[v5,8/8] gdb: Document qIsAddressTagged packet
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Commit Message
This commit documents the qIsAddressTagged packet.
Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
Reviewed-by: Eli Zaretskii <eliz@gnu.org>
---
gdb/NEWS | 10 ++++++++++
gdb/doc/gdb.texinfo | 37 ++++++++++++++++++++++++++++++++++---
2 files changed, 44 insertions(+), 3 deletions(-)
Comments
> From: Gustavo Romero <gustavo.romero@linaro.org>
> Cc: luis.machado@arm.com,
> thiago.bauermann@linaro.org,
> eliz@gnu.org,
> tom@tromey.com,
> gustavo.romero@linaro.org
> Date: Wed, 17 Apr 2024 21:04:24 +0000
>
> This commit documents the qIsAddressTagged packet.
>
> Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
> Reviewed-by: Eli Zaretskii <eliz@gnu.org>
> ---
> gdb/NEWS | 10 ++++++++++
> gdb/doc/gdb.texinfo | 37 ++++++++++++++++++++++++++++++++++---
> 2 files changed, 44 insertions(+), 3 deletions(-)
Thanks.
> diff --git a/gdb/NEWS b/gdb/NEWS
> index feb3a37393a..1693a7a15f8 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -192,6 +192,16 @@ QThreadOptions in qSupported
> QThreadOptions packet, and the qSupported response can contain the
> set of thread options the remote stub supports.
>
> +qIsAddressTagged
> + 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/<PID>/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
This part is OK.
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -44093,6 +44093,35 @@ 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 qIsAddressTagged:@var{address}
> +@cindex check if a given address is in a memory tagged region
> +@cindex @samp{qIsAddressTagged} packet
The index entries should come _before_ the @item, so that the
index-search commands of an Info reader place you on the line produced
from @item, not after that line. Sorry I didn't mention that earlier.
OK with the above nit fixed.
Approved-By: Eli Zaretskii <eliz@gnu.org>
@@ -192,6 +192,16 @@ QThreadOptions in qSupported
QThreadOptions packet, and the qSupported response can contain the
set of thread options the remote stub supports.
+qIsAddressTagged
+ 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/<PID>/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
@@ -44093,6 +44093,35 @@ 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 qIsAddressTagged:@var{address}
+@cindex check if a given address is in a memory tagged region
+@cindex @samp{qIsAddressTagged} packet
+@anchor {qIsAddressTagged}
+Check if address @var{address} is in a memory tagged region; if it is, it's
+said to be @dfn{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 to this packet should all be in two hex digit format, as follows:
+
+@item @samp{01}
+Address @var{address} is tagged.
+
+@item @samp{00}
+Address @var{address} is not tagged.
+
+@item E @var{nn}
+An error occurred whose code is @var{nn}. This means that address could not
+be checked for some reason.
+
+@item @w{}
+An empty reply indicates that @samp{qIsAddressTagged} is not supported by the
+stub.
+@end table
+
@item QMemTags:@var{start address},@var{length}:@var{type}:@var{tag bytes}
@anchor{QMemTags}
@cindex store memory tags
@@ -45141,9 +45170,11 @@ 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{qIsAddressTagged} (@pxref{qIsAddressTagged}) packet
+is not supported by the stub. Access to the @file{/proc/@var{pid}/smaps}
+file is done via @samp{vFile} requests.
@end table