* [PATCH] ARM: errata: Workaround for Cortex-A12 erratum 818325
@ 2014-08-18 9:58 ` Kever Yang
0 siblings, 0 replies; 8+ messages in thread
From: Kever Yang @ 2014-08-18 9:58 UTC (permalink / raw)
To: Russell King
Cc: Will Deacon, Shawn Guo, Gregory CLEMENT, Nicolas Pitre,
Marc Carino, Mahesh Sivasubramanian, Jonathan Austin, heiko,
addy.ke, xjq, cf, hj, huangtao, Ben Dooks, linux-arm-kernel,
linux-kernel, Kever Yang
From: Huang Tao <huangtao@rock-chips.com>
On Cortex-A12 (r0p0..r0p1-00lac0-rc11), when a CPU executes a sequence of
two conditional store instructions with opposite condition code and
updating the same register, the system might enter a deadlock if the
second conditional instruction is an UNPREDICTABLE STR or STM
instruction. This workaround setting bit[12] of the Feature Register
prevents the erratum. This bit disables an optimisation applied to a
sequence of 2 instructions that use opposing condition codes.
Signed-off-by: Huang Tao <huangtao@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
---
arch/arm/Kconfig | 13 +++++++++++++
arch/arm/mm/proc-v7.S | 15 ++++++++++++++-
2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 32cbbd5..4545835 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1245,6 +1245,19 @@ config ARM_ERRATA_773022
loop buffer may deliver incorrect instructions. This
workaround disables the loop buffer to avoid the erratum.
+config ARM_ERRATA_818325
+ bool "ARM errata: Execution of an UNPREDICTABLE STR or STM instruction might deadlock"
+ depends on CPU_V7
+ help
+ This option enables the workaround for the 818325 Cortex-A12
+ (r0p0..r0p1-00lac0-rc11) erratum. When a CPU executes a sequence of
+ two conditional store instructions with opposite condition code and
+ updating the same register, the system might enter a deadlock if the
+ second conditional instruction is an UNPREDICTABLE STR or STM
+ instruction. This workaround setting bit[12] of the Feature Register
+ prevents the erratum. This bit disables an optimisation applied to a
+ sequence of 2 instructions that use opposing condition codes.
+
endmenu
source "arch/arm/common/Kconfig"
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index b5d67db..5ffdf97 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -408,7 +408,20 @@ __v7_setup:
mcrle p15, 0, r10, c1, c0, 1 @ write aux control register
#endif
-4: mov r10, #0
+ /* Cortex-A12 Errata */
+4: ldr r10, =0x00000c0d @ Cortex-A12 primary part number
+ teq r0, r10
+ bne 5f
+#ifdef CONFIG_ARM_ERRATA_818325
+ teq r6, #0x00 @ present in r0p0
+ teqne r6, #0x01 @ present in r0p1-00lac0-rc11
+ mrceq p15, 0, r10, c15, c0, 1 @ read diagnostic register
+ orreq r10, r10, #1 << 12 @ set bit #12
+ mcreq p15, 0, r10, c15, c0, 1 @ write diagnostic register
+ isb
+#endif
+
+5: mov r10, #0
mcr p15, 0, r10, c7, c5, 0 @ I+BTB cache invalidate
#ifdef CONFIG_MMU
mcr p15, 0, r10, c8, c7, 0 @ invalidate I + D TLBs
--
1.8.3.2
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH] ARM: errata: Workaround for Cortex-A12 erratum 818325
@ 2014-08-18 9:58 ` Kever Yang
0 siblings, 0 replies; 8+ messages in thread
From: Kever Yang @ 2014-08-18 9:58 UTC (permalink / raw)
To: linux-arm-kernel
From: Huang Tao <huangtao@rock-chips.com>
On Cortex-A12 (r0p0..r0p1-00lac0-rc11), when a CPU executes a sequence of
two conditional store instructions with opposite condition code and
updating the same register, the system might enter a deadlock if the
second conditional instruction is an UNPREDICTABLE STR or STM
instruction. This workaround setting bit[12] of the Feature Register
prevents the erratum. This bit disables an optimisation applied to a
sequence of 2 instructions that use opposing condition codes.
