linux-kernel - Re: [PATCH] perf tools: fix endian conversion reading event attr from header

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Message-ID: <4E2064A2.10807@gmail.com>
Date:	Fri, 15 Jul 2011 10:02:42 -0600
From:	David Ahern <dsahern@...il.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
CC:	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	acme@...stprotocols.net, mingo@...e.hu, peterz@...radead.org,
	paulus@...ba.org
Subject: Re: [PATCH] perf tools: fix endian conversion reading event attr
 from header

On 07/15/2011 09:47 AM, Frederic Weisbecker wrote:
>> -		if (perf_header__getbuffer64(header, fd, &f_attr, sizeof(f_attr)))
>> +		if (readn(fd, &f_attr, sizeof(f_attr)) <= 0)
>>  			goto out_errno;
>>  
>> +		if (header->needs_swap) {
>> +			f_attr.attr.type = bswap_32(f_attr.attr.type);
>> +			f_attr.attr.size = bswap_32(f_attr.attr.size);
>> +			mem_bswap_64(&f_attr.attr.config,
>> +				     sizeof(struct perf_event_attr) - 8);
>> +		}
>> +
> 
> Good catch!

A long, painful discovery

> But would be nice to also handle the wakeup_events and bp_type fields.
> 

I did not think those values were used in userspace, so did not touch
them. But then your inquiry pushed me into cscope and I found the
perf_event__attr_swap() function. I'll redo the patch leveraging the
swapping done there.

David
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