Re: [PATCH] powerpc/64: option to force run-at-load to test relocation

[Michael Ellerman]

Balbir Singh  writes:
> On 12/10/16 17:57, Nicholas Piggin wrote:
>> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
>> index 79da0641..bc9ceac 100644
>> --- a/arch/powerpc/kernel/head_64.S
>> +++ b/arch/powerpc/kernel/head_64.S
>> @@ -111,8 +111,12 @@ __secondary_hold_acknowledge:
>>  .globl  __run_at_load
>>  __run_at_load:
>>  DEFINE_FIXED_SYMBOL(__run_at_load)
>> +#ifdef CONFIG_RELOCATABLE_TEST
>> +.long   0x1 /* Test relocation, do not relocate to 0 */
>> +#else
>>  .long   0x72756e30  /* "run0" -- relocate to 0 by default */
>>  #endif
>> +#endif
>
> Could we do something like
>
> config RELOCATION_VALUE
>   default 0x72756e30
>   default 1  if CONFIG_RELOCTABLE_TEST

I'm not a fan of using kconfig logic when plain #defines would achieve
the same result, eg:

#ifdef CONFIG_RELOCATABLE_TEST
#define RUN_AT_LOAD_DEFAULT 1   /* Test relocation, do not relocate to 
0 */
#else
#define RUN_AT_LOAD_DEFAULT 0x72756e30  /* "run0" -- relocate to 0 by default */
#endif

.globl  __run_at_load
__run_at_load:
DEFINE_FIXED_SYMBOL(__run_at_load)
.long   RUN_AT_LOAD_DEFAULT


Which is probably nicer to look at than Nick's version, but not by a
huge margin. I'd merge either.

cheers

Re: [PATCH] powerpc/64: option to force run-at-load to test relocation

[Balbir Singh]

On 13/10/16 13:25, Nicholas Piggin wrote:
> On Wed, 12 Oct 2016 18:35:21 +1100
> Balbir Singh  wrote:
> 
>> On 12/10/16 17:57, Nicholas Piggin wrote:
>>> This adds a config option that can help exercise the case when
>>> the kernel is not running at PAGE_OFFSET.
>>>
>>> Signed-off-by: Nicholas Piggin 
>>> ---
>>>  arch/powerpc/Kconfig   | 9 +
>>>  arch/powerpc/kernel/head_64.S  | 4 
>>>  arch/powerpc/kernel/setup-common.c | 3 +++
>>>  3 files changed, 16 insertions(+)
>>>
>>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>>> index 65fba4c..5d43cb8 100644
>>> --- a/arch/powerpc/Kconfig
>>> +++ b/arch/powerpc/Kconfig
>>> @@ -478,6 +478,15 @@ config RELOCATABLE
>>>   setting can still be useful to bootwrappers that need to know the
>>>   load address of the kernel (eg. u-boot/mkimage).
>>>  
>>> +config RELOCATABLE_TEST
>>> +   bool "Test relocatable kernel"
>>> +   depends on (PPC64 && RELOCATABLE)
>>> +   default n
>>> +   help
>>> + This runs the relocatable kernel at the address it was initially
>>> + loaded at, which tends to be non-zero and therefore test the
>>> + relocation code.
>>> +
>>>  config CRASH_DUMP
>>> bool "Build a kdump crash kernel"
>>> depends on PPC64 || 6xx || FSL_BOOKE || (44x && !SMP)
>>> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
>>> index 79da0641..bc9ceac 100644
>>> --- a/arch/powerpc/kernel/head_64.S
>>> +++ b/arch/powerpc/kernel/head_64.S
>>> @@ -111,8 +111,12 @@ __secondary_hold_acknowledge:
>>> .globl  __run_at_load
>>>  __run_at_load:
>>>  DEFINE_FIXED_SYMBOL(__run_at_load)
>>> +#ifdef CONFIG_RELOCATABLE_TEST
>>> +   .long   0x1 /* Test relocation, do not relocate to 0 */
>>> +#else
>>> .long   0x72756e30  /* "run0" -- relocate to 0 by default */
>>>  #endif
>>> +#endif  
>>
>> Could we do something like
>>
>> config RELOCATION_VALUE
>>  default 0x72756e30
>>  default 1  if CONFIG_RELOCTABLE_TEST
>>
>> and then get
>>
>>  .long CONFIG_RELOCATION_VALUE
> 
> Normally I'm up for reducing ifdefs in S and c files, but in this case
> I'm not sure. I like being able to see the two possible values in the
> source. I don't really mind though. If you or Michael feel strongly, I'm
> happy to change it.
> 

I guess it depends, for me parsing two .long's under #ifdef seems a little
more work than a .long with a constant depending on the configuration.