Signed-off-by: Huang Tao <huangtao@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
---
arch/arm/Kconfig | 13 +++++++++++++
arch/arm/mm/proc-v7.S | 15 ++++++++++++++-
2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 32cbbd5..4545835 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1245,6 +1245,19 @@ config ARM_ERRATA_773022
loop buffer may deliver incorrect instructions. This
workaround disables the loop buffer to avoid the erratum.
+config ARM_ERRATA_818325
+ bool "ARM errata: Execution of an UNPREDICTABLE STR or STM instruction might deadlock"
+ depends on CPU_V7
+ help
+ This option enables the workaround for the 818325 Cortex-A12
+ (r0p0..r0p1-00lac0-rc11) erratum. When a CPU executes a sequence of
+ two conditional store instructions with opposite condition code and
+ updating the same register, the system might enter a deadlock if the
+ second conditional instruction is an UNPREDICTABLE STR or STM
+ instruction. This workaround setting bit[12] of the Feature Register
+ prevents the erratum. This bit disables an optimisation applied to a
+ sequence of 2 instructions that use opposing condition codes.
+
endmenu
source "arch/arm/common/Kconfig"
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index b5d67db..5ffdf97 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -408,7 +408,20 @@ __v7_setup:
mcrle p15, 0, r10, c1, c0, 1 @ write aux control register
#endif
-4: mov r10, #0
+ /* Cortex-A12 Errata */
+4: ldr r10, =0x00000c0d @ Cortex-A12 primary part number
+ teq r0, r10
+ bne 5f
+#ifdef CONFIG_ARM_ERRATA_818325
+ teq r6, #0x00 @ present in r0p0
+ teqne r6, #0x01 @ present in r0p1-00lac0-rc11
+ mrceq p15, 0, r10, c15, c0, 1 @ read diagnostic register
+ orreq r10, r10, #1 << 12 @ set bit #12
+ mcreq p15, 0, r10, c15, c0, 1 @ write diagnostic register
+ isb
+#endif
+
+5: mov r10, #0
mcr p15, 0, r10, c7, c5, 0 @ I+BTB cache invalidate
#ifdef CONFIG_MMU
mcr p15, 0, r10, c8, c7, 0 @ invalidate I + D TLBs
--
1.8.3.2
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] ARM: errata: Workaround for Cortex-A12 erratum 818325
2014-08-18 9:58 ` Kever Yang
@ 2014-08-26 8:49 ` Kever Yang
-1 siblings, 0 replies; 8+ messages in thread
From: Kever Yang @ 2014-08-26 8:49 UTC (permalink / raw)
To: Russell King
Cc: Will Deacon, Shawn Guo, Gregory CLEMENT, Nicolas Pitre,
Marc Carino, Mahesh Sivasubramanian, Jonathan Austin, heiko,
addy.ke, xjq, cf, hj, huangtao, Ben Dooks, linux-arm-kernel,
linux-kernel
Hi Russell,
I'd value your feedback on this if you have a moment.
I think this will need by rk3288 soc.
Thanks
On 08/18/2014 05:58 PM, Kever Yang wrote:
> From: Huang Tao <huangtao@rock-chips.com>
>
> On Cortex-A12 (r0p0..r0p1-00lac0-rc11), when a CPU executes a sequence of
> two conditional store instructions with opposite condition code and
> updating the same register, the system might enter a deadlock if the
> second conditional instruction is an UNPREDICTABLE STR or STM
> instruction. This workaround setting bit[12] of the Feature Register
> prevents the erratum. This bit disables an optimisation applied to a
> sequence of 2 instructions that use opposing condition codes.
>
> Signed-off-by: Huang Tao <huangtao@rock-chips.com>
> Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
> ---
>
> arch/arm/Kconfig | 13 +++++++++++++
> arch/arm/mm/proc-v7.S | 15 ++++++++++++++-
> 2 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 32cbbd5..4545835 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1245,6 +1245,19 @@ config ARM_ERRATA_773022
> loop buffer may deliver incorrect instructions. This
> workaround disables the loop buffer to avoid the erratum.
