* [PATCH] ARM: NOMMU: Fix exc_ret for XIP
@ 2019-10-03 11:41 Vladimir Murzin
2019-10-04 0:56 ` afzal mohammed
2019-10-12 6:37 ` afzal mohammed
0 siblings, 2 replies; 6+ messages in thread
From: Vladimir Murzin @ 2019-10-03 11:41 UTC (permalink / raw)
To: linux-arm-kernel; +Cc: alexandre.torgue, afzal.mohd.ma, linux, sza
It was reported that 72cd4064fcca "NOMMU: Toggle only bits in
EXC_RETURN we are really care of" breaks NOMMU+XIP combination.
It happens because saved EXC_RETURN gets overwritten when data
section is relocated.
The fix is to propagate EXC_RETURN via register and let relocation
code to commit that value into memory.
Fixes: 72cd4064fcca ("ARM: 8830/1: NOMMU: Toggle only bits in EXC_RETURN we are really care of")
Reported-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Tested-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
arch/arm/kernel/head-common.S | 5 +++--
arch/arm/kernel/head-nommu.S | 2 ++
arch/arm/mm/proc-v7m.S | 5 ++---
3 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index a7810be..4a39828 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -68,7 +68,7 @@ ENDPROC(__vet_atags)
* The following fragment of code is executed with the MMU on in MMU mode,
* and uses absolute addresses; this is not position independent.
*
- * r0 = cp#15 control register
+ * r0 = cp#15 control register (exc_ret for M-class)
* r1 = machine ID
* r2 = atags/dtb pointer
* r9 = processor ID
@@ -137,7 +137,8 @@ __mmap_switched_data:
#ifdef CONFIG_CPU_CP15
.long cr_alignment @ r3
#else
- .long 0 @ r3
+M_CLASS(.long exc_ret) @ r3
+AR_CLASS(.long 0) @ r3
#endif
.size __mmap_switched_data, . - __mmap_switched_data
diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S
index afa350f..0fc814b 100644
--- a/arch/arm/kernel/head-nommu.S
+++ b/arch/arm/kernel/head-nommu.S
@@ -201,6 +201,8 @@ M_CLASS(streq r3, [r12, #PMSAv8_MAIR1])
bic r0, r0, #V7M_SCB_CCR_IC
#endif
str r0, [r12, V7M_SCB_CCR]
+ /* Pass exc_ret to __mmap_switched */
+ mov r0, r10
#endif /* CONFIG_CPU_CP15 elif CONFIG_CPU_V7M */
ret lr
ENDPROC(__after_proc_init)
diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S
index 1448f14..efebf41 100644
--- a/arch/arm/mm/proc-v7m.S
+++ b/arch/arm/mm/proc-v7m.S
@@ -136,9 +136,8 @@ __v7m_setup_cont:
cpsie i
svc #0
1: cpsid i
- ldr r0, =exc_ret
- orr lr, lr, #EXC_RET_THREADMODE_PROCESSSTACK
- str lr, [r0]
+ /* Calculate exc_ret */
+ orr r10, lr, #EXC_RET_THREADMODE_PROCESSSTACK
ldmia sp, {r0-r3, r12}
str r5, [r12, #11 * 4] @ restore the original SVC vector entry
mov lr, r6 @ restore LR
--
2.7.4
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^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] ARM: NOMMU: Fix exc_ret for XIP
2019-10-03 11:41 [PATCH] ARM: NOMMU: Fix exc_ret for XIP Vladimir Murzin
@ 2019-10-04 0:56 ` afzal mohammed
2019-10-04 10:35 ` Vladimir Murzin
2019-10-12 6:37 ` afzal mohammed
1 sibling, 1 reply; 6+ messages in thread
From: afzal mohammed @ 2019-10-04 0:56 UTC (permalink / raw)
To: Vladimir Murzin, linux; +Cc: sza, linux-arm-kernel, alexandre.torgue
On Thu, Oct 03, 2019 at 12:41:28PM +0100, Vladimir Murzin wrote:
> It was reported that 72cd4064fcca "NOMMU: Toggle only bits in
> EXC_RETURN we are really care of" breaks NOMMU+XIP combination.
> It happens because saved EXC_RETURN gets overwritten when data
> section is relocated.
>
> The fix is to propagate EXC_RETURN via register and let relocation
> code to commit that value into memory.
>
> Fixes: 72cd4064fcca ("ARM: 8830/1: NOMMU: Toggle only bits in EXC_RETURN we are really care of")
Thanks Vladimir, cc stable as well ?
Regards
afzal
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] ARM: NOMMU: Fix exc_ret for XIP
2019-10-04 0:56 ` afzal mohammed
@ 2019-10-04 10:35 ` Vladimir Murzin
0 siblings, 0 replies; 6+ messages in thread
From: Vladimir Murzin @ 2019-10-04 10:35 UTC (permalink / raw)
To: afzal mohammed, linux; +Cc: sza, linux-arm-kernel, alexandre.torgue
On 10/4/19 1:56 AM, afzal mohammed wrote:
> On Thu, Oct 03, 2019 at 12:41:28PM +0100, Vladimir Murzin wrote:
>
>> It was reported that 72cd4064fcca "NOMMU: Toggle only bits in
>> EXC_RETURN we are really care of" breaks NOMMU+XIP combination.
