* Improper TTBCR for arm 32bit kernel decompression
@ 2016-09-09 16:34 ` Srinivas Ramana
0 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-09 16:34 UTC (permalink / raw)
To: linux, will.deacon, nicolas.pitre
Cc: linux-arm-msm, linux-arm-kernel, linux-kernel
Hello,
While trying to boot arm-32 bit kernel, I came across a problem where
TTBCR is in improper state. If the bootloader uses the long descriptor
format and jumps to kernel decompressor code, TTBCR may not be in the
right state. So, as soon as the MMU is enabled, execution can not
proceed further.
Before enabling the MMU, it is required to clear the TTBCR.PD0 field to
use TTBR0 for translation table walks. Also, TTBCR.N should be reset to
'0' to indicate the correct base address width. The 'commit
dbece45894d3a ("ARM: 7501/1: decompressor: reset ttbcr for VMSA ARMv7
cores")' does the reset of TTBCR.N, but doesn't consider all the bits
for the size of TTBCR.N.
when i tried the below change where i explicitly clear TTBCR.PD0 and use
correct mask for TTBCR.N, I see proper memory after MMU is enabled and
decompression succeeds.
Request your comments on the change below. If it looks good, I can
submit a patch for inclusion.
---------------------8<----------------------------------
diff --git a/arch/arm/boot/compressed/head.S
b/arch/arm/boot/compressed/head.S
index af11c2f..5769f1f 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -779,7 +779,8 @@ __armv7_mmu_cache_on:
orrne r0, r0, #1 @ MMU enabled
movne r1, #0xfffffffd @ domain 0 = client
bic r6, r6, #1 << 31 @ 32-bit translation system
- bic r6, r6, #3 << 0 @ use only ttbr0
+ bic r6, r6, #7 << 0 @ width of base address
field
+ bic r6, r6, #1 << 4 @ use only ttbr0
mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
mcrne p15, 0, r1, c3, c0, 0 @ load domain access
control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
---------------------8<----------------------------------
Thanks,
-- Srinivas R
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative
Project.
^ permalink raw reply related [flat|nested] 24+ messages in thread
* Improper TTBCR for arm 32bit kernel decompression
@ 2016-09-09 16:34 ` Srinivas Ramana
0 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-09 16:34 UTC (permalink / raw)
To: linux-arm-kernel
Hello,
While trying to boot arm-32 bit kernel, I came across a problem where
TTBCR is in improper state. If the bootloader uses the long descriptor
format and jumps to kernel decompressor code, TTBCR may not be in the
right state. So, as soon as the MMU is enabled, execution can not
proceed further.
Before enabling the MMU, it is required to clear the TTBCR.PD0 field to
use TTBR0 for translation table walks. Also, TTBCR.N should be reset to
'0' to indicate the correct base address width. The 'commit
dbece45894d3a ("ARM: 7501/1: decompressor: reset ttbcr for VMSA ARMv7
cores")' does the reset of TTBCR.N, but doesn't consider all the bits
for the size of TTBCR.N.
when i tried the below change where i explicitly clear TTBCR.PD0 and use
correct mask for TTBCR.N, I see proper memory after MMU is enabled and
decompression succeeds.
Request your comments on the change below. If it looks good, I can
submit a patch for inclusion.
---------------------8<----------------------------------
diff --git a/arch/arm/boot/compressed/head.S
b/arch/arm/boot/compressed/head.S
index af11c2f..5769f1f 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -779,7 +779,8 @@ __armv7_mmu_cache_on:
orrne r0, r0, #1 @ MMU enabled
movne r1, #0xfffffffd @ domain 0 = client
bic r6, r6, #1 << 31 @ 32-bit translation system
- bic r6, r6, #3 << 0 @ use only ttbr0
+ bic r6, r6, #7 << 0 @ width of base address
field
+ bic r6, r6, #1 << 4 @ use only ttbr0
mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
mcrne p15, 0, r1, c3, c0, 0 @ load domain access
control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
---------------------8<----------------------------------
Thanks,
-- Srinivas R
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative
Project.
^ permalink raw reply related [flat|nested] 24+ messages in thread
* Re: Improper TTBCR for arm 32bit kernel decompression
2016-09-09 16:34 ` Srinivas Ramana
@ 2016-09-09 17:36 ` Nicolas Pitre
-1 siblings, 0 replies; 24+ messages in thread
From: Nicolas Pitre @ 2016-09-09 17:36 UTC (permalink / raw)
To: Srinivas Ramana
Cc: linux, will.deacon, linux-arm-msm, linux-arm-kernel, linux-kernel
On Fri, 9 Sep 2016, Srinivas Ramana wrote:
> Hello,
>
> While trying to boot arm-32 bit kernel, I came across a problem where TTBCR is
> in improper state. If the bootloader uses the long descriptor format and jumps
> to kernel decompressor code, TTBCR may not be in the right state. So, as soon
> as the MMU is enabled, execution can not proceed further.
>
> Before enabling the MMU, it is required to clear the TTBCR.PD0 field to use
> TTBR0 for translation table walks. Also, TTBCR.N should be reset to '0' to
> indicate the correct base address width. The 'commit dbece45894d3a ("ARM:
> 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")' does the reset of
> TTBCR.N, but doesn't consider all the bits for the size of TTBCR.N.
>
> when i tried the below change where i explicitly clear TTBCR.PD0 and use
> correct mask for TTBCR.N, I see proper memory after MMU is enabled and
> decompression succeeds.
>
> Request your comments on the change below. If it looks good, I can submit a
> patch for inclusion.
>
> ---------------------8<----------------------------------
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index af11c2f..5769f1f 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -779,7 +779,8 @@ __armv7_mmu_cache_on:
> orrne r0, r0, #1 @ MMU enabled
> movne r1, #0xfffffffd @ domain 0 = client
> bic r6, r6, #1 << 31 @ 32-bit translation system
> - bic r6, r6, #3 << 0 @ use only ttbr0
> + bic r6, r6, #7 << 0 @ width of base address field
> + bic r6, r6, #1 << 4 @ use only ttbr0
You could combine those instructions like this:
bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
Nicolas
^ permalink raw reply [flat|nested] 24+ messages in thread
* Improper TTBCR for arm 32bit kernel decompression
@ 2016-09-09 17:36 ` Nicolas Pitre
0 siblings, 0 replies; 24+ messages in thread
From: Nicolas Pitre @ 2016-09-09 17:36 UTC (permalink / raw)
To: linux-arm-kernel
On Fri, 9 Sep 2016, Srinivas Ramana wrote:
> Hello,
>
> While trying to boot arm-32 bit kernel, I came across a problem where TTBCR is
> in improper state. If the bootloader uses the long descriptor format and jumps
> to kernel decompressor code, TTBCR may not be in the right state. So, as soon
> as the MMU is enabled, execution can not proceed further.
>
> Before enabling the MMU, it is required to clear the TTBCR.PD0 field to use
> TTBR0 for translation table walks. Also, TTBCR.N should be reset to '0' to
> indicate the correct base address width. The 'commit dbece45894d3a ("ARM:
> 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")' does the reset of
> TTBCR.N, but doesn't consider all the bits for the size of TTBCR.N.
>
> when i tried the below change where i explicitly clear TTBCR.PD0 and use
> correct mask for TTBCR.N, I see proper memory after MMU is enabled and
> decompression succeeds.
>
> Request your comments on the change below. If it looks good, I can submit a
> patch for inclusion.
