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([2804:7f0:b402:d0dc:3e7c:3fff:fe7a:e83b]) by smtp.gmail.com with ESMTPSA id n16-20020aa79850000000b006e64ddfa71asm13218899pfq.170.2024.04.03.23.48.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Apr 2024 23:48:58 -0700 (PDT) From: Gustavo Romero To: gdb-patches@sourceware.org Cc: luis.machado@arm.com, thiago.bauermann@linaro.org, gustavo.romero@linaro.org Subject: [PATCH v3 7/7] gdb: Document qMemTagCheckAddr packet Date: Thu, 4 Apr 2024 06:48:19 +0000 Message-Id: <20240404064819.2848899-8-gustavo.romero@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240404064819.2848899-1-gustavo.romero@linaro.org> References: <20240404064819.2848899-1-gustavo.romero@linaro.org> MIME-Version: 1.0 X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces+patchwork=sourceware.org@sourceware.org This commit documents the 'qMemTagCheckAddr' packet and the associated feature 'memory-tagging-check-addr' that informs if this packet is supported by the target. Signed-off-by: Gustavo Romero Reviewed-By: Eli Zaretskii --- gdb/NEWS | 9 ++++++++ gdb/doc/gdb.texinfo | 50 ++++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 56 insertions(+), 3 deletions(-) diff --git a/gdb/NEWS b/gdb/NEWS index feb3a37393a..1158715f41c 100644 --- a/gdb/NEWS +++ b/gdb/NEWS @@ -192,6 +192,15 @@ QThreadOptions in qSupported QThreadOptions packet, and the qSupported response can contain the set of thread options the remote stub supports. +qMemTagCheckAddr + This new packet allows GDB to query the stub about a given address to check if + it is tagged or not. Many memory tagging-related GDB commands need to perform + this check before they read/write the allocation tag related to an address. + Currently, however, this is done through a 'vFile' request to read the file + /proc//smaps and check if the address is in a region reported as memory + tagged. Since not all targets have a notion of what the smaps file is about, + this new packet provides a more generic way to perform such a check. + *** Changes in GDB 14 * GDB now supports the AArch64 Scalable Matrix Extension 2 (SME2), which diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index 82a617e9ad3..afd57ff874c 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -44093,6 +44093,37 @@ 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 qMemTagCheckAddr:@var{address} +@anchor {qMemTagCheckAddr} +@cindex check if a given address is in a memory tagged region. +@cindex @samp{qMemTagCheckAddr} packet +Check if address @var{address} is in a memory tagged region; if it is, it's said +to be tagged. The target is responsible for checking it, as this is +architecture-specific. + +@var{address} is the address to be checked. + +Reply: +@table @samp +Replies are in a 2 hex digits format. + +@item @var{01} +Address @var{address} is tagged. + +@item @var{00} +Address @var{address} is not tagged. + +@item E @var{nn} +An error occurred. This means that address could not be checked for some +reason. + +@item @w{} +An empty reply indicates that @samp{qMemTagCheckAddr} is not supported by the +stub. This situation should not occur because @value{GDBN} will only send this +packet if the stub has advertised support for memory tagging check via the +@samp{memory-tagging-check-addr} feature in @samp{qSupported}. +@end table + @item QMemTags:@var{start address},@var{length}:@var{type}:@var{tag bytes} @anchor{QMemTags} @cindex store memory tags @@ -44914,6 +44945,11 @@ These are the currently defined stub features and their properties: @tab @samp{-} @tab No +@item @samp{memory-tagging-check-addr} +@tab No +@tab @samp{-} +@tab No + @end multitable These are the currently defined stub features, in more detail: @@ -45141,9 +45177,17 @@ 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. +For AArch64 GNU/Linux systems, this feature can require access to the +@file{/proc/@var{pid}/smaps} file so memory mapping page flags can be inspected, +if @samp{memory-tagging-check-addr} feature (see below) is not supported by the +stub. Access to the @file{/proc/@var{pid}/smaps} file is done via @samp{vFile} +requests. + +@item memory-tagging-check-addr +The remote stub supports and implements the required memory tagging address +check functionality and understands the @samp{qMemTagCheckAddr} +(@pxref{qMemTagCheckAddr}) packet, which is used for address checking instead +of accessing the @file{/proc/@var{pid}/smaps} file. @end table