This patch fixes the tst-tlsmod[5/6].so build in system that uses
-Wl,--as-needed as default in linker option. Without this option
the testing shared library that does not have libc.so in DT_NEEDED
and the tst-tls9-static fails in architecture that use the
./sysdeps/unix/sysv/linux/<arch>/dl-static.c trick.
The nested function referred to has gone away so remove the
comment. Also move the variable declaration down to where other
variables of a similar lifetime are declared for clarity.
2014-04-03 Will Newton <will.newton@linaro.org>
* elf/dl-lookup.c (do_lookup_x): Remove comment
referring to nested function and move variable
declarations down to before first use.
An application that erroneously tries to repeatedly dlopen("a.out", ...)
may hit assertion failure:
Inconsistency detected by ld.so: dl-tls.c: 474: _dl_allocate_tls_init:
Assertion `listp != ((void *)0)' failed!
dlopen() actually fails with "./a.out: cannot dynamically load executable",
but it does so after incrementing dl_tls_max_dtv_idx.
Once we run out of TLS_SLOTINFO_SURPLUS (62), we exit with above assertion
failure.
2014-03-24 Paul Pluzhnikov <ppluzhnikov@google.com>
[BZ #16634]
* elf/dl-load.c (open_verify): Add mode parameter.
Error early when ET_EXEC and mode does not have __RTLD_OPENEXEC.
(open_path): Change from boolean 'secure' to complete flag 'mode'
(_dl_map_object): Adjust.
* elf/Makefile (tests): Add tst-dlopen-aout.
* elf/tst-dlopen-aout.c: New test.
This script works fine under bash as-is, so we don't need ksh anymore.
Once we tweak the function style, the code even works (for the most part)
under a POSIX shell. The localized strings will be prepended with a $,
but it is otherwise functional.
This patch systematically renames miscellaneous tests so their outputs
use a *.out name (unless the test is just running some glibc program
with its conventional output file name, rather than a special program
at all, as in catgets tests generating *.cat). In the case of the
iconv test test-iconvconfig, output is redirected where it wasn't
before.
In various places the "generated" variable is updated to reflect the
revised test names; in iconvdata/Makefile a typo (mmtrace-tst-loading)
is also fixed. resolv/Makefile sets both "generate" (which appears
unused) and "generated". Bitrot in the settings of these variables
could no doubt be fixed so that "make clean" after build and testing
leaves results the same as after configure (and indeed the
tests-special / xtests-special variables could be used to simplify
things, by removing those files automatically rather than listing them
manually in these variables), and "make distclean" leaves an empty
build directory, but right now it appears various files don't get
deleted. I think they are liable to continue to bitrot in the absence
of routine testing that these targets actually work, given that
building in the source directory isn't supported and that was the main
use of such makefile targets.
Tested x86_64.
* elf/Makefile (tests-special): Rename tests to end with .out.
($(objpfx)noload-mem): Likewise.
($(objpfx)tst-leaks1-mem): Likewise.
($(objpfx)tst-leaks1-static-mem.out): Likewise.
* iconv/Makefile (xtests-special): Change test-iconvconfig to
$(objpfx)test-iconvconfig.out.
(test-iconvconfig): Change to $(objpfx)test-iconvconfig.out. Use
set -e inside subshell and redirect output to file.
* iconvdata/Makefile (generated): Rename tests to end with .out.
Correct type.
(tests-special): Rename tests to end with .out.
($(objpfx)mtrace-tst-loading): Likewise.
* intl/Makefile (generated): Likewise.
(tests-special): Likewise.
($(objpfx)mtrace-tst-gettext): Likewise.
* misc/Makefile (generated): Likewise.
(tests-special): Likewise.
($(objpfx)tst-error1-mem): Likewise.
* nptl/Makefile (tests-special): Likewise.
($(objpfx)tst-stack3-mem): Likewise.
(generated): Likewise.
* posix/Makefile (generated): Likewise.
(tests-special): Likewise.
(xtests-special): Likewise.
($(objpfx)tst-fnmatch-mem): Likewise.
($(objpfx)bug-regex2-mem): Likewise.
($(objpfx)bug-regex14-mem): Likewise.
($(objpfx)bug-regex21-mem): Likewise.
($(objpfx)bug-regex31-mem): Likewise.
