The old exception handling implementation used function interposition
to replace the dynamic loader implementation (no TLS support) with the
libc implementation (TLS support). This results in problems if the
link order between the dynamic loader and libc is reversed (bug 25486).
The new implementation moves the entire implementation of the
exception handling functions back into the dynamic loader, using
THREAD_GETMEM and THREAD_SETMEM for thread-local data support.
These depends on Hurd support for these macros, added in commit
b65a82e4e7 ("hurd: Add THREAD_GET/SETMEM/_NC").
One small obstacle is that the exception handling facilities are used
before the TCB has been set up, so a check is needed if the TCB is
available. If not, a regular global variable is used to store the
exception handling information.
Also rename dl-error.c to dl-catch.c, to avoid confusion with the
dlerror function.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Building for nios2-linux-gnu has recently started showing a localplt
test failure, arising from a reference to __floatunsidf from
getloadavg after commit b5c8a3aa82
("Linux: implement getloadavg(3) using sysinfo(2)") (this is an
architecture with soft-fp in libc). Add this as a permitted local PLT
reference in localplt.data.
Tested with build-many-glibcs.py for nios2-linux-gnu.
Wean mtrace away from the malloc hooks and move them into the debug
DSO. Split the API away from the implementation so that we can add
the API to libc.so as well as libc_malloc_debug.so, with the libc
implementations being empty.
Update localplt data since memalign no longer has any callers after
this change.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Exporting functions and relying on symbol interposition from libc.so
makes the choice of implementation dependent on DT_NEEDED order, which
is not what some compiler drivers expect.
This commit replaces one magic mechanism (symbol interposition) with
another one (preprocessor-/compiler-based redirection). This makes
the hand-over from the minimal malloc to the full malloc more
explicit.
Removing the ABI symbols is backwards-compatible because libc.so is
always in scope, and the dynamic loader will find the malloc-related
symbols there since commit f0b2132b35
("ld.so: Support moving versioned symbols between sonames
[BZ #24741]").
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The recent difftime changes introduced localplt test failures on nios2
and sparc32, two configurations where some soft-fp functions are
defined in / exported from libc.so, and where the difftime changes
affected the particular set of floating-point operations used in
libc.so. This patch adds those functions to localplt.data, alongside
other such functions already there. (In the sparc32 case, and more
generally on any platform where long double is a software
floating-point type, it would probably be more efficient to avoid
using long double at all in difftime, but that's a pre-existing
issue.)
Tested with build-many-glibcs.py for its nios2 and sparcv9
configurations.
[BZ #24023]
* sysdeps/unix/sysv/linux/nios2/localplt.data: Allow __floatundidf
PLT reference in libc.so.
* sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data: Allow
_Q_lltoq and _Q_qtod PLT references in libc.so.
This commit separates allocating and raising exceptions. This
simplifies catching and re-raising them because it is no longer
necessary to make a temporary, on-stack copy of the exception message.
A recent GCC change to expand floating-point classification built-in
functions inline using integer rather than floating-point arithmetic
in some cases resulted in localplt test failures for nios2 and sparc32
<https://sourceware.org/ml/libc-testresults/2017-q2/msg00320.html>.
This patch updates the localplt.data files in question to mark the
relevant symbols as optional / add a new optional symbol. (The GCC
patch has been reverted because of other problems it caused, but one
can assume it will be applied again, without changes that would affect
the PLT entries generated, once those issues have been resolved.)
Tested with build-many-glibcs.py.
* sysdeps/unix/sysv/linux/nios2/localplt.data (__gtdf2): Mark
libc.so PLT entry optional.
(__gtsf2): Likewise.
(__unorddf2): Likewise.
(__unordsf2): Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data (_Q_fgt):
New optional libc.so PLT entry.
It is no longer needed since commit 6c444ad6e9
(elf: Do not use memalign for TCB/TLS blocks allocation [BZ #17730]).
Applications do not link against ld.so and will use the definition in
libc.so, so there is no ABI impact.
This change moves the main implementation of _dl_catch_error,
_dl_signal_error to libc.so, where TLS variables can be used
directly. This removes a writable function pointer from the
rtld_global variable.
For use during initial relocation, minimal implementations of these
functions are provided in ld.so. These are eventually interposed
by the libc.so implementations. This is implemented by compiling
elf/dl-error-skeleton.c twice, via elf/dl-error.c and
elf/dl-error-minimal.c.
As a side effect of this change, the static version of dl-error.c
no longer includes support for the
_dl_signal_cerror/_dl_receive_error mechanism because it is only
used in ld.so.
This patch updates nios2 localplt.data so the localplt test passes in
my compile-only all-ABIs glibc testing. A new PLT entry for
__extendsfdf2 is added.
Tested for nios2.
* sysdeps/unix/sysv/linux/nios2/localplt.data: Add __extendsfdf2
for libc.so.
