[PATCH v2 1/1] Documentation for MPX.

[Walfred Tedeschi <walfred.tedeschi@intel.com>]

Hello Eli and Pedro,

I tried to cover all feedback you gave me.
Concerning the footnote I have reduced it to avoid
early confusion, the topic will be explained anyhow later.

Thanks a lot for your review,
-Fred

Pedro: I am just back from christmas as you can see. :-)

2013-11-28  Walfred Tedeschi  <walfred.tedeschi@intel.com>

	* NEWS:  Add section for Intel(R) Architecture Instructions
	Extesions mentioning MPX.
doc/
	* gdb.texinfo (i386 Features): Add MPX feature registers.
	(x86 Specific featuresx86 Architecture-specific Issues): Adds
	a subsubsection for MPX and describes the display of the
	boundary registers.


---
 gdb/NEWS            |  2 ++
 gdb/doc/gdb.texinfo | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/gdb/NEWS b/gdb/NEWS
index 9fc3638..fdb33d4 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -5558,3 +5558,5 @@ GDB now handles cross debugging.  If you are remotely debugging between
 two different machines, type ``./configure host -target=targ''.
 Host is the machine where GDB will run; targ is the machine
 where the program that you are debugging will run.
+
+ *  GDB now supports access to Intel(R) MPX registers on GNU/Linux.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index d854f46..7eacba2 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -21363,6 +21363,40 @@ be returned in a register.
 @kindex show struct-convention
 Show the current setting of the convention to return @code{struct}s
 from functions.
+
+@cindex Intel(R) Memory Protection Extensions (MPX).
+@subsubsection Intel(R) @dfn{Memory Protection Extensions} (MPX).
+
+@item bnd0raw..bnd3raw and bnd0@dots{}bnd3 registers display.
+Memory Protection Extension (MPX) adds the bound registers @samp{BND0}
+@footnote{The register named with capital letters represent the architecture
+registers.} through @samp{BND3}.  Bound registers store a pair of 64-bit values
+which are the lower bound and upper bound.  Bounds are effective addresses or
+memory locations.  The upper bounds are architecturally represented in 1's
+complement form.  A bound having lower bound = 0, and upper bound = 0
+(1's complement of all bits set) will allow access to the entire address space.
+
+Architecture registers @samp{BND0} through @samp{BND3} are
+represented in @value{GDBN} as @samp{bnd0raw} through @samp{bnd3raw}.
+Pseudo registers @samp{bnd0} through @samp{bnd3} display the upper bound
+performing the complement of one operation on the upper bound value, i.e.@
+when upper bound in @samp{bnd0raw} is 0 in the @value{GDBN} @samp{bnd0} it will
+be @code{0xfff@dots{}}.  In this sense it can also be noted that the upper bounds are
+inclusive.
+
+As an example, assume that the register BND0 holds bounds for a pointer having
+access allowed for the range between 0x32 and 0x71.  The values present on
+bnd0raw and bnd registers are presented as follows:
+
+@smallexample
+	bnd0raw = @{0x32, 0xffffffff8e@}
+	bnd0 = @{lbound = 0x32, ubound = 0x71@} : size 64
+@end smallexample
+
+This way the raw value can be accessed via bnd0raw@dots{}bnd3raw.  Any change
+on bnd0@dots{}bnd3 or bnd0raw@dots{}bnd3raw is reflect on its counterpart.  When the
+bnd0@dots{}bnd3 registers are displayed via Python, the display includes the memory size,
+in bits, accessible to the pointer.
 @end table
 
 @node Alpha
@@ -43138,6 +43172,16 @@ describe the upper 128 bits of @sc{ymm} registers:
 @samp{ymm0h} through @samp{ymm15h} for amd64
 @end itemize
 
+The @samp{org.gnu.gdb.i386.mpx} is an optional feature representing Intel(R)
+Memory Protection Extension (MPX).  It should describe the following registers:
+
+@itemize @minus
+@item
+@samp{bnd0raw} through @samp{bnd3raw} for i386 and amd64.
+@item
+@samp{bndcfgu} and @samp{bndstatus} for i386 and amd64.
+@end itemize
+
 The @samp{org.gnu.gdb.i386.linux} feature is optional.  It should
 describe a single register, @samp{orig_eax}.
 
-- 
1.8.1.2