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brooks e94d2a0f8b Extend mmap/mprotect API to specify the max page
protections.

A new macro PROT_MAX() alters a protection value so it can be OR'd with
a regular protection value to specify the maximum permissions.  If
present, these flags specify the maximum permissions.

While these flags are non-portable, they can be used in portable code
with simple ifdefs to expand PROT_MAX() to 0.

This change allows (e.g.) a region that must be writable during run-time
linking or JIT code generation to be made permanently read+execute after
writes are complete.  This complements W^X protections allowing more
precise control by the programmer.

This change alters mprotect argument checking and returns an error when
unhandled protection flags are set.  This differs from POSIX (in that
POSIX only specifies an error), but is the documented behavior on Linux
and more closely matches historical mmap behavior.

In addition to explicit setting of the maximum permissions, an
experimental sysctl vm.imply_prot_max causes mmap to assume that the
initial permissions requested should be the maximum when the sysctl is
set to 1.  PROT_NONE mappings are excluded from this for compatibility
with rtld and other consumers that use such mappings to reserve
address space before mapping contents into part of the reservation.  A
final version this is expected to provide per-binary and per-process
opt-in/out options and this sysctl will go away in its current form.
As such it is undocumented.

Reviewed by:	emaste, kib (prior version), markj
Additional suggestions from:	alc
Obtained from:	CheriBSD
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D18880
2019-09-25 09:01:10 +02:00
config Sync with upstream gcc. 2016-06-23 15:54:55 -04:00
etc Remove spurious empty line in changelog entry. 2016-03-22 10:29:22 +01:00
include Sync with upstream gcc. 2016-06-23 15:54:55 -04:00
libgloss Adjust nios2 and m68k semihosting for sys/stat.h changes. 2019-09-04 09:44:35 +02:00
newlib Extend mmap/mprotect API to specify the max page 2019-09-25 09:01:10 +02:00
texinfo
winsup Document the last change 2019-09-24 20:04:28 -04:00
.drone.yml Continuous Integration: Add Tea CI build configuration. 2016-06-28 13:42:59 +02:00
.gitattributes Add .gitattributes 2015-03-09 20:53:11 +01:00
.gitignore Add *.swp (Vim swap files) to .gitignore 2015-03-17 12:03:30 +01:00
COPYING
COPYING.LIB Sync toplevel with upstream GCC. 2016-03-22 10:25:20 +01:00
COPYING.LIBGLOSS Add Synopsys license for newlib and libgloss 2015-11-12 14:16:32 +01:00
COPYING.NEWLIB AMD GCN Port contributed by Andrew Stubbs <ams@codesourcery.com> 2019-01-15 10:48:08 -05:00
COPYING3
COPYING3.LIB
ChangeLog Sync with upstream gcc. 2016-06-23 15:54:55 -04:00
MAINTAINERS MAINTAINERS: clarify policy with config/ (and other top level files) 2012-05-12 03:10:17 +00:00
Makefile.def Sync with upstream gcc. 2016-06-23 15:54:55 -04:00
Makefile.in Introduce @unless/@endunless and postbootstrap Makefile targets 2018-06-30 00:12:40 -03:00
Makefile.tpl Introduce @unless/@endunless and postbootstrap Makefile targets 2018-06-30 00:12:40 -03:00
README
README-maintainer-mode
compile Sync toplevel with upstream GCC. 2016-03-22 10:25:20 +01:00
config-ml.in Sync toplevel with upstream GCC. 2016-03-22 10:25:20 +01:00
config.guess Update config.guess, config.sub to gcc master branch versions 2019-01-15 14:13:30 -05:00
config.rpath
config.sub Update config.guess, config.sub to gcc master branch versions 2019-01-15 14:13:30 -05:00
configure Introduce @unless/@endunless and postbootstrap Makefile targets 2018-06-30 00:12:40 -03:00
configure.ac Introduce @unless/@endunless and postbootstrap Makefile targets 2018-06-30 00:12:40 -03:00
depcomp Sync toplevel with upstream GCC. 2016-03-22 10:25:20 +01:00
djunpack.bat
install-sh Sync toplevel with upstream GCC. 2016-03-22 10:25:20 +01:00
libtool.m4 Sync toplevel with upstream GCC. 2016-03-22 10:25:20 +01:00
ltgcc.m4
ltmain.sh PR target/59788 2014-02-05 13:17:47 +00:00
ltoptions.m4
ltsugar.m4
ltversion.m4
lt~obsolete.m4
makefile.vms
missing Sync toplevel with upstream GCC. 2016-03-22 10:25:20 +01:00
mkdep
mkinstalldirs Sync toplevel with upstream GCC. 2016-03-22 10:25:20 +01:00
move-if-change Sync toplevel with upstream GCC. 2016-03-22 10:25:20 +01:00
setup.com
src-release * src-release (do-proto-toplevel): Support subdir-path-prefixed 2013-10-15 20:45:52 +00:00
symlink-tree
ylwrap Sync toplevel with upstream GCC. 2016-03-22 10:25:20 +01:00

README

		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

Much of the code and documentation enclosed is copyright by
the Free Software Foundation, Inc.  See the file COPYING or
COPYING.LIB in the various directories, for a description of the
GNU General Public License terms under which you can copy the files.

REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info
on where and how to report problems.