Re: [PATCH -next v2] arm64: fix build warning for ARM64_MEMSTART_SHIFT

Re: [PATCH -next v2] arm64: fix build warning for ARM64_MEMSTART_SHIFT

[Catalin Marinas]

On Mon, Jul 24, 2023 at 05:27:51PM +0000, Zhang Jianhua wrote:
> When building with W=1, the following warning occurs.
> 
> arch/arm64/include/asm/kernel-pgtable.h:129:41: error: "PUD_SHIFT" is not defined, evaluates to 0 [-Werror=undef]
>   129 | #define ARM64_MEMSTART_SHIFT            PUD_SHIFT
>       |                                         ^~~~~~~~~
> arch/arm64/include/asm/kernel-pgtable.h:142:5: note: in expansion of macro ‘ARM64_MEMSTART_SHIFT’
>   142 | #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
>       |     ^~~~~~~~~~~~~~~~~~~~

Another thing that's missing here is that the warning is probably when
this file is included from asm-offests.h or some .S file.

> diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
> index 577773870b66..51bdce66885d 100644
> --- a/arch/arm64/include/asm/kernel-pgtable.h
> +++ b/arch/arm64/include/asm/kernel-pgtable.h
> @@ -125,12 +125,14 @@
>   * (64k granule), or a multiple that can be mapped using contiguous bits
>   * in the page tables: 32 * PMD_SIZE (16k granule)
>   */
> -#if defined(CONFIG_ARM64_4K_PAGES)
> +#if defined(CONFIG_ARM64_4K_PAGES) && defined(PUD_SHIFT)
>  #define ARM64_MEMSTART_SHIFT		PUD_SHIFT

That's not the correct fix since PUD_SHIFT should always be defined.
When CONFIG_PGTABLE_LEVELS == 3, pgtable-types.h includes
asm-generic/pgtable-nopud.h and this defines PUD_SHIFT. We either got
ARM64_MEMSTART_SHIFT defined in the wrong file or kernel-pgtable.h does
not pull the relevant headers (either directly or via an included
header). Even if kernel-pgtable.h ends up including the nopud/nopmd
headers, P*D_SHIFT is guarded by an #indef __ASSEMBLY__ in those files.

Something like below appears to fix this, though I'm not particularly
fond of guarding the ARM64_MEMSTART_* definitions by #ifndef
__ASSEMBLY__ for no apparent reason (could add a comment though):

-----------------------8<---------------------------
diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
index 577773870b66..fcea7e87a6ca 100644
--- a/arch/arm64/include/asm/kernel-pgtable.h
+++ b/arch/arm64/include/asm/kernel-pgtable.h
@@ -118,6 +118,8 @@
 #define SWAPPER_RX_MMUFLAGS	(SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
 #endif
 
+#ifndef __ASSEMBLY__
+
 /*
  * To make optimal use of block mappings when laying out the linear
  * mapping, round down the base of physical memory to a size that can
@@ -145,4 +147,6 @@
 #define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
 #endif
 
+#endif /* __ASSEMBLY__ */
+
 #endif	/* __ASM_KERNEL_PGTABLE_H */
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index e4944d517c99..22b36f2d5d93 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -6,6 +6,7 @@
 #define __ASM_PGTABLE_HWDEF_H
 
 #include <asm/memory.h>
+#include <asm/pgtable-types.h>
 
 /*
  * Number of page-table levels required to address 'va_bits' wide
diff --git a/arch/arm64/include/asm/pgtable-types.h b/arch/arm64/include/asm/pgtable-types.h
index b8f158ae2527..ae86e66fdb11 100644
--- a/arch/arm64/include/asm/pgtable-types.h
+++ b/arch/arm64/include/asm/pgtable-types.h
@@ -11,6 +11,8 @@
 
 #include <asm/types.h>
 
+#ifndef __ASSEMBLY__
+
 typedef u64 pteval_t;
 typedef u64 pmdval_t;
 typedef u64 pudval_t;
@@ -44,6 +46,8 @@ typedef struct { pteval_t pgprot; } pgprot_t;
 #define pgprot_val(x)	((x).pgprot)
 #define __pgprot(x)	((pgprot_t) { (x) } )
 
+#endif /* __ASSEMBLY__ */
+
 #if CONFIG_PGTABLE_LEVELS == 2
 #include <asm-generic/pgtable-nopmd.h>
 #elif CONFIG_PGTABLE_LEVELS == 3
-----------------------8<---------------------------

To avoid guarding the ARM64_MEMSTART_* definitions, we could instead
move the P*D_SHIFT definitions in asm-generic/pgtable-nop*d.h outside
the #ifndef __ASSEMBLY__ block.

