linux-kernel - Re: [tip:x86/urgent] x86/vdso: Discard the __bug

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Message-ID: <53A9C6EB.50900@zytor.com>
Date:	Tue, 24 Jun 2014 11:43:55 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andy Lutomirski <luto@...capital.net>
CC:	Ingo Molnar <mingo@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	"linux-tip-commits@...r.kernel.org" 
	<linux-tip-commits@...r.kernel.org>
Subject: Re: [tip:x86/urgent] x86/vdso: Discard the __bug_table section

On 06/24/2014 11:37 AM, Andy Lutomirski wrote:
>>
>> diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
>> index f42e2ddc663d..94158e100f26 100644
>> --- a/arch/x86/vdso/vdso2c.h
>> +++ b/arch/x86/vdso/vdso2c.h
>> @@ -99,8 +99,9 @@ static void BITSFUNC(copy_section)(struct
>> BITSFUNC(fake_sections) *out,
>>         if (!copy)
>>                 return;
>>
>> -       if (out->count >= out->max_count)
>> -               fail("too many copied sections (max = %d)\n",
>> out->max_count);
>> +       if (out->count > out->max_count)
>> +               fail("too many copied sections (max = %d, need = %d)\n",
>> +                    out->max_count, out->count);
>>
> 
> I think the old test was correct: we haven't incremented count yet
> (it's a couple lines below), so count is the zero-based index to which
> we're writing.
> 
> I thought of doing the need = %d thing, but I think that the output is
> a foregone conclusion: count == max_count + 1 when this fails.  A list
> of all the section names would be more interesting, but eu-readelf -S
> will tell is that.
> 

Well, I have reproduced this failure.  eu-readelf output included.

	-hpa


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