTHREAD_MUTEX_HAVE_PREV): Define also for __PTHREAD_MUTEX_USE_UNION
case.
* sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION): New
defines.
* sysdeps/alpha/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/arm/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/hppa/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/powerpc/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/sparc/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/x86/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
Instead of rely on runtime check to assure correct pthread types
size a better strategy would use _Static_assert to trigger an error
on build time (and thus allowing to check to potentially ABI breakage
on cross-compiling make check).
This patch moves nptl/tst-typesizes.c to libpthread build time on
each specific initialization routine and also remove some runtime
redundant asserts for the same type sizes.
Checked on x86_64-linux-gnu and with a build check for all affected
ABIs (aarch64-linux-gnu, alpha-linux-gnu, arm-linux-gnueabihf,
hppa-linux-gnu, i686-linux-gnu, ia64-linux-gnu, m68k-linux-gnu,
microblaze-linux-gnu, mips64-linux-gnu, mips64-n32-linux-gnu,
mips-linux-gnu, powerpc64le-linux-gnu, powerpc-linux-gnu,
s390-linux-gnu, s390x-linux-gnu, sh4-linux-gnu, sparc64-linux-gnu,
sparcv9-linux-gnu, tilegx-linux-gnu, tilegx-linux-gnu-x32,
tilepro-linux-gnu, x86_64-linux-gnu, and x86_64-linux-x32).
nptl: Add tests for internal pthread_mutex_t offsets
This patch adds a new build test to check for internal fields
offsets for user visible internal field. Although currently
the only field which is statically initialized to a non zero value
is pthread_mutex_t.__data.__kind value, the tests also check the
offset of __kind, __spins, __elision (if supported), and __list
internal member. A internal header (pthread-offset.h) is added
to each major ABI with the reference value.
Checked on x86_64-linux-gnu and with a build check for all affected
ABIs (aarch64-linux-gnu, alpha-linux-gnu, arm-linux-gnueabihf,
hppa-linux-gnu, i686-linux-gnu, ia64-linux-gnu, m68k-linux-gnu,
microblaze-linux-gnu, mips64-linux-gnu, mips64-n32-linux-gnu,
mips-linux-gnu, powerpc64le-linux-gnu, powerpc-linux-gnu,
s390-linux-gnu, s390x-linux-gnu, sh4-linux-gnu, sparc64-linux-gnu,
sparcv9-linux-gnu, tilegx-linux-gnu, tilegx-linux-gnu-x32,
tilepro-linux-gnu, x86_64-linux-gnu, and x86_64-linux-x32).
This patch simplify Linux sigqueue implementation by assuming
__NR_rt_sigqueueinfo existence due minimum kernel requirement
(it pre-dates Linux git inclusion for Linux 2.6.12).
Simplify Linux sig{timed}wait{info} implementations
This patch simplifies sig{timed}wait{info} by:
- Assuming __NR_rt_sigtimedwait existence on all architectures due minimum
kernel version requirement (it pre-dates Linux git inclusion for Linux
2.6.12).
- Call __sigtimedwait on both sigwait and sigwaitinfo.
- Now that sigwait is based on an internal sigtimedwait call and it is
present of both libc.so and libpthread.so we need to add an external
private definition of __sigtimedwait for libpthread.so call.
Checked on x86_64-linux-gnu.
* sysdeps/unix/sysv/linux/Versions (libc) [GLIBC_PRIVATE]: Add
__sigtimedwait.
* sysdeps/unix/sysv/linux/sigtimedwait.c: Simplify includes and
assume __NR_rt_sigtimedwait.
* sysdeps/unix/sysv/linux/sigwait.c (__sigwait): Call __sigtimedwait
and add LIBC_CANCEL_HANDLED for cancellation marking.
* sysdeps/unix/sysv/linux/sigwaitinfo.c (__sigwaitinfo): Likewise.
This patch refactor ARM memchr ifunc selector to a C implementation.
No functional change is expected, including ifunc resolution rules.
It also reorganize the ifunc options code:
1. The memchr_impl.S is renamed to memchr_neon.S and multiple
compilation options (which route to armv6t2/memchr one) is
removed. The code to build if __ARM_NEON__ is defined is
also simplified.
2. A memchr_noneon is added (which as build along previous ifunc
resolution) and includes the armv6t2 direct.