-- 
Catalin

[PATCH -next v2] arm64: fix build warning for ARM64_MEMSTART_SHIFT

[Zhang Jianhua]

When building with W=1, the following warning occurs.

arch/arm64/include/asm/kernel-pgtable.h:129:41: error: "PUD_SHIFT" is not defined, evaluates to 0 [-Werror=undef]
  129 | #define ARM64_MEMSTART_SHIFT            PUD_SHIFT
      |                                         ^~~~~~~~~
arch/arm64/include/asm/kernel-pgtable.h:142:5: note: in expansion of macro ‘ARM64_MEMSTART_SHIFT’
  142 | #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
      |     ^~~~~~~~~~~~~~~~~~~~

The reason is that PUD_SHIFT isn't defined if CONFIG_PGTABLE_LEVELS == 3
and CONFIG_VA_BITS == 39. For this scenario, the macro ARM64_MEMSTART_SHIFT
would be defined to different value of PUD_SHIFT/CONT_PMD_SHIFT/CONT_PMD_SHIFT
according to different config, any of them would be undefined as long as
the value is equal to PGDIR_SHIFT, so add judgement before reference and
set the default value.

Signed-off-by: Zhang Jianhua <chris.zjh@huawei.com>
---
v2:
	Add define judgement of PUD_SHIFT/CONT_PMD_SHIFT/CONT_PMD_SHIFT before
	use them, instead of define PUD_SHIFT only.
---
---
 arch/arm64/include/asm/kernel-pgtable.h | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
index 577773870b66..51bdce66885d 100644
--- a/arch/arm64/include/asm/kernel-pgtable.h
+++ b/arch/arm64/include/asm/kernel-pgtable.h
@@ -125,12 +125,14 @@
  * (64k granule), or a multiple that can be mapped using contiguous bits
  * in the page tables: 32 * PMD_SIZE (16k granule)
  */
-#if defined(CONFIG_ARM64_4K_PAGES)
+#if defined(CONFIG_ARM64_4K_PAGES) && defined(PUD_SHIFT)
 #define ARM64_MEMSTART_SHIFT		PUD_SHIFT
-#elif defined(CONFIG_ARM64_16K_PAGES)
+#elif defined(CONFIG_ARM64_16K_PAGES) && defined(CONT_PMD_SHIFT)
 #define ARM64_MEMSTART_SHIFT		CONT_PMD_SHIFT
-#else
+#elif defined(CONFIG_ARM64_64K_PAGES) && defined(PMD_SHIFT)
 #define ARM64_MEMSTART_SHIFT		PMD_SHIFT
+#else
+#define ARM64_MEMSTART_SHIFT		PGDIR_SHIFT
 #endif
 
 /*
-- 
2.34.1

Re: [PATCH -next v2] arm64: fix build warning for ARM64_MEMSTART_SHIFT

[Anshuman Khandual]

On 7/24/23 20:41, Catalin Marinas wrote:
> On Mon, Jul 24, 2023 at 05:27:51PM +0000, Zhang Jianhua wrote:
>> When building with W=1, the following warning occurs.
>>
>> arch/arm64/include/asm/kernel-pgtable.h:129:41: error: "PUD_SHIFT" is not defined, evaluates to 0 [-Werror=undef]
>>   129 | #define ARM64_MEMSTART_SHIFT            PUD_SHIFT
>>       |                                         ^~~~~~~~~
>> arch/arm64/include/asm/kernel-pgtable.h:142:5: note: in expansion of macro ‘ARM64_MEMSTART_SHIFT’
>>   142 | #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
>>       |     ^~~~~~~~~~~~~~~~~~~~
> 
> Another thing that's missing here is that the warning is probably when
> this file is included from asm-offests.h or some .S file.
> 
>> diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
>> index 577773870b66..51bdce66885d 100644
>> --- a/arch/arm64/include/asm/kernel-pgtable.h
>> +++ b/arch/arm64/include/asm/kernel-pgtable.h
>> @@ -125,12 +125,14 @@
>>   * (64k granule), or a multiple that can be mapped using contiguous bits
>>   * in the page tables: 32 * PMD_SIZE (16k granule)
>>   */
>> -#if defined(CONFIG_ARM64_4K_PAGES)
>> +#if defined(CONFIG_ARM64_4K_PAGES) && defined(PUD_SHIFT)
>>  #define ARM64_MEMSTART_SHIFT		PUD_SHIFT
> 
> That's not the correct fix since PUD_SHIFT should always be defined.
> When CONFIG_PGTABLE_LEVELS == 3, pgtable-types.h includes
> asm-generic/pgtable-nopud.h and this defines PUD_SHIFT. We either got

