[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <561659EC.7030508@arm.com>
Date: Thu, 8 Oct 2015 12:56:28 +0100
From: "Suzuki K. Poulose" <Suzuki.Poulose@....com>
To: Catalin Marinas <catalin.marinas@....com>
Cc: linux-arm-kernel@...ts.infradead.org, mark.rutland@....com,
Vladimir.Murzin@....com, steve.capper@...aro.org,
ard.biesheuvel@...aro.org, marc.zyngier@....com,
will.deacon@....com, linux-kernel@...r.kernel.org,
edward.nevill@...aro.org, aph@...hat.com, james.morse@....com,
andre.przywara@....com, dave.martin@....com
Subject: Re: [PATCH v2 16/22] arm64/debug: Make use of the system wide safe
value
On 08/10/15 12:11, Catalin Marinas wrote:
> On Mon, Oct 05, 2015 at 06:02:05PM +0100, Suzuki K. Poulose wrote:
>> @@ -137,13 +138,17 @@ extern struct pmu perf_ops_bp;
>> /* Determine number of BRP registers available. */
>> static inline int get_num_brps(void)
>> {
>> - return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1;
>> + return 1 +
>> + cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1),
>> + ID_AA64DFR0_BRPS_SHIFT);
>> }
>
> cpuid_feature_extract_field() is fine but we should we bother with
> read_system_reg vs just read_cpuid?
> Similar question for patch 17/22.
Well, we would have already TAINTed the kernel, if these fields are different.
It is just the matter of, whether we want to provide the safer value on a tainted
kernel or not. I am open to suggestions.
Thanks
Suzuki
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists