Add --enable-fortify-source option.
It is now possible to enable fortification through a configure option.
The level may be given as parameter, if none is provided, the configure
script will determine what is the highest level possible that can be set
considering GCC built-ins availability and set it.
If level is explicitly set to 3, configure checks if the compiler
supports the built-in function necessary for it or raise an error if it
isn't.
If the configure option isn't explicitly enabled, it _FORTIFY_SOURCE is
forcibly undefined (and therefore disabled).
The result of the configure checks are new variables, ${fortify_source}
and ${no_fortify_source} that can be used to appropriately populate
CFLAGS.
A dedicated patch will follow to make use of this variable in Makefiles
when necessary.
Updated NEWS and INSTALL.
Adding dedicated x86_64 variant that enables the configuration.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
ISO C2x defines scanf %b for input of binary integers (with an
optional 0b or 0B prefix). Implement such support, along with the
corresponding SCNb* macros in <inttypes.h>. Unlike the support for
binary integers with 0b or 0B prefix with scanf %i, this is supported
in all versions of scanf (independent of the standards mode used for
compilation), because there are no backwards compatibility concerns
(%b wasn't previously a supported format) the way there were for %i.
Tested for x86_64 and x86.
ISO C2x defines printf length modifiers wN (for intN_t / int_leastN_t
/ uintN_t / uint_leastN_t) and wfN (for int_fastN_t / uint_fastN_t).
Add support for those length modifiers (such a feature was previously
requested in bug 24466). scanf support is to be added separately.
GCC 13 has format checking support for these modifiers.
When used with the support for registering format specifiers, these
modifiers are translated to existing flags in struct printf_info,
rather than trying to add some way of distinguishing them without
breaking the printf_info ABI. C2x requires an error to be returned
for unsupported values of N; this is implemented for printf-family
functions, but the parse_printf_format interface doesn't support error
returns, so such an error gets discarded by that function.
Tested for x86_64 and x86.
These functions are about to be added to POSIX, under Austin Group
issue 986.
The fortified strlcat implementation does not raise SIGABRT if the
destination buffer does not contain a null terminator, it just
inherits the non-failing regular strlcat behavior.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
This patch enables libmvec on AArch64. The proposed change is mainly
implementing build infrastructure to add the new routines to ABI,
tests and benchmarks. I have demonstrated how this all fits together
by adding implementations for vector cos, in both single and double
precision, targeting both Advanced SIMD and SVE.
The implementations of the routines themselves are just loops over the
scalar routine from libm for now, as we are more concerned with
getting the plumbing right at this point. We plan to contribute vector
routines from the Arm Optimized Routines repo that are compliant with
requirements described in the libmvec wiki.
Building libmvec requires minimum GCC 10 for SVE ACLE. To avoid raising
the minimum GCC by such a big jump, we allow users to disable libmvec
if their compiler is too old.
Note that at this point users have to manually call the vector math
functions. This seems to be acceptable to some downstream users.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Created tunable glibc.pthread.stack_hugetlb to control when hugepages
can be used for stack allocation.
In case THP are enabled and glibc.pthread.stack_hugetlb is set to
0, glibc will madvise the kernel not to use allow hugepages for stack
allocations.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
And make always supported. The configure option was added on glibc 2.25
and some features require it (such as hwcap mask, huge pages support, and
lock elisition tuning). It also simplifies the build permutations.
Changes from v1:
* Remove glibc.rtld.dynamic_sort changes, it is orthogonal and needs
more discussion.
* Cleanup more code.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
It is the default since 2.26 and it has bitrotten over the years,
By using it multiple malloc tests fails:
FAIL: malloc/tst-memalign-2
FAIL: malloc/tst-memalign-2-malloc-hugetlb1
FAIL: malloc/tst-memalign-2-malloc-hugetlb2
FAIL: malloc/tst-memalign-2-mcheck
FAIL: malloc/tst-mxfast-malloc-hugetlb1
FAIL: malloc/tst-mxfast-malloc-hugetlb2
FAIL: malloc/tst-tcfree2
FAIL: malloc/tst-tcfree2-malloc-hugetlb1
FAIL: malloc/tst-tcfree2-malloc-hugetlb2
Checked on x86_64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
WG14 recently accepted two additions to the printf/scanf %b/%B
support: there are now PRIb* and SCNb* macros in <inttypes.h>, and
printf %B is now an optional feature defined in normative text,
instead of recommended practice, with corresponding PRIB* macros that
can also be used to test whether that optional feature is supported.
See N3072 items 14 and 15 for details (those changes were accepted,
some other changes in that paper weren't).
