From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id +B+9BzzlkV8PSQAAWB0awg (envelope-from ) for ; Thu, 22 Oct 2020 16:02:04 -0400 Received: by simark.ca (Postfix, from userid 112) id 1AC7B1EFC7; Thu, 22 Oct 2020 16:02:04 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-1.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 341071F068 for ; Thu, 22 Oct 2020 16:01:58 -0400 (EDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 607B73987510; Thu, 22 Oct 2020 20:01:57 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 607B73987510 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1603396917; bh=hbjo5GMUfqInGZXzvQTIwDk7sBDdB204skz+IM9Yg1g=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=HV6iEO9N5DWq6lMZN36m68dG5SqtbuR9RO3lsyq/ECyFTBpPu1tiTecTVdz2Tk5GS wAsmJ1HxfJLrI9J9fI+DUswMwItV0kP2MhKIjT1yUCVIBMIQsWFxuiORIlNJ7vyLnd gUuCASSbfZu2SAvxleOFI0oAECCpLZLju+cm2jto= Received: from mail-qt1-x843.google.com (mail-qt1-x843.google.com [IPv6:2607:f8b0:4864:20::843]) by sourceware.org (Postfix) with ESMTPS id 4479139874BF for ; Thu, 22 Oct 2020 20:01:55 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 4479139874BF Received: by mail-qt1-x843.google.com with SMTP id m65so2244256qte.11 for ; Thu, 22 Oct 2020 13:01:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=hbjo5GMUfqInGZXzvQTIwDk7sBDdB204skz+IM9Yg1g=; b=c/v0S6EA7xRYQB2IbW+mQVDK95XLUi2Mf+ZX/sDIHld37Beo8vmyxkXGH3kvp/sWy9 s2NE5NkQh1WL2/G0P2T6JrXlNM78N6/7OFTfu4MScN/xwc9DcSZy5ewd0xZzEb+03u30 1qVH/5RDVqHyrZukcfN3ysrh7TPgiEDqRR2kqOsu6Fej5l6N05pqbiKC+Axf4mJAvPv/ BW1dWSJVjgdv24EMdg27RQvCgBerGbYfddjMwJ8ta5IAG/4OrLjkyJ1Yhsaxn8b0uSs/ 2dHzxnNUXOxqmxSehR0Irw+Wb5YI1/CyhR5Ble5L+v4RmyIiUCaYps9JM3+tsihFuy0L Bisg== X-Gm-Message-State: AOAM533GrpbXydbTgQ8GgD/ZQ2HPSGA8KQhl+0TJ5tgbRWb1M8PVH8bU SEovmzriIuGahRTSJWxbI1/lkLjWPqULIQ== X-Google-Smtp-Source: ABdhPJzg3216rPh80FV6jm6o709EHKH36JBjXjL1zPRaxH+i0pYGewnyoA0rC460SJ+gqSS7XgCmHQ== X-Received: by 2002:aed:3e95:: with SMTP id n21mr3739820qtf.271.1603396914629; Thu, 22 Oct 2020 13:01:54 -0700 (PDT) Received: from localhost.localdomain ([2804:7f0:8284:1487:b9b1:f72a:8f1:600]) by smtp.gmail.com with ESMTPSA id a21sm1711208qkk.98.2020.10.22.13.01.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Oct 2020 13:01:54 -0700 (PDT) To: gdb-patches@sourceware.org Subject: [PATCH v2 20/24] Documentation for the new mtag commands Date: Thu, 22 Oct 2020 17:00:10 -0300 Message-Id: <20201022200014.5189-21-luis.machado@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201022200014.5189-1-luis.machado@linaro.org> References: <20201022200014.5189-1-luis.machado@linaro.org> X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Luis Machado via Gdb-patches Reply-To: Luis Machado Cc: david.spickett@linaro.org Errors-To: gdb-patches-bounces@sourceware.org Sender: "Gdb-patches" Document the new "mtag" command prefix and all of its subcommands. gdb/doc/ChangeLog: YYYY-MM-DD Luis Machado * gdb.texinfo (Memory Tagging): New subsection and node. (AArch64 Memory Tagging Extension): New subsection. --- gdb/doc/gdb.texinfo | 78 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index b778e48dd4..5056a021a5 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -10810,6 +10810,49 @@ target supports computing the CRC checksum of a block of memory (@pxref{qCRC packet}). @end table +@node Memory Tagging +@subsection Memory Tagging + +Memory tagging is a memory protection technology that uses tags to validate +memory accesses through pointers. The pointer tag must match the memory tag +for the memory access to be validated. + +There are two types of tags: logical and allocation. A logical tag is +stored in the pointers themselves. A allocation tag is the tag associated +with the physical address space, against which the logical tags from pointers +are compared. + +If the underlying architecture supports memory tagging, like AArch64 MTE +or SPARC ADI do, @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 stored at the address given by @var{address_expression}. +@kindex mtag setltag +@item mtag setltag @var{address_expression} @var{tag_bytes} +Print the address given by @var{address_expression}, augmented with a logical +tag of @var{tag_bytes}. +@kindex mtag showatag +@item mtag showatag @var{address_expression} +Show the allocation tag associated with the memory address given by +@var{address_expression}. +@kindex mtag setatag +@item mtag setatag @var{starting_address} @var{length} @var{tag_bytes} +Set the allocation tag(s) 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} +Check that the logical tag stored at the address given by +@var{address_expression} matches the allocation tag for the same address. +@end table + @node Auto Display @section Automatic Display @cindex automatic display @@ -24895,6 +24938,41 @@ 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. +@xref{Memory Tagging}. + +To aid debugging, @value{GDBN} will output additional information when SIGSEGV +signals are generated as a result of memory tag failures. + +If the tag violation is synchronous, the following will be shown: + +@smallexample +Program received signal SIGSEGV, Segmentation fault +Memory tag violation while accessing address 0x0000fffff7ff8000 +Allocation tag 0x0000000000000001. +@end smallexample + +If the tag violation is asynchronous, the fault address is not available. +In this case @value{GDBN} will show the following: + +@smallexample +Program received signal SIGSEGV, Segmentation fault +Memory tag violation +Fault address unavailable. +@end smallexample + +A special register, @code{tag_ctl}, is made available through the +@code{org.gnu.gdb.aarch64.mte} feature. This register exposes some +options that can be controlled at runtime and emulates the @code{prctl} +option @code{PR_SET_TAGGED_ADDR_CTRL}. For further information, see the +documentation in the Linux kernel. + @node i386 @subsection x86 Architecture-specific Issues -- 2.17.1