diff options
| -rw-r--r-- | gdb/doc/gdb.texinfo | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index 73221e0..d42317f 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -9891,6 +9891,10 @@ 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}. @@ -10658,7 +10662,8 @@ 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}. @@ -10753,6 +10758,20 @@ 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 @@ -10819,8 +10838,17 @@ 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: |