Add the corresponding PRI* macros to glibc and update one place in the
manual referring to %B as recommended. (SCNb* should naturally be
added at the same time as the corresponding scanf %b support.)
Tested for x86_64 and x86.
C2x adds binary integer constants starting with 0b or 0B, and supports
those constants for the %i scanf format (in addition to the %b format,
which isn't yet implemented for scanf in glibc). Implement that scanf
support for glibc.
As with the strtol support, this is incompatible with previous C
standard versions, in that such an input string starting with 0b or 0B
was previously required to be parsed as 0 (with the rest of the input
potentially matching subsequent parts of the scanf format string).
Thus this patch adds 12 new __isoc23_* functions per long double
format (12, 24 or 36 depending on how many long double formats the
glibc configuration supports), with appropriate header redirection
support (generally very closely following that for the __isoc99_*
scanf functions - note that __GLIBC_USE (DEPRECATED_SCANF) takes
precedence over __GLIBC_USE (C2X_STRTOL), so the case of GNU
extensions to C89 continues to get old-style GNU %a and does not get
this new feature). The function names would remain as __isoc23_* even
if C2x ends up published in 2024 rather than 2023.
When scanf %b support is added, I think it will be appropriate for all
versions of scanf to follow C2x rules for inputs to the %b format
(given that there are no compatibility concerns for a new format).
Tested for x86_64 (full glibc testsuite). The first version was also
tested for powerpc (32-bit) and powerpc64le (stdio-common/ and wcsmbs/
tests), and with build-many-glibcs.py.
The Linux kernel upstream commit 71bdea6f798b ("parisc: Align parisc
MADV_XXX constants with all other architectures") dropped the
parisc-specific MADV_* values in favour of the same constants as
other architectures. In the same commit a wrapper was added which
translates the old values to the standard MADV_* values to avoid
breakage of existing programs.
This upstream patch has been downported to all stable kernel trees as
well.
This patch now drops the parisc specific constants from glibc to
allow newly compliled programs to use the standard MADV_* constants.
v2: Added NEWS section, based on feedback from Florian Weimer
Signed-off-by: Helge Deller <deller@gmx.de>
C2x adds binary integer constants starting with 0b or 0B, and supports
those constants in strtol-family functions when the base passed is 0
or 2. Implement that strtol support for glibc.
As discussed at
<https://sourceware.org/pipermail/libc-alpha/2020-December/120414.html>,
this is incompatible with previous C standard versions, in that such
an input string starting with 0b or 0B was previously required to be
parsed as 0 (with the rest of the string unprocessed). Thus, as
proposed there, this patch adds 20 new __isoc23_* functions with
appropriate header redirection support. This patch does *not* do
anything about scanf %i (which will need 12 new functions per long
double variant, so 12, 24 or 36 depending on the glibc configuration),
instead leaving that for a future patch. The function names would
remain as __isoc23_* even if C2x ends up published in 2024 rather than
2023.
Making this change leads to the question of what should happen to
internal uses of these functions in glibc and its tests. The header
redirection (which applies for _GNU_SOURCE or any other feature test
macros enabling C2x features) has the effect of redirecting internal
uses but without those uses then ending up at a hidden alias (see the
comment in include/stdio.h about interaction with libc_hidden_proto).
It seems desirable for the default for internal uses to be the same
versions used by normal code using _GNU_SOURCE, so rather than doing
anything to disable that redirection, similar macro definitions to
those in include/stdio.h are added to the include/ headers for the new
functions.
Given that the default for uses in glibc is for the redirections to
apply, the next question is whether the C2x semantics are correct for
all those uses. Uses with the base fixed to 10, 16 or any other value
other than 0 or 2 can be ignored. I think this leaves the following
internal uses to consider (an important consideration for review of
this patch will be both whether this list is complete and whether my
conclusions on all entries in it are correct):
benchtests/bench-malloc-simple.c
benchtests/bench-string.h
elf/sotruss-lib.c
math/libm-test-support.c
nptl/perf.c
nscd/nscd_conf.c
nss/nss_files/files-parse.c
posix/tst-fnmatch.c
posix/wordexp.c
resolv/inet_addr.c
rt/tst-mqueue7.c
soft-fp/testit.c
stdlib/fmtmsg.c
support/support_test_main.c
support/test-container.c
sysdeps/pthread/tst-mutex10.c
I think all of these places are OK with the new semantics, except for
resolv/inet_addr.c, where the POSIX semantics of inet_addr do not
allow for binary constants; thus, I changed that file (to use
__strtoul_internal, whose semantics are unchanged) and added a test
for this case. In the case of posix/wordexp.c I think accepting
binary constants is OK since POSIX explicitly allows additional forms
of shell arithmetic expressions, and in stdlib/fmtmsg.c SEV_LEVEL is
not in POSIX so again I think accepting binary constants is OK.
