From 0f01515a247b458e04fb3992b578e5f6b095e03d Mon Sep 17 00:00:00 2001 From: Luis Machado Date: Mon, 15 Jun 2020 15:43:03 -0300 Subject: [PATCH] Documentation for memory tagging remote packets Document the remote packet changes to support memory tagging. gdb/doc/ChangeLog: 2021-03-24 Luis Machado * gdb.texinfo (General Query Packets): Document qMemTags and QMemTags. Document the "memory-tagging" feature. (ARM-Specific Protocol Details): Document memory tag types. --- gdb/doc/ChangeLog | 6 +++ gdb/doc/gdb.texinfo | 114 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 120 insertions(+) diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog index 625aa29728d..6dc6a6569e9 100644 --- a/gdb/doc/ChangeLog +++ b/gdb/doc/ChangeLog @@ -1,3 +1,9 @@ +2021-03-24 Luis Machado + + * gdb.texinfo (General Query Packets): Document qMemTags and + QMemTags. Document the "memory-tagging" feature. + (ARM-Specific Protocol Details): Document memory tag types. + 2021-03-18 Andrew Burgess * python.texinfo (Parameters In Python): Return empty string in diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index 80ccf74a049..e26ce4e9b6b 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -40992,6 +40992,87 @@ is a sequence of thread IDs, @var{threadid} (eight hex digits), from the target. See @code{remote.c:parse_threadlist_response()}. @end table +@item qMemTags:@var{start address},@var{length}:@var{type} +@anchor{qMemTags} +@cindex fetch memory tags +@cindex @samp{qMemTags} packet +Fetch memory tags of type @var{type} from the address range +@w{@r{[}@var{start address}, @var{start address} + @var{length}@r{)}}. The +target is responsible for calculating how many tags will be returned, as this +is architecture-specific. + +@var{start address} is the starting address of the memory range. + +@var{length} is the length, in bytes, of the memory range. + +@var{type} is the type of tag the request wants to fetch. The type is a signed +integer. + +Reply: +@table @samp +@item @var{mxx}@dots{} +Hex encoded sequence of uninterpreted bytes, @var{xx}@dots{}, representing the +tags found in the requested memory range. + +@item E @var{nn} +An error occured. This means that fetching of memory tags failed for some +reason. + +@item @w{} +An empty reply indicates that @samp{qMemTags} is not supported by the stub, +although this should not happen given @value{GDBN} will only send this packet +if the stub has advertised support for memory tagging via @samp{qSupported}. +@end table + +@item QMemTags:@var{start address},@var{length}:@var{type}:@var{tag bytes} +@anchor{QMemTags} +@cindex store memory tags +@cindex @samp{QMemTags} packet +Store memory tags of type @var{type} to the address range +@w{@r{[}@var{start address}, @var{start address} + @var{length}@r{)}}. The +target is responsible for interpreting the type, the tag bytes and modifying +the memory tag granules accordingly, given this is architecture-specific. + +The interpretation of how many tags (@var{nt}) should be written to how many +memory tag granules (@var{ng}) is also architecture-specific. The behavior is +implementation-specific, but the following is suggested. + +If the number of memory tags, @var{nt}, is greater than or equal to the +number of memory tag granules, @var{ng}, only @var{ng} tags will be +stored. + +If @var{nt} is less than @var{ng}, the behavior is that of a fill operation, +and the tag bytes will be used as a pattern that will get repeated until +@var{ng} tags are stored. + +@var{start address} is the starting address of the memory range. The address +does not have any restriction on alignment or size. + +@var{length} is the length, in bytes, of the memory range. + +@var{type} is the type of tag the request wants to fetch. The type is a signed +integer. + +@var{tag bytes} is a sequence of hex encoded uninterpreted bytes which will be +interpreted by the target. Each pair of hex digits is interpreted as a +single byte. + +Reply: +@table @samp +@item OK +The request was successful and the memory tag granules were modified +accordingly. + +@item E @var{nn} +An error occured. This means that modifying the memory tag granules failed +for some reason. + +@item @w{} +An empty reply indicates that @samp{QMemTags} is not supported by the stub, +although this should not happen given @value{GDBN} will only send this packet +if the stub has advertised support for memory tagging via @samp{qSupported}. +@end table + @item qOffsets @cindex section offsets, remote request @cindex @samp{qOffsets} packet @@ -41659,6 +41740,11 @@ These are the currently defined stub features and their properties: @tab @samp{-} @tab No +@item @samp{memory-tagging} +@tab No +@tab @samp{-} +@tab No + @end multitable These are the currently defined stub features, in more detail: @@ -41873,6 +41959,16 @@ The remote stub understands the @samp{QThreadEvents} packet. @item no-resumed The remote stub reports the @samp{N} stop reply. + +@item memory-tagging +The remote stub supports and implements the required memory tagging +functionality and understands the @samp{qMemTags} (@pxref{qMemTags}) and +@samp{QMemTags} (@pxref{QMemTags}) packets. + +For AArch64 GNU/Linux systems, this feature also requires access to the +@file{/proc/@var{pid}/smaps} file so memory mapping page flags can be inspected. +This is done via the @samp{vFile} requests. + @end table @item qSymbol:: @@ -42354,6 +42450,7 @@ details of XML target descriptions for each architecture. @menu * ARM Breakpoint Kinds:: +* ARM Memory Tag Types:: @end menu @node ARM Breakpoint Kinds @@ -42375,6 +42472,23 @@ These breakpoint kinds are defined for the @samp{Z0} and @samp{Z1} packets. @end table +@node ARM Memory Tag Types +@subsubsection @acronym{ARM} Memory Tag Types +@cindex memory tag types, @acronym{ARM} + +These memory tag types are defined for the @samp{qMemTag} and @samp{QMemTag} +packets. + +@table @r + +@item 0 +MTE logical tag + +@item 1 +MTE allocation tag + +@end table + @node MIPS-Specific Protocol Details @subsection @acronym{MIPS}-specific Protocol Details -- 2.30.2