linux-kernel - Re: [PATCH V2 3/3] perf/x86/intel/uncore: Validate MMIO address before accessing

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Date:   Thu, 28 May 2020 09:49:16 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     David Laight <David.Laight@...LAB.COM>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:     "ak@...ux.intel.com" <ak@...ux.intel.com>
Subject: Re: [PATCH V2 3/3] perf/x86/intel/uncore: Validate MMIO address
 before accessing



On 5/28/2020 9:33 AM, David Laight wrote:
> From: kan.liang@...ux.intel.com
>> Sent: 28 May 2020 14:15
> ...
>> +static inline bool is_valid_mmio_offset(struct intel_uncore_box *box,
>> +					unsigned long offset)
> 
> You need a better name, needs to start 'uncore_' and 'mmio'
> probably isn't right either.
>

Sure

>> +{
>> +	if (box->pmu->type->mmio_map_size > offset)
>> +		return true;
> 
> Swap over.
> Conditionals always read best if 'variable op constant'.
> So you want:
> 	if (offset < box->pmu->type->mmio_map_size)
> 		return true;
> 

Sure

>> +
>> +	pr_warn_once("perf uncore: Access invalid address of %s.\n",
>> +		     box->pmu->type->name);
> 
> Pretty hard to debug without the invalid offset.
> 

I will dump the box->io_addr and offset for debugging.

Thanks,
Kan
> I've no idea what the code is supposed to be doing though.
> 
> 	David
> 
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