Right, PUD_SHIFT is always defined irrespective of page table levels.

> ARM64_MEMSTART_SHIFT defined in the wrong file or kernel-pgtable.h does
> not pull the relevant headers (either directly or via an included
> header). Even if kernel-pgtable.h ends up including the nopud/nopmd
> headers, P*D_SHIFT is guarded by an #indef __ASSEMBLY__ in those files.
> 
> Something like below appears to fix this, though I'm not particularly
> fond of guarding the ARM64_MEMSTART_* definitions by #ifndef
> __ASSEMBLY__ for no apparent reason (could add a comment though):
> 
> -----------------------8<---------------------------
> diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
> index 577773870b66..fcea7e87a6ca 100644
> --- a/arch/arm64/include/asm/kernel-pgtable.h
> +++ b/arch/arm64/include/asm/kernel-pgtable.h
> @@ -118,6 +118,8 @@
>  #define SWAPPER_RX_MMUFLAGS	(SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
>  #endif
>  
> +#ifndef __ASSEMBLY__
> +
>  /*
>   * To make optimal use of block mappings when laying out the linear
>   * mapping, round down the base of physical memory to a size that can
> @@ -145,4 +147,6 @@
>  #define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
>  #endif
>  
> +#endif /* __ASSEMBLY__ */
> +
>  #endif	/* __ASM_KERNEL_PGTABLE_H */
> diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
> index e4944d517c99..22b36f2d5d93 100644
> --- a/arch/arm64/include/asm/pgtable-hwdef.h
> +++ b/arch/arm64/include/asm/pgtable-hwdef.h
> @@ -6,6 +6,7 @@
>  #define __ASM_PGTABLE_HWDEF_H
>  
>  #include <asm/memory.h>
> +#include <asm/pgtable-types.h>
>  
>  /*
>   * Number of page-table levels required to address 'va_bits' wide
> diff --git a/arch/arm64/include/asm/pgtable-types.h b/arch/arm64/include/asm/pgtable-types.h
> index b8f158ae2527..ae86e66fdb11 100644
> --- a/arch/arm64/include/asm/pgtable-types.h
> +++ b/arch/arm64/include/asm/pgtable-types.h
> @@ -11,6 +11,8 @@
>  
>  #include <asm/types.h>
>  
> +#ifndef __ASSEMBLY__
> +
>  typedef u64 pteval_t;
>  typedef u64 pmdval_t;
>  typedef u64 pudval_t;
> @@ -44,6 +46,8 @@ typedef struct { pteval_t pgprot; } pgprot_t;
>  #define pgprot_val(x)	((x).pgprot)
>  #define __pgprot(x)	((pgprot_t) { (x) } )
>  
> +#endif /* __ASSEMBLY__ */
> +
>  #if CONFIG_PGTABLE_LEVELS == 2
>  #include <asm-generic/pgtable-nopmd.h>
>  #elif CONFIG_PGTABLE_LEVELS == 3
> -----------------------8<---------------------------
> 
> To avoid guarding the ARM64_MEMSTART_* definitions, we could instead
> move the P*D_SHIFT definitions in asm-generic/pgtable-nop*d.h outside
> the #ifndef __ASSEMBLY__ block.

OR could ARM64_MEMSTART_SHIFT and ARM64_MEMSTART_ALIGN computation blocks
be moved inside arch/arm64/mm/init.c, where it is used exclusively. Seems
to be solving the problem as well.

