Both tests try to dlopen libm.so at runtime, so make them depend on it
so that they're executed if libm.so has been updated.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
They are no longer needed after everything has been moved into
libc. The _dl_vsym test has to be removed because the symbol
cannot be used outside libc anymore.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
In dlerror_run, free corresponds to the local malloc in the
namespace, but GLRO (dl_catch_error) uses the malloc from the base
namespace. elf/tst-dlmopen-gethostbyname triggers this mismatch,
but it does not crash, presumably because of a fastbin deallocation.
Fixes commit c2059edce2 ("elf: Use
_dl_catch_error from base namespace in dl-libc.c [BZ #27646]") and
commit b2964eb1d9 ("dlfcn: Failures
after dlmopen should not terminate process [BZ #24772]").
librt.so is no longer installed for PTHREAD_IN_LIBC, and tests
are not linked against it. $(librt) is introduced globally for
shared tests that need to be linked for both PTHREAD_IN_LIBC
and !PTHREAD_IN_LIBC.
GLIBC_PRIVATE symbols that were needed during the transition are
removed again.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Previously, the installed objects were named like libc-2.33.so,
and the ABI soname libc.so.6 was just a symbolic link.
The Makefile targets to install these symbolic links are no longer
needed after this, so they are removed with this commit. The more
general $(make-link) command (which invokes scripts/rellns-sh) is
retained because other symbolic links are still needed.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@rehdat.com>
This introduces <dl-is_dso.h> and the _dl_is_dso function. A
test ensures that the official names of libc.so, ld.so, and their
versioned names are recognized.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Revert "elf: Fix DTV gap reuse logic [BZ #27135]"
This reverts commit 572bd547d5.
It turns out that the _dl_next_tls_modid in _dl_map_object_from_fd keeps
returning the same modid over and over again if there is a gap and
more than TLS-using module is loaded in one dlopen call. This corrupts
TLS data structures. The bug is still present after a revert, but
empirically it is much more difficult to trigger (because it involves a
dlopen failure).
If lib->flags (in the cache) did not match GLRO (dl_correct_cache_id),
searching for further glibc-hwcaps entries did not happen, and it
was possible that the best glibc-hwcaps was not found. By accident,
this causes a test failure for elf/tst-glibc-hwcaps-prepend-cache
on armv7l.
This commit changes the cache lookup logic to continue searching
if (a) no match has been found, (b) a named glibc-hwcaps match
has been found(), or (c) non-glibc-hwcaps match has been found
and the entry flags and cache default flags do not match.
_DL_CACHE_DEFAULT_ID is used instead of GLRO (dl_correct_cache_id)
because the latter is only written once on i386 if loading
of libc.so.5 libraries is selected, so GLRO (dl_correct_cache_id)
should probably removed in a future change.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
For the legacy ABI with supports 32-bit time_t it calls the 64-bit
time directly, since the LFS symbols calls the 64-bit time_t ones
internally.
Checked on i686-linux-gnu and x86_64-linux-gnu.
Reviewed-by: Lukasz Majewski <lukma@denx.de>
dlerrror_run in elf/dl-libc.c needs to call GLRO (dl_catch_error)
from the base namespace, just like the exported dlerror
implementation.
Fixes commit b2964eb1d9 ("dlfcn:
Failures after dlmopen should not terminate process [BZ #24772]").
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Since commit 0c1c3a771e
("dlfcn: Move dlopen into libc") libdl.a is empty, so linking
against it is no longer necessary.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The testcase elf/tst-tls9-static sometimes fails with:
cannot open 'tst-tlsmod5.so': tst-tlsmod5.so: cannot open shared object file: No such file or directory
cannot open 'tst-tlsmod6.so': tst-tlsmod6.so: cannot open shared object file: No such file or directory
After recent commit
6f1c701026
"dlfcn: Cleanups after -ldl is no longer required"
the libdl variable is not set anymore and thus the
dependencies were missing.
Consolidate all hooks structures into a single one. There are
no static dlopen ABI concerns because glibc 2.34 already comes
with substantial ABI-incompatible changes in this area. (Static
dlopen requires the exact same dynamic glibc version that was used
for static linking.)
The new approach uses a pointer to the hooks structure into
_rtld_global_ro and initalizes it in __rtld_static_init. This avoids
a back-and-forth with various callback functions.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This commit removes the ELF constructor and internal variables from
dlfcn/dlfcn.c. The file now serves the same purpose as
nptl/libpthread-compat.c, so it is renamed to dlfcn/libdl-compat.c.
