[PATCH] ARM: V7M: Add dsb before jumping in handler mode

[PATCH] ARM: V7M: Add dsb before jumping in handler mode

[Alexandre TORGUE]

According to ARM AN321 (section 4.12):

"If the vector table is in writable memory such as SRAM, either relocated
by VTOR or a device dependent memory remapping mechanism, then
architecturally a memory barrier instruction is required after the vector
table entry is updated, and if the exception is to be activated
immediately"

Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Signed-off-by: Alexandre TORGUE <alexandre.torgue@st.com>

diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S
index 7229d8d..2ddc435 100644
--- a/arch/arm/mm/proc-v7m.S
+++ b/arch/arm/mm/proc-v7m.S
@@ -104,6 +104,7 @@ __v7m_setup:
 	badr	r1, 1f
 	ldr	r5, [r12, #11 * 4]	@ read the SVC vector entry
 	str	r1, [r12, #11 * 4]	@ write the temporary SVC vector entry
+	dsb
 	mov	r6, lr			@ save LR
 	ldr	sp, =init_thread_union + THREAD_START_SP
 	cpsie	i
-- 
1.9.1

Re: [PATCH] ARM: V7M: Add dsb before jumping in handler mode

[Vladimir Murzin]

On 13/06/16 15:12, Alexandre TORGUE wrote:
> According to ARM AN321 (section 4.12):
> 
> "If the vector table is in writable memory such as SRAM, either relocated
> by VTOR or a device dependent memory remapping mechanism, then
> architecturally a memory barrier instruction is required after the vector
> table entry is updated, and if the exception is to be activated
> immediately"
> 
> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> Signed-off-by: Alexandre TORGUE <alexandre.torgue@st.com>
> 

Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>

> diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S
> index 7229d8d..2ddc435 100644
> --- a/arch/arm/mm/proc-v7m.S
> +++ b/arch/arm/mm/proc-v7m.S
> @@ -104,6 +104,7 @@ __v7m_setup:
>  	badr	r1, 1f
>  	ldr	r5, [r12, #11 * 4]	@ read the SVC vector entry
>  	str	r1, [r12, #11 * 4]	@ write the temporary SVC vector entry
> +	dsb
>  	mov	r6, lr			@ save LR
>  	ldr	sp, =init_thread_union + THREAD_START_SP
>  	cpsie	i
> 

Re: [PATCH] ARM: V7M: Add dsb before jumping in handler mode

[Vladimir Murzin]

On 15/06/16 16:36, Vladimir Murzin wrote:
> On 13/06/16 15:12, Alexandre TORGUE wrote:
>> According to ARM AN321 (section 4.12):
>>
>> "If the vector table is in writable memory such as SRAM, either relocated
>> by VTOR or a device dependent memory remapping mechanism, then
>> architecturally a memory barrier instruction is required after the vector
>> table entry is updated, and if the exception is to be activated
>> immediately"
>>
>> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
>> Signed-off-by: Alexandre TORGUE <alexandre.torgue@st.com>
>>
> 
> Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
> 
>> diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S
>> index 7229d8d..2ddc435 100644
>> --- a/arch/arm/mm/proc-v7m.S
>> +++ b/arch/arm/mm/proc-v7m.S
>> @@ -104,6 +104,7 @@ __v7m_setup:
>>  	badr	r1, 1f
>>  	ldr	r5, [r12, #11 * 4]	@ read the SVC vector entry
>>  	str	r1, [r12, #11 * 4]	@ write the temporary SVC vector entry
>> +	dsb
>>  	mov	r6, lr			@ save LR
>>  	ldr	sp, =init_thread_union + THREAD_START_SP
>>  	cpsie	i
>>
> 

Alex, xan you drop it into RMK's Patch system [1] please?

[1] http://www.armlinux.org.uk/developer/patches/

Thanks
Vladimir

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