musl - an implementation of the standard library for Linux-based systems
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Szabolcs Nagy 610c5a8524 fix TLS layout of TLS variant I when there is a gap above TP
In TLS variant I the TLS is above TP (or above a fixed offset from TP)
but on some targets there is a reserved gap above TP before TLS starts.

This matters for the local-exec tls access model when the offsets of
TLS variables from the TP are hard coded by the linker into the
executable, so the libc must compute these offsets the same way as the
linker.  The tls offset of the main module has to be

	alignup(GAP_ABOVE_TP, main_tls_align).

If there is no TLS in the main module then the gap can be ignored
since musl does not use it and the tls access models of shared
libraries are not affected.

The previous setup only worked if (tls_align & -GAP_ABOVE_TP) == 0
(i.e. TLS did not require large alignment) because the gap was
treated as a fixed offset from TP.  Now the TP points at the end
of the pthread struct (which is aligned) and there is a gap above
it (which may also need alignment).

The fix required changing TP_ADJ and __pthread_self on affected
targets (aarch64, arm and sh) and in the tlsdesc asm the offset to
access the dtv changed too.
2018-06-02 19:38:44 -04:00
arch fix TLS layout of TLS variant I when there is a gap above TP 2018-06-02 19:38:44 -04:00
crt add s390x port 2016-11-11 23:06:21 -05:00
dist
include fix default feature profile in tar.h 2018-03-28 15:53:45 -04:00
ldso fix TLS layout of TLS variant I when there is a gap above TP 2018-06-02 19:38:44 -04:00
src fix TLS layout of TLS variant I when there is a gap above TP 2018-06-02 19:38:44 -04:00
tools add CFI generation script for x86_64 2015-10-13 18:09:46 -04:00
.gitignore remove obsolete gitignore rules 2016-07-06 00:21:25 -04:00
COPYRIGHT update authors/contributors list 2018-02-21 14:19:01 -05:00
INSTALL add powerpc64 and s390x to list of supported archs in INSTALL file 2017-08-29 20:48:02 -04:00
Makefile adjust makefile target-specific CFLAGS rules to be more robust & complete 2018-03-24 22:47:36 -04:00
README update version reference in the README file 2014-06-25 14:16:53 -04:00
VERSION release 1.1.19 2018-02-22 13:39:19 -05:00
WHATSNEW release 1.1.19 2018-02-22 13:39:19 -05:00
configure use explicit dynamic-list rather than symbolic-functions for linking 2018-04-17 19:23:00 -04:00
dynamic.list allow interposition/replacement of allocator (malloc) 2018-04-18 14:22:49 -04:00

README

    musl libc

musl, pronounced like the word "mussel", is an MIT-licensed
implementation of the standard C library targetting the Linux syscall
API, suitable for use in a wide range of deployment environments. musl
offers efficient static and dynamic linking support, lightweight code
and low runtime overhead, strong fail-safe guarantees under correct
usage, and correctness in the sense of standards conformance and
safety. musl is built on the principle that these goals are best
achieved through simple code that is easy to understand and maintain.

The 1.1 release series for musl features coverage for all interfaces
defined in ISO C99 and POSIX 2008 base, along with a number of
non-standardized interfaces for compatibility with Linux, BSD, and
glibc functionality.

For basic installation instructions, see the included INSTALL file.
Information on full musl-targeted compiler toolchains, system
bootstrapping, and Linux distributions built on musl can be found on
the project website:

    http://www.musl-libc.org/