From: Tony Lindgren <tony@atomide.com>
To: Matthijs van Duin <matthijsvanduin@gmail.com>
Cc: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>,
Sebastian Reichel <sre@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
Pavel Machek <pavel@ucw.cz>
Subject: Re: ARM errata 430973 on multi platform kernels
Date: Mon, 6 Apr 2015 08:19:40 -0700 [thread overview]
Message-ID: <20150406151939.GG18048@atomide.com> (raw)
In-Reply-To: <CAALWOA_0r1syy4nPBOvf1evhd5_oX=LWjdZAsQGAoGk8OoXTwg@mail.gmail.com>
* Matthijs van Duin <matthijsvanduin@gmail.com> [150405 16:53]:
> Cortex-A8 errata doc states in its workaround for erratum 430973:
>
> > By default, the BTB Invalidate instruction is treated as a NOP on Cortex-A8.
> > However, it is possible to enable the BTB Invalidate instruction such that it
> > actually does a full invalidate of the BTB by setting the IBE bit (bit 6) in
> > the CP15 Auxiliary Control Register. As a consequence of erratum 687067, the
> > L1 System Array Debug Register should be cleared to 0 before the IBE bit is
> > set using the following code sequence:
> > MOV r1, #0
> > MCR p15, 0, r1, c15, c1, 0 ; write instruction data 0 register
> > MRC p15, 0, R1, c1, c0, 1 ; read Aux Ctl Register
> > ORR R1, R1 #(1 << 6) ; set IBE to 1
> > MCR p15, 0, R1, c1, c0, 1 ; write Aux Ctl Register
> > The above code needs to be executed in Secure state. ARM Limited recommends
> > that this code is added to the boot monitor.
>
> The 430973 workaround code in proc-v7.S will do absolutely nothing if
> executed in non-secure state. Ditto for the 458693 workaround, and the
> 460075 workaround should trigger an undefined instruction exception.
> Maybe linux is started in secure mode on some targets and this code
> was written for one of those?
That's only for HS omaps, for those we currently only do it in the
nokia_n900_legacy_init that calls rx51_secure_update_aux_cr.
> I scanned DM814x secure ROM for any (ARM or Thumb) write to
> Instruction L1 System Array Debug Register 0, but I found none, hence
> my warning to watch out for erratum 687067.
OK
> Adding the full set of BTB invalidates while making sure IBE is
> disabled on sufficiently recent Cortex-A8 revisions would be optimal
> for the Cortex-A8. But, apparently (based on the description of the
> ARMv7 CPUID registers) there are also processors which only require
> BTB invalidates when code is modified, but not when context-switching,
> so there may be performance considerations there...
Attempting to summarize all that's been discussed.. It sounds like we
need the following implemented:
1. For cortex-a8 revisions affected by 458693, we can do a custom
cpu_v7_switch_mm function that always does flush BTAC/BTB.
2. For HS cortex-a8 processors other than n900 affected by 458693,
we need to implement functions similar to rx51_secure_update_aux_cr,
the bootrom on n900 is different from TI HS omaps so the SMC call
numbering may be different.
3. For later cortex-a8 processors not affected by 458693, we need
to clear IBE bit to avoid erratum 687067.
Regards,
Tony
WARNING: multiple messages have this Message-ID (diff)
From: tony@atomide.com (Tony Lindgren)
To: linux-arm-kernel@lists.infradead.org
Subject: ARM errata 430973 on multi platform kernels
Date: Mon, 6 Apr 2015 08:19:40 -0700 [thread overview]
Message-ID: <20150406151939.GG18048@atomide.com> (raw)
In-Reply-To: <CAALWOA_0r1syy4nPBOvf1evhd5_oX=LWjdZAsQGAoGk8OoXTwg@mail.gmail.com>
* Matthijs van Duin <matthijsvanduin@gmail.com> [150405 16:53]:
> Cortex-A8 errata doc states in its workaround for erratum 430973:
>
> > By default, the BTB Invalidate instruction is treated as a NOP on Cortex-A8.
> > However, it is possible to enable the BTB Invalidate instruction such that it
> > actually does a full invalidate of the BTB by setting the IBE bit (bit 6) in
> > the CP15 Auxiliary Control Register. As a consequence of erratum 687067, the
> > L1 System Array Debug Register should be cleared to 0 before the IBE bit is
> > set using the following code sequence:
> > MOV r1, #0
> > MCR p15, 0, r1, c15, c1, 0 ; write instruction data 0 register
> > MRC p15, 0, R1, c1, c0, 1 ; read Aux Ctl Register
> > ORR R1, R1 #(1 << 6) ; set IBE to 1
> > MCR p15, 0, R1, c1, c0, 1 ; write Aux Ctl Register
> > The above code needs to be executed in Secure state. ARM Limited recommends
> > that this code is added to the boot monitor.
