[PATCH v2 5/6] ARM: mm: Update runtime patching code to THUMB2 mode
Sricharan R
r.sricharan at ti.com
Sat Aug 3 08:51:49 EDT 2013
Hi Nicolas,
On Saturday 03 August 2013 09:10 AM, Nicolas Pitre wrote:
> On Wed, 31 Jul 2013, Santosh Shilimkar wrote:
>
>> From: Sricharan R <r.sricharan at ti.com>
>>
>> Update the runtime patching code to support Thumb2. In testing the
>> 64 bit patching code, the issue was uncovered.
>>
>> For better review, the patch is kept separate. If needed it can be
>> merged into "ARM: LPAE: Correct virt_to_phys patching for 64 bit
>> physical addresses"
>>
>> Cc: Nicolas Pitre <nico at linaro.org>
>> Cc: Russell King <linux at arm.linux.org.uk>
>>
>> Signed-off-by: Sricharan R <r.sricharan at ti.com>
>> [santosh.shilimkar at ti.com: reduced #ifdef, updated commit log]
>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
>> ---
>> arch/arm/kernel/head.S | 69 ++++++++++++++++++++++++++++--------------------
>> 1 file changed, 40 insertions(+), 29 deletions(-)
>>
>> diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
>> index aa3b0f7..a70d330 100644
>> --- a/arch/arm/kernel/head.S
>> +++ b/arch/arm/kernel/head.S
>> @@ -573,62 +573,73 @@ ENDPROC(__fixup_pv_table)
>>
>> .text
>> __fixup_a_pv_table:
>> -#ifdef CONFIG_THUMB2_KERNEL
>> - lsls r6, #24
>> - beq 2f
>> - clz r7, r6
>> - lsr r6, #24
>> - lsl r6, r7
>> - bic r6, #0x0080
>> - lsrs r7, #1
>> - orrcs r6, #0x0080
>> - orr r6, r6, r7, lsl #12
>> - orr r6, #0x4000
>> - b 2f
>> -1: add r7, r3
>> - ldrh ip, [r7, #2]
>> - and ip, 0x8f00
>> - orr ip, r6 @ mask in offset bits 31-24
>> - strh ip, [r7, #2]
>> -2: cmp r4, r5
>> - ldrcc r7, [r4], #4 @ use branch for delay slot
>> - bcc 1b
>> - bx lr
>> -#else
>> adr r0, 5f
>> b 4f
>> 1: ldr ip, [r7, r3]
>> + THUMB( 1: add r7, r3)
>> + THUMB( ldrh ip, [r7])
>> + THUMB( ldrh r6, [r7, #2])
>> + THUMB( orr ip, r6, ip, lsl #16)
>> + ARM( 1: ldr ip, [r7, r3])
>> lsr r6, ip, #20 @ extract opcode
> Please don't do this.
>
> - Remember my comment about using mnemonics such as "lsr" in an
> ARM-mode compiled kernel when old binutils are used.
Ok, i will remove this to be generic.
> - There is rather little commonalities between the patching of ARM
> instructions vs Thumb instructions. Especially after you take into
> account my previous comments. Interlacing them makes it harder
> to follow as well in this case.
>
>
> Nicolas
Ok, then i will keep it under #ifdef CONFIG_THUMB2_KERNEL
as it was originally.
Regards,
Sricharan
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