This patch optimizes the FPSCR update on exception and rounding change
functions by just updating its value if new value if different from
current one. It also optimizes fedisableexcept and feenableexcept by
removing an unecessary FPSCR read.
__int128 was added in GCC 4.6 and __int128_t was added before x86-64
was supported. This patch replaces __int128 with __int128_t so that
the installed bits/link.h can be used with older GCC.
* sysdeps/x86/bits/link.h (La_x86_64_regs): Replace __int128
with __int128_t.
(La_x86_64_retval): Likewise.
In the glibc manual we have a "Roadmap to the manual" section at
the end of the "Introduction" chapter.
The introductory text says "Here is an overview of the contents
of the remaining chapters of this manual.", but then proceeds to
list chapters out of order and some chapter are never referenced.
This commit reorders the overview to correctly match the manual
order.
See:
https://sourceware.org/ml/libc-alpha/2014-02/msg00823.html
This patch removes the arch specific powerpc implementation and instead
uses the linux default one. Although the current powerpc implementation
already constains the required memory barriers for correct
initialization, the default implementation shows a better performance on
newer chips.
Calling setcontext from a signal handler can be done safely so
it is sufficient to note that it is not recommended.
Also mention in setcontext documentation that the behaviour of
setcontext when restoring a context created by a call to a signal
handler is unspecified.
2014-04-17 Will Newton <will.newton@linaro.org>
* manual/setjmp.texi (System V contexts): Add note that
calling setcontext on a context created by a call to a
signal handler is undefined. Update text to note that
setcontext from a signal handler is possible but not
recommended.
On aarch64 calling swapcontext clobbers the state of the signal
stack (BZ #16629). Check that the address and size of the signal
stack before and after the call to swapcontext remains the same.
ChangeLog:
2014-04-17 Will Newton <will.newton@linaro.org>
[BZ #16629]
* stdlib/tst-setcontext.c: Include signal.h.
(main): Check that the signal stack before and
after swapcontext is the same.
The current implementation of setcontext uses rt_sigreturn to restore
the contents of registers. This contrasts with the way most other
architectures implement setcontext:
powerpc64, mips, tile:
Call rt_sigreturn if context was created by a call to a signal handler,
otherwise restore in user code.
powerpc32:
Call swapcontext system call and don't call sigreturn or rt_sigreturn.
x86_64, sparc, hppa, sh, ia64, m68k, s390, arm:
Only support restoring "synchronous" contexts, that is contexts
created by getcontext, and restoring in user code and don't call
sigreturn or rt_sigreturn.
alpha:
Call sigreturn (but not rt_sigreturn) in all cases to do the restore.
The text of the setcontext manpage suggests that the requirement to be
able to restore a signal handler created context has been dropped from
SUSv2:
If the context was obtained by a call to a signal handler, then old
standard text says that "program execution continues with the program
instruction following the instruction interrupted by the signal".
However, this sentence was removed in SUSv2, and the present verdict
is "the result is unspecified".
Implementing setcontext by calling rt_sigreturn unconditionally causes
problems when used with sigaltstack as in BZ #16629. On this basis it
seems that aarch64 is broken and that new ports should only support
restoring contexts created with getcontext and do not need to call
rt_sigreturn at all.
This patch re-implements the aarch64 setcontext function to restore
the context in user code in a similar manner to x86_64 and other ports.
ChangeLog:
2014-04-17 Will Newton <will.newton@linaro.org>
[BZ #16629]
* sysdeps/unix/sysv/linux/aarch64/setcontext.S (__setcontext):
Re-implement to restore registers in user code and avoid
rt_sigreturn system call.
Besides fixing the bugzilla, this also fixes corner-cases where the high
and low double differ greatly in magnitude, and handles a denormal
input without resorting to a fp rescale.
[BZ #16740]
[BZ #16619]
* sysdeps/ieee754/ldbl-128ibm/s_frexpl.c (__frexpl): Rewrite.
* math/libm-test.inc (frexp_test_data): Add tests.
Using -lm and -lpthread results in the shared objects in the system
being used to link against. This happened to work for libm because
there haven't been any changes to the libm ABI recently that could
break the existing benchmarks. This doesn't always work for the
pthread benchmarks. The correct way to build against libraries in the
build directory is to have the binaries explicitly depend on them so
that $(+link) can pick them up.
We initialize _r_debug for static binaries to allows debug
agents to treat static binaries a little more like dyanmic
ones. This simplifies the work a debug agent has to do to
access TLS in a static binary via libthread_db.
Tested on x86_64.
See:
https://sourceware.org/ml/libc-alpha/2014-04/msg00183.html
[BZ #16831]
* csu/libc-start.c (LIBC_START_MAIN) [!SHARED]: Call
_dl_debug_initialize.
The SELinux team has indicated to me that glibc's SELinux checks
in nscd are not being carried out as they would expect the API
to be used today. They would like to move away from static header
defines for class and permissions and instead use dynamic checks
at runtime that provide an answer which is dependent on the runtime
status of SELinux i.e. more dynamic.
The following patch is a minimal change that moves us forward in
this direction.
It does the following:
* Stop checking for SELinux headers that define NSCD__SHMEMHOST.
Check only for the presence or absence of the library.
* Don't encode the specific SELinux permission constants into a
table at build time, and instead use the symbolic name for the
permission as expected.
* Lookup the "What do we do if we don't know this permission?"
policy and use that if we find SELinux's policy is older than
the glibc policy e.g. we make a request for a permission that
SELinux doesn't know about.
* Lastly, translate the class and permission and then make
the permission check. This is done every time we lookup
a permission, and this is the expected way to use the API.
SELinux will optimize this for us, and we expect the network
latencies to hide these extra library calls.
Tested on x86, x86-64, and via Fedora Rawhide since November 2013.
See:
https://sourceware.org/ml/libc-alpha/2014-04/msg00179.html