Functions such as __strtol_internal, which are only exported for
compatibility with old binaries from when those were used in inline
functions in headers, have unchanged semantics; the __*_l_internal
versions (purely internal to libc and not exported) have a new
argument to specify whether to accept binary constants.
As well as for the standard functions, the header redirection also
applies to the *_l versions (GNU extensions), and to legacy functions
such as strtoq, to avoid confusing inconsistency (the *q functions
redirect to __isoc23_*ll rather than needing their own __isoc23_*
entry points). For the functions that are only declared with
_GNU_SOURCE, this means the old versions are no longer available for
normal user programs at all. An internal __GLIBC_USE_C2X_STRTOL macro
is used to control the redirections in the headers, and cases in glibc
that wish to avoid the redirections - the function implementations
themselves and the tests of the old versions of the GNU functions -
then undefine and redefine that macro to allow the old versions to be
accessed. (There would of course be greater complexity should we wish
to make any of the old versions into compat symbols / avoid them being
defined at all for new glibc ABIs.)
strtol_l.c has some similarity to strtol.c in gnulib, but has already
diverged some way (and isn't listed at all at
https://sourceware.org/glibc/wiki/SharedSourceFiles unlike strtoll.c
and strtoul.c); I haven't made any attempts at gnulib compatibility in
the changes to that file.
I note incidentally that inttypes.h and wchar.h are missing the
__nonnull present on declarations of this family of functions in
stdlib.h; I didn't make any changes in that regard for the new
declarations added.
Add a NEWS entry noting the removal of the legacy hwcaps search
mechanism for shared objects.
Signed-off-by: Javier Pello <devel@otheo.eu>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The ahosts, ahostsv4, ahostsv6 commands unconditionally pass
AI_ADDRCONFIG to getaddrinfo, which is not always desired.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This reverts commit 6f85dbf102.
Once this change hits the release branches, it will require relinking
of all statically linked applications before static dlopen works
again, for the majority of updates on release branches: The NEWS file
is regularly updated with bug references, so the __libc_early_init
suffix changes, and static dlopen cannot find the function anymore.
While this ABI check is still technically correct (we do require
rebuilding & relinking after glibc updates to keep static dlopen
working), it is too drastic for stable release branches.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The files NEWS, include/link.h, and sysdeps/generic/ldsodefs.h
contribute to the version fingerprint used for detection. The
fingerprint can be further refined using the --with-extra-version-id
configure argument.
_dl_call_libc_early_init is replaced with _dl_lookup_libc_early_init.
The new function is used store a pointer to libc.so's
__libc_early_init function in the libc_map_early_init member of the
ld.so namespace structure. This function pointer can then be called
directly, so the separate invocation function is no longer needed.
The versioned symbol lookup needs the symbol versioning data
structures, so the initialization of libc_map and libc_map_early_init
is now done from _dl_check_map_versions, after this information
becomes available. (_dl_map_object_from_fd does not set this up
in time, so the initialization code had to be moved from there.)
This means that the separate initialization code can be removed from
dl_main because _dl_check_map_versions covers all maps, including
the initial executable loaded by the kernel. The lookup still happens
before relocation and the invocation of IFUNC resolvers, so IFUNC
resolvers are protected from ABI mismatch.
The __libc_early_init function pointer is not protected because
so little code runs between the pointer write and the invocation
(only dynamic linker code and IFUNC resolvers).
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Rather than buffering 16 MiB of entropy in userspace (by way of
chacha20), simply call getrandom() every time.
This approach is doubtlessly slower, for now, but trying to prematurely
optimize arc4random appears to be leading toward all sorts of nasty
properties and gotchas. Instead, this patch takes a much more
conservative approach. The interface is added as a basic loop wrapper
around getrandom(), and then later, the kernel and libc together can
work together on optimizing that.
This prevents numerous issues in which userspace is unaware of when it
really must throw away its buffer, since we avoid buffering all
together. Future improvements may include userspace learning more from
the kernel about when to do that, which might make these sorts of
chacha20-based optimizations more possible. The current heuristic of 16
MiB is meaningless garbage that doesn't correspond to anything the
kernel might know about. So for now, let's just do something
conservative that we know is correct and won't lead to cryptographic
issues for users of this function.