>
> ---------------------8<----------------------------------
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index af11c2f..5769f1f 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -779,7 +779,8 @@ __armv7_mmu_cache_on:
> orrne r0, r0, #1 @ MMU enabled
> movne r1, #0xfffffffd @ domain 0 = client
> bic r6, r6, #1 << 31 @ 32-bit translation system
> - bic r6, r6, #3 << 0 @ use only ttbr0
> + bic r6, r6, #7 << 0 @ width of base address field
> + bic r6, r6, #1 << 4 @ use only ttbr0
You could combine those instructions like this:
bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
Nicolas
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: Improper TTBCR for arm 32bit kernel decompression
2016-09-09 17:36 ` Nicolas Pitre
@ 2016-09-10 5:50 ` Srinivas Ramana
-1 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-10 5:50 UTC (permalink / raw)
To: Ramana, Srinivas; +Cc: linux-arm-kernel, linux-kernel
On 09/09/2016 11:06 PM, Nicolas Pitre wrote:
> On Fri, 9 Sep 2016, Srinivas Ramana wrote:
>
>> Hello,
>>
>> While trying to boot arm-32 bit kernel, I came across a problem where TTBCR is
>> in improper state. If the bootloader uses the long descriptor format and jumps
>> to kernel decompressor code, TTBCR may not be in the right state. So, as soon
>> as the MMU is enabled, execution can not proceed further.
>>
>> Before enabling the MMU, it is required to clear the TTBCR.PD0 field to use
>> TTBR0 for translation table walks. Also, TTBCR.N should be reset to '0' to
>> indicate the correct base address width. The 'commit dbece45894d3a ("ARM:
>> 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")' does the reset of
>> TTBCR.N, but doesn't consider all the bits for the size of TTBCR.N.
>>
>> when i tried the below change where i explicitly clear TTBCR.PD0 and use
>> correct mask for TTBCR.N, I see proper memory after MMU is enabled and
>> decompression succeeds.
>>
>> Request your comments on the change below. If it looks good, I can submit a
>> patch for inclusion.
>>
>> ---------------------8<----------------------------------
>> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
>> index af11c2f..5769f1f 100644
>> --- a/arch/arm/boot/compressed/head.S
>> +++ b/arch/arm/boot/compressed/head.S
>> @@ -779,7 +779,8 @@ __armv7_mmu_cache_on:
>> orrne r0, r0, #1 @ MMU enabled
>> movne r1, #0xfffffffd @ domain 0 = client
>> bic r6, r6, #1 << 31 @ 32-bit translation system
>> - bic r6, r6, #3 << 0 @ use only ttbr0
>> + bic r6, r6, #7 << 0 @ width of base address field
>> + bic r6, r6, #1 << 4 @ use only ttbr0
>
> You could combine those instructions like this:
>
> bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
Sure, Thanks for the suggestion. I can incorporate this and submit a
patch. Can i use your Acked-by?
Thanks,
-- Srinivas R
>
> Nicolas
> --
> To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative
Project.
^ permalink raw reply [flat|nested] 24+ messages in thread
* Improper TTBCR for arm 32bit kernel decompression
@ 2016-09-10 5:50 ` Srinivas Ramana
0 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-10 5:50 UTC (permalink / raw)
To: linux-arm-kernel
On 09/09/2016 11:06 PM, Nicolas Pitre wrote:
> On Fri, 9 Sep 2016, Srinivas Ramana wrote:
>
>> Hello,
>>
>> While trying to boot arm-32 bit kernel, I came across a problem where TTBCR is
>> in improper state. If the bootloader uses the long descriptor format and jumps
>> to kernel decompressor code, TTBCR may not be in the right state. So, as soon
>> as the MMU is enabled, execution can not proceed further.
>>
>> Before enabling the MMU, it is required to clear the TTBCR.PD0 field to use
>> TTBR0 for translation table walks. Also, TTBCR.N should be reset to '0' to
>> indicate the correct base address width. The 'commit dbece45894d3a ("ARM:
>> 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")' does the reset of
>> TTBCR.N, but doesn't consider all the bits for the size of TTBCR.N.
>>
>> when i tried the below change where i explicitly clear TTBCR.PD0 and use
>> correct mask for TTBCR.N, I see proper memory after MMU is enabled and
>> decompression succeeds.
>>
>> Request your comments on the change below. If it looks good, I can submit a
>> patch for inclusion.
>>
>> ---------------------8<----------------------------------
>> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
>> index af11c2f..5769f1f 100644
>> --- a/arch/arm/boot/compressed/head.S
>> +++ b/arch/arm/boot/compressed/head.S
>> @@ -779,7 +779,8 @@ __armv7_mmu_cache_on:
>> orrne r0, r0, #1 @ MMU enabled
>> movne r1, #0xfffffffd @ domain 0 = client
>> bic r6, r6, #1 << 31 @ 32-bit translation system
>> - bic r6, r6, #3 << 0 @ use only ttbr0
>> + bic r6, r6, #7 << 0 @ width of base address field
>> + bic r6, r6, #1 << 4 @ use only ttbr0
>
> You could combine those instructions like this:
>
> bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
Sure, Thanks for the suggestion. I can incorporate this and submit a
patch. Can i use your Acked-by?
Thanks,
-- Srinivas R
>
> Nicolas
> --
> To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
> the body of a message to majordomo at vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative
Project.
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: Improper TTBCR for arm 32bit kernel decompression
2016-09-09 17:36 ` Nicolas Pitre
@ 2016-09-10 8:12 ` Srinivas Ramana
-1 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-10 8:12 UTC (permalink / raw)
To: Nicolas Pitre
Cc: linux, will.deacon, linux-arm-msm, linux-arm-kernel, linux-kernel
On 09/09/2016 11:06 PM, Nicolas Pitre wrote:
> On Fri, 9 Sep 2016, Srinivas Ramana wrote:
>
>> Hello,
>>
>> While trying to boot arm-32 bit kernel, I came across a problem where TTBCR is
>> in improper state. If the bootloader uses the long descriptor format and jumps
>> to kernel decompressor code, TTBCR may not be in the right state. So, as soon
>> as the MMU is enabled, execution can not proceed further.
>>
>> Before enabling the MMU, it is required to clear the TTBCR.PD0 field to use
>> TTBR0 for translation table walks. Also, TTBCR.N should be reset to '0' to
>> indicate the correct base address width. The 'commit dbece45894d3a ("ARM:
>> 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")' does the reset of
>> TTBCR.N, but doesn't consider all the bits for the size of TTBCR.N.
>>
>> when i tried the below change where i explicitly clear TTBCR.PD0 and use
>> correct mask for TTBCR.N, I see proper memory after MMU is enabled and
>> decompression succeeds.
>>
>> Request your comments on the change below. If it looks good, I can submit a
>> patch for inclusion.
>>
>> ---------------------8<----------------------------------
>> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
>> index af11c2f..5769f1f 100644
>> --- a/arch/arm/boot/compressed/head.S
>> +++ b/arch/arm/boot/compressed/head.S
>> @@ -779,7 +779,8 @@ __armv7_mmu_cache_on:
>> orrne r0, r0, #1 @ MMU enabled
>> movne r1, #0xfffffffd @ domain 0 = client
>> bic r6, r6, #1 << 31 @ 32-bit translation system
>> - bic r6, r6, #3 << 0 @ use only ttbr0
>> + bic r6, r6, #7 << 0 @ width of base address field
>> + bic r6, r6, #1 << 4 @ use only ttbr0
>
> You could combine those instructions like this:
>
> bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
Sure, I can do that. Thanks for the suggestion. Will send out a patch
for review.