The use of libdl-shared-only-routines ensures that libdl.a is empty.
This commit adjusts the test suite not to use $(libdl). The libdl.so
symbolic link is no longer installed.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
In elf/Makefile, remove the $(libdl) dependency from testobj1.so
because it the unused libdl DSO now causes elf/tst-unused-deps to
fail.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Once libpthread is empty and no longer marked NODELETE, it no longer
can be used for testing.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Use the __nptl_tls_static_size_for_stack inline function instead,
and the GLRO (dl_tls_static_align) value directly.
The computation of GLRO (dl_tls_static_align) in
_dl_determine_tlsoffset ensures that the alignment is at least
TLS_TCB_ALIGN, which at least STACK_ALIGN (see allocate_stack).
Therefore, the additional rounding-up step is removed.
ALso move the initialization of the default stack size from
__pthread_initialize_minimal_internal to __pthread_early_init.
This introduces an extra system call during single-threaded startup,
but this simplifies the initialization sequence. No locking is
needed around the writes to __default_pthread_attr because the
process is single-threaded at this point.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Coverity discovered that paths allocated by chroot_canon are not freed
in a couple of routines in ldconfig.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
A coverity run identified a number of resource leaks in cache.c.
There are a couple of simple memory leaks where a local allocation is
not freed before function return. Then there is a mmap leak and a
file descriptor leak where a map is not unmapped in the error case and
a file descriptor remains open respectively.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This helps to clarify that the caching of these fields in libpthread
(in __static_tls_size, __static_tls_align_m1) is unnecessary.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
After static dlopen, a copy of ld.so is loaded into the inner
namespace, but that copy is not initialized at all. Some
architectures run into serious problems as result, which is why the
_dl_var_init mechanism was invented. With libpthread moving into
libc and parts into ld.so, more architectures impacted, so it makes
sense to switch to a generic mechanism which performs the partial
initialization.
As a result, getauxval now works after static dlopen (bug 20802).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(FYI, this is a repost of
https://sourceware.org/pipermail/libc-alpha/2019-July/105035.html now
that FSF papers have been signed and confirmed on FSF side).
This trivial patch attemps to fix BZ 24106. Basically the bash locally
used when building glibc on the host shall not leak on the installed
glibc, as the system where it is installed might be different and use
another bash location.
So I have looked for all occurences of @BASH@ or $(BASH) in installed
files, and replaced it by /bin/bash. This was suggested by Florian
Weimer in the bug report.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
For some reason only dlopen failure caused dtv gaps to be reused.
It is possible that the intent was to never reuse modids for a
different module, but after dlopen failure all gaps are reused
not just the ones caused by the unfinished dlopened.
So the code has to handle reused modids already which seems to
work, however the data races at thread creation and tls access
(see bug 19329 and bug 27111) may be more severe if slots are
reused so this is scheduled after those fixes. I think fixing
the races are not simpler if reuse is disallowed and reuse has
other benefits, so set GL(dl_tls_dtv_gaps) whenever entries are
removed from the middle of the slotinfo list. The value does
not have to be correct: incorrect true value causes the next
modid query to do a slotinfo walk, incorrect false will leave
gaps and new entries are added at the end.
Fixes bug 27135.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Test concurrent dlopen and pthread_create when the loaded modules have
TLS. This triggers dl-tls assertion failures more reliably than the
nptl/tst-stack4 test.
The dlopened module has 100 DT_NEEDED dependencies with TLS, they were
reused from an existing TLS test. The number of created threads during
dlopen depends on filesystem speed and hardware, but at most 3 threads
are alive at a time to limit resource usage.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This is a follow up patch to the fix for bug 19329. This adds relaxed
MO atomics to accesses that were previously data races but are now
race conditions, and where relaxed MO is sufficient.
