From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jan Beulich" <JBeulich@suse.com>
Subject: Re: [PATCH] x86/traps: Misc tweaks to several printk()s
Date: Wed, 15 Jul 2015 10:03:43 +0100
Message-ID: <55A63E0F0200007800091296@mail.emea.novell.com>
References: <1436896485-25577-1-git-send-email-andrew.cooper3@citrix.com>
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To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Xen-devel <xen-devel@lists.xen.org>
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>>> On 14.07.15 at 19:54, <andrew.cooper3@citrix.com> wrote:
> @@ -626,8 +626,9 @@ static void do_trap(struct cpu_user_regs *regs, int use_error_code)
>  
>      if ( likely((fixup = search_exception_table(regs->eip)) != 0) )
>      {
> -        dprintk(XENLOG_ERR, "Trap %d: %p -> %p\n",
> -                trapnr, _p(regs->eip), _p(fixup));
> +        printk(XENLOG_INFO "Exception [#%d, ec=%04x] (%s): %ps %p -> %p\n",
> +               trapnr, use_error_code ? regs->error_code : 0, trapstr(trapnr),
> +               _p(regs->eip), _p(regs->eip), _p(fixup));

But why the transition dprintk() -> printk()?

> @@ -2677,9 +2678,9 @@ static int emulate_privileged_op(struct cpu_user_regs *regs)
>  
>              if ( (rdmsr_safe(regs->ecx, val) != 0) || (msr_content != val) )
>          invalid:
> -                gdprintk(XENLOG_WARNING, "Domain attempted WRMSR %p from "
> -                        "0x%016"PRIx64" to 0x%016"PRIx64".\n",
> -                        _p(regs->ecx), val, msr_content);
> +                gprintk(XENLOG_WARNING,
> +                        "attempted WRMSR 0x%08x: 0x%016"PRIx64" -> 0x%016"PRIx64"\n",
> +                        regs->_ecx, val, msr_content);

In cases where the values can't usefully be taken to be decimal I'd
prefer the 0x prefixes to be omitted.

> @@ -2813,10 +2814,11 @@ static int emulate_privileged_op(struct cpu_user_regs *regs)
>          case MSR_EFER:
>   rdmsr_normal:
>              /* Everyone can read the MSR space. */
> -            /* gdprintk(XENLOG_WARNING,"Domain attempted RDMSR %p.\n",
> -                        _p(regs->ecx));*/
>              if ( rdmsr_safe(regs->ecx, val) )
> +            {
> +                gprintk(XENLOG_WARNING, "attempted RDMSR 0x%08x\n", regs->_ecx);
>                  goto fail;
> +            }

Do you really see this to be useful in production builds?

Jan