Thanks,
-- Srinivas R
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative
Project.
^ permalink raw reply [flat|nested] 24+ messages in thread
* Improper TTBCR for arm 32bit kernel decompression
@ 2016-09-10 8:12 ` Srinivas Ramana
0 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-10 8:12 UTC (permalink / raw)
To: linux-arm-kernel
On 09/09/2016 11:06 PM, Nicolas Pitre wrote:
> On Fri, 9 Sep 2016, Srinivas Ramana wrote:
>
>> Hello,
>>
>> While trying to boot arm-32 bit kernel, I came across a problem where TTBCR is
>> in improper state. If the bootloader uses the long descriptor format and jumps
>> to kernel decompressor code, TTBCR may not be in the right state. So, as soon
>> as the MMU is enabled, execution can not proceed further.
>>
>> Before enabling the MMU, it is required to clear the TTBCR.PD0 field to use
>> TTBR0 for translation table walks. Also, TTBCR.N should be reset to '0' to
>> indicate the correct base address width. The 'commit dbece45894d3a ("ARM:
>> 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")' does the reset of
>> TTBCR.N, but doesn't consider all the bits for the size of TTBCR.N.
>>
>> when i tried the below change where i explicitly clear TTBCR.PD0 and use
>> correct mask for TTBCR.N, I see proper memory after MMU is enabled and
>> decompression succeeds.
>>
>> Request your comments on the change below. If it looks good, I can submit a
>> patch for inclusion.
>>
>> ---------------------8<----------------------------------
>> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
>> index af11c2f..5769f1f 100644
>> --- a/arch/arm/boot/compressed/head.S
>> +++ b/arch/arm/boot/compressed/head.S
>> @@ -779,7 +779,8 @@ __armv7_mmu_cache_on:
>> orrne r0, r0, #1 @ MMU enabled
>> movne r1, #0xfffffffd @ domain 0 = client
>> bic r6, r6, #1 << 31 @ 32-bit translation system
>> - bic r6, r6, #3 << 0 @ use only ttbr0
>> + bic r6, r6, #7 << 0 @ width of base address field
>> + bic r6, r6, #1 << 4 @ use only ttbr0
>
> You could combine those instructions like this:
>
> bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
Sure, I can do that. Thanks for the suggestion. Will send out a patch
for review.
Thanks,
-- Srinivas R
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative
Project.
^ permalink raw reply [flat|nested] 24+ messages in thread
* [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
2016-09-10 8:12 ` Srinivas Ramana
@ 2016-09-12 6:57 ` Srinivas Ramana
-1 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-12 6:57 UTC (permalink / raw)
To: linux, nicolas.pitre, will.deacon
Cc: linux-arm-kernel, linux-kernel, linux-arm-msm, Srinivas Ramana
If the bootloader uses the long descriptor format and jumps to
kernel decompressor code, TTBCR may not be in a right state.
Before enabling the MMU, it is required to clear the TTBCR.PD0
field to use TTBR0 for translation table walks.
The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
doesn't consider all the bits for the size of TTBCR.N.
Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
indicate the use of TTBR0 and the correct base address width.
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
---
arch/arm/boot/compressed/head.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index af11c2f8f3b7..fc6d541549a2 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
orrne r0, r0, #1 @ MMU enabled
movne r1, #0xfffffffd @ domain 0 = client
bic r6, r6, #1 << 31 @ 32-bit translation system
- bic r6, r6, #3 << 0 @ use only ttbr0
+ bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.,
is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply related [flat|nested] 24+ messages in thread
* [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
@ 2016-09-12 6:57 ` Srinivas Ramana
0 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-12 6:57 UTC (permalink / raw)
To: linux-arm-kernel
If the bootloader uses the long descriptor format and jumps to
kernel decompressor code, TTBCR may not be in a right state.
Before enabling the MMU, it is required to clear the TTBCR.PD0
field to use TTBR0 for translation table walks.
The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
doesn't consider all the bits for the size of TTBCR.N.
Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
indicate the use of TTBR0 and the correct base address width.
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
---
arch/arm/boot/compressed/head.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index af11c2f8f3b7..fc6d541549a2 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
orrne r0, r0, #1 @ MMU enabled
movne r1, #0xfffffffd @ domain 0 = client
bic r6, r6, #1 << 31 @ 32-bit translation system
- bic r6, r6, #3 << 0 @ use only ttbr0
+ bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.,
is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply related [flat|nested] 24+ messages in thread
* Re: [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
2016-09-12 6:57 ` Srinivas Ramana
@ 2016-09-12 10:23 ` Russell King - ARM Linux
-1 siblings, 0 replies; 24+ messages in thread
From: Russell King - ARM Linux @ 2016-09-12 10:23 UTC (permalink / raw)
To: Srinivas Ramana
Cc: nicolas.pitre, will.deacon, linux-arm-kernel, linux-kernel,
linux-arm-msm
On Mon, Sep 12, 2016 at 12:27:00PM +0530, Srinivas Ramana wrote:
> If the bootloader uses the long descriptor format and jumps to
> kernel decompressor code, TTBCR may not be in a right state.
> Before enabling the MMU, it is required to clear the TTBCR.PD0
> field to use TTBR0 for translation table walks.
>
> The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
> reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
There's no need to single-quote the commit part of this sentence.
> doesn't consider all the bits for the size of TTBCR.N.
>
> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
> indicate the use of TTBR0 and the correct base address width.
>
Adding a properly formatted Fixes: line here would be a bonus if we
need to backport it to stable trees.
> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
> ---
> arch/arm/boot/compressed/head.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index af11c2f8f3b7..fc6d541549a2 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
> orrne r0, r0, #1 @ MMU enabled
> movne r1, #0xfffffffd @ domain 0 = client
> bic r6, r6, #1 << 31 @ 32-bit translation system
> - bic r6, r6, #3 << 0 @ use only ttbr0
> + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
Provided this is correct (I've not checked, I'd like an ack from one of
the ARM people, and I'd prefer to see a tested-by as well), and the above
points are addressed, it can be dropped into the patch system. Thanks.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 24+ messages in thread
* [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
@ 2016-09-12 10:23 ` Russell King - ARM Linux
0 siblings, 0 replies; 24+ messages in thread
From: Russell King - ARM Linux @ 2016-09-12 10:23 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, Sep 12, 2016 at 12:27:00PM +0530, Srinivas Ramana wrote:
> If the bootloader uses the long descriptor format and jumps to
> kernel decompressor code, TTBCR may not be in a right state.
> Before enabling the MMU, it is required to clear the TTBCR.PD0
> field to use TTBR0 for translation table walks.
>
> The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
> reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
There's no need to single-quote the commit part of this sentence.
> doesn't consider all the bits for the size of TTBCR.N.
>
> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
> indicate the use of TTBR0 and the correct base address width.
>
Adding a properly formatted Fixes: line here would be a bonus if we
need to backport it to stable trees.
> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
> ---
> arch/arm/boot/compressed/head.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index af11c2f8f3b7..fc6d541549a2 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
> orrne r0, r0, #1 @ MMU enabled
> movne r1, #0xfffffffd @ domain 0 = client
> bic r6, r6, #1 << 31 @ 32-bit translation system
> - bic r6, r6, #3 << 0 @ use only ttbr0
> + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
Provided this is correct (I've not checked, I'd like an ack from one of
the ARM people, and I'd prefer to see a tested-by as well), and the above
points are addressed, it can be dropped into the patch system. Thanks.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently@9.6Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
2016-09-12 6:57 ` Srinivas Ramana
@ 2016-09-12 17:51 ` Robin Murphy
-1 siblings, 0 replies; 24+ messages in thread
From: Robin Murphy @ 2016-09-12 17:51 UTC (permalink / raw)
To: Srinivas Ramana, linux, nicolas.pitre, will.deacon
Cc: linux-arm-msm, linux-kernel, linux-arm-kernel
On 12/09/16 07:57, Srinivas Ramana wrote:
> If the bootloader uses the long descriptor format and jumps to
> kernel decompressor code, TTBCR may not be in a right state.
> Before enabling the MMU, it is required to clear the TTBCR.PD0
> field to use TTBR0 for translation table walks.
>
> The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
> reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
> doesn't consider all the bits for the size of TTBCR.N.
>
> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
> indicate the use of TTBR0 and the correct base address width.
>
> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
> ---
> arch/arm/boot/compressed/head.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index af11c2f8f3b7..fc6d541549a2 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
> orrne r0, r0, #1 @ MMU enabled
> movne r1, #0xfffffffd @ domain 0 = client
> bic r6, r6, #1 << 31 @ 32-bit translation system
Hmm, if TTBCR.EAE _was_ actually set...
> - bic r6, r6, #3 << 0 @ use only ttbr0
> + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
> mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
> mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
...then strictly the TLBIALL needs to happen after the ISB following
this update. Otherwise per B3.10.2 of DDI406C.c I think we might be into
unpredictable territory - i.e. if the TLB happens to treat long- and
short-descriptor entries differently then the TLBI beforehand (with EAE
set) may be at liberty to only discard long-descriptor entries and leave
bogus short-descriptor entries sitting around.
In other words, something like (completely untested):
---8<---
diff --git a/arch/arm/boot/compressed/head.S
b/arch/arm/boot/compressed/head.S
index af11c2f8f3b7..536b7781024a 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -764,7 +764,6 @@ __armv7_mmu_cache_on:
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
tst r11, #0xf @ VMSA
- mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
#endif
mrc p15, 0, r0, c1, c0, 0 @ read control reg
bic r0, r0, #1 << 28 @ clear SCTLR.TRE
@@ -783,8 +782,11 @@ __armv7_mmu_cache_on:
mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
-#endif
mcr p15, 0, r0, c7, c5, 4 @ ISB
+ mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
+#else
+ mcr p15, 0, r0, c7, c5, 4 @ ISB
+#endif
mcr p15, 0, r0, c1, c0, 0 @ load control register
mrc p15, 0, r0, c1, c0, 0 @ and read it back
---8<---
Robin.
^ permalink raw reply related [flat|nested] 24+ messages in thread
* [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
@ 2016-09-12 17:51 ` Robin Murphy
0 siblings, 0 replies; 24+ messages in thread
From: Robin Murphy @ 2016-09-12 17:51 UTC (permalink / raw)
To: linux-arm-kernel
On 12/09/16 07:57, Srinivas Ramana wrote:
> If the bootloader uses the long descriptor format and jumps to
> kernel decompressor code, TTBCR may not be in a right state.
> Before enabling the MMU, it is required to clear the TTBCR.PD0
> field to use TTBR0 for translation table walks.
>
> The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
> reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
> doesn't consider all the bits for the size of TTBCR.N.
>
> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
> indicate the use of TTBR0 and the correct base address width.
>
> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
> ---
> arch/arm/boot/compressed/head.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index af11c2f8f3b7..fc6d541549a2 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
> orrne r0, r0, #1 @ MMU enabled
> movne r1, #0xfffffffd @ domain 0 = client
> bic r6, r6, #1 << 31 @ 32-bit translation system
Hmm, if TTBCR.EAE _was_ actually set...
> - bic r6, r6, #3 << 0 @ use only ttbr0
> + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
> mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
> mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
...then strictly the TLBIALL needs to happen after the ISB following
this update. Otherwise per B3.10.2 of DDI406C.c I think we might be into
unpredictable territory - i.e. if the TLB happens to treat long- and
short-descriptor entries differently then the TLBI beforehand (with EAE
set) may be at liberty to only discard long-descriptor entries and leave
bogus short-descriptor entries sitting around.
In other words, something like (completely untested):
---8<---
diff --git a/arch/arm/boot/compressed/head.S
b/arch/arm/boot/compressed/head.S
index af11c2f8f3b7..536b7781024a 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -764,7 +764,6 @@ __armv7_mmu_cache_on:
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
tst r11, #0xf @ VMSA
- mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
#endif
mrc p15, 0, r0, c1, c0, 0 @ read control reg
bic r0, r0, #1 << 28 @ clear SCTLR.TRE
@@ -783,8 +782,11 @@ __armv7_mmu_cache_on:
mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
-#endif
mcr p15, 0, r0, c7, c5, 4 @ ISB
+ mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
+#else
+ mcr p15, 0, r0, c7, c5, 4 @ ISB
+#endif
mcr p15, 0, r0, c1, c0, 0 @ load control register
mrc p15, 0, r0, c1, c0, 0 @ and read it back
---8<---
Robin.
^ permalink raw reply related [flat|nested] 24+ messages in thread
* Re: [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
2016-09-12 17:51 ` Robin Murphy
@ 2016-09-13 14:52 ` Srinivas Ramana
-1 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-13 14:52 UTC (permalink / raw)
To: Robin Murphy
Cc: linux, nicolas.pitre, will.deacon, linux-arm-msm, linux-kernel,
linux-arm-kernel
On 09/12/2016 11:21 PM, Robin Murphy wrote:
> On 12/09/16 07:57, Srinivas Ramana wrote:
>> If the bootloader uses the long descriptor format and jumps to
>> kernel decompressor code, TTBCR may not be in a right state.
>> Before enabling the MMU, it is required to clear the TTBCR.PD0
>> field to use TTBR0 for translation table walks.
>>
>> The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
>> reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
>> doesn't consider all the bits for the size of TTBCR.N.
>>
>> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
>> indicate the use of TTBR0 and the correct base address width.
>>
>> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
>> ---
>> arch/arm/boot/compressed/head.S | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
>> index af11c2f8f3b7..fc6d541549a2 100644
>> --- a/arch/arm/boot/compressed/head.S
>> +++ b/arch/arm/boot/compressed/head.S
>> @@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
>> orrne r0, r0, #1 @ MMU enabled
>> movne r1, #0xfffffffd @ domain 0 = client
>> bic r6, r6, #1 << 31 @ 32-bit translation system
>
> Hmm, if TTBCR.EAE _was_ actually set...
>
>> - bic r6, r6, #3 << 0 @ use only ttbr0
>> + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
>> mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
>> mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
>> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
>
> ...then strictly the TLBIALL needs to happen after the ISB following
> this update. Otherwise per B3.10.2 of DDI406C.c I think we might be into
> unpredictable territory - i.e. if the TLB happens to treat long- and
> short-descriptor entries differently then the TLBI beforehand (with EAE
> set) may be at liberty to only discard long-descriptor entries and leave
> bogus short-descriptor entries sitting around.
Yes, it seems this has to be taken care of, along with resetting
TTBCR.PD0 and TTBCR.N. Do you say that this needs to be done in the same
patch or a different one?