($(objpfx)tst-vfork3-mem): Likewise.
($(objpfx)tst-rxspencer-no-utf8-mem): Likewise.
($(objpfx)tst-pcre-mem): Likewise.
($(objpfx)tst-boost-mem): Likewise.
($(objpfx)bug-ga2-mem): Likewise.
($(objpfx)bug-glob2-mem): Likewise.
* resolv/Makefile (generate): Likewise.
(tests-special): Likewise.
(xtests-special): Likewise.
(generated): Likewise.
($(objpfx)mtrace-tst-leaks): Likewise.
($(objpfx)mtrace-tst-leaks2): Likewise.
localedata:
* Makefile (generated): Rename tests to end with .out.
(tests-special): Likewise.
($(objpfx)mtrace-tst-leaks): Likewise.
This patch is a revised and updated version of
<https://sourceware.org/ml/libc-alpha/2014-01/msg00196.html>.
In order to generate overall summaries of the results of all tests in
the glibc testsuite, we need to identify and concatenate the files
with the results of individual tests.
Tomas Dohnalek's patch used $(common-objpfx)*/*.test-result for this.
However, the normal glibc approach is explicit enumeration of the
expected set of files with a given property, rather than all files
matching some pattern like that. Furthermore, we would like to be
able to mark tests as UNRESOLVED if the file with their results is for
some reason missing, and in future we would like to be able to mark
tests as UNSUPPORTED if they are disabled for a particular
configuration (rather than simply having them missing from the list of
tests as at present). Such handling of tests that were not run or did
not record results requires an explicit enumeration of tests.
For the tests following the default makefile rules, $(tests) (and
$(xtests)) provides such an enumeration. Others, however, are added
directly as dependencies of the "tests" and "xtests" makefile
targets. This patch changes the makefiles to put them in variables
tests-special and xtests-special, with appropriate dependencies on the
tests listed there then being added centrally.
Those variables are used in Rules and so need to be set before Rules
is included in a subdirectory makefile, which is often earlier in the
makefile than the dependencies were present before. We previously
discussed the question of where to include Rules; see the question at
<https://sourceware.org/ml/libc-alpha/2012-11/msg00798.html>, and a
discussion in
<https://sourceware.org/ml/libc-alpha/2013-01/msg00337.html> of why
Rules is included early rather than late in subdirectory makefiles.
It was necessary to avoid an indirection through the check-abi target
and get the check-abi-* targets for individual libraries into the
tests-special variable. The intl/ test $(objpfx)tst-gettext.out,
previously built only because of dependencies from other tests, was
also added to tests-special for the same reason.
The entries in tests-special are the full makefile targets, complete
with $(objpfx) and .out. If a future change causes tests to be named
consistently with a .out suffix, this can be changed to include just
the path relative to $(objpfx), without .out.
Tested x86_64, including that the same set of files is generated in
the build directory by a build and testsuite run both before and after
the patch (except for changes to the
elf/tst-null-argv.debug.out.<number> file name), and a build with
run-built-tests=no to verify there aren't any more obvious instances
of the issue Marcus Shawcroft reported with a previous version in
<https://sourceware.org/ml/libc-alpha/2014-01/msg00462.html>.
* Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
(tests): Depend on $(tests-special).
* Makerules (check-abi-list): New variable.
(check-abi): Depend on $(check-abi-list).
[$(subdir) = elf] (tests-special): Add
$(objpfx)check-abi-libc.out.
[$(build-shared) = yes && subdir] (tests-special): Add
$(check-abi-list).
[$(build-shared) = yes && subdir] (tests): Do not depend on
check-abi.
* Rules (tests): Depend on $(tests-special).
(xtests): Depend on $(xtests-special).
* catgets/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* conform/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* elf/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* grp/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* iconv/Makefile (xtests): Change dependencies to ....
(xtests-special): ... additions to this variable.
* iconvdata/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* intl/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable. Also add
$(objpfx)tst-gettext.out.
* io/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* libio/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* malloc/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* misc/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* nptl/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* nptl_db/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* posix/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
(xtests): Change dependencies to ....
(xtests-special): ... additions to this variable.
* resolv/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
(xtests): Change dependencies to ....
(xtests-special): ... additions to this variable.