>
> +config ARM_ERRATA_818325
> + bool "ARM errata: Execution of an UNPREDICTABLE STR or STM instruction might deadlock"
> + depends on CPU_V7
> + help
> + This option enables the workaround for the 818325 Cortex-A12
> + (r0p0..r0p1-00lac0-rc11) erratum. When a CPU executes a sequence of
> + two conditional store instructions with opposite condition code and
> + updating the same register, the system might enter a deadlock if the
> + second conditional instruction is an UNPREDICTABLE STR or STM
> + instruction. This workaround setting bit[12] of the Feature Register
> + prevents the erratum. This bit disables an optimisation applied to a
> + sequence of 2 instructions that use opposing condition codes.
> +
> endmenu
>
> source "arch/arm/common/Kconfig"
> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> index b5d67db..5ffdf97 100644
> --- a/arch/arm/mm/proc-v7.S
> +++ b/arch/arm/mm/proc-v7.S
> @@ -408,7 +408,20 @@ __v7_setup:
> mcrle p15, 0, r10, c1, c0, 1 @ write aux control register
> #endif
>
> -4: mov r10, #0
> + /* Cortex-A12 Errata */
> +4: ldr r10, =0x00000c0d @ Cortex-A12 primary part number
> + teq r0, r10
> + bne 5f
> +#ifdef CONFIG_ARM_ERRATA_818325
> + teq r6, #0x00 @ present in r0p0
> + teqne r6, #0x01 @ present in r0p1-00lac0-rc11
> + mrceq p15, 0, r10, c15, c0, 1 @ read diagnostic register
> + orreq r10, r10, #1 << 12 @ set bit #12
> + mcreq p15, 0, r10, c15, c0, 1 @ write diagnostic register
> + isb
> +#endif
> +
> +5: mov r10, #0
> mcr p15, 0, r10, c7, c5, 0 @ I+BTB cache invalidate
> #ifdef CONFIG_MMU
> mcr p15, 0, r10, c8, c7, 0 @ invalidate I + D TLBs
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] ARM: errata: Workaround for Cortex-A12 erratum 818325
@ 2014-08-26 8:49 ` Kever Yang
0 siblings, 0 replies; 8+ messages in thread
From: Kever Yang @ 2014-08-26 8:49 UTC (permalink / raw)
To: linux-arm-kernel
Hi Russell,
I'd value your feedback on this if you have a moment.
I think this will need by rk3288 soc.
Thanks
On 08/18/2014 05:58 PM, Kever Yang wrote:
> From: Huang Tao <huangtao@rock-chips.com>
>
> On Cortex-A12 (r0p0..r0p1-00lac0-rc11), when a CPU executes a sequence of
> two conditional store instructions with opposite condition code and
> updating the same register, the system might enter a deadlock if the
> second conditional instruction is an UNPREDICTABLE STR or STM
> instruction. This workaround setting bit[12] of the Feature Register
> prevents the erratum. This bit disables an optimisation applied to a
> sequence of 2 instructions that use opposing condition codes.
>
> Signed-off-by: Huang Tao <huangtao@rock-chips.com>
> Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
> ---
>
> arch/arm/Kconfig | 13 +++++++++++++
> arch/arm/mm/proc-v7.S | 15 ++++++++++++++-
> 2 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 32cbbd5..4545835 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1245,6 +1245,19 @@ config ARM_ERRATA_773022
> loop buffer may deliver incorrect instructions. This
> workaround disables the loop buffer to avoid the erratum.
>
> +config ARM_ERRATA_818325
> + bool "ARM errata: Execution of an UNPREDICTABLE STR or STM instruction might deadlock"
> + depends on CPU_V7
> + help
> + This option enables the workaround for the 818325 Cortex-A12
> + (r0p0..r0p1-00lac0-rc11) erratum. When a CPU executes a sequence of
> + two conditional store instructions with opposite condition code and
> + updating the same register, the system might enter a deadlock if the
> + second conditional instruction is an UNPREDICTABLE STR or STM
> + instruction. This workaround setting bit[12] of the Feature Register
> + prevents the erratum. This bit disables an optimisation applied to a
> + sequence of 2 instructions that use opposing condition codes.