The race conditions all follow the pattern that the write is behind the
dlopen lock, but a read can happen concurrently (e.g. during tls access)
without holding the lock. For slotinfo entries the read value only
matters if it reads from a synchronized write in dlopen or dlclose,
otherwise the related dtv entry is not valid to access so it is fine
to leave it in an inconsistent state. The same applies for
GL(dl_tls_max_dtv_idx) and GL(dl_tls_generation), but there the
algorithm relies on the fact that the read of the last synchronized
write is an increasing value.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
DTV setup at thread creation (_dl_allocate_tls_init) is changed
to take the dlopen lock, GL(dl_load_lock). Avoiding data races
here without locks would require design changes: the map that is
accessed for static TLS initialization here may be concurrently
freed by dlclose. That use after free may be solved by only
locking around static TLS setup or by ensuring dlclose does not
free modules with static TLS, however currently every link map
with TLS has to be accessed at least to see if it needs static
TLS. And even if that's solved, still a lot of atomics would be
needed to synchronize DTV related globals without a lock. So fix
both bug 19329 and bug 27111 with a lock that prevents DTV setup
running concurrently with dlopen or dlclose.
_dl_update_slotinfo at TLS access still does not use any locks
so CONCURRENCY NOTES are added to explain the synchronization.
The early exit from the slotinfo walk when max_modid is reached
is not strictly necessary, but does not hurt either.
An incorrect acquire load was removed from _dl_resize_dtv: it
did not synchronize with any release store or fence and
synchronization is now handled separately at thread creation
and TLS access time.
There are still a number of racy read accesses to globals that
will be changed to relaxed MO atomics in a followup patch. This
should not introduce regressions compared to existing behaviour
and avoid cluttering the main part of the fix.
Not all TLS access related data races got fixed here: there are
additional races at lazy tlsdesc relocations see bug 27137.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
All the stack lists are now in _rtld_global, so it is possible
to change stack permissions directly from there, instead of
calling into libpthread to do the change.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Permissions of the cached stacks may have to be updated if an object
is loaded that requires executable stacks, so the dynamic loader
needs to know about these cached stacks.
The move of in_flight_stack and stack_cache_actsize is a requirement for
merging __reclaim_stacks into the fork implementation in libc.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This is an early variant of __tls_init_tp, primarily for initializing
thread-related elements of _rtld_global/GL.
Some existing initialization code not needed for NPTL is moved into
the generic version of this function.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
If libpthread is included in libc, it is not necessary to delay
initialization of the lock/unlock function pointers until libpthread
is loaded. This eliminates two unprotected function pointers
from _rtld_global and removes some initialization code from
libpthread.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Previously, the source file nptl/cancellation.c was compiled multiple
times, for libc, libpthread, librt. This commit switches to a single
implementation, with new __pthread_enable_asynccancel@@GLIBC_PRIVATE,
__pthread_disable_asynccancel@@GLIBC_PRIVATE exports.
The almost-unused CANCEL_ASYNC and CANCEL_RESET macros are replaced
by LIBC_CANCEL_ASYNC and LIBC_CANCEL_ASYNC macros. They call the
__pthread_* functions unconditionally now. The macros are still
needed because shared code uses them; Hurd has different definitions.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The stack list is available in ld.so since commit
1daccf403b ("nptl: Move stack list
variables into _rtld_global"), so it's possible to walk the stack
list directly in ld.so and perform the initialization there.
This eliminates an unprotected function pointer from _rtld_global
and reduces the libpthread initialization code.
TLS_INIT_TP is processor-specific, so it is not a good place to
put thread library initialization code (it would have to be repeated
for all CPUs). Introduce __tls_init_tp as a separate function,
to be called immediately after TLS_INIT_TP. Move the existing
stack list setup code for NPTL to this function.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Calling free directly may end up freeing a pointer allocated by the
dynamic loader using malloc from libc.so in the base namespace using
the allocator from libc.so in a secondary namespace, which results in
crashes.
This commit redirects the free call through GLRO and the dynamic
linker, to reach the correct namespace. It also cleans up the dlerror
handling along the way, so that pthread_setspecific is no longer
needed (which avoids triggering bug 24774).
Commit 9e78f6f6e7 ("Implement
_dl_catch_error, _dl_signal_error in libc.so [BZ #16628]") has the
side effect that distinct namespaces, as created by dlmopen, now have
separate implementations of the rtld exception mechanism. This means
that the call to _dl_catch_error from libdl in a secondary namespace
does not actually install an exception handler because the
thread-local variable catch_hook in the libc.so copy in the secondary
namespace is distinct from that of the base namepace. As a result, a
dlsym/dlopen/... failure in a secondary namespace terminates the process
with a dynamic linker error because it looks to the exception handler
mechanism as if no handler has been installed.