* stdio-common/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
(do-tst-unbputc): Remove target.
(do-tst-printf): Likewise.
* stdlib/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* string/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
* sysdeps/x86/Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
localedata:
* Makefile (tests): Change dependencies to ....
(tests-special): ... additions to this variable.
While it may be argued that nested functions make the resulting
code easier to read, or worse to read the following two bugs
make it difficult to debug:
Bug 8300 - no local symbol information within nested or nesting
procedures
https://sourceware.org/bugzilla/show_bug.cgi?id=8300
Bug 53927 - wrong value for DW_AT_static_link
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53927
Until these are fixed I've made check_match a full function.
After they are fixed we can resume arguing about the merits
of nested functions on readability and maintenance.
This commit fixes a bug where the dynamic loader would crash
when loading audit libraries, via LD_AUDIT, where those libraries
used TLS. The dynamic loader was not considering that the audit
libraries would use TLS and failed to bump the TLS generation
counter leaving TLS usage inconsistent after loading the audit
libraries.
https://sourceware.org/ml/libc-alpha/2014-02/msg00569.html
This patch splits makefile rules that generate a file then run cmp to
check the contents of that file into separate rules to generate and
compare the file. This simplifies making those tests generate PASS /
FAIL results, by removing the need to insert && between commands in
the test so that a $(evaluate-test) call is reached. It also avoids
the oddity of the .out file being an intermediate file rather than the
final result generated, as noted for some of these tests in
<https://sourceware.org/ml/libc-alpha/2012-10/msg00894.html>.
In many cases, the rule to run the program was no longer needed
because the default rules for running test programs on the host to
generate a .out file sufficed. (I'm not asserting the commands run
after this patch are *exactly* the same as before, simply that the
rules did nothing special that appeared deliberate or relevant to
anything about what the tests were testing. In cases where the rules
redirected stderr as well as stdout, I left the existing rule's
redirection in place to avoid changing what gets compared with the
expected results.)
It's clear there is a lot in common between the various -cmp.out rules
and it might be possible in future to refactor them into more generic
support for the case of comparing test output against a baseline.
(Some baselines are *.exp, some *.expect, some directly embedded in
the makefiles, and nptl/tst-cleanupx0.expect appears unused.)
Tested x86_64.
* elf/Makefile ($(objpfx)order.out): Remove rule.
[$(run-built-tests) = yes] (tests): Depend on
$(objpfx)order-cmp.out.
($(objpfx)order-cmp.out): New rule.
[$(run-built-tests) = yes] (tests): Depend on
$(objpfx)tst-array1-cmp.out, $(objpfx)tst-array1-static-cmp.out,
$(objpfx)tst-array2-cmp.out, $(objpfx)tst-array3-cmp.out,
$(objpfx)tst-array4-cmp.out, $(objpfx)tst-array5-cmp.out and
$(objpfx)tst-array5-static-cmp.out.
($(objpfx)tst-array1.out): Remove rule.
($(objpfx)tst-array1-cmp.out): New rule.
($(objpfx)tst-array1-static.out): Remove rule.
($(objpfx)tst-array1-static-cmp.out): New rule.
($(objpfx)tst-array2.out): Remove rule.
($(objpfx)tst-array2-cmp.out): New rule.
($(objpfx)tst-array3.out): Remove rule.
($(objpfx)tst-array3-cmp.out): New rule.
($(objpfx)tst-array4.out): Remove rule.
($(objpfx)tst-array4-cmp.out): New rule.
($(objpfx)tst-array5.out): Remove rule.
($(objpfx)tst-array5-cmp.out): New rule.
($(objpfx)tst-array5-static.out): Remove rule.
($(objpfx)tst-array5-static-cmp.out): New rule.
[$(run-built-tests) = yes] (tests): Depend on
$(objpfx)order2-cmp.out.
($(objpfx)order2.out): Remove rule.
($(objpfx)order2-cmp.out): New rule.
($(objpfx)tst-initorder.out): Remove rule.
[$(run-built-tests) = yes] (tests): Depend on
$(objpfx)tst-initorder-cmp.out.
($(objpfx)tst-initorder-cmp.out): New rule.
($(objpfx)tst-initorder2.out): Remove rule.
[$(run-built-tests) = yes] (tests): Depend on
$(objpfx)tst-initorder2-cmp.out.