> +
> endmenu
>
> source "arch/arm/common/Kconfig"
> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> index b5d67db..5ffdf97 100644
> --- a/arch/arm/mm/proc-v7.S
> +++ b/arch/arm/mm/proc-v7.S
> @@ -408,7 +408,20 @@ __v7_setup:
> mcrle p15, 0, r10, c1, c0, 1 @ write aux control register
> #endif
>
> -4: mov r10, #0
> + /* Cortex-A12 Errata */
> +4: ldr r10, =0x00000c0d @ Cortex-A12 primary part number
> + teq r0, r10
> + bne 5f
> +#ifdef CONFIG_ARM_ERRATA_818325
> + teq r6, #0x00 @ present in r0p0
> + teqne r6, #0x01 @ present in r0p1-00lac0-rc11
> + mrceq p15, 0, r10, c15, c0, 1 @ read diagnostic register
> + orreq r10, r10, #1 << 12 @ set bit #12
> + mcreq p15, 0, r10, c15, c0, 1 @ write diagnostic register
> + isb
> +#endif
> +
> +5: mov r10, #0
> mcr p15, 0, r10, c7, c5, 0 @ I+BTB cache invalidate
> #ifdef CONFIG_MMU
> mcr p15, 0, r10, c8, c7, 0 @ invalidate I + D TLBs
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] ARM: errata: Workaround for Cortex-A12 erratum 818325
2014-08-18 9:58 ` Kever Yang
@ 2014-08-26 10:14 ` Will Deacon
-1 siblings, 0 replies; 8+ messages in thread
From: Will Deacon @ 2014-08-26 10:14 UTC (permalink / raw)
To: Kever Yang
Cc: Russell King, Shawn Guo, Gregory CLEMENT, Nicolas Pitre,
Marc Carino, Mahesh Sivasubramanian, Jonathan Austin, heiko,
addy.ke, xjq, cf, hj, huangtao, Ben Dooks, linux-arm-kernel,
linux-kernel
On Mon, Aug 18, 2014 at 10:58:09AM +0100, Kever Yang wrote:
> From: Huang Tao <huangtao@rock-chips.com>
>
> On Cortex-A12 (r0p0..r0p1-00lac0-rc11), when a CPU executes a sequence of
> two conditional store instructions with opposite condition code and
> updating the same register, the system might enter a deadlock if the
> second conditional instruction is an UNPREDICTABLE STR or STM
> instruction. This workaround setting bit[12] of the Feature Register
> prevents the erratum. This bit disables an optimisation applied to a
> sequence of 2 instructions that use opposing condition codes.
>
> Signed-off-by: Huang Tao <huangtao@rock-chips.com>
> Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
> ---
The Rk3288 I have advertises itself as an r0p1 Cortex-A12 CPU, so isn't
affected by this issue. Until we have an SoC supported in mainline that
requires this workaround, I don't think we should merge it.
Also, please consider setting these bits in your firmware if possible.
The feature register isn't writable from the non-secure side, so if you
want to use virtualisation you'll need to do this differently.
Will
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] ARM: errata: Workaround for Cortex-A12 erratum 818325
@ 2014-08-26 10:14 ` Will Deacon
0 siblings, 0 replies; 8+ messages in thread
From: Will Deacon @ 2014-08-26 10:14 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, Aug 18, 2014 at 10:58:09AM +0100, Kever Yang wrote:
> From: Huang Tao <huangtao@rock-chips.com>
>
> On Cortex-A12 (r0p0..r0p1-00lac0-rc11), when a CPU executes a sequence of
> two conditional store instructions with opposite condition code and
> updating the same register, the system might enter a deadlock if the
> second conditional instruction is an UNPREDICTABLE STR or STM
> instruction. This workaround setting bit[12] of the Feature Register
> prevents the erratum. This bit disables an optimisation applied to a
> sequence of 2 instructions that use opposing condition codes.
>
> Signed-off-by: Huang Tao <huangtao@rock-chips.com>
> Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
> ---
The Rk3288 I have advertises itself as an r0p1 Cortex-A12 CPU, so isn't
affected by this issue. Until we have an SoC supported in mainline that
requires this workaround, I don't think we should merge it.
Also, please consider setting these bits in your firmware if possible.
The feature register isn't writable from the non-secure side, so if you
want to use virtualisation you'll need to do this differently.