I don't feel too strongly about it either

Balbir Singh.

Re: [PATCH] powerpc/64: option to force run-at-load to test relocation

[Nicholas Piggin]

On Wed, 12 Oct 2016 18:35:21 +1100
Balbir Singh  wrote:

> On 12/10/16 17:57, Nicholas Piggin wrote:
> > This adds a config option that can help exercise the case when
> > the kernel is not running at PAGE_OFFSET.
> > 
> > Signed-off-by: Nicholas Piggin 
> > ---
> >  arch/powerpc/Kconfig   | 9 +
> >  arch/powerpc/kernel/head_64.S  | 4 
> >  arch/powerpc/kernel/setup-common.c | 3 +++
> >  3 files changed, 16 insertions(+)
> > 
> > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> > index 65fba4c..5d43cb8 100644
> > --- a/arch/powerpc/Kconfig
> > +++ b/arch/powerpc/Kconfig
> > @@ -478,6 +478,15 @@ config RELOCATABLE
> >   setting can still be useful to bootwrappers that need to know the
> >   load address of the kernel (eg. u-boot/mkimage).
> >  
> > +config RELOCATABLE_TEST
> > +   bool "Test relocatable kernel"
> > +   depends on (PPC64 && RELOCATABLE)
> > +   default n
> > +   help
> > + This runs the relocatable kernel at the address it was initially
> > + loaded at, which tends to be non-zero and therefore test the
> > + relocation code.
> > +
> >  config CRASH_DUMP
> > bool "Build a kdump crash kernel"
> > depends on PPC64 || 6xx || FSL_BOOKE || (44x && !SMP)
> > diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
> > index 79da0641..bc9ceac 100644
> > --- a/arch/powerpc/kernel/head_64.S
> > +++ b/arch/powerpc/kernel/head_64.S
> > @@ -111,8 +111,12 @@ __secondary_hold_acknowledge:
> > .globl  __run_at_load
> >  __run_at_load:
> >  DEFINE_FIXED_SYMBOL(__run_at_load)
> > +#ifdef CONFIG_RELOCATABLE_TEST
> > +   .long   0x1 /* Test relocation, do not relocate to 0 */
> > +#else
> > .long   0x72756e30  /* "run0" -- relocate to 0 by default */
> >  #endif
> > +#endif  
> 
> Could we do something like
> 
> config RELOCATION_VALUE
>   default 0x72756e30
>   default 1  if CONFIG_RELOCTABLE_TEST
> 
> and then get
> 
>   .long CONFIG_RELOCATION_VALUE

Normally I'm up for reducing ifdefs in S and c files, but in this case
I'm not sure. I like being able to see the two possible values in the
source. I don't really mind though. If you or Michael feel strongly, I'm
happy to change it.


> > . = 0x60
> >  /*
> > diff --git a/arch/powerpc/kernel/setup-common.c 
> > b/arch/powerpc/kernel/setup-common.c
> > index dba265c..18e0f19 100644
> > --- a/arch/powerpc/kernel/setup-common.c
> > +++ b/arch/powerpc/kernel/setup-common.c
> > @@ -795,6 +795,9 @@ static __init void print_system_info(void)
> > pr_info("mmu_features  = 0x%08x\n", cur_cpu_spec->mmu_features);
> >  #ifdef CONFIG_PPC64
> > pr_info("firmware_features = 0x%016lx\n", powerpc_firmware_features);
> > +
> > +   if (get_paca()->kernelbase != PAGE_OFFSET)
> > +   pr_info("kernelbase= 0x%llx\n", get_paca()->kernelbase);
> >  #endif
> >
> 
> Do we need this? We get physical_offset if we are relocated.

You're right, that hunk can go.

Thanks,
Nick

Re: [PATCH] powerpc/64: option to force run-at-load to test relocation

[Balbir Singh]

