Re: [tip:x86/urgent] x86/vdso: Discard the __bug_table section

From: Andy Lutomirski
Date: Tue Jun 24 2014 - 15:41:18 EST


On Tue, Jun 24, 2014 at 11:43 AM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> 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.

It's branch profiling. Patches coming.

>
> -hpa
>



--
Andy Lutomirski
AMA Capital Management, LLC
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