>
> The 430973 workaround code in proc-v7.S will do absolutely nothing if
> executed in non-secure state. Ditto for the 458693 workaround, and the
> 460075 workaround should trigger an undefined instruction exception.
> Maybe linux is started in secure mode on some targets and this code
> was written for one of those?
That's only for HS omaps, for those we currently only do it in the
nokia_n900_legacy_init that calls rx51_secure_update_aux_cr.
> I scanned DM814x secure ROM for any (ARM or Thumb) write to
> Instruction L1 System Array Debug Register 0, but I found none, hence
> my warning to watch out for erratum 687067.
OK
> Adding the full set of BTB invalidates while making sure IBE is
> disabled on sufficiently recent Cortex-A8 revisions would be optimal
> for the Cortex-A8. But, apparently (based on the description of the
> ARMv7 CPUID registers) there are also processors which only require
> BTB invalidates when code is modified, but not when context-switching,
> so there may be performance considerations there...
Attempting to summarize all that's been discussed.. It sounds like we
need the following implemented:
1. For cortex-a8 revisions affected by 458693, we can do a custom
cpu_v7_switch_mm function that always does flush BTAC/BTB.
2. For HS cortex-a8 processors other than n900 affected by 458693,
we need to implement functions similar to rx51_secure_update_aux_cr,
the bootrom on n900 is different from TI HS omaps so the SMC call
numbering may be different.
3. For later cortex-a8 processors not affected by 458693, we need
to clear IBE bit to avoid erratum 687067.
Regards,
Tony
next prev parent reply other threads:[~2015-04-06 15:23 UTC|newest]
Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-01 19:07 [PATCH RESEND] ARM: dts: OMAP3-N900: Add microphone bias voltages Jarkko Nikula
2015-03-30 16:30 ` Jarkko Nikula
[not found] ` <55197A12.1050009-FVTvWyuFUl3QT0dZR+AlfA@public.gmane.org>
2015-03-30 16:42 ` Tony Lindgren
2015-03-30 17:45 ` Jarkko Nikula
[not found] ` <55198BA4.5010207-FVTvWyuFUl3QT0dZR+AlfA@public.gmane.org>
2015-03-30 17:50 ` Tony Lindgren
2015-03-31 12:32 ` Sebastian Reichel
2015-04-01 19:47 ` Tony Lindgren
2015-04-03 16:35 ` ARM errata 430973 on multi platform kernels (was: OMAP3-N900: Add microphone bias voltages) Sebastian Reichel
2015-04-03 18:39 ` Tony Lindgren
2015-04-03 18:39 ` Tony Lindgren
2015-04-03 19:21 ` Robert Nelson
2015-04-03 19:21 ` Robert Nelson
2015-04-05 13:00 ` Sebastian Reichel
2015-04-05 13:00 ` Sebastian Reichel
2015-04-05 13:26 ` Pali Rohár
2015-04-05 13:26 ` Pali Rohár
2015-04-05 13:45 ` Sebastian Reichel
2015-04-05 13:45 ` Sebastian Reichel
2015-04-05 13:52 ` Pali Rohár
2015-04-05 13:52 ` Pali Rohár
2015-04-06 17:38 ` Sebastian Reichel
2015-04-06 17:38 ` Sebastian Reichel
2015-04-03 20:42 ` Pavel Machek
2015-04-03 20:42 ` Pavel Machek
2015-04-03 22:08 ` ARM errata 430973 on multi platform kernels Ivaylo Dimitrov
2015-04-03 22:08 ` Ivaylo Dimitrov
2015-04-03 22:15 ` Tony Lindgren
2015-04-03 22:15 ` Tony Lindgren
2015-04-03 22:47 ` Ivaylo Dimitrov
2015-04-03 22:47 ` Ivaylo Dimitrov
2015-04-03 22:52 ` Tony Lindgren
2015-04-03 22:52 ` Tony Lindgren
2015-04-05 4:13 ` Matthijs van Duin
2015-04-05 4:13 ` Matthijs van Duin
2015-04-05 7:23 ` Ivaylo Dimitrov
2015-04-05 7:23 ` Ivaylo Dimitrov
