linux-kernel - Re: [PATCH] APEI/ERST: Fix error message formatting

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Date:	Mon, 29 Jul 2013 08:50:19 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
	Joe Perches <joe@...ches.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Borislav Petkov <bp@...e.de>,
	Anton Vorontsov <anton@...msg.org>,
	Colin Cross <ccross@...roid.com>,
	Kees Cook <keescook@...omium.org>,
	Tony Luck <tony.luck@...el.com>, Len Brown <lenb@...nel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"Huang, Ying" <ying.huang@...el.com>
Subject: Re: [PATCH] APEI/ERST: Fix error message formatting

On Mon, Jul 29, 2013 at 8:40 AM, Borislav Petkov <bp@...en8.de> wrote:
> On Mon, Jul 29, 2013 at 08:28:05AM -0600, Bjorn Helgaas wrote:
>> > @@ -186,7 +186,7 @@ static int erst_exec_stall(struct apei_exec_context *ctx,
>> >
>> >         if (ctx->value > FIRMWARE_MAX_STALL) {
>> >                 if (!in_nmi())
>> > -                       pr_warning(FW_WARN ERST_PFX
>> > +                       pr_warn(FW_WARN
>> >                         "Too long stall time for stall instruction: %llx.\n",
>>
>> You didn't change this part, but this and similar messages look less
>> useful than they could be.  We're printing in hex, but there's no
>> indication in the output (no "0x" prefix).  And there's no instruction
>> pointer or anything to help connect this back to the source of the
>> problem.
>
> Sounds like we don't want to print ctx->value at all but simply signal
> about the stall? Or?

If I were the firmware developer and got a report about this message,
I think the information I would want is ctx->ip, so I could identify
the corresponding source code.  But I don't know much about the ERST
interpreter, so I don't know if "ctx->ip" is the right place to look.
Maybe there's a method name or table name that would be needed in
addition.

It just seems like "ERST: Too long stall time for stall instruction:
4732." all by itself doesn't really contain any actionable
information.

Bjorn
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