>
> In other words, something like (completely untested):
>
> ---8<---
> diff --git a/arch/arm/boot/compressed/head.S
> b/arch/arm/boot/compressed/head.S
> index af11c2f8f3b7..536b7781024a 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -764,7 +764,6 @@ __armv7_mmu_cache_on:
> mov r0, #0
> mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
> tst r11, #0xf @ VMSA
> - mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
Shouldn't this be still there for the same reason you explained above? I
mean to discard the long descriptor entries when EAE was 1 (before we
reset it).
> #endif
> mrc p15, 0, r0, c1, c0, 0 @ read control reg
> bic r0, r0, #1 << 28 @ clear SCTLR.TRE
> @@ -783,8 +782,11 @@ __armv7_mmu_cache_on:
> mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
> mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
> -#endif
> mcr p15, 0, r0, c7, c5, 4 @ ISB
> + mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
> +#else
> + mcr p15, 0, r0, c7, c5, 4 @ ISB
> +#endif
> mcr p15, 0, r0, c1, c0, 0 @ load control register
> mrc p15, 0, r0, c1, c0, 0 @ and read it back
> ---8<---
>
> Robin.
>
i have tested this change (flush I, D, TLBs after TTB control is
written) and don't see any issue. But on my setup decompression is
successful even without this (probably not hitting the case in discussion).
Thanks,
-- Srinivas R
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative
Project.
^ permalink raw reply [flat|nested] 24+ messages in thread
* [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
@ 2016-09-13 14:52 ` Srinivas Ramana
0 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-13 14:52 UTC (permalink / raw)
To: linux-arm-kernel
On 09/12/2016 11:21 PM, Robin Murphy wrote:
> On 12/09/16 07:57, Srinivas Ramana wrote:
>> If the bootloader uses the long descriptor format and jumps to
>> kernel decompressor code, TTBCR may not be in a right state.
>> Before enabling the MMU, it is required to clear the TTBCR.PD0
>> field to use TTBR0 for translation table walks.
>>
>> The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
>> reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
>> doesn't consider all the bits for the size of TTBCR.N.
>>
>> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
>> indicate the use of TTBR0 and the correct base address width.
>>
>> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
>> ---
>> arch/arm/boot/compressed/head.S | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
>> index af11c2f8f3b7..fc6d541549a2 100644
>> --- a/arch/arm/boot/compressed/head.S
>> +++ b/arch/arm/boot/compressed/head.S
>> @@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
>> orrne r0, r0, #1 @ MMU enabled
>> movne r1, #0xfffffffd @ domain 0 = client
>> bic r6, r6, #1 << 31 @ 32-bit translation system
>
> Hmm, if TTBCR.EAE _was_ actually set...
>
>> - bic r6, r6, #3 << 0 @ use only ttbr0
>> + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
>> mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
>> mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
>> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
>
> ...then strictly the TLBIALL needs to happen after the ISB following
> this update. Otherwise per B3.10.2 of DDI406C.c I think we might be into
> unpredictable territory - i.e. if the TLB happens to treat long- and
> short-descriptor entries differently then the TLBI beforehand (with EAE
> set) may be at liberty to only discard long-descriptor entries and leave
> bogus short-descriptor entries sitting around.
Yes, it seems this has to be taken care of, along with resetting
TTBCR.PD0 and TTBCR.N. Do you say that this needs to be done in the same
patch or a different one?
>
> In other words, something like (completely untested):
>
> ---8<---
> diff --git a/arch/arm/boot/compressed/head.S
> b/arch/arm/boot/compressed/head.S
> index af11c2f8f3b7..536b7781024a 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -764,7 +764,6 @@ __armv7_mmu_cache_on:
> mov r0, #0
> mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
> tst r11, #0xf @ VMSA
> - mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
Shouldn't this be still there for the same reason you explained above? I
mean to discard the long descriptor entries when EAE was 1 (before we
reset it).
> #endif
> mrc p15, 0, r0, c1, c0, 0 @ read control reg
> bic r0, r0, #1 << 28 @ clear SCTLR.TRE
> @@ -783,8 +782,11 @@ __armv7_mmu_cache_on:
> mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
> mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
> -#endif
> mcr p15, 0, r0, c7, c5, 4 @ ISB
> + mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
> +#else
> + mcr p15, 0, r0, c7, c5, 4 @ ISB
> +#endif
> mcr p15, 0, r0, c1, c0, 0 @ load control register
> mrc p15, 0, r0, c1, c0, 0 @ and read it back
> ---8<---
>
> Robin.
>
i have tested this change (flush I, D, TLBs after TTB control is
written) and don't see any issue. But on my setup decompression is
successful even without this (probably not hitting the case in discussion).
Thanks,
-- Srinivas R
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative
Project.
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
2016-09-13 14:52 ` Srinivas Ramana
@ 2016-09-27 12:16 ` Srinivas Ramana
-1 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-27 12:16 UTC (permalink / raw)
To: Robin Murphy
Cc: linux, nicolas.pitre, will.deacon, linux-arm-msm, linux-kernel,
linux-arm-kernel
Hi Robin,
On 09/13/2016 08:22 PM, Srinivas Ramana wrote:
> On 09/12/2016 11:21 PM, Robin Murphy wrote:
>> On 12/09/16 07:57, Srinivas Ramana wrote:
>>> If the bootloader uses the long descriptor format and jumps to
>>> kernel decompressor code, TTBCR may not be in a right state.
>>> Before enabling the MMU, it is required to clear the TTBCR.PD0
>>> field to use TTBR0 for translation table walks.
>>>
>>> The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
>>> reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
>>> doesn't consider all the bits for the size of TTBCR.N.
>>>
>>> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
>>> indicate the use of TTBR0 and the correct base address width.
>>>
>>> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
>>> ---
>>> arch/arm/boot/compressed/head.S | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/boot/compressed/head.S
>>> b/arch/arm/boot/compressed/head.S
>>> index af11c2f8f3b7..fc6d541549a2 100644
>>> --- a/arch/arm/boot/compressed/head.S
>>> +++ b/arch/arm/boot/compressed/head.S
>>> @@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
>>> orrne r0, r0, #1 @ MMU enabled
>>> movne r1, #0xfffffffd @ domain 0 = client
>>> bic r6, r6, #1 << 31 @ 32-bit translation system
>>
>> Hmm, if TTBCR.EAE _was_ actually set...
>>
>>> - bic r6, r6, #3 << 0 @ use only ttbr0
>>> + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
>>> mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
>>> mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
>>> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
>>
>> ...then strictly the TLBIALL needs to happen after the ISB following
>> this update. Otherwise per B3.10.2 of DDI406C.c I think we might be into
>> unpredictable territory - i.e. if the TLB happens to treat long- and
>> short-descriptor entries differently then the TLBI beforehand (with EAE
>> set) may be at liberty to only discard long-descriptor entries and leave
>> bogus short-descriptor entries sitting around.
> Yes, it seems this has to be taken care of, along with resetting
> TTBCR.PD0 and TTBCR.N. Do you say that this needs to be done in the same
> patch or a different one?
>>
>> In other words, something like (completely untested):
>>
>> ---8<---
>> diff --git a/arch/arm/boot/compressed/head.S
>> b/arch/arm/boot/compressed/head.S
>> index af11c2f8f3b7..536b7781024a 100644
>> --- a/arch/arm/boot/compressed/head.S
>> +++ b/arch/arm/boot/compressed/head.S
>> @@ -764,7 +764,6 @@ __armv7_mmu_cache_on:
>> mov r0, #0
>> mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
>> tst r11, #0xf @ VMSA
>> - mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
>
> Shouldn't this be still there for the same reason you explained above? I
> mean to discard the long descriptor entries when EAE was 1 (before we
> reset it).