This patch might be considered along the lines of, "optimization is the
root of all evil," in that the much more complex implementation it
replaces moves too fast without considering security implications,
whereas the incremental approach done here is a much safer way of going
about things. Once this lands, we can take our time in optimizing this
properly using new interplay between the kernel and userspace.
getrandom(0) is used, since that's the one that ensures the bytes
returned are cryptographically secure. But on systems without it, we
fallback to using /dev/urandom. This is unfortunate because it means
opening a file descriptor, but there's not much of a choice. Secondly,
as part of the fallback, in order to get more or less the same
properties of getrandom(0), we poll on /dev/random, and if the poll
succeeds at least once, then we assume the RNG is initialized. This is a
rough approximation, as the ancient "non-blocking pool" initialized
after the "blocking pool", not before, and it may not port back to all
ancient kernels, though it does to all kernels supported by glibc
(≥3.2), so generally it's the best approximation we can do.
The motivation for including arc4random, in the first place, is to have
source-level compatibility with existing code. That means this patch
doesn't attempt to litigate the interface itself. It does, however,
choose a conservative approach for implementing it.
Cc: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Cristian Rodríguez <crrodriguez@opensuse.org>
Cc: Paul Eggert <eggert@cs.ucla.edu>
Cc: Mark Harris <mark.hsj@gmail.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The implementation is based on scalar Chacha20 with per-thread cache.
It uses getrandom or /dev/urandom as fallback to get the initial entropy,
and reseeds the internal state on every 16MB of consumed buffer.
To improve performance and lower memory consumption the per-thread cache
is allocated lazily on first arc4random functions call, and if the
memory allocation fails getentropy or /dev/urandom is used as fallback.
The cache is also cleared on thread exit iff it was initialized (so if
arc4random is not called it is not touched).
Although it is lock-free, arc4random is still not async-signal-safe
(the per thread state is not updated atomically).
The ChaCha20 implementation is based on RFC8439 [1], omitting the final
XOR of the keystream with the plaintext because the plaintext is a
stream of zeros. This strategy is similar to what OpenBSD arc4random
does.
The arc4random_uniform is based on previous work by Florian Weimer,
where the algorithm is based on Jérémie Lumbroso paper Optimal Discrete
Uniform Generation from Coin Flips, and Applications (2013) [2], who
credits Donald E. Knuth and Andrew C. Yao, The complexity of nonuniform
random number generation (1976), for solving the general case.
The main advantage of this method is the that the unit of randomness is not
the uniform random variable (uint32_t), but a random bit. It optimizes the
internal buffer sampling by initially consuming a 32-bit random variable
and then sampling byte per byte. Depending of the upper bound requested,
it might lead to better CPU utilization.
Checked on x86_64-linux-gnu, aarch64-linux, and powerpc64le-linux-gnu.
Co-authored-by: Florian Weimer <fweimer@redhat.com>
Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
[1] https://datatracker.ietf.org/doc/html/rfc8439
[2] https://arxiv.org/pdf/1304.1916.pdf
This change provides implementations for the mbrtoc8 and c8rtomb
functions adopted for C++20 via WG21 P0482R6 and for C2X via WG14
N2653. It also provides the char8_t typedef from WG14 N2653.
The mbrtoc8 and c8rtomb functions are declared in uchar.h in C2X
mode or when the _GNU_SOURCE macro or C++20 __cpp_char8_t feature
test macro is defined.
The char8_t typedef is declared in uchar.h in C2X mode or when the
_GNU_SOURCE macro is defined and the C++20 __cpp_char8_t feature
test macro is not defined (if __cpp_char8_t is defined, then char8_t
is a builtin type).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
It was added on Linux 5.12 (2a1867219c7b27f928e2545782b86daaf9ad50bd)
to allow change the properties of a mount or a mount tree using file
descriptors which the new mount api is based on.
Checked on x86_64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.2 (a07b20004793d8926f78d63eb5980559f7813404)
to return a O_PATH-opened file descriptor to an existing mountpoint.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.2 (cf3cba4a429be43e5527a3f78859b1bfd9ebc5fb)
that can be used to pick an existing mountpoint into an filesystem
context which can thereafter be used to reconfigure a superblock
with fsconfig syscall.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.2 (ecdab150fddb42fe6a739335257949220033b782)
as a way to a configure filesystem creation context and trigger
actions upon it, to be used in conjunction with fsopen, fspick and
fsmount.
The fsconfig_command commands are currently only defined as an enum,
so they can't be checked on tst-mount-consts.py with current test
support.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Previously, they were assumed to be in ISO-8859-1, and that the output
charset overlapped with ISO-8859-1 for the characters actually used.
However, this did not work as intended on many architectures even for
an ISO-8859-1 output encoding because of the char signedness bug in
lr_getc. Therefore, this commit switches to UTF-8 without making
provisions for backwards compatibility.