This commit restores GLRO (dl_catch_error) and uses it to set the
handler in the base namespace.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
It's necessary to stub out __libc_disable_asynccancel and
__libc_enable_asynccancel via rtld-stubbed-symbols because the new
direct references to the unwinder result in symbol conflicts when the
rtld exception handling from libc is linked in during the construction
of librtld.map.
unwind-forcedunwind.c is merged into unwind-resume.c. libc now needs
the functions that were previously only used in libpthread.
The GLIBC_PRIVATE exports of __libc_longjmp and __libc_siglongjmp are
no longer needed, so switch them to hidden symbols.
The symbol __pthread_unwind_next has been moved using
scripts/move-symbol-to-libc.py.
Reviewed-by: Adhemerva Zanella <adhemerval.zanella@linaro.org>
Remove generic tlsdesc code related to lazy tlsdesc processing since
lazy tlsdesc relocation is no longer supported. This includes removing
GL(dl_load_lock) from _dl_make_tlsdesc_dynamic which is only called at
load time when that lock is already held.
Added a documentation comment too.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
map is not valid to access here because it can be freed by a concurrent
dlclose: during tls access (via __tls_get_addr) _dl_update_slotinfo is
called without holding dlopen locks. So don't check the modid of map.
The map == 0 and map != 0 code paths can be shared (avoiding the dtv
resize in case of map == 0 is just an optimization: larger dtv than
necessary would be fine too).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Since
commit a509eb117f
Avoid late dlopen failure due to scope, TLS slotinfo updates [BZ #25112]
the generation counter update is not needed in the failure path.
That commit ensures allocation in _dl_add_to_slotinfo happens before
the demarcation point in dlopen (it is called twice, first time is for
allocation only where dlopen can still be reverted on failure, then
second time actual dtv updates are done which then cannot fail).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The test dlopens a large number of modules with TLS, they are reused
from an existing test.
The test relies on the reuse of slotinfo entries after dlclose, without
bug 27135 fixed this needs a failing dlopen. With a slotinfo list that
has non-monotone increasing generation counters, bug 27136 can trigger.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The max modid is a valid index in the dtv, it should not be skipped.
The bug is observable if the last module has modid == 64 and its
generation is same or less than the max generation of the previous
modules. Then dtv[0].counter implies dtv[64] is initialized but
it isn't. Fixes bug 27136.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
When parse_tunables tries to erase a tunable marked as SXID_ERASE for
setuid programs, it ends up setting the envvar string iterator
incorrectly, because of which it may parse the next tunable
incorrectly. Given that currently the implementation allows malformed
and unrecognized tunables pass through, it may even allow SXID_ERASE
tunables to go through.
This change revamps the SXID_ERASE implementation so that:
- Only valid tunables are written back to the tunestr string, because
of which children of SXID programs will only inherit a clean list of
identified tunables that are not SXID_ERASE.
- Unrecognized tunables get scrubbed off from the environment and
subsequently from the child environment.
- This has the side-effect that a tunable that is not identified by
the setxid binary, will not be passed on to a non-setxid child even
if the child could have identified that tunable. This may break
applications that expect this behaviour but expecting such tunables
to cross the SXID boundary is wrong.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Instead of passing GLIBC_TUNABLES via the environment, pass the
environment variable from parent to child. This allows us to test
multiple variables to ensure better coverage.
The test list currently only includes the case that's already being
tested. More tests will be added later.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The simplification of tunable_set interfaces took care of
signed/unsigned conversions while setting values, but comparison with
bounds ended up being incorrect; comparing TUNABLE_SIZE_T values for
example will fail because SIZE_MAX is seen as -1.
Add comparison helpers that take tunable types into account and use
them to do comparison instead.
dlopen updates libname_list by writing to lastp->next, but concurrent
reads in _dl_name_match_p were not synchronized when it was called
without holding GL(dl_load_lock), which can happen during lazy symbol
resolution.
This patch fixes the race between _dl_name_match_p reading lastp->next
and add_name_to_object writing to it. This could cause segfault on
targets with weak memory order when lastp->next->name is read, which
was observed on an arm system. Fixes bug 21349.
(Code is from Maninder Singh, comments and description is from Szabolcs
Nagy.)
Co-authored-by: Vaneet Narang <v.narang@samsung.com>
Co-authored-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This does not change the emitted code since __libc_start_main does not
return, but is important for formal flags compliance.