Re: [PATCH -next v2] arm64: fix build warning for ARM64_MEMSTART_SHIFT

[zhangjianhua (E)]

在 2023/7/25 12:22, Anshuman Khandual 写道:
>
> On 7/24/23 20:41, Catalin Marinas wrote:
>> On Mon, Jul 24, 2023 at 05:27:51PM +0000, Zhang Jianhua wrote:
>>> When building with W=1, the following warning occurs.
>>>
>>> arch/arm64/include/asm/kernel-pgtable.h:129:41: error: "PUD_SHIFT" is not defined, evaluates to 0 [-Werror=undef]
>>>    129 | #define ARM64_MEMSTART_SHIFT            PUD_SHIFT
>>>        |                                         ^~~~~~~~~
>>> arch/arm64/include/asm/kernel-pgtable.h:142:5: note: in expansion of macro ‘ARM64_MEMSTART_SHIFT’
>>>    142 | #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
>>>        |     ^~~~~~~~~~~~~~~~~~~~
>> Another thing that's missing here is that the warning is probably when
>> this file is included from asm-offests.h or some .S file.
>>
>>> diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
>>> index 577773870b66..51bdce66885d 100644
>>> --- a/arch/arm64/include/asm/kernel-pgtable.h
>>> +++ b/arch/arm64/include/asm/kernel-pgtable.h
>>> @@ -125,12 +125,14 @@
>>>    * (64k granule), or a multiple that can be mapped using contiguous bits
>>>    * in the page tables: 32 * PMD_SIZE (16k granule)
>>>    */
>>> -#if defined(CONFIG_ARM64_4K_PAGES)
>>> +#if defined(CONFIG_ARM64_4K_PAGES) && defined(PUD_SHIFT)
>>>   #define ARM64_MEMSTART_SHIFT		PUD_SHIFT
>> That's not the correct fix since PUD_SHIFT should always be defined.
>> When CONFIG_PGTABLE_LEVELS == 3, pgtable-types.h includes
>> asm-generic/pgtable-nopud.h and this defines PUD_SHIFT. We either got
> Right, PUD_SHIFT is always defined irrespective of page table levels.
>
>> ARM64_MEMSTART_SHIFT defined in the wrong file or kernel-pgtable.h does
>> not pull the relevant headers (either directly or via an included
>> header). Even if kernel-pgtable.h ends up including the nopud/nopmd
>> headers, P*D_SHIFT is guarded by an #indef __ASSEMBLY__ in those files.
>>
>> Something like below appears to fix this, though I'm not particularly
>> fond of guarding the ARM64_MEMSTART_* definitions by #ifndef
>> __ASSEMBLY__ for no apparent reason (could add a comment though):
>>
>> -----------------------8<---------------------------
>> diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
>> index 577773870b66..fcea7e87a6ca 100644
>> --- a/arch/arm64/include/asm/kernel-pgtable.h
>> +++ b/arch/arm64/include/asm/kernel-pgtable.h
>> @@ -118,6 +118,8 @@
>>   #define SWAPPER_RX_MMUFLAGS	(SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
>>   #endif
>>   
>> +#ifndef __ASSEMBLY__
>> +
>>   /*
>>    * To make optimal use of block mappings when laying out the linear
>>    * mapping, round down the base of physical memory to a size that can
>> @@ -145,4 +147,6 @@
>>   #define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
>>   #endif
>>   
>> +#endif /* __ASSEMBLY__ */
>> +
>>   #endif	/* __ASM_KERNEL_PGTABLE_H */
>> diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
>> index e4944d517c99..22b36f2d5d93 100644
>> --- a/arch/arm64/include/asm/pgtable-hwdef.h
>> +++ b/arch/arm64/include/asm/pgtable-hwdef.h
>> @@ -6,6 +6,7 @@
>>   #define __ASM_PGTABLE_HWDEF_H
>>   
>>   #include <asm/memory.h>
>> +#include <asm/pgtable-types.h>
>>   
>>   /*
>>    * Number of page-table levels required to address 'va_bits' wide
>> diff --git a/arch/arm64/include/asm/pgtable-types.h b/arch/arm64/include/asm/pgtable-types.h
>> index b8f158ae2527..ae86e66fdb11 100644
>> --- a/arch/arm64/include/asm/pgtable-types.h
>> +++ b/arch/arm64/include/asm/pgtable-types.h
>> @@ -11,6 +11,8 @@
>>   
>>   #include <asm/types.h>
>>   
>> +#ifndef __ASSEMBLY__
>> +
>>   typedef u64 pteval_t;
>>   typedef u64 pmdval_t;
>>   typedef u64 pudval_t;
>> @@ -44,6 +46,8 @@ typedef struct { pteval_t pgprot; } pgprot_t;
>>   #define pgprot_val(x)	((x).pgprot)
>>   #define __pgprot(x)	((pgprot_t) { (x) } )
>>   
>> +#endif /* __ASSEMBLY__ */
>> +
>>   #if CONFIG_PGTABLE_LEVELS == 2
>>   #include <asm-generic/pgtable-nopmd.h>
>>   #elif CONFIG_PGTABLE_LEVELS == 3
>> -----------------------8<---------------------------
>>
>> To avoid guarding the ARM64_MEMSTART_* definitions, we could instead
>> move the P*D_SHIFT definitions in asm-generic/pgtable-nop*d.h outside
>> the #ifndef __ASSEMBLY__ block.
> OR could ARM64_MEMSTART_SHIFT and ARM64_MEMSTART_ALIGN computation blocks
> be moved inside arch/arm64/mm/init.c, where it is used exclusively. Seems
> to be solving the problem as well.