>> #endif
>> mrc p15, 0, r0, c1, c0, 0 @ read control reg
>> bic r0, r0, #1 << 28 @ clear SCTLR.TRE
>> @@ -783,8 +782,11 @@ __armv7_mmu_cache_on:
>> mcrne p15, 0, r3, c2, c0, 0 @ load page table
>> pointer
>> mcrne p15, 0, r1, c3, c0, 0 @ load domain access
>> control
>> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
>> -#endif
>> mcr p15, 0, r0, c7, c5, 4 @ ISB
>> + mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
>> +#else
>> + mcr p15, 0, r0, c7, c5, 4 @ ISB
>> +#endif
>> mcr p15, 0, r0, c1, c0, 0 @ load control register
>> mrc p15, 0, r0, c1, c0, 0 @ and read it back
>> ---8<---
>>
>> Robin.
>>
> i have tested this change (flush I, D, TLBs after TTB control is
> written) and don't see any issue. But on my setup decompression is
> successful even without this (probably not hitting the case in discussion).
>
>
> Thanks,
> -- Srinivas R
>
Would like your feedback on the above. Can we get the TTBCR fix merged
first?(will send final patch with Russell Kings comments fixed)
For testing the TLB flush change we may have to check if we can create a
failure case.
Thanks,
-- Srinivas R
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative
Project.
^ permalink raw reply [flat|nested] 24+ messages in thread
* [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
@ 2016-09-27 12:16 ` Srinivas Ramana
0 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-27 12:16 UTC (permalink / raw)
To: linux-arm-kernel
Hi Robin,
On 09/13/2016 08:22 PM, Srinivas Ramana wrote:
> On 09/12/2016 11:21 PM, Robin Murphy wrote:
>> On 12/09/16 07:57, Srinivas Ramana wrote:
>>> If the bootloader uses the long descriptor format and jumps to
>>> kernel decompressor code, TTBCR may not be in a right state.
>>> Before enabling the MMU, it is required to clear the TTBCR.PD0
>>> field to use TTBR0 for translation table walks.
>>>
>>> The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
>>> reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
>>> doesn't consider all the bits for the size of TTBCR.N.
>>>
>>> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
>>> indicate the use of TTBR0 and the correct base address width.
>>>
>>> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
>>> ---
>>> arch/arm/boot/compressed/head.S | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/boot/compressed/head.S
>>> b/arch/arm/boot/compressed/head.S
>>> index af11c2f8f3b7..fc6d541549a2 100644
>>> --- a/arch/arm/boot/compressed/head.S
>>> +++ b/arch/arm/boot/compressed/head.S
>>> @@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
>>> orrne r0, r0, #1 @ MMU enabled
>>> movne r1, #0xfffffffd @ domain 0 = client
>>> bic r6, r6, #1 << 31 @ 32-bit translation system
>>
>> Hmm, if TTBCR.EAE _was_ actually set...
>>
>>> - bic r6, r6, #3 << 0 @ use only ttbr0
>>> + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
>>> mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
>>> mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
>>> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
>>
>> ...then strictly the TLBIALL needs to happen after the ISB following
>> this update. Otherwise per B3.10.2 of DDI406C.c I think we might be into
>> unpredictable territory - i.e. if the TLB happens to treat long- and
>> short-descriptor entries differently then the TLBI beforehand (with EAE
>> set) may be at liberty to only discard long-descriptor entries and leave
>> bogus short-descriptor entries sitting around.
> Yes, it seems this has to be taken care of, along with resetting
> TTBCR.PD0 and TTBCR.N. Do you say that this needs to be done in the same
> patch or a different one?
>>
>> In other words, something like (completely untested):
>>
>> ---8<---
>> diff --git a/arch/arm/boot/compressed/head.S
>> b/arch/arm/boot/compressed/head.S
>> index af11c2f8f3b7..536b7781024a 100644
>> --- a/arch/arm/boot/compressed/head.S
>> +++ b/arch/arm/boot/compressed/head.S
>> @@ -764,7 +764,6 @@ __armv7_mmu_cache_on:
>> mov r0, #0
>> mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
>> tst r11, #0xf @ VMSA
>> - mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
>
> Shouldn't this be still there for the same reason you explained above? I
> mean to discard the long descriptor entries when EAE was 1 (before we
> reset it).
>> #endif
>> mrc p15, 0, r0, c1, c0, 0 @ read control reg
>> bic r0, r0, #1 << 28 @ clear SCTLR.TRE
>> @@ -783,8 +782,11 @@ __armv7_mmu_cache_on:
>> mcrne p15, 0, r3, c2, c0, 0 @ load page table
>> pointer
>> mcrne p15, 0, r1, c3, c0, 0 @ load domain access
>> control
>> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
>> -#endif
>> mcr p15, 0, r0, c7, c5, 4 @ ISB
>> + mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
>> +#else
>> + mcr p15, 0, r0, c7, c5, 4 @ ISB
>> +#endif
>> mcr p15, 0, r0, c1, c0, 0 @ load control register
>> mrc p15, 0, r0, c1, c0, 0 @ and read it back
>> ---8<---
>>
>> Robin.
>>
> i have tested this change (flush I, D, TLBs after TTB control is
> written) and don't see any issue. But on my setup decompression is
> successful even without this (probably not hitting the case in discussion).
>
>
> Thanks,
> -- Srinivas R
>
Would like your feedback on the above. Can we get the TTBCR fix merged
first?(will send final patch with Russell Kings comments fixed)
For testing the TLB flush change we may have to check if we can create a
failure case.
Thanks,
-- Srinivas R
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative
Project.
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
2016-09-27 12:16 ` Srinivas Ramana
@ 2016-09-27 12:54 ` Robin Murphy
-1 siblings, 0 replies; 24+ messages in thread
From: Robin Murphy @ 2016-09-27 12:54 UTC (permalink / raw)
To: Srinivas Ramana
Cc: nicolas.pitre, linux-arm-msm, will.deacon, linux, linux-kernel,
linux-arm-kernel
On 27/09/16 13:16, Srinivas Ramana wrote:
> Hi Robin,
Sorry! This one had slipped my mind already...
> On 09/13/2016 08:22 PM, Srinivas Ramana wrote:
>> On 09/12/2016 11:21 PM, Robin Murphy wrote:
>>> On 12/09/16 07:57, Srinivas Ramana wrote:
>>>> If the bootloader uses the long descriptor format and jumps to
>>>> kernel decompressor code, TTBCR may not be in a right state.
>>>> Before enabling the MMU, it is required to clear the TTBCR.PD0
>>>> field to use TTBR0 for translation table walks.
>>>>
>>>> The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
>>>> reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
>>>> doesn't consider all the bits for the size of TTBCR.N.
>>>>
>>>> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
>>>> indicate the use of TTBR0 and the correct base address width.
>>>>
>>>> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
>>>> ---
>>>> arch/arm/boot/compressed/head.S | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/arm/boot/compressed/head.S
>>>> b/arch/arm/boot/compressed/head.S
>>>> index af11c2f8f3b7..fc6d541549a2 100644
>>>> --- a/arch/arm/boot/compressed/head.S
>>>> +++ b/arch/arm/boot/compressed/head.S
>>>> @@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
>>>> orrne r0, r0, #1 @ MMU enabled
>>>> movne r1, #0xfffffffd @ domain 0 = client
>>>> bic r6, r6, #1 << 31 @ 32-bit translation system
>>>
>>> Hmm, if TTBCR.EAE _was_ actually set...