Will
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] ARM: errata: Workaround for Cortex-A12 erratum 818325
2014-08-26 10:14 ` Will Deacon
@ 2014-08-26 11:36 ` Russell King - ARM Linux
-1 siblings, 0 replies; 8+ messages in thread
From: Russell King - ARM Linux @ 2014-08-26 11:36 UTC (permalink / raw)
To: Will Deacon
Cc: Kever Yang, Shawn Guo, Gregory CLEMENT, Nicolas Pitre,
Marc Carino, Mahesh Sivasubramanian, Jonathan Austin, heiko,
addy.ke, xjq, cf, hj, huangtao, Ben Dooks, linux-arm-kernel,
linux-kernel
On Tue, Aug 26, 2014 at 11:14:14AM +0100, Will Deacon wrote:
> On Mon, Aug 18, 2014 at 10:58:09AM +0100, Kever Yang wrote:
> > From: Huang Tao <huangtao@rock-chips.com>
> >
> > On Cortex-A12 (r0p0..r0p1-00lac0-rc11), when a CPU executes a sequence of
> > two conditional store instructions with opposite condition code and
> > updating the same register, the system might enter a deadlock if the
> > second conditional instruction is an UNPREDICTABLE STR or STM
> > instruction. This workaround setting bit[12] of the Feature Register
> > prevents the erratum. This bit disables an optimisation applied to a
> > sequence of 2 instructions that use opposing condition codes.
> >
> > Signed-off-by: Huang Tao <huangtao@rock-chips.com>
> > Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
> > ---
>
> The Rk3288 I have advertises itself as an r0p1 Cortex-A12 CPU, so isn't
> affected by this issue. Until we have an SoC supported in mainline that
> requires this workaround, I don't think we should merge it.
>
> Also, please consider setting these bits in your firmware if possible.
> The feature register isn't writable from the non-secure side, so if you
> want to use virtualisation you'll need to do this differently.
I think we're at the point where we start insisting that workarounds
which are simple enable/disable feature bit operations (in other words,
which can be handled by updating a control register in the firmware or
boot loader) must be done that way, and we are not going to add such
workarounds to the kernel anymore.
--
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] ARM: errata: Workaround for Cortex-A12 erratum 818325
@ 2014-08-26 11:36 ` Russell King - ARM Linux
0 siblings, 0 replies; 8+ messages in thread
From: Russell King - ARM Linux @ 2014-08-26 11:36 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Aug 26, 2014 at 11:14:14AM +0100, Will Deacon wrote:
> On Mon, Aug 18, 2014 at 10:58:09AM +0100, Kever Yang wrote:
> > From: Huang Tao <huangtao@rock-chips.com>
> >
> > On Cortex-A12 (r0p0..r0p1-00lac0-rc11), when a CPU executes a sequence of
> > two conditional store instructions with opposite condition code and
> > updating the same register, the system might enter a deadlock if the
> > second conditional instruction is an UNPREDICTABLE STR or STM
> > instruction. This workaround setting bit[12] of the Feature Register
> > prevents the erratum. This bit disables an optimisation applied to a
> > sequence of 2 instructions that use opposing condition codes.
> >
> > Signed-off-by: Huang Tao <huangtao@rock-chips.com>
> > Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
> > ---
>
> The Rk3288 I have advertises itself as an r0p1 Cortex-A12 CPU, so isn't
> affected by this issue. Until we have an SoC supported in mainline that
> requires this workaround, I don't think we should merge it.
>
> Also, please consider setting these bits in your firmware if possible.
> The feature register isn't writable from the non-secure side, so if you
> want to use virtualisation you'll need to do this differently.
I think we're at the point where we start insisting that workarounds
which are simple enable/disable feature bit operations (in other words,
which can be handled by updating a control register in the firmware or
boot loader) must be done that way, and we are not going to add such
workarounds to the kernel anymore.
--
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2014-08-26 11:36 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-08-18 9:58 [PATCH] ARM: errata: Workaround for Cortex-A12 erratum 818325 Kever Yang
2014-08-18 9:58 ` Kever Yang
2014-08-26 8:49 ` Kever Yang
2014-08-26 8:49 ` Kever Yang
2014-08-26 10:14 ` Will Deacon
2014-08-26 10:14 ` Will Deacon
2014-08-26 11:36 ` Russell King - ARM Linux
2014-08-26 11:36 ` Russell King - ARM Linux
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