[U-Boot] [PATCH v8 1/3] armv8: Support loading 32-bit OS in AArch32 execution state

[Alexander Graf]

On 11/22/2016 06:07 PM, york sun wrote:
> On 11/22/2016 09:02 AM, Alexander Graf wrote:
>> On 11/21/2016 10:48 PM, york sun wrote:
>>> On 11/21/2016 01:07 PM, Alexander Graf wrote:
>>>> On 21/11/2016 21:45, york sun wrote:
>>>>> On 11/21/2016 12:40 PM, Alexander Graf wrote:
>>>>>> On 21/11/2016 21:23, york sun wrote:
>>>>>>> On 11/09/2016 07:02 PM, Alison Wang wrote:
>>>>>>>> To support loading a 32-bit OS, the execution state will change from
>>>>>>>> AArch64 to AArch32 when jumping to kernel.
>>>>>>>>
>>>>>>>> The architecture information will be got through checking FIT image,
>>>>>>>> then U-Boot will load 32-bit OS or 64-bit OS automatically.
>>>>>>>>
>>>>>>>> Signed-off-by: Ebony Zhu <ebony.zhu at nxp.com>
>>>>>>>> Signed-off-by: Alison Wang <alison.wang at nxp.com>
>>>>>>>> Signed-off-by: Chenhui Zhao <chenhui.zhao at nxp.com>
>>>>>>>> ---
>>>>>>>> Changes in v8:
>>>>>>>> - Fix the issue when U-Boot is running in EL2 or EL1.
>>>>>>>>
>>>>>>> Alison,
>>>>>>>
>>>>>>> There is a conflict when merging with upstream code. Alex Graf merged
>>>>>>> his change to support EFI booting. See commit
>>>>>>> 69bd459d343fe1e5a68a6f187d8c99c78c6fc6ce. Specifically these lines
>>>>>>>
>>>>>>>
>>>>>>>            if (current_el() == 3) {
>>>>>>>                    smp_kick_all_cpus();
>>>>>>>                    dcache_disable();
>>>>>>>                    armv8_switch_to_el2();
>>>>>>>                    dcache_enable();
>>>>>>>            }
>>>>>>>
>>>>>>> Function armv8_switch_to_el2() didn't take any argument before you
>>>>>>> change. With your proposed change to support 32-bit OS, you added
>>>>>>> arguments to this function, and presume this function always load OS.
>>>>>>> This may be flawed. Would it be possible to keep armv8_switch_to_el2()
>>>>>>> but introduce another function to carry out switching EL while loading OS?
>>>>>> Alison introduced it based on my comments - and I'd prefer if we only
>>>>>> have the function call based version :).
>>>>>>
>>>>>> It should be reasonably straight forward to move to it here. Just create
>>>>>> a new helper stub that enables the dcache and calls entry().
>>>>>>
>>>>> Alex,
>>>>>
>>>>> Do you always load OS when calling armv8_switch_to_el2()? In this case
>>>>> of efi booting, kernel entry point needs to be passed to the new
>>>>> armv8_switch_to_el2 function. The new armv8_switch_to_el2 function
>>>>> doesn't return, so you cannot continue to run the code.
>>>> We always call some random function pointer in the new flow. That can be
>>>> a kernel entry point, but it can also just be a function pointer. In
>>>> this case, the code would basically look like this:
>>>>
>>>> static ulong efi_run_in_el2(ulong (*entry), void *arg1, void *arg2)
>>>> {
>>>>        dcache_enable();
>>>>        return entry(arg1, arg2);
>>>> }
>>>>
>>>> if (current_el() == 3) {
>>>>        ...
>>>>        return armv8_switch_to_el2(efi_run_in_el2, entry,
>>>> &loaded_image_info, &systab);
>>>> }
>>>>
>>> Alex,
>>>
>>> Since you are most familiar with EFI boot code, can you send a patch to
>>> address this? I can squash it with Alison's patch after testing. My
>>> current test branch is
>>> https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fgit.denx.de%2F%3Fp%3Du-boot%2Fu-boot-fsl-qoriq.git%3Ba%3Dshortlog%3Bh%3Drefs%2Fheads%2Ftest_qoriq&data=01%7C01%7Cyork.sun%40nxp.com%7C0b9b6fdb53c94e1a953d08d412f9502f%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0&sdata=ALW8GdHxkPJghve%2BxbKQ1E9ssjFxSOf35PvVuY34ZiA%3D&reserved=0.
>> While trying to fix this up, I ran across another compile breakage:
>>
>> arch/arm/cpu/armv8/fsl-layerscape/mp.c:114: undefined reference to
>> `initiator_type'
>> arch/arm/cpu/armv8/fsl-layerscape/mp.c:123: undefined reference to
>> `initiator_type'
>>
> Possibly cause by a new set of patches sent by Priyanka for LS2088A.
> Let's use upstream master branch plus Alison's three patches.

No worries, the patch below fixes it. Just wanted to let you know.

Alex


diff --git a/arch/arm/cpu/armv8/fsl-layerscape/cpu.c 
b/arch/arm/cpu/armv8/fsl-layerscape/cpu.c
index 59b0870..d6ee546 100644
--- a/arch/arm/cpu/armv8/fsl-layerscape/cpu.c
+++ b/arch/arm/cpu/armv8/fsl-layerscape/cpu.c
@@ -191,7 +191,7 @@ void enable_caches(void)
  }
  #endif

-inline u32 initiator_type(u32 cluster, int init_id)
+u32 initiator_type(u32 cluster, int init_id)
  {
         struct ccsr_gur *gur = (void *)(CONFIG_SYS_FSL_GUTS_ADDR);
         u32 idx = (cluster >> (init_id * 8)) & TP_CLUSTER_INIT_MASK;