>>>
>>>> - bic r6, r6, #3 << 0 @ use only ttbr0
>>>> + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
>>>> mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
>>>> mcrne p15, 0, r1, c3, c0, 0 @ load domain access
>>>> control
>>>> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
>>>
>>> ...then strictly the TLBIALL needs to happen after the ISB following
>>> this update. Otherwise per B3.10.2 of DDI406C.c I think we might be into
>>> unpredictable territory - i.e. if the TLB happens to treat long- and
>>> short-descriptor entries differently then the TLBI beforehand (with EAE
>>> set) may be at liberty to only discard long-descriptor entries and leave
>>> bogus short-descriptor entries sitting around.
>> Yes, it seems this has to be taken care of, along with resetting
>> TTBCR.PD0 and TTBCR.N. Do you say that this needs to be done in the same
>> patch or a different one?
>>>
>>> In other words, something like (completely untested):
>>>
>>> ---8<---
>>> diff --git a/arch/arm/boot/compressed/head.S
>>> b/arch/arm/boot/compressed/head.S
>>> index af11c2f8f3b7..536b7781024a 100644
>>> --- a/arch/arm/boot/compressed/head.S
>>> +++ b/arch/arm/boot/compressed/head.S
>>> @@ -764,7 +764,6 @@ __armv7_mmu_cache_on:
>>> mov r0, #0
>>> mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
>>> tst r11, #0xf @ VMSA
>>> - mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
>>
>> Shouldn't this be still there for the same reason you explained above? I
>> mean to discard the long descriptor entries when EAE was 1 (before we
>> reset it).
>>> #endif
>>> mrc p15, 0, r0, c1, c0, 0 @ read control reg
>>> bic r0, r0, #1 << 28 @ clear SCTLR.TRE
>>> @@ -783,8 +782,11 @@ __armv7_mmu_cache_on:
>>> mcrne p15, 0, r3, c2, c0, 0 @ load page table
>>> pointer
>>> mcrne p15, 0, r1, c3, c0, 0 @ load domain access
>>> control
>>> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
>>> -#endif
>>> mcr p15, 0, r0, c7, c5, 4 @ ISB
>>> + mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
>>> +#else
>>> + mcr p15, 0, r0, c7, c5, 4 @ ISB
>>> +#endif
>>> mcr p15, 0, r0, c1, c0, 0 @ load control register
>>> mrc p15, 0, r0, c1, c0, 0 @ and read it back
>>> ---8<---
>>>
>>> Robin.
>>>
>> i have tested this change (flush I, D, TLBs after TTB control is
>> written) and don't see any issue. But on my setup decompression is
>> successful even without this (probably not hitting the case in
>> discussion).
>>
>>
>> Thanks,
>> -- Srinivas R
>>
>
> Would like your feedback on the above. Can we get the TTBCR fix merged
> first?(will send final patch with Russell Kings comments fixed)
>
> For testing the TLB flush change we may have to check if we can create a
> failure case.
Yeah, the TLBI being in the wrong place is a separate, pre-existing
problem; as far as this patch goes, it does what it claims to do, and
matches what the ARMv7 (and ARMv6) docs say, so:
Acked-by: Robin Murphy <robin.murphy@arm.com>
>
> Thanks,
> -- Srinivas R
>
^ permalink raw reply [flat|nested] 24+ messages in thread
* [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
@ 2016-09-27 12:54 ` Robin Murphy
0 siblings, 0 replies; 24+ messages in thread
From: Robin Murphy @ 2016-09-27 12:54 UTC (permalink / raw)
To: linux-arm-kernel
On 27/09/16 13:16, Srinivas Ramana wrote:
> Hi Robin,
Sorry! This one had slipped my mind already...
> On 09/13/2016 08:22 PM, Srinivas Ramana wrote:
>> On 09/12/2016 11:21 PM, Robin Murphy wrote:
>>> On 12/09/16 07:57, Srinivas Ramana wrote:
>>>> If the bootloader uses the long descriptor format and jumps to
>>>> kernel decompressor code, TTBCR may not be in a right state.
>>>> Before enabling the MMU, it is required to clear the TTBCR.PD0
>>>> field to use TTBR0 for translation table walks.
>>>>
>>>> The 'commit dbece45894d3a ("ARM: 7501/1: decompressor:
>>>> reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but
>>>> doesn't consider all the bits for the size of TTBCR.N.
>>>>
>>>> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
>>>> indicate the use of TTBR0 and the correct base address width.
>>>>
>>>> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
>>>> ---
>>>> arch/arm/boot/compressed/head.S | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/arm/boot/compressed/head.S
>>>> b/arch/arm/boot/compressed/head.S
>>>> index af11c2f8f3b7..fc6d541549a2 100644
>>>> --- a/arch/arm/boot/compressed/head.S
>>>> +++ b/arch/arm/boot/compressed/head.S
>>>> @@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
>>>> orrne r0, r0, #1 @ MMU enabled
>>>> movne r1, #0xfffffffd @ domain 0 = client
>>>> bic r6, r6, #1 << 31 @ 32-bit translation system
>>>
>>> Hmm, if TTBCR.EAE _was_ actually set...
>>>
>>>> - bic r6, r6, #3 << 0 @ use only ttbr0
>>>> + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
>>>> mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
>>>> mcrne p15, 0, r1, c3, c0, 0 @ load domain access
>>>> control
>>>> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
>>>
>>> ...then strictly the TLBIALL needs to happen after the ISB following
>>> this update. Otherwise per B3.10.2 of DDI406C.c I think we might be into
>>> unpredictable territory - i.e. if the TLB happens to treat long- and
>>> short-descriptor entries differently then the TLBI beforehand (with EAE
>>> set) may be at liberty to only discard long-descriptor entries and leave
>>> bogus short-descriptor entries sitting around.
>> Yes, it seems this has to be taken care of, along with resetting
>> TTBCR.PD0 and TTBCR.N. Do you say that this needs to be done in the same
>> patch or a different one?
>>>
>>> In other words, something like (completely untested):
>>>
>>> ---8<---
>>> diff --git a/arch/arm/boot/compressed/head.S
>>> b/arch/arm/boot/compressed/head.S
>>> index af11c2f8f3b7..536b7781024a 100644
>>> --- a/arch/arm/boot/compressed/head.S
>>> +++ b/arch/arm/boot/compressed/head.S
>>> @@ -764,7 +764,6 @@ __armv7_mmu_cache_on:
>>> mov r0, #0
>>> mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
>>> tst r11, #0xf @ VMSA
>>> - mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
>>
>> Shouldn't this be still there for the same reason you explained above? I
>> mean to discard the long descriptor entries when EAE was 1 (before we
>> reset it).
>>> #endif
>>> mrc p15, 0, r0, c1, c0, 0 @ read control reg
>>> bic r0, r0, #1 << 28 @ clear SCTLR.TRE
>>> @@ -783,8 +782,11 @@ __armv7_mmu_cache_on:
>>> mcrne p15, 0, r3, c2, c0, 0 @ load page table
>>> pointer
>>> mcrne p15, 0, r1, c3, c0, 0 @ load domain access
>>> control
>>> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
>>> -#endif
>>> mcr p15, 0, r0, c7, c5, 4 @ ISB
>>> + mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
>>> +#else
>>> + mcr p15, 0, r0, c7, c5, 4 @ ISB
>>> +#endif
>>> mcr p15, 0, r0, c1, c0, 0 @ load control register
>>> mrc p15, 0, r0, c1, c0, 0 @ and read it back
>>> ---8<---
>>>
>>> Robin.
