提交: bfebd6b058af2f9eeb32af05d7a32422eb4af0b9 - binutils_os216 (git)

GNU Binutils with patches for OS216

Commit MetaInfo

• 修訂: bfebd6b058af2f9eeb32af05d7a32422eb4af0b9 (tree)
• 時間: 2020-06-16 21:58:33
• 作者: Luis Machado <luis.machado@lina...>
• Commiter: Luis Machado

Log Message

Documentation for the new mtag commands

Document the new "mtag" command prefix and all of its subcommands.

gdb/doc/ChangeLog:

YYYY-MM-DD Luis Machado <[e-mail]>

* gdb.textinfo (Memory Tagging): New subsection.
(AArch64 Memory Tagging Extension): New subsection.

Change Summary

• modified: gdb/doc/gdb.texinfo

差異

--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -10714,6 +10714,49 @@ target supports computing the CRC checksum of a block of memory
 (@pxref{qCRC packet}).
 @end table
 
+@subsection Memory Tagging
+
+Memory tagging is a memory protection technology that validates accesses
+through pointers via a tag.  Both the pointer tag and the memory tag in the
+physical address space must match for the memory access to be validated.
+
+There are two types of tags: logical and allocation.  The logical tag is
+stored in the pointers themselves.  The allocation tag is the tag associated
+with the physical address space, against which the logical tags from pointers
+are validated.
+
+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{mtag} commands are the following:
+
+@table @code
+@kindex mtag showltag
+@item mtag showltag @var{address_expression}
+Show the logical tag contained in the pointer resulting from evaluating the
+argument expression.
+@kindex mtag setltag
+@item mtag setltag @var{address_expression} @var{tag_bytes}
+Print the resulting pointer from evaluating the argument expression with a
+logical tag of @var{tag_bytes}.
+@kindex mtag showatag
+@item mtag showatag @var{address_expression}
+Show the allocation tag from the memory address pointed to by the evaluation
+of the argument expression.
+@kindex mtag setatag
+@item mtag setatag @var{starting_address} @var{length} @var{tag_bytes}
+Set the allocation tag for memory range @r{[}@var{starting_address},
+@var{starting_address} + @var{length}@r{)} to @var{tag_bytes}.
+@kindex mtag check
+@item mtag check @var{address_expression}
+Given the pointer resulting from evaluating the argument expression,  check that
+the logical tag and the allocation tags match.
+@end table
+
 @node Auto Display
 @section Automatic Display
 @cindex automatic display
@@ -24753,6 +24796,21 @@ When GDB prints a backtrace, any addresses that required unmasking will be
 postfixed with the marker [PAC].  When using the MI, this is printed as part
 of the @code{addr_flags} field.
 
+@subsubsection AArch64 Memory Tagging Extension.
+@cindex AArch64 Memory Tagging Extension.
+
+When @value{GDBN} is debugging the AArch64 architecture, the program is
+using the v8.5-A feature Memory Tagging Extension (MTE) and there is support
+in the kernel for MTE, @value{GDBN} will make memory tagging functionality
+available for inspection and editing of logical and allocation tags.
+
+@value{GDBN} will also output additional information for memory tag
+violations, which come as SIGSEGV signals, so developers can have a clue
+about what caused the crash. The logical and allocation tags will be shown
+alongside the fault address, if available.
+
+A new register set is made available through the MTE feature.
+
 @node i386
 @subsection x86 Architecture-specific Issues