Imagelibrary/binutils-gdb
1
0
Fork 1
mirror of https://github.com/bminor/binutils-gdb.git synced 2025-12-26 17:18:55 +00:00
Code Issues Packages Projects Releases Wiki Activity

Document new "x" and "print" memory tagging extensions

Browse Source 
Document the changes to the "print" and "x" commands to support memory
tagging.

gdb/doc/ChangeLog:

YYYY-MM-DD  Luis Machado  <luis.machado@linaro.org>

	* gdb.texinfo (Data): Document memory tagging changes to the "print"
	command.
	(Examining Memory): Document memory tagging changes to the "x"
	command.
	(Memory Tagging): Update with more information on changes to the "x"
	and "print" commands.
This commit is contained in:
Luis Machado
2020-06-15 15:51:21 -03:00
parent c809eaadc1
commit df7edbc7ee
1 changed files with 31 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
gdb/doc/gdb.texinfo
View File

@@ -9893,6 +9893,10 @@ If you omit @var{expr}, @value{GDBN} displays the last value again (from the
conveniently inspect the same value in an alternative format.
@end table
If the architecture supports memory tagging, the @code{print} command will
display pointer/memory tag mismatches if what is being printed is a pointer
or reference type.
A more low-level way of examining data is with the @code{x} command.
It examines data in memory at a specified address and prints it in a
specified format. @xref{Memory, ,Examining Memory}.
@@ -10660,7 +10664,8 @@ number is specified, memory is examined backward from @var{addr}.
@item @var{f}, the display format
The display format is one of the formats used by @code{print}
(@samp{x}, @samp{d}, @samp{u}, @samp{o}, @samp{t}, @samp{a}, @samp{c},
@samp{f}, @samp{s}), and in addition @samp{i} (for machine instructions).
@samp{f}, @samp{s}), @samp{i} (for machine instructions) and
@samp{m} (for displaying memory tags).
The default is @samp{x} (hexadecimal) initially. The default changes
each time you use either @code{x} or @code{print}.
@@ -10755,6 +10760,20 @@ counter is shown with a @code{=>} marker. For example:
0x804838c <main+24>: call 0x80482d4 <puts@@plt>
@end smallexample
If the architecture supports memory tagging, the tags can be displayed by
using @samp{m}. The information will be displayed once per granule size
(the amount of bytes a particular memory tag covers). For example, AArch64
has a granule size of 16 bytes, so it will display a tag every 16 bytes.
Due to the way @value{GDBN} prints information with the @code{x} command (not
aligned to a particular boundary), the tag information will refer to the
initial address displayed on a particular line. If a memory tag boundary
is crossed in the middle of a line displayed by the @code{x} command, it
will be displayed in the next line.
The @samp{m} format doesn't affect any other specified formats that were
passed to the @code{x} command.
@cindex @code{$_}, @code{$__}, and value history
The addresses and contents printed by the @code{x} command are not saved
in the value history because there is often too much of them and they
@@ -10821,8 +10840,17 @@ If the underlying architecture supports memory tagging, like AArch64,
@value{GDBN} can make use of it to validate addresses and pointers against
memory allocation tags.
A command prefix of @code{mtag} gives access to the various memory tagging
commands.
The @code{print} and @code{x} commands will display tag information when
appropriate, and a command prefix of @code{mtag} gives access to the
various memory tagging commands.
The @code{print} command will automatically attempt to validate the logical
tag against the allocation tag for pointers and addresses, and will display
a message in case of failure.
The @code{x} command has a @code{m} modifier. When present, this modifier
will make the @code{x} command output allocation tag information for a given
memory region that is being examined.
The @code{mtag} commands are the following: