x86/CET: Document glibc.tune.x86_ibt and glibc.tune.x86_shstk

* manual/tunables.texi: Document glibc.tune.x86_ibt and
	glibc.tune.x86_shstk.
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H.J. Lu 2018-07-18 11:34:35 -07:00
parent e6c695099b
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@ -1,3 +1,8 @@
2018-07-18 H.J. Lu <hongjiu.lu@intel.com>
* manual/tunables.texi: Document glibc.tune.x86_ibt and
glibc.tune.x86_shstk.
2018-07-18 H.J. Lu <hongjiu.lu@intel.com>
* NEWS: Mention --enable-cet.

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@ -356,3 +356,31 @@ to set threshold in bytes for non temporal store.
This tunable is specific to i386 and x86-64.
@end deftp
@deftp Tunable glibc.tune.x86_ibt
The @code{glibc.tune.x86_ibt} tunable allows the user to control how
indirect branch tracking (IBT) should be enabled. Accepted values are
@code{on}, @code{off}, and @code{permissive}. @code{on} always turns
on IBT regardless of whether IBT is enabled in the executable and its
dependent shared libraries. @code{off} always turns off IBT regardless
of whether IBT is enabled in the executable and its dependent shared
libraries. @code{permissive} is the same as the default which disables
IBT on non-CET executables and shared libraries.
This tunable is specific to i386 and x86-64.
@end deftp
@deftp Tunable glibc.tune.x86_shstk
The @code{glibc.tune.x86_shstk} tunable allows the user to control how
the shadow stack (SHSTK) should be enabled. Accepted values are
@code{on}, @code{off}, and @code{permissive}. @code{on} always turns on
SHSTK regardless of whether SHSTK is enabled in the executable and its
dependent shared libraries. @code{off} always turns off SHSTK regardless
of whether SHSTK is enabled in the executable and its dependent shared
libraries. @code{permissive} changes how dlopen works on non-CET shared
libraries. By default, when SHSTK is enabled, dlopening a non-CET shared
library returns an error. With @code{permissive}, it turns off SHSTK
instead.
This tunable is specific to i386 and x86-64.
@end deftp