This also cleans up the cosmetic inconsistency in the stack protector
flags in csu, especially the incorrect value of STACK_PROTECTOR_LEVEL.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Enabling --enable-stack-protector=all causes the following tests to fail:
FAIL: elf/ifuncmain9picstatic
FAIL: elf/ifuncmain9static
Nick Alcock (who committed the stack protector code) marked the IFUNC
resolvers with inhibit_stack_protector when he done the original work and
suggested doing so again @ BZ #25680. This patch adds
inhibit_stack_protector to ifuncmain9.
After patch is applied, --enable-stack-protector=all does not fail the
above tests.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
In this case, use the link map of the dynamic loader itself as
a replacement. This is more than just a hack: if we ever support
DT_RUNPATH/DT_RPATH for the dynamic loader, reporting it for
ld.so --help (without further command line arguments) would be the
right thing to do.
Fixes commit 3324213125 ("elf: Always
set l in _dl_init_paths (bug 23462)").
After d1d5471579 ("Remove dead
DL_DST_REQ_STATIC code.") we always setup the link map l to make the
static and shared cases the same. The bug is that in elf/dl-load.c
(_dl_init_paths) we conditionally set l only in the #ifdef SHARED
case, but unconditionally use it later. The simple solution is to
remove the #ifdef SHARED conditional, because it's no longer needed,
and unconditionally setup l for both the static and shared cases. A
regression test is added to run a static binary with
LD_LIBRARY_PATH='$ORIGIN' which crashes before the fix and runs after
the fix.
Co-Authored-By: Florian Weimer <fweimer@redhat.com>
It turns out the startup code in csu/elf-init.c has a perfect pair of
ROP gadgets (see Marco-Gisbert and Ripoll-Ripoll, "return-to-csu: A
New Method to Bypass 64-bit Linux ASLR"). These functions are not
needed in dynamically-linked binaries because DT_INIT/DT_INIT_ARRAY
are already processed by the dynamic linker. However, the dynamic
linker skipped the main program for some reason. For maximum
backwards compatibility, this is not changed, and instead, the main
map is consulted from __libc_start_main if the init function argument
is a NULL pointer.
For statically linked binaries, the old approach based on linker
symbols is still used because there is nothing else available.
A new symbol version __libc_start_main@@GLIBC_2.34 is introduced because
new binaries running on an old libc would not run their ELF
constructors, leading to difficult-to-debug issues.
The elision interfaces are closely aligned between the targets that
implement them, so declare them in the generic <lowlevellock.h>
file.
Empty .c stubs are provided, so that fewer makefile updates
under sysdeps are needed. Also simplify initialization via
__libc_early_init.
The symbols __lll_clocklock_elision, __lll_lock_elision,
__lll_trylock_elision, __lll_unlock_elision, __pthread_force_elision
move into libc. For the time being, non-hidden references are used
from libpthread to access them, but once that part of libpthread
is moved into libc, hidden symbols will be used again. (Hidden
references seem desirable to reduce the likelihood of transactions
aborts.)
The kernel does not put the vDSO at special addresses, so writev can
write the name directly. Also remove the incorrect comment about not
setting l_name.
Andy Lutomirski confirmed in
<https://lore.kernel.org/linux-api/442A16C0-AE5A-4A44-B261-FE6F817EAF3C@amacapital.net/>
that this copy is not necessary.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The glibc.malloc.mmap_max tunable as well as al of the INT_32 tunables
don't have use for negative values, so pin the hardcoded limits in the
non-negative range of INT. There's no real benefit in any of those
use cases for the extended range of unsigned, so I have avoided added
a new type to keep things simple.
The TUNABLE_SET interface took a primitive C type argument, which
resulted in inconsistent type conversions internally due to incorrect
dereferencing of types, especialy on 32-bit architectures. This
change simplifies the TUNABLE setting logic along with the interfaces.
Now all numeric tunable values are stored as signed numbers in
tunable_num_t, which is intmax_t. All calls to set tunables cast the
input value to its primitive type and then to tunable_num_t for
storage. This relies on gcc-specific (although I suspect other
compilers woul also do the same) unsigned to signed integer conversion
semantics, i.e. the bit pattern is conserved. The reverse conversion
is guaranteed by the standard.