($(objpfx)tst-initorder2-cmp.out): New rule.
[$(run-built-tests) = yes] (tests): Depend on
$(objpfx)tst-unused-dep-cmp.out.
($(objpfx)tst-unused-dep-cmp.out): Do not run cmp.
($(objpfx)tst-unused-dep-cmp.out): New rule.
* stdio-common/Makefile [$(run-built-tests) = yes] (tests): Depend
on $(objpfx)tst-setvbuf1-cmp.out.
($(objpfx)tst-setvbuf1.out): Do not run cmp.
($(objpfx)tst-setvbuf1-cmp.out): New rule.
* string/Makefile [$(run-built-tests) = yes] (tests): Depend
$(objpfx)tst-svc-cmp.out instead of $(objpfx)tst-svc.out.
($(objpfx)tst-svc.out): Remove rule.
($(objpfx)tst-svc-cmp.out): New rule.
nptl:
* Makefile ($(objpfx)tst-cleanup0.out): Do not run cmp.
[$(run-built-tests) = yes] (tests): Depend on
$(objpfx)tst-cleanup0-cmp.out.
($(objpfx)tst-cleanup0-cmp.out): New rule.
If you rerun "make check" in a tree where some tests have already been
run, it will rerun ABI tests because those do not create an output
file.
This patch changes those tests to create .out files so they only get
rerun if the dependencies (on the ABI baselines and the generated
.symlist files) indicate they should be rerun.
Tested x86_64.
* Makerules (check-abi-%): Change target to
$(objpfx)check-abi-%.out.
(check-abi target): Update dependencies.
(check-abi-pattern variable): Redirect output of diff to $@.
(check-abi variable): Likewise.
* elf/Makefile (check-abi): Update dependencies.
MIPS has its own version of dl-lookup.c to deal with differences
between undefined symbol semantics in the PIC and non-PIC ABIs. This
is often liable to get out of date with respect to the generic file
(for example, the recent __builtin_expect changes didn't cover ports,
and it's not obvious to anyone changing dl-lookup.c that there would
be architecture-specific versions).
This patch adds a macro that dl-machine.h can define that is used in
the appropriate place in dl-lookup.c, so that MIPS no longer needs its
own version of that file.
Tested for mips64 that the only changes to disassembly of installed
shared libraries appear to be ld.so changes attributable to different
line numbers and paths in assertions.
* elf/dl-lookup.c (ELF_MACHINE_SYM_NO_MATCH): Define if not
already defined.
(do_lookup_x): Use ELF_MACHINE_SYM_NO_MATCH.
* sysdeps/mips/dl-lookup.c: Remove.
* sysdeps/mips/dl-machine.h (ELF_MACHINE_SYM_NO_MATCH): New macro.
This reverts commit 1f33d36a8a.
Conflicts:
elf/dl-misc.c
Also reverts the follow commits that were bug fixes to new code introduced
in the above commit:
063b2acbceb627fdd585e81c64bba1
Fixes to address issues from BZ #15022 resolution, as follows:
* TLS updates to csu/libc-tls.c -- we now have a proper main map, so
there's no longer a need to create a separate fake one to keep TLS
structures,
* random updates to elf/dl-close.c -- LM_ID_BASE is now a valid name
space ID for static executables as well, so assert that we don't
unload the main map. Similarly dl_nns isn't supposed to be 0 for
static executables anymore,
* actual BZ #16046 fix to elf/dl-iteratephdr.c -- the dl_iterate_phdr
special function for static executables isn't needed anymore, provided
that l_phdr and l_phnum members of the main map have been properly
initialized (done in _dl_non_dynamic_init in elf/dl-support.c now),
* ld.so.cache loader update to elf/dl-load.c --
GL(dl_ns)[LM_ID_BASE]._ns_loaded is now always initialized in static
executables so can become the fallback loader map to check for
DF_1_NODEFLIB, provided that the l_flags_1 member of the main map has
been properly initialized (done in elf/dl-support.c now); this also
ensures previous semantics elsewhere in elf/dl-load.c,
* matching updates to elf/dl-support.c -- to complement the two fixes
above.
2013-12-19 Paul Pluzhnikov <ppluzhnikov@google.com>
* elf/dl-misc.c (ptr_to_signal_safe_allocator_header): New function.
