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.
These prototypes are duplicated in many places. Add a dedicated
header for holding prototypes for program-specific functions to
avoid that.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
ARM now supports loading unmarked objects from
the dynamic loader cache. Unmarked objects can
be used with the hard-float or soft-float ABI.
We must support loading unmarked objects during
the transition period from a binutils that does
not mark objects to one that does mark them with
the correct ELF flags.
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
We setup $(READELF) and use it everywhere, so fix the two places
that were using readelf directly.
Reported-by: Denis M. <god@politeia.in>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
* sysdeps/generic/ldconfig.h (FLAG_AARCH64_LIB64): New macro.
* elf/cache.c (print_entry): Print ",AArch64" for
FLAG_AARCH64_LIB64.
Signed-off-by: Steve McIntyre <steve.mcintyre@linaro.org>
Reviewed-by: Carlos O'Donell <carlos@systemhalted.org>
* sysdeps/generic/ldconfig.h (FLAG_ARM_LIBHF): New macro.
* elf/cache.c (print_entry): Print ",hard-float" for
FLAG_ARM_LIBHF.
Signed-off-by: Steve McIntyre <steve.mcintyre@linaro.org>
Reviewed-by: Carlos O'Donell <carlos@systemhalted.org>
This hook is useful for any arch-specific functionality that
should be done on loaded objects. For the tile architecture,
the hook is already provided (though we switch to using the new
macro name with this commit) and implements a simulator notifier
so that the simulator can load Elf symbols to match the object
and generate better error messages for PC's.
Also, remove a spurious definition of DL_UNMAP in dl-runtime.c
* elf/Makefile (tests): Remove conditional for have-initfini-array
since this is now always required and the variable does not exist
anymore.
(tests-static): Likewise.
(modules-names): Likewise.
* elf/tst-array1.c (fini_array): Make writeable so that it can be
merged with constructor/destructor.
(init_array): Likewise.
* elf/tst-array2dep.c (fini_array): Likewise.
(init_array): Likewise.
Commit glibc-2.14~10 disallowed rtld self loading to avoid a segfault
that used to happen when rtld was loading itself in normal mode.
Unfortunately, that commit disallowed all modes of self loading,
including those that used to work before. This change limits the check
for self loading to normal mode only, so that instruments like ldd could
handle rtld properly.
* csu/libc-tls.c (static_dtv): Renamed to ...
(_dl_static_dtv): This. Make it global.
(_dl_initial_dtv): Removed.
(__libc_setup_tls): Updated.
* elf/dl-tls.c (DL_INITIAL_DTV): New macro.
(_dl_deallocate_tls): Replace GL(dl_initial_dtv) with
DL_INITIAL_DTV.
When unmapping the first object in a namespace, the runtime linker
did not update the externally visible pointer. This resulted in
debuggers seeing pointers to memory that had been freed.
Add support for STT_GNU_IFUNC symbols and the new R_390_IRELATIVE
relocation. Provide optimized version of memcpy, memset, and memcmp
for z10 and z196.
[BZ #13579] Do not free l_initfini and allow it to be reused
on subsequent dl_open calls for the same library. This fixes
the invalid memory access in do_lookup_x when the previously
free'd l_initfini was accessed through l_searchlist when a
library had been opened for the second time.
[BZ #13882]
* elf/dl-deps.c (_dl_map_object_deps): Fix cycle detection. Use
uint16_t for elements in the "seen" array to avoid char overflows.
* elf/dl-fini.c (_dl_sort_fini): Likewise.
* elf/dl-open.c (dl_open_worker): Likewise.
When a stack is marked executable due to loading a DSO that requires
an executable stack, the logic tends to leave out a portion of stack
after the first frame, thus causing a difference in the value returned
by pthread_getattr_np before and after the stack is marked
executable. It ought to be possible to fix this by marking the rest of
the stack as executable too, but in the interest of marking as less of
the stack as executable as possible, the path this fix takes is to
make pthread_getattr_np also look at the first frame as the underflow
end of the stack and compute size and stack top accordingly.
The above happens only for the main process stack. NPTL thread stacks
are not affected by this change.
The current implementation of __strtoul_internal seems to only pretend
to support hex and octal strings by detecting a preceding 0x or 0 and
marking base as 8 or 16. When it comes to the actual processing of the
string, it only considers numeric values within, thus breaking hex
values that may have [a-f] in them. Fixed with this commit.
It may sometimes be desirable to make the dynamic linker only pick up
libraries from the library path and rpath and not look at the
ld.so.cache that ldconfig generates. An example of such a use case is
the glibc testsuite where the dynamic linker must not be influenced by
any external paths or caches.
This change adds a new option --inhibit-ldcache that when used, tells
the dynamic linker to not use ld.so.cache even if it is available.
* elf/rtld.c (dl_main): If DL_DEBUG_UNUSED is enabled, turn off
lazy binding.
* elf/dl-lookup (_dl_lookup_symbol_x): If DL_DEBUG_UNUSED, ignore
undefined symbol errors.
* elf/rtlc.c (dl_main): Skip VDSO when checking for unused
DT_NEEDED entries.
* sysdeps/sparc/sparc32/dl-machine.h (elf_machine_rela): Protect local
variables with appropriate CPP guards.
* sysdeps/sparc/sparc32/dl-trampoline.S: Propagate the stack_ptr from the
frame pointer, not the stack pointer. Correct layout comments. Fix test
on resulting framesize and the management of the outregs buffer for pltexit.
Preserve floating point return values across _dl_call_pltexit call.
* sysdeps/sparc/sparc64/dl-trampoline.S: Fix test on resulting
framesize and the management of the outregs buffer for pltexit.
Preserve floating point return values across _dl_call_pltexit
call.
* elf/sotruss-lib.c (la_sparc32_gnu_pltenter, la_sparc64_gnu_pltenter,
la_sparc32_gnu_pltexit, la_sparc64_gnu_pltexit): New functions.
(print_exit): Fix format string for return register value.
update_get_addr returns a link_map*, but the return expression
was of type char*. Fix by relying on gcc's void* arithmetic
extension and auto-conversion from void*.
We never seem to have hit this problem but way relative relocations
were skipped was wrong. There are relative relocations only in the
DT_REL/DT_RELA section. The elf_dynamic_do_##reloc function skipped
the entries in all calls, though.
When dynamically loading a library along with several dependencies, calls to
_dl_add_to_slotinfo and _dl_update_slotinfo can become intermixed. As a
consequence, _dl_update_slotinfo will update the generation counter of the dtv
although not all of the slots belonging to that generation have been added.
Subsequent calls to _dl_add_to_slotinfo will add more slots to the same
generation, for which no storage will be allocated, as the dtv generation
checks will claim no work is necessary. This will lead to uninitialized dtv
entries and will likely cause a SIGSEGV when thread local variables are
accessed.
