linux-kernel - [PATCH v4 6/6] ramoops: Add max_reason optional field to ramoops DT node

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Message-Id: <20200515184434.8470-7-keescook@chromium.org>
Date:   Fri, 15 May 2020 11:44:34 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Pavel Tatashin <pasha.tatashin@...een.com>
Cc:     Kees Cook <keescook@...omium.org>, Petr Mladek <pmladek@...e.com>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Benson Leung <bleung@...omium.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v4 6/6] ramoops: Add max_reason optional field to ramoops DT node

From: Pavel Tatashin <pasha.tatashin@...een.com>

Currently, it is possible to dump kmsges for panic, or oops.
With max_reason it is possible to dump messages for other
kmesg_dump events, for example reboot, halt, shutdown, kexec.

Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
Link: https://lore.kernel.org/lkml/20200506211523.15077-6-keescook@chromium.org/
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 .../devicetree/bindings/reserved-memory/ramoops.txt | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/reserved-memory/ramoops.txt b/Documentation/devicetree/bindings/reserved-memory/ramoops.txt
index 0eba562fe5c6..b7886fea368c 100644
--- a/Documentation/devicetree/bindings/reserved-memory/ramoops.txt
+++ b/Documentation/devicetree/bindings/reserved-memory/ramoops.txt
@@ -30,7 +30,7 @@ Optional properties:
 - ecc-size: enables ECC support and specifies ECC buffer size in bytes
   (defaults to 0: no ECC)
 
-- record-size: maximum size in bytes of each dump done on oops/panic
+- record-size: maximum size in bytes of each kmsg dump.
   (defaults to 0: disabled)
 
 - console-size: size in bytes of log buffer reserved for kernel messages
@@ -45,7 +45,16 @@ Optional properties:
 - unbuffered: if present, use unbuffered mappings to map the reserved region
   (defaults to buffered mappings)
 
-- no-dump-oops: if present, only dump panics (defaults to panics and oops)
+- max-reason: if present, sets maximum type of kmsg dump reasons to store
+  (defaults to 2: log Oopses and Panics). This can be set to INT_MAX to
+  store all kmsg dumps. See include/linux/kmsg_dump.h KMSG_DUMP_* for other
+  kmsg dump reason values. Setting this to 0 (KMSG_DUMP_UNDEF), means the
+  reason filtering will be controlled by the printk.always_kmsg_dump boot
+  param: if unset, it will be KMSG_DUMP_OOPS, otherwise KMSG_DUMP_MAX.
+
+- no-dump-oops: deprecated, use max_reason instead. If present, and
+  max_reason is not specified, it is equivalent to max_reason = 1
+  (KMSG_DUMP_PANIC).
 
 - flags: if present, pass ramoops behavioral flags (defaults to 0,
   see include/linux/pstore_ram.h RAMOOPS_FLAG_* for flag values).
-- 
2.20.1