3. Same as 2. for loader object.
Alongside the aforementioned changes, it also some cleanus:
- Internal memchr definition (__GI_memcpy) is now a hidden
symbol.
- No need to create hidden definition for the ifunc variants.
Checked on armv7-linux-gnueabihf and with a build for arm-linux-gnueabi,
arm-linux-gnueabihf with and without multiarch support and with both
GCC 7.1 and GCC mainline.
This patch refactor ARM memcpy ifunc selector to a C implementation.
No functional change is expected, including ifunc resolution rules.
It also adds some cleanup:
- Internal memcpy hidden definition (__GI_memcpy) is now a hidden
symbol.
- No need to create hidden definition for the ifunc variants.
Checked on armv7-linux-gnueabihf and with a build for arm-linux-gnueabi,
arm-linux-gnueabihf with and without multiarch support and with both
GCC 7.1 and GCC mainline. I also checked with the some possible
multiarch different configurations that trigger different memcpy
buids (__ARM_NEON__ && !__SOFT_FP__, !__ARM_NEON__ && !__SOFT_FP__, and
!__ARM_NEON__ && __SOFT_FP__).
H.J. Lu [Mon, 6 Nov 2017 16:29:48 +0000 (08:29 -0800)]
Use newly built crt*.o files to build shared objects [BZ #22362]
When multi-lib GCC is used to build glibc, the search order of GCC driver
for crt*.o is -B*/`gcc -print-multi-directory`, the installed diretory,
-B*/. This patch adds multi-lib support to csu/Makefile so that
-B/glibc-build-directory/csu/ will pick up the newly built crt*.o.
Joseph Myers [Mon, 6 Nov 2017 13:26:15 +0000 (13:26 +0000)]
Do not declare _Float128 support for powerpc64le -mlong-double-64 (bug 22402).
The powerpc bits/floatn.h declares _Float128 support to be present
when the compiler supports it for powerpc64le. However, in the case
where -mlong-double-64 is used, __MATH_TG does not actually support
_Float128; it only supports _Float128 in the distinct-long-double
case.
This shows up as a build failure when building glibc mainline with GCC
mainline, given the recently added sanity check in math.h for
configurations supported by __MATH_TG, as the compat code for
-mlong-double-64 fails to build. However, the bug was logically
present before that change (including in 2.26), just less visible.
This patch fixes the build failure by declaring _Float128 to be
unsupported in that case. (Of course this can't actually stop users
calling the type-generic macros with _Float128 arguments with
-mlong-double-64, just as they could be called with other unsupported
types on other platforms, but perhaps makes it less likely by making
all the type-specific _Float128 interfaces invisible in that case.)
Tested compilation for powerpc64le with build-many-glibcs.py.
[BZ #22402]
* sysdeps/powerpc/bits/floatn.h: Include <bits/long-double.h>.
[__NO_LONG_DOUBLE_MATH] (__HAVE_FLOAT128): Define to 0.
Joseph Myers [Fri, 3 Nov 2017 23:50:00 +0000 (23:50 +0000)]
Handle more _FloatN, _FloatNx types in __MATH_TG.
Continuing the preparation for additional _FloatN / _FloatNx type
support, this patch prepares __MATH_TG to handle more such types.
Various unhandled cases, which do not correspond to any current glibc
configuration, have explicit #errors added. _Float32 and _Float64x
are then handled appropriately in the _Generic case, which is the only
one, other than the cases where use of sizeof is sufficient, where
they should ever be explicit types at the language level instead of
typedefs. There is no need to handle _Float64 or _Float32x explicitly
there because the default case calling a double function is correct
for those types.
Joseph Myers [Fri, 3 Nov 2017 21:11:50 +0000 (21:11 +0000)]
Handle more _FloatN, _FloatNx types in tgmath.h.
Continuing the preparation for additional _FloatN / _FloatNx type
support, this patch improves how <tgmath.h> handles such types.
Use of #error is added for cases of distinct types that are not
supported by the header, to indicate that additional work on the
header would be needed if, for example, _Float16 support were added to
glibc. Given that #error, types with the same format as other types
are handled automatically by the sizeof-based logic, so the only case
needing special handling is that where _Float64x exists, has the same
format as _Float128, does not have the same format as long double, and
is not a typedef for _Float128. In this case (which will apply for
powerpc64le once _Float64x support is added to glibc), the
__builtin_types_compatible_p calls testing for _Float128 need
corresponding calls testing for _Float64x, which this patch adds.