Add _SC_MINSIGSTKSZ for the minimum signal stack size derived from
AT_MINSIGSTKSZ, which is the minimum number of bytes of free stack
space required in order to gurantee successful, non-nested handling
of a single signal whose handler is an empty function, and _SC_SIGSTKSZ
which is the suggested minimum number of bytes of stack space required
for a signal stack.
If AT_MINSIGSTKSZ isn't available, sysconf (_SC_MINSIGSTKSZ) returns
MINSIGSTKSZ. On Linux/x86 with XSAVE, the signal frame used by kernel
is composed of the following areas and laid out as:
------------------------------
| alignment padding |
------------------------------
| xsave buffer |
------------------------------
| fsave header (32-bit only) |
------------------------------
| siginfo + ucontext |
------------------------------
Compute AT_MINSIGSTKSZ value as size of xsave buffer + size of fsave
header (32-bit only) + size of siginfo and ucontext + alignment padding.
If _SC_SIGSTKSZ_SOURCE or _GNU_SOURCE are defined, MINSIGSTKSZ and SIGSTKSZ
are redefined as
/* Default stack size for a signal handler: sysconf (SC_SIGSTKSZ). */
# undef SIGSTKSZ
# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
/* Minimum stack size for a signal handler: SIGSTKSZ. */
# undef MINSIGSTKSZ
# define MINSIGSTKSZ SIGSTKSZ
Compilation will fail if the source assumes constant MINSIGSTKSZ or
SIGSTKSZ.
The reason for not simply increasing the kernel's MINSIGSTKSZ #define
(apart from the fact that it is rarely used, due to glibc's shadowing
definitions) was that userspace binaries will have baked in the old
value of the constant and may be making assumptions about it.
For example, the type (char [MINSIGSTKSZ]) changes if this #define
changes. This could be a problem if an newly built library tries to
memcpy() or dump such an object defined by and old binary.
Bounds-checking and the stack sizes passed to things like sigaltstack()
and makecontext() could similarly go wrong.
The existing code specifies -Wl,--defsym=malloc=0 and other malloc.os
definitions before libc_pic.a so that libc_pic.a(malloc.os) is not
fetched. This trick is used to avoid multiple definition errors which
would happen as a chain result:
dl-allobjs.os has an undefined __libc_scratch_buffer_set_array_size
__libc_scratch_buffer_set_array_size fetches libc_pic.a(scratch_buffer_set_array_size.os)
libc_pic.a(scratch_buffer_set_array_size.os) has an undefined free
free fetches libc_pic.a(malloc.os)
libc_pic.a(malloc.os) has an undefined __libc_message
__libc_message fetches libc_pic.a(libc_fatal.os)
libc_fatal.os will cause a multiple definition error (__GI___libc_fatal)
>>> defined at dl-fxstatat64.c
>>> /tmp/p/glibc/Release/elf/dl-allobjs.os:(__GI___libc_fatal)
>>> defined at libc_fatal.c
>>> libc_fatal.os:(.text+0x240) in archive /tmp/p/glibc/Release/libc_pic.a
LLD processes --defsym after all input files, so this trick does not
suppress multiple definition errors with LLD. Split the step into two
and use an object file to make the intention more obvious and make LLD
work.
This is conceptually more appropriate because --defsym defines a SHN_ABS
symbol while a normal definition is relative to the image base.
See https://sourceware.org/pipermail/libc-alpha/2020-March/111910.html
for discussions about the --defsym semantics.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
For configurations with cross-compiling equal to 'maybe' or 'no',
ldconfig will not run and thus the ld.so.cache will not be created
on the container testroot.pristine.
This lead to failures on both tst-glibc-hwcaps-prepend-cache and
tst-ldconfig-ld_so_conf-update on environments where the same
compiler can be used to build different ABIs (powerpc and x86 for
instance).
This patch addas a new test-container hook, ldconfig.run, that
triggers a ldconfig execution prior the test execution.
Checked on x86_64-linux-gnu and i686-linux-gnu.
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>
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>
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>
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>
Since __libc_init_secure is called before ARCH_SETUP_TLS, it must use
"int $0x80" for system calls in i386 static PIE. Add startup_getuid,
startup_geteuid, startup_getgid and startup_getegid to <startup.h>.
Update __libc_init_secure to use them.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Set the default _dl_sysinfo in _dl_aux_init to avoid RELATIVE relocation
in static PIE.