On 12/10/16 17:57, Nicholas Piggin wrote:
> This adds a config option that can help exercise the case when
> the kernel is not running at PAGE_OFFSET.
> 
> Signed-off-by: Nicholas Piggin 
> ---
>  arch/powerpc/Kconfig   | 9 +
>  arch/powerpc/kernel/head_64.S  | 4 
>  arch/powerpc/kernel/setup-common.c | 3 +++
>  3 files changed, 16 insertions(+)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 65fba4c..5d43cb8 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -478,6 +478,15 @@ config RELOCATABLE
> setting can still be useful to bootwrappers that need to know the
> load address of the kernel (eg. u-boot/mkimage).
>  
> +config RELOCATABLE_TEST
> + bool "Test relocatable kernel"
> + depends on (PPC64 && RELOCATABLE)
> + default n
> + help
> +   This runs the relocatable kernel at the address it was initially
> +   loaded at, which tends to be non-zero and therefore test the
> +   relocation code.
> +
>  config CRASH_DUMP
>   bool "Build a kdump crash kernel"
>   depends on PPC64 || 6xx || FSL_BOOKE || (44x && !SMP)
> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
> index 79da0641..bc9ceac 100644
> --- a/arch/powerpc/kernel/head_64.S
> +++ b/arch/powerpc/kernel/head_64.S
> @@ -111,8 +111,12 @@ __secondary_hold_acknowledge:
>   .globl  __run_at_load
>  __run_at_load:
>  DEFINE_FIXED_SYMBOL(__run_at_load)
> +#ifdef CONFIG_RELOCATABLE_TEST
> + .long   0x1 /* Test relocation, do not relocate to 0 */
> +#else
>   .long   0x72756e30  /* "run0" -- relocate to 0 by default */
>  #endif
> +#endif

Could we do something like

config RELOCATION_VALUE
default 0x72756e30
default 1  if CONFIG_RELOCTABLE_TEST

and then get

.long CONFIG_RELOCATION_VALUE




>  
>   . = 0x60
>  /*
> diff --git a/arch/powerpc/kernel/setup-common.c 
> b/arch/powerpc/kernel/setup-common.c
> index dba265c..18e0f19 100644
> --- a/arch/powerpc/kernel/setup-common.c
> +++ b/arch/powerpc/kernel/setup-common.c
> @@ -795,6 +795,9 @@ static __init void print_system_info(void)
>   pr_info("mmu_features  = 0x%08x\n", cur_cpu_spec->mmu_features);
>  #ifdef CONFIG_PPC64
>   pr_info("firmware_features = 0x%016lx\n", powerpc_firmware_features);
> +
> + if (get_paca()->kernelbase != PAGE_OFFSET)
> + pr_info("kernelbase= 0x%llx\n", get_paca()->kernelbase);
>  #endif
>  

Do we need this? We get physical_offset if we are relocated.

>  #ifdef CONFIG_PPC_STD_MMU_64
> 

Balbir Singh.

[PATCH] powerpc/64: option to force run-at-load to test relocation

[Nicholas Piggin]

This adds a config option that can help exercise the case when
the kernel is not running at PAGE_OFFSET.

Signed-off-by: Nicholas Piggin 
---
 arch/powerpc/Kconfig   | 9 +
 arch/powerpc/kernel/head_64.S  | 4 
 arch/powerpc/kernel/setup-common.c | 3 +++
 3 files changed, 16 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 65fba4c..5d43cb8 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -478,6 +478,15 @@ config RELOCATABLE
  setting can still be useful to bootwrappers that need to know the
  load address of the kernel (eg. u-boot/mkimage).
 
+config RELOCATABLE_TEST
+   bool "Test relocatable kernel"
+   depends on (PPC64 && RELOCATABLE)
+   default n
+   help
+ This runs the relocatable kernel at the address it was initially
+ loaded at, which tends to be non-zero and therefore test the
+ relocation code.
+
 config CRASH_DUMP
bool "Build a kdump crash kernel"
depends on PPC64 || 6xx || FSL_BOOKE || (44x && !SMP)
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 79da0641..bc9ceac 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -111,8 +111,12 @@ __secondary_hold_acknowledge:
.globl  __run_at_load
 __run_at_load:
 DEFINE_FIXED_SYMBOL(__run_at_load)
+#ifdef CONFIG_RELOCATABLE_TEST
+   .long   0x1 /* Test relocation, do not relocate to 0 */
+#else
.long   0x72756e30  /* "run0" -- relocate to 0 by default */
 #endif
+#endif
 
. = 0x60
 /*
diff --git a/arch/powerpc/kernel/setup-common.c 
b/arch/powerpc/kernel/setup-common.c
index dba265c..18e0f19 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -795,6 +795,9 @@ static __init void print_system_info(void)
pr_info("mmu_features  = 0x%08x\n", cur_cpu_spec->mmu_features);
 #ifdef CONFIG_PPC64
pr_info("firmware_features = 0x%016lx\n", powerpc_firmware_features);
+
+   if (get_paca()->kernelbase != PAGE_OFFSET)
+   pr_info("kernelbase= 0x%llx\n", get_paca()->kernelbase);
 #endif
 
 #ifdef CONFIG_PPC_STD_MMU_64
-- 
2.9.3