2015-04-05 16:50 ` Matthijs van Duin
2015-04-05 16:50 ` Matthijs van Duin
2015-04-05 16:52 ` Matthijs van Duin
2015-04-05 16:52 ` Matthijs van Duin
2015-04-05 21:08 ` Ivaylo Dimitrov
2015-04-05 21:08 ` Ivaylo Dimitrov
2015-04-05 23:52 ` Matthijs van Duin
2015-04-05 23:52 ` Matthijs van Duin
2015-04-06 15:19 ` Tony Lindgren [this message]
2015-04-06 15:19 ` Tony Lindgren
2015-04-06 15:40 ` Tony Lindgren
2015-04-06 15:40 ` Tony Lindgren
2015-04-06 17:14 ` Ivaylo Dimitrov
2015-04-06 17:14 ` Ivaylo Dimitrov
2015-04-06 17:42 ` Tony Lindgren
2015-04-06 17:42 ` Tony Lindgren
2015-04-06 18:14 ` Matthijs van Duin
2015-04-06 18:14 ` Matthijs van Duin
2015-04-07 2:23 ` Tony Lindgren
2015-04-07 2:23 ` Tony Lindgren
2015-04-07 3:12 ` Sebastian Reichel
2015-04-07 3:12 ` Sebastian Reichel
2015-04-07 3:49 ` Matthijs van Duin
2015-04-07 3:49 ` Matthijs van Duin
2015-04-07 14:48 ` Tony Lindgren
2015-04-07 14:48 ` Tony Lindgren
2015-04-09 22:37 ` Grazvydas Ignotas
2015-04-09 22:37 ` Grazvydas Ignotas
2015-04-09 22:44 ` Tony Lindgren
2015-04-09 22:44 ` Tony Lindgren
2015-04-09 23:44 ` Nishanth Menon
2015-04-09 23:44 ` Nishanth Menon
2015-04-10 22:05 ` Grazvydas Ignotas
2015-04-10 22:05 ` Grazvydas Ignotas
2015-04-10 23:08 ` Tony Lindgren
2015-04-10 23:08 ` Tony Lindgren
2015-04-16 16:53 ` Matthijs van Duin
2015-04-16 16:53 ` Matthijs van Duin
2015-04-07 13:58 ` Russell King - ARM Linux
2015-04-07 13:58 ` Russell King - ARM Linux
2015-04-07 13:57 ` Russell King - ARM Linux
2015-04-07 13:57 ` Russell King - ARM Linux
2015-04-07 15:22 ` Tony Lindgren
2015-04-07 15:22 ` Tony Lindgren
2015-04-07 15:44 ` Tony Lindgren
2015-04-07 15:44 ` Tony Lindgren
2015-04-08 23:08 ` Russell King - ARM Linux
2015-04-08 23:08 ` Russell King - ARM Linux
2015-04-08 23:15 ` Tony Lindgren
2015-04-08 23:15 ` Tony Lindgren
2015-04-08 23:06 ` Russell King - ARM Linux
2015-04-08 23:06 ` Russell King - ARM Linux
2015-04-09 13:48 ` Russell King - ARM Linux
2015-04-09 13:48 ` Russell King - ARM Linux
2015-04-09 15:09 ` Tony Lindgren
2015-04-09 15:09 ` Tony Lindgren
2015-04-09 15:30 ` Russell King - ARM Linux
2015-04-09 15:30 ` Russell King - ARM Linux
2015-04-15 16:31 ` Sebastian Reichel
2015-04-15 16:31 ` Sebastian Reichel
2015-04-16 16:08 ` Tony Lindgren
2015-04-16 16:08 ` Tony Lindgren
2015-04-17 18:41 ` Sebastian Reichel
2015-04-17 18:41 ` Sebastian Reichel
2015-04-20 23:40 ` Tony Lindgren
2015-04-20 23:40 ` Tony Lindgren
2015-04-23 10:25 ` Russell King - ARM Linux
2015-04-23 10:25 ` Russell King - ARM Linux
2015-04-23 14:17 ` Tony Lindgren
2015-04-23 14:17 ` Tony Lindgren
2015-04-28 18:13 ` Russell King - ARM Linux
2015-04-28 18:13 ` Russell King - ARM Linux
2015-04-29 14:40 ` Tony Lindgren
2015-04-29 14:40 ` Tony Lindgren
2015-05-04 14:24 ` Tony Lindgren
2015-05-04 14:24 ` Tony Lindgren
2015-04-24 8:54 ` Matthijs van Duin
2015-04-24 8:54 ` Matthijs van Duin
2015-04-28 18:11 ` Russell King - ARM Linux
2015-04-28 18:11 ` Russell King - ARM Linux
2015-05-02 6:51 ` Matthijs van Duin
2015-05-02 6:51 ` Matthijs van Duin
2015-04-05 13:39 ` Sebastian Reichel
2015-04-05 13:39 ` Sebastian Reichel
2015-04-06 15:24 ` Tony Lindgren
2015-04-06 15:24 ` Tony Lindgren
2015-05-04 16:07 ` [PATCH RESEND] ARM: dts: OMAP3-N900: Add microphone bias voltages Tony Lindgren
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