This is needed for fixing bug 27072 on x86.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
On x86, ifuncmain6pie failed with:
[hjl@gnu-cfl-2 build-i686-linux]$ ./elf/ifuncmain6pie --direct
./elf/ifuncmain6pie: IFUNC symbol 'foo' referenced in '/export/build/gnu/tools-build/glibc-32bit/build-i686-linux/elf/ifuncmod6.so' is defined in the executable and creates an unsatisfiable circular dependency.
[hjl@gnu-cfl-2 build-i686-linux]$ readelf -rW elf/ifuncmod6.so | grep foo
00003ff4 00000706 R_386_GLOB_DAT 0000400c foo_ptr
00003ff8 00000406 R_386_GLOB_DAT 00000000 foo
0000400c 00000401 R_386_32 00000000 foo
[hjl@gnu-cfl-2 build-i686-linux]$
Remove non-JUMP_SLOT relocations against foo in ifuncmod6.so, which
trigger the circular IFUNC dependency, and build ifuncmain6pie with
-Wl,-z,lazy.
Store ISA level in the portion of the unused upper 32 bits of the hwcaps
field in cache and the unused pad field in aux cache. ISA level is stored
and checked only for shared objects in glibc-hwcaps subdirectories. The
shared objects in the default directories aren't checked since there are
no fallbacks for these shared objects.
Tested on x86-64-v2, x86-64-v3 and x86-64-v4 machines with
--disable-hardcoded-path-in-tests and --enable-hardcoded-path-in-tests.
Since commit 2f056e8a5d
"aarch64: define PI_STATIC_AND_HIDDEN",
building glibc with gcc-8 on aarch64 fails with
/BLD/elf/librtld.os: in function `elf_get_dynamic_info':
/SRC/elf/get-dynamic-info.h:70:(.text+0xad8): relocation truncated to
fit: R_AARCH64_ADR_PREL_PG_HI21 against symbol `_rtld_local' defined
in .data section in /BLD/elf/librtld.os
This is a gcc bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98618
The bug is fixed on gcc-10 and not yet backported. gcc-9 is affected,
but the issue happens to not trigger in glibc, gcc-8 and older seems
to miscompile rtld.os.
Rewriting the affected code in elf_get_dynamic_info seems to make the
issue go away on <= gcc-9.
The change makes the logic a bit clearer too (by separating the index
computation and array update) and drops an older gcc workaround (since
gcc 4.6 is no longer supported).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
GCC 11 supports -march=x86-64-v[234] to enable x86 micro-architecture ISA
levels:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97250
and -mneeded to emit GNU_PROPERTY_X86_ISA_1_NEEDED property with
GNU_PROPERTY_X86_ISA_1_V[234] marker:
https://gitlab.com/x86-psABIs/x86-64-ABI/-/merge_requests/13
Binutils support for GNU_PROPERTY_X86_ISA_1_V[234] marker were added by
commit b0ab06937385e0ae25cebf1991787d64f439bf12
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Fri Oct 30 06:49:57 2020 -0700
x86: Support GNU_PROPERTY_X86_ISA_1_BASELINE marker
and
commit 32930e4edbc06bc6f10c435dbcc63131715df678
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Fri Oct 9 05:05:57 2020 -0700
x86: Support GNU_PROPERTY_X86_ISA_1_V[234] marker
GNU_PROPERTY_X86_ISA_1_NEEDED property in x86 ELF binaries indicate the
micro-architecture ISA level required to execute the binary. The marker
must be added by programmers explicitly in one of 3 ways:
1. Pass -mneeded to GCC.
2. Add the marker in the linker inputs as this patch does.
3. Pass -z x86-64-v[234] to the linker.
Add GNU_PROPERTY_X86_ISA_1_BASELINE and GNU_PROPERTY_X86_ISA_1_V[234]
marker support to ld.so if binutils 2.32 or newer is used to build glibc:
1. Add GNU_PROPERTY_X86_ISA_1_BASELINE and GNU_PROPERTY_X86_ISA_1_V[234]
markers to elf.h.
2. Add GNU_PROPERTY_X86_ISA_1_BASELINE and GNU_PROPERTY_X86_ISA_1_V[234]
marker to abi-note.o based on the ISA level used to compile abi-note.o,
assuming that the same ISA level is used to compile the whole glibc.
3. Add isa_1 to cpu_features to record the supported x86 ISA level.
4. Rename _dl_process_cet_property_note to _dl_process_property_note and
add GNU_PROPERTY_X86_ISA_1_V[234] marker detection.