The following Elisp code can be used to convert locale definition files
to UTF-8:
(defun glibc/convert-localedef (from to)
(interactive "r")
(save-excursion
(save-restriction
(narrow-to-region from to)
(goto-char (point-min))
(save-match-data
(while (re-search-forward "<U\\([0-9a-fA-F]+\\)>" nil t)
(let* ((codepoint (string-to-number (match-string 1) 16))
(converted
(cond
((memq codepoint '(?/ ?\ ?< ?>))
(string ?/ codepoint))
((= codepoint ?\") "<U0022>")
(t (string codepoint)))))
(replace-match converted t)))))))
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.2 (2db154b3ea8e14b04fee23e3fdfd5e9d17fbc6ae)
as way t move a mount from one place to another and, in the next
commit, allow to attach an unattached mount tree.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
It was added on 5.2 (93766fbd2696c2c4453dd8e1070977e9cd4e6b6d) to
provide a way by which a filesystem opened with fsopen and configured
by a series of fsconfig calls can have a detached mount object
created for it.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.2 (24dcb3d90a1f67fe08c68a004af37df059d74005)
to start the process of preparing to create a superblock that will
then be mountable, using an fd as a context handle.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Added in Linux 5.15 (884a7e5964e06ed93c7771c0d7cf19c09a8946f1), the new
syscalls allows a caller to free the memory of a dying target process.
Checked on x86_64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.10 (ecb8ac8b1f146915aa6b96449b66dd48984caacc)
with the same functionality as madvise but using a pidfd of the target
process.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This was added on Linux 5.1(3eb39f47934f9d5a3027fe00d906a45fe3a15fad)
as a way to avoid the race condition of using kill (where PID might be
reused by the kernel between between obtaining the pid and sending the
signal).
If the siginfo_t argument is NULL then pidfd_send_signal is equivalent
to kill. If it is not NULL pidfd_send_signal is equivalent to
rt_sigqueueinfo.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
This was added on Linux 5.6 (8649c322f75c96e7ced2fec201e123b2b073bf09)
as a way to retrieve a file descriptors for another process though
pidfd (created either with CLONE_PIDFD or pidfd_getfd). The
functionality is similar to recvmmsg SCM_RIGHTS.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
This was added on Linux 5.3 (32fcb426ec001cb6d5a4a195091a8486ea77e2df)
as a way to retrieve a pid file descriptors for process that has not
been created CLONE_PIDFD (by usual fork/clone).
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The Linux version used by i686 and m68k provide three overrrides for
generic code:
1. DISTINGUISH_LIB_VERSIONS to print additional information when
libc5 is used by a dependency.
2. EXTRA_LD_ENVVARS to that enabled LD_LIBRARY_VERSION environment
variable.
3. EXTRA_UNSECURE_ENVVARS to add two environment variables related
to aout support.
None are really requires, it has some decades since libc5 or aout
suppported was removed and Linux even remove support for aout files.
The LD_LIBRARY_VERSION is also dead code, dl_correct_cache_id is not
used anywhere.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
The kernel version check is used to avoid glibc to run on older
kernels where some syscall are not available and fallback code are
not enabled to handle graciously fail. However, it does not prevent
if the kernel does not correctly advertise its version through
vDSO note, uname or procfs.
Also kernel version checks are sometime not desirable by users,
where they want to deploy on different system with different kernel
version knowing the minimum set of syscall is always presented on
such systems.
The kernel version check has been removed along with the
LD_ASSUME_KERNEL environment variable. The minimum kernel used to
built glibc is still provided through NT_GNU_ABI_TAG ELF note and
also printed when libc.so is issued.
Checked on x86_64-linux-gnu.
In commit 063f9ba220 the NEWS section
was accidentally added to the glibc 2.34 NEWS section. The NEWS entry
should have been added to glibc 2.35 which contained the committed
fix. This moves the NEWS entry to correct section.
The fix for BZ#22716 replacde LD_TRACE_LOADED_OBJECTS with
LD_TRACE_PRELINKING so mtrace could record executable address
position.
To provide the same information, LD_TRACE_LOADED_OBJECTS is
extended where a value or '2' also prints the executable address
as well. It avoid adding another loader environment variable
to be used solely for mtrace. The vDSO will be printed as
a default library (with '=>' pointing the same name), which is
ok since both mtrace and ldd already handles it.
The mtrace script is changed to also parse the new format. To
correctly support PIE and non-PIE executables, both the default
mtrace address and the one calculated as used (it fixes mtrace
for non-PIE exectuable as for BZ#22716 for PIE).
Checked on x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