(__signal_safe_memalign, __signal_safe_free): Use it.
(__signal_safe_realloc): Likewise.
[BZ 15846] As discussed in the recent thread on my $EXEC_ORIGIN patch
and in BZ 15846, getauxval() presently has no unambiguous way of
reporting an error condition. It currently returns zero on error, but
this may also be a valid result for some auxv entries. As there is no
clear invalid result for all current and future auxv entries, this patch
sets errno (following a suggestion in the BZ entry).
This version of the patch also adds documentation and tests for the
value-not-found conditions in getauxval().
This is a follow-on to the previous patch to support the ELFv2 ABI in the
dynamic loader, split off into its own patch since it is just an optional
optimization.
In the ELFv2 ABI, most functions define both a global and a local entry
point; the local entry requires r2 to be already set up by the caller
to point to the callee's TOC; while the global entry does not require
the caller to know about the callee's TOC, but it needs to set up r12
to the callee's entry point address.
Now, when setting up a PLT slot, the dynamic linker will usually need
to enter the target function's global entry point. However, if the
linker can prove that the target function is in the same DSO as the
PLT slot itself, and the whole DSO only uses a single TOC (which the
linker will let ld.so know via a DT_PPC64_OPT entry), then it is
possible to actually enter the local entry point address into the
PLT slot, for a slight improvement in performance.
Note that this uncovered a problem on the first call via _dl_runtime_resolve,
because that routine neglected to restore the caller's TOC before calling
the target function for the first time, since it assumed that function
would always reload its own TOC anyway ...
This patch adds support for the ELFv2 ABI feature to remove function
descriptors. See this GCC patch for in-depth discussion:
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01141.html
This mostly involves two types of changes: updating assembler source
files to the new logic, and updating the dynamic loader.
After the refactoring in the previous patch, most of the assembler source
changes can be handled simply by providing ELFv2 versions of the
macros in sysdep.h. One somewhat non-obvious change is in __GI__setjmp:
this used to "fall through" to the immediately following __setjmp ENTRY
point. This is no longer safe in the ELFv2 since ENTRY defines both
a global and a local entry point, and you cannot simply fall through
to a global entry point as it requires r12 to be set up.
Also, makecontext needs to be updated to set up registers according to
the new ABI for calling into the context's start routine.
The dynamic linker changes mostly consist of removing special code
to handle function descriptors. We also need to support the new PLT
and glink format used by the the ELFv2 linker, see:
https://sourceware.org/ml/binutils/2013-10/msg00376.html
In addition, the dynamic linker now verifies that the dynamic libraries
it loads match its own ABI.
The hack in VDSO_IFUNC_RET to "synthesize" a function descriptor
for vDSO routines is also no longer necessary for ELFv2.
This patch updates glibc in accordance with the binutils patch checked in here:
https://sourceware.org/ml/binutils/2013-10/msg00372.html
This changes the various R_PPC64_..._HI and _HA relocations to report
32-bit overflows. The motivation is that existing uses of @h / @ha
are to build up 32-bit offsets (for the "medium model" TOC access
that GCC now defaults to), and we'd really like to see failures at
link / load time rather than silent truncations.
For those rare cases where a modifier is needed to build up a 64-bit
constant, new relocations _HIGH / _HIGHA are supported.
The patch also fixes a bug in overflow checking for the R_PPC64_ADDR30
and R_PPC64_ADDR32 relocations.
On hppa and ia64, the macro DL_AUTO_FUNCTION_ADDRESS() uses the
variable fptr[2] in it's own scope.
The content of fptr[] is thus undefined right after the macro exits.
Newer gcc's (>= 4.7) reuse the stack space of this variable triggering
a segmentation fault in dl-init.c:69.
To fix this we rewrite the macros to make the call directly to init
and fini without needing to pass back a constructed function pointer.
It was noted in 2005 (BZ #832), 2006 (BZ #3266), and 2007 [1] that ldd
fails on shells other than Bash >= 3.0 because of the pipefail option
around try_trace (added on 2004-12-08). EGLIBC was patched in 2008 [2]
(r6912) to make the pipefail check run only on shells that support it,
but RTLD output would still be lost on other shells with certain SELinux
policies.