>>>
>> i have tested this change (flush I, D, TLBs after TTB control is
>> written) and don't see any issue. But on my setup decompression is
>> successful even without this (probably not hitting the case in
>> discussion).
>>
>>
>> Thanks,
>> -- Srinivas R
>>
>
> Would like your feedback on the above. Can we get the TTBCR fix merged
> first?(will send final patch with Russell Kings comments fixed)
>
> For testing the TLB flush change we may have to check if we can create a
> failure case.
Yeah, the TLBI being in the wrong place is a separate, pre-existing
problem; as far as this patch goes, it does what it claims to do, and
matches what the ARMv7 (and ARMv6) docs say, so:
Acked-by: Robin Murphy <robin.murphy@arm.com>
>
> Thanks,
> -- Srinivas R
>
^ permalink raw reply [flat|nested] 24+ messages in thread
* [PATCH v1] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
2016-09-27 12:54 ` Robin Murphy
@ 2016-09-28 12:45 ` Srinivas Ramana
-1 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-28 12:45 UTC (permalink / raw)
To: linux, nicolas.pitre, will.deacon, robin.murphy
Cc: linux-arm-kernel, linux-kernel, linux-arm-msm, Srinivas Ramana
If the bootloader uses the long descriptor format and jumps to
kernel decompressor code, TTBCR may not be in a right state.
Before enabling the MMU, it is required to clear the TTBCR.PD0
field to use TTBR0 for translation table walks.
The commit dbece45894d3a ("ARM: 7501/1: decompressor:
reset ttbcr for VMSA ARMv7 cores") does the reset of TTBCR.N, but
doesn't consider all the bits for the size of TTBCR.N.
Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
indicate the use of TTBR0 and the correct base address width.
Fixes: dbece45894d3 ("ARM: 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")
Acked-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
---
arch/arm/boot/compressed/head.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index af11c2f8f3b7..fc6d541549a2 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
orrne r0, r0, #1 @ MMU enabled
movne r1, #0xfffffffd @ domain 0 = client
bic r6, r6, #1 << 31 @ 32-bit translation system
- bic r6, r6, #3 << 0 @ use only ttbr0
+ bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.,
is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply related [flat|nested] 24+ messages in thread
* [PATCH v1] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
@ 2016-09-28 12:45 ` Srinivas Ramana
0 siblings, 0 replies; 24+ messages in thread
From: Srinivas Ramana @ 2016-09-28 12:45 UTC (permalink / raw)
To: linux-arm-kernel
If the bootloader uses the long descriptor format and jumps to
kernel decompressor code, TTBCR may not be in a right state.
Before enabling the MMU, it is required to clear the TTBCR.PD0
field to use TTBR0 for translation table walks.
The commit dbece45894d3a ("ARM: 7501/1: decompressor:
reset ttbcr for VMSA ARMv7 cores") does the reset of TTBCR.N, but
doesn't consider all the bits for the size of TTBCR.N.
Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
indicate the use of TTBR0 and the correct base address width.
Fixes: dbece45894d3 ("ARM: 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")
Acked-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
---
arch/arm/boot/compressed/head.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index af11c2f8f3b7..fc6d541549a2 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -779,7 +779,7 @@ __armv7_mmu_cache_on:
orrne r0, r0, #1 @ MMU enabled
movne r1, #0xfffffffd @ domain 0 = client
bic r6, r6, #1 << 31 @ 32-bit translation system
- bic r6, r6, #3 << 0 @ use only ttbr0
+ bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0
mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.,
is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply related [flat|nested] 24+ messages in thread
* Re: [PATCH v1] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
2016-09-28 12:45 ` Srinivas Ramana
@ 2016-09-28 22:00 ` Russell King - ARM Linux
-1 siblings, 0 replies; 24+ messages in thread
From: Russell King - ARM Linux @ 2016-09-28 22:00 UTC (permalink / raw)
To: Srinivas Ramana
Cc: nicolas.pitre, will.deacon, robin.murphy, linux-arm-kernel,
linux-kernel, linux-arm-msm
On Wed, Sep 28, 2016 at 06:15:28PM +0530, Srinivas Ramana wrote:
> If the bootloader uses the long descriptor format and jumps to
> kernel decompressor code, TTBCR may not be in a right state.
> Before enabling the MMU, it is required to clear the TTBCR.PD0
> field to use TTBR0 for translation table walks.
>
> The commit dbece45894d3a ("ARM: 7501/1: decompressor:
> reset ttbcr for VMSA ARMv7 cores") does the reset of TTBCR.N, but
> doesn't consider all the bits for the size of TTBCR.N.
>
> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
> indicate the use of TTBR0 and the correct base address width.
>
> Fixes: dbece45894d3 ("ARM: 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")
> Acked-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
Please submit to the patch system, thanks.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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^ permalink raw reply [flat|nested] 24+ messages in thread
* [PATCH v1] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
@ 2016-09-28 22:00 ` Russell King - ARM Linux
0 siblings, 0 replies; 24+ messages in thread
From: Russell King - ARM Linux @ 2016-09-28 22:00 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, Sep 28, 2016 at 06:15:28PM +0530, Srinivas Ramana wrote:
> If the bootloader uses the long descriptor format and jumps to
> kernel decompressor code, TTBCR may not be in a right state.
> Before enabling the MMU, it is required to clear the TTBCR.PD0
> field to use TTBR0 for translation table walks.
>
> The commit dbece45894d3a ("ARM: 7501/1: decompressor:
> reset ttbcr for VMSA ARMv7 cores") does the reset of TTBCR.N, but
> doesn't consider all the bits for the size of TTBCR.N.
>
> Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
> indicate the use of TTBR0 and the correct base address width.
>
> Fixes: dbece45894d3 ("ARM: 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")
> Acked-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
Please submit to the patch system, thanks.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 24+ messages in thread
end of thread, other threads:[~2016-09-28 22:00 UTC | newest]
Thread overview: 24+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-09-09 16:34 Improper TTBCR for arm 32bit kernel decompression Srinivas Ramana
2016-09-09 16:34 ` Srinivas Ramana
2016-09-09 17:36 ` Nicolas Pitre
2016-09-09 17:36 ` Nicolas Pitre
2016-09-10 5:50 ` Srinivas Ramana
2016-09-10 5:50 ` Srinivas Ramana
2016-09-10 8:12 ` Srinivas Ramana
2016-09-10 8:12 ` Srinivas Ramana
2016-09-12 6:57 ` [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7 Srinivas Ramana
2016-09-12 6:57 ` Srinivas Ramana
2016-09-12 10:23 ` Russell King - ARM Linux
2016-09-12 10:23 ` Russell King - ARM Linux
2016-09-12 17:51 ` Robin Murphy
2016-09-12 17:51 ` Robin Murphy
2016-09-13 14:52 ` Srinivas Ramana
2016-09-13 14:52 ` Srinivas Ramana
2016-09-27 12:16 ` Srinivas Ramana
2016-09-27 12:16 ` Srinivas Ramana
2016-09-27 12:54 ` Robin Murphy
2016-09-27 12:54 ` Robin Murphy
2016-09-28 12:45 ` [PATCH v1] " Srinivas Ramana
2016-09-28 12:45 ` Srinivas Ramana
2016-09-28 22:00 ` Russell King - ARM Linux
2016-09-28 22:00 ` Russell King - ARM Linux
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