5. Update _rtld_main_check and _dl_open_check to check loaded objects
with the incompatible ISA level.
6. Add a testcase to verify that dlopen an x86-64-v4 shared object fails
on lesser platforms.
7. Use <get-isa-level.h> in dl-hwcaps-subdirs.c and tst-glibc-hwcaps.c.
Tested under i686, x32 and x86-64 modes on x86-64-v2, x86-64-v3 and
x86-64-v4 machines.
Marked elf/tst-isa-level-1 with x86-64-v4, ran it on x86-64-v3 machine
and got:
[hjl@gnu-cfl-2 build-x86_64-linux]$ ./elf/tst-isa-level-1
./elf/tst-isa-level-1: CPU ISA level is lower than required
[hjl@gnu-cfl-2 build-x86_64-linux]$
I've updated copyright dates in glibc for 2021. This is the patch for
the changes not generated by scripts/update-copyrights and subsequent
build / regeneration of generated files. As well as the usual annual
updates, mainly dates in --version output (minus csu/version.c which
previously had to be handled manually but is now successfully updated
by update-copyrights), there is a small change to the copyright notice
in NEWS which should let NEWS get updated automatically next year.
Please remember to include 2021 in the dates for any new files added
in future (which means updating any existing uncommitted patches you
have that add new files to use the new copyright dates in them).
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
Add a new glibc tunable: mem.tagging. This is a decimal constant in
the range 0-255 but used as a bit-field.
Bit 0 enables use of tagged memory in the malloc family of functions.
Bit 1 enables precise faulting of tag failure on platforms where this
can be controlled.
Other bits are currently unused, but if set will cause memory tag
checking for the current process to be enabled in the kernel.
Change sbrk to fail for !__libc_initial (in the generic
implementation). As a result, sbrk is (relatively) safe to use
for the __libc_initial case (from the main libc). It is therefore
no longer necessary to avoid using it in that case (or updating the
brk cache), and the __libc_initial flag does not need to be updated
as part of dlmopen or static dlopen.
As before, direct brk system calls on Linux may lead to memory
corruption.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Otherwise, it will not participate in the dependency sorting.
Fixes commit 9ffa50b26b
("elf: Include libc.so.6 as main program in dependency sort
(bug 20972)").
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The failure paths in _dl_map_object_from_fd did not clean every
potentially allocated resource up.
Handle l_phdr, l_libname and mapped segments in the common failure
handling code.
There are various bits that may not be cleaned properly on failure
(e.g. executable stack, incomplete dl_map_segments) fixing those
need further changes.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
_dl_map_object_from_fd has complex error handling with cleanups.
It was managed by a separate function to avoid code bloat at
every failure case, but since the code was changed to use gotos
there is no longer such code bloat from inlining.
Maintaining a separate error handling function is harder as it
needs to access local state which has to be passed down. And the
same lose function was used in open_verify which is error prone.
The goto labels are changed since there is no longer a call.
The new code generates slightly smaller binary.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Since elf.h is a public header file copied to other projects,
try to make it free from spelling typos.
This change fixes the following spelling typos in comments of elf.h:
Auxialiary -> Auxiliary
tenatively -> tentatively
compatability -> compatibility
_dl_map_object_deps always sorts the initially loaded object first
during dependency sorting. This means it is relocated last in
dl_open_worker. This results in crashes in IFUNC resolvers without
lazy bindings if libraries are preloaded that refer to IFUNCs in
libc.so.6: the resolvers are called when libc.so.6 has not been
relocated yet, so references to _rtld_global_ro etc. crash.
The fix is to check against the libc.so.6 link map recorded by the
__libc_early_init framework, and let it participate in the dependency
sort.
This fixes bug 20972.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
To handle GNU property notes on aarch64 some segments need to
be mmaped again, so the fd of the loaded ELF module is needed.
When the fd is not available (kernel loaded modules), then -1
is passed.
The fd is passed to both _dl_process_pt_gnu_property and
_dl_process_pt_note for consistency. Target specific note
processing functions are updated accordingly.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Program headers are processed in two pass: after the first pass
load segments are mmapped so in the second pass target specific
note processing logic can access the notes.
The second pass is moved later so various link_map fields are
set up that may be useful for note processing such as l_phdr.
The second pass should be before the fd is closed so that is
available.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