This patch rewrites try_trace to work on any POSIX-conformant shell in
such a way as to also work with such SELinux policies. It also obviates
one difference between glibc and EGLIBC.
URL: https://sourceware.org/ml/libc-alpha/2007-01/msg00041.html
URL: http://www.eglibc.org/archives/patches/msg00526.html
2013-09-11 P. J. McDermott <pj@pehjota.net>
[BZ #832]
* elf/ldd.bash.in (try_trace): More robustly and portably work around
SELinux terminal write permissions by using a command substitution
instead of a pipeline and pipefail option.
Statically built binaries use __pointer_chk_guard_local,
while dynamically built binaries use __pointer_chk_guard.
Provide the right definition depending on the test case
we are building.
The pointer guard used for pointer mangling was not initialized for
static applications resulting in the security feature being disabled.
The pointer guard is now correctly initialized to a random value for
static applications. Existing static applications need to be
recompiled to take advantage of the fix.
The test tst-ptrguard1-static and tst-ptrguard1 add regression
coverage to ensure the pointer guards are sufficiently random
and initialized to a default value.
It has been a long practice for software using IEEE 754 floating-point
arithmetic run on MIPS processors to use an encoding of Not-a-Number
(NaN) data different to one used by software run on other processors.
And as of IEEE 754-2008 revision [1] this encoding does not follow one
recommended in the standard, as specified in section 6.2.1, where it
is stated that quiet NaNs should have the first bit (d1) of their
significand set to 1 while signalling NaNs should have that bit set to
0, but MIPS software interprets the two bits in the opposite manner.
As from revision 3.50 [2][3] the MIPS Architecture provides for
processors that support the IEEE 754-2008 preferred NaN encoding format.
As the two formats (further referred to as "legacy NaN" and "2008 NaN")
are incompatible to each other, tools have to provide support for the
two formats to help people avoid using incompatible binary modules.
The change is comprised of two functional groups of features, both of
which are required for correct support.
1. Dynamic linker support.
To enforce the NaN encoding requirement in dynamic linking a new ELF
file header flag has been defined. This flag is set for 2008-NaN
shared modules and executables and clear for legacy-NaN ones. The
dynamic linker silently ignores any incompatible modules it
encounters in dependency processing.
To avoid unnecessary processing of incompatible modules in the
presence of a shared module cache, a set of new cache flags has been
defined to mark 2008-NaN modules for the three ABIs supported.
Changes to sysdeps/unix/sysv/linux/mips/readelflib.c have been made
following an earlier code quality suggestion made here:
http://sourceware.org/ml/libc-ports/2009-03/msg00036.html
and are therefore a little bit more extensive than the minimum
required.
Finally a new name has been defined for the dynamic linker so that
2008-NaN and legacy-NaN binaries can coexist on a single system that
supports dual-mode operation and that a legacy dynamic linker that
does not support verifying the 2008-NaN ELF file header flag is not
chosen to interpret a 2008-NaN binary by accident.
2. Floating environment support.
IEEE 754-2008 features are controlled in the Floating-Point Control
and Status (FCSR) register and updates are needed to floating
environment support so that the 2008-NaN flag is set correctly and
the kernel default, inferred from the 2008-NaN ELF file header flag
at the time an executable is loaded, respected.
As the NaN encoding format is a property of GCC code generation that is
both a user-selected GCC configuration default and can be overridden
with GCC options, code that needs to know what NaN encoding standard it
has been configured for checks for the __mips_nan2008 macro that is
defined internally by GCC whenever the 2008-NaN mode has been selected.
This mode is determined at the glibc configuration time and therefore a
few consistency checks have been added to catch cases where compilation
flags have been overridden by the user.
The 2008 NaN set of features relies on kernel support as the in-kernel
floating-point emulator needs to be aware of the NaN encoding used even
on hard-float processors and configure the FPU context according to the
value of the 2008 NaN ELF file header flag of the executable being
started. As at this time work on kernel support is still in progress
and the relevant changes have not made their way yet to linux.org master
repository.
Therefore the minimum version supported has been artificially set to
10.0.0 so that 2008-NaN code is not accidentally run on a Linux kernel
that does not suppport it. It is anticipated that the version is
adjusted later on to the actual initial linux.org kernel version to
support this feature. Legacy NaN encoding support is unaffected, older
kernel versions remain supported.