Joseph Myers [Fri, 3 Nov 2017 17:09:21 +0000 (17:09 +0000)]
Declare strtof, strfromf functions for more _FloatN, _FloatNx types.
Continuing the preparation for additional _FloatN / _FloatNx type
support, this patch arranges for <stdlib.h> to declare strtof and
strfromf functions for all such types, similarly to the declarations
already present for _Float128.
Szabolcs Nagy [Tue, 24 Oct 2017 16:49:14 +0000 (17:49 +0100)]
aarch64: optimize _dl_tlsdesc_dynamic fast path
Remove some load/store instructions from the dynamic tlsdesc resolver
fast path. This gives around 20% faster tls access in dlopened shared
libraries (assuming glibc ran out of static tls space).
Szabolcs Nagy [Fri, 20 Oct 2017 16:35:12 +0000 (17:35 +0100)]
[BZ #18572] arm: Disable lazy initialization of tlsdesc entries
Follow up to
https://sourceware.org/ml/libc-alpha/2015-11/msg00272.html
Always do tls descriptor initialization at load time during relocation
processing (as if DF_BIND_NOW were set for the binary) to avoid barriers
at every tls access. This patch mimics bind-now semantics in the lazy
relocation code of the arm target (elf_machine_lazy_rel).
Ideally the static linker should be updated too to not emit tlsdesc
relocs in DT_REL*, so elf_machine_lazy_rel is not called on them at all.
[BZ #18572]
* sysdeps/arm/dl-machine.h (elf_machine_lazy_rel): Do symbol binding
non-lazily for R_ARM_TLS_DESC.
This only implemented support for the lazy binding case (and thus
closed the bugzilla ticket prematurely), however tlsdesc on arm is
not correct with lazy binding because there is a data race between
the lazy initialization code and tlsdesc resolver functions.
Lazy initialization of tlsdesc entries will be removed from arm to
fix the data races and thus this half-finished prelinker support
is no longer useful.
[BZ #17078]
* sysdeps/arm/dl-machine.h (elf_machine_rela): Remove the
R_ARM_TLS_DESC case.
(elf_machine_lazy_rel): Remove the prelink check.
Szabolcs Nagy [Wed, 27 Sep 2017 15:55:14 +0000 (16:55 +0100)]
aarch64: Disable lazy symbol binding of TLSDESC
Always do TLS descriptor initialization at load time during relocation
processing to avoid barriers at every TLS access. In non-dlopened shared
libraries the overhead of tls access vs static global access is > 3x
bigger when lazy initialization is used (_dl_tlsdesc_return_lazy)
compared to bind-now (_dl_tlsdesc_return) so the barriers dominate tls
access performance.
TLSDESC relocs are in DT_JMPREL which are processed at load time using
elf_machine_lazy_rel which is only supposed to do lightweight
initialization using the DT_TLSDESC_PLT trampoline (the trampoline code
jumps to the entry point in DT_TLSDESC_GOT which does the lazy tlsdesc
initialization at runtime). This patch changes elf_machine_lazy_rel
in aarch64 to do the symbol binding and initialization as if DF_BIND_NOW
was set, so the non-lazy code path of elf/do-rel.h was replicated.
The static linker could be changed to emit TLSDESC relocs in DT_REL*,
which are processed non-lazily, but the goal of this patch is to always
guarantee bind-now semantics, even if the binary was produced with an
old linker, so the barriers can be dropped in tls descriptor functions.
After this change the synchronizing ldar instructions can be dropped
as well as the lazy initialization machinery including the DT_TLSDESC_GOT
setup.
I believe this should be done on all targets, including ones where no
barrier is needed for lazy initialization. There is very little gain in
optimizing for large number of symbolic tlsdesc relocations which is an
extremely uncommon case. And currently the tlsdesc entries are only
readonly protected with -z now and some hardennings against writable
JUMPSLOT relocs don't work for TLSDESC so they are a security hazard.
(But to fix that the static linker has to be changed.)
* sysdeps/aarch64/dl-machine.h (elf_machine_lazy_rel): Do symbol
binding and initialization non-lazily for R_AARCH64_TLSDESC.
git://sourceware.org / glibc.git / log