>> It happens because saved EXC_RETURN gets overwritten when data
>> section is relocated.
>>
>> The fix is to propagate EXC_RETURN via register and let relocation
>> code to commit that value into memory.
>>
>> Fixes: 72cd4064fcca ("ARM: 8830/1: NOMMU: Toggle only bits in EXC_RETURN we are really care of")
>
> Thanks Vladimir, cc stable as well ?
I believe they they watch "Fixes" tag ;)
Cheers
Vladimir
>
> Regards
> afzal
>
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] ARM: NOMMU: Fix exc_ret for XIP
2019-10-03 11:41 [PATCH] ARM: NOMMU: Fix exc_ret for XIP Vladimir Murzin
2019-10-04 0:56 ` afzal mohammed
@ 2019-10-12 6:37 ` afzal mohammed
2019-10-12 7:24 ` Russell King - ARM Linux admin
1 sibling, 1 reply; 6+ messages in thread
From: afzal mohammed @ 2019-10-12 6:37 UTC (permalink / raw)
To: Vladimir Murzin, Russell King
Cc: alexandre.torgue, linux, linux-arm-kernel, sza
Hi Vladimir,
On Thu, Oct 03, 2019 at 12:41:28PM +0100, Vladimir Murzin wrote:
> It was reported that 72cd4064fcca "NOMMU: Toggle only bits in
> EXC_RETURN we are really care of" breaks NOMMU+XIP combination.
> It happens because saved EXC_RETURN gets overwritten when data
> section is relocated.
>
> The fix is to propagate EXC_RETURN via register and let relocation
> code to commit that value into memory.
>
> Fixes: 72cd4064fcca ("ARM: 8830/1: NOMMU: Toggle only bits in EXC_RETURN we are really care of")
>
> Reported-by: afzal mohammed <afzal.mohd.ma@gmail.com>
> Tested-by: afzal mohammed <afzal.mohd.ma@gmail.com>
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Can you please put this into rmk's patch system.
STM32 Cortex-M boards are currently not booting in mainline, this
change makes them boot again, verified on stm32f429 discovery board.
Regards
afzal
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] ARM: NOMMU: Fix exc_ret for XIP
2019-10-12 6:37 ` afzal mohammed
@ 2019-10-12 7:24 ` Russell King - ARM Linux admin
2019-10-12 9:20 ` afzal mohammed
0 siblings, 1 reply; 6+ messages in thread
From: Russell King - ARM Linux admin @ 2019-10-12 7:24 UTC (permalink / raw)
To: afzal mohammed; +Cc: Vladimir Murzin, alexandre.torgue, linux-arm-kernel, sza
On Sat, Oct 12, 2019 at 12:07:25PM +0530, afzal mohammed wrote:
> Hi Vladimir,
>
> On Thu, Oct 03, 2019 at 12:41:28PM +0100, Vladimir Murzin wrote:
>
> > It was reported that 72cd4064fcca "NOMMU: Toggle only bits in
> > EXC_RETURN we are really care of" breaks NOMMU+XIP combination.
> > It happens because saved EXC_RETURN gets overwritten when data
> > section is relocated.
> >
> > The fix is to propagate EXC_RETURN via register and let relocation
> > code to commit that value into memory.
> >
> > Fixes: 72cd4064fcca ("ARM: 8830/1: NOMMU: Toggle only bits in EXC_RETURN we are really care of")
> >
> > Reported-by: afzal mohammed <afzal.mohd.ma@gmail.com>
> > Tested-by: afzal mohammed <afzal.mohd.ma@gmail.com>
> > Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
>
> Can you please put this into rmk's patch system.
>
> STM32 Cortex-M boards are currently not booting in mainline, this
> change makes them boot again, verified on stm32f429 discovery board.
Please check linux-next - or see 8914/1.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] ARM: NOMMU: Fix exc_ret for XIP
2019-10-12 7:24 ` Russell King - ARM Linux admin
@ 2019-10-12 9:20 ` afzal mohammed
0 siblings, 0 replies; 6+ messages in thread
From: afzal mohammed @ 2019-10-12 9:20 UTC (permalink / raw)
To: Russell King - ARM Linux admin
Cc: Vladimir Murzin, alexandre.torgue, linux-arm-kernel, sza
Hi Russell,
On Sat, Oct 12, 2019 at 08:24:50AM +0100, Russell King - ARM Linux admin wrote:
> On Sat, Oct 12, 2019 at 12:07:25PM +0530, afzal mohammed wrote:
> > Can you please put this into rmk's patch system.
> Please check linux-next - or see 8914/1.
Oh sorry, i checked only incoming in the patch system earlier, didn't
check the applied one, seeing it there, thanks.
Regards
afzal
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^ permalink raw reply [flat|nested] 6+ messages in thread
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2019-10-03 11:41 [PATCH] ARM: NOMMU: Fix exc_ret for XIP Vladimir Murzin
2019-10-04 0:56 ` afzal mohammed
2019-10-04 10:35 ` Vladimir Murzin
2019-10-12 6:37 ` afzal mohammed
2019-10-12 7:24 ` Russell King - ARM Linux admin
2019-10-12 9:20 ` afzal mohammed
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