[1] "IEEE Standard for Floating-Point Arithmetic", IEEE Computer
Society, IEEE Std 754-2008, 29 August 2008
[2] "MIPS Architecture For Programmers, Volume I-A: Introduction to the
MIPS32 Architecture", MIPS Technologies, Inc., Document Number:
MD00082, Revision 3.50, September 20, 2012
[3] "MIPS Architecture For Programmers, Volume I-A: Introduction to the
MIPS64 Architecture", MIPS Technologies, Inc., Document Number:
MD00083, Revision 3.50, September 20, 2012
Long ago static startup did not parse the auxiliary vector and therefore
could not get at any `AT_FPUCW' tag to check whether upon FPU context
allocation the kernel would use a FPU control word setting different to
that provided by the `__fpu_control' variable. Static startup therefore
always initialized the FPU control word, forcing immediate FPU context
allocation even for binaries that otherwise never used the FPU.
As from GIT commit f8f900ecb9 static
startup supports parsing the auxiliary vector, so now it can avoid
explicit initialization of the FPU control word, just as can dynamic
startup, in the usual case where the setting written to the FPU control
word would be the same as the kernel uses. This defers FPU context
allocation until the binary itself actually pokes at the FPU.
Note that the `AT_FPUCW' tag is usually absent from the auxiliary vector
in which case _FPU_DEFAULT is assumed to be the kernel default.
This change creates a link map in static executables to serve as the
global search list for dlopen. It fixes a problem with the inability
to access the global symbol object and a crash on an attempt to map a
DSO into the global scope. Some code that has become dead after the
addition of this link map is removed too and test cases are provided.
Resolves: #15465
The program name may be unavailable if the user application tampers
with argc and argv[]. Some parts of the dynamic linker caters for
this while others don't, so this patch consolidates the check and
fallback into a single macro and updates all users.
In dl-hwcaps.c the comment read that rounding was done
to ElfW(Addr), but it's actually rounded to ElfW(Word).
In ldconfig.c we make each comment a sentence and
mention that the "tls" pseudo-hwcap is just for legacy
installations where TLS was optional.
---
2013-05-22 Carlos O'Donell <carlos@redhat.com>
* elf/ldconfig.c (is_hwcap_platform): Make comments full setences.
(main): Mention "tls" pseudo-hwcap is legacy.
* elf/dl-hwcaps.c (_dl_important_hwcaps): Correct rounding comment.
Loading of the vDSO pseudo-hwcap from the type 2 GNU note is
a rather arcane and poorly documented process. Given that I had
a chance to review this code today I thought I would add all
of the things I had to lookup to verify the validity of the
process.
With a single .note.GNU the vDSO can register up to 64 flags,
though in practice you are limited to 64 - _DL_FIRST_EXTRA
bits which on x86 is 12 bits.
The only use of this that I know of is in the Xen support
in Linux where they use the 1st bit to indicate "nosegneg".
I see "We use bit 1 to avoid bugs in some versions of glibc
when bit 0 is used; the choice is otherwise arbitrary.", but
no reference to a glibc bug anywhere. The code as-is should
support bit zero, so we still have that free for future use.
The kernel, glibc, and ld.so.cache must coordinate to ensure
that bit values don't go too high and are used consistently.
---
2013-05-13 Carlos O'Donell <carlos@redhat.com>
* elf/dl-hwcaps.c (_dl_important_hwcaps): Comment vDSO hwcap loading.
* elf/ldconfig.c (is_hwcap_platform): Comment each hwcap check.
(main): Comment "tls" pseudo-hwcap.
The algorithm for scanning dependencies upon dlclose is
less than immediately obvious. This patch adds two bits
of comments that explain why you start the dependency
search at l_initfini[1], and why you need to restart
the search.
---
2013-05-09 Carlos O'Donell <carlos@redhat.com>
* elf/dl-close.c (_dl_close_worker): Add comments.
The seen array was doubled in size recently, but the memset to clear
the array was not adjusted. We adjust the memset to always be correct
regardless of the size of seen.
---
2013-04-06 Carlos O'Donell <carlos@redhat.com>
[BZ #15309]
* elf/dl-open.c (dl_open_worker): memset all of seen array.