This method can avoid the current compilation warning, but does not 
solve the problem

that PUD_SHIFT and PMD_SHIFT undefined in fact, and it is contrary to 
XXX_SHIFT should

always be defined. Maybe it would be more appropriate to solve this 
issue directly.

Re: [PATCH -next v2] arm64: fix build warning for ARM64_MEMSTART_SHIFT

[Catalin Marinas]

On Tue, Jul 25, 2023 at 04:47:46PM +0800, zhangjianhua (E) wrote:
> 在 2023/7/25 12:22, Anshuman Khandual 写道:
> > On 7/24/23 20:41, Catalin Marinas wrote:
> > > On Mon, Jul 24, 2023 at 05:27:51PM +0000, Zhang Jianhua wrote:
> > > > When building with W=1, the following warning occurs.
> > > > 
> > > > arch/arm64/include/asm/kernel-pgtable.h:129:41: error: "PUD_SHIFT" is not defined, evaluates to 0 [-Werror=undef]
> > > >    129 | #define ARM64_MEMSTART_SHIFT            PUD_SHIFT
> > > >        |                                         ^~~~~~~~~
> > > > arch/arm64/include/asm/kernel-pgtable.h:142:5: note: in expansion of macro ‘ARM64_MEMSTART_SHIFT’
> > > >    142 | #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
> > > >        |     ^~~~~~~~~~~~~~~~~~~~
> > > 
> > > Another thing that's missing here is that the warning is probably when
> > > this file is included from asm-offests.h or some .S file.
> > > 
> > > > diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
> > > > index 577773870b66..51bdce66885d 100644
> > > > --- a/arch/arm64/include/asm/kernel-pgtable.h
> > > > +++ b/arch/arm64/include/asm/kernel-pgtable.h
> > > > @@ -125,12 +125,14 @@
> > > >    * (64k granule), or a multiple that can be mapped using contiguous bits
> > > >    * in the page tables: 32 * PMD_SIZE (16k granule)
> > > >    */
> > > > -#if defined(CONFIG_ARM64_4K_PAGES)
> > > > +#if defined(CONFIG_ARM64_4K_PAGES) && defined(PUD_SHIFT)
> > > >   #define ARM64_MEMSTART_SHIFT		PUD_SHIFT
> > > That's not the correct fix since PUD_SHIFT should always be defined.
> > > When CONFIG_PGTABLE_LEVELS == 3, pgtable-types.h includes
> > > asm-generic/pgtable-nopud.h and this defines PUD_SHIFT. We either got
> > 
> > Right, PUD_SHIFT is always defined irrespective of page table levels.
> > 
> > > ARM64_MEMSTART_SHIFT defined in the wrong file or kernel-pgtable.h does
> > > not pull the relevant headers (either directly or via an included
> > > header). Even if kernel-pgtable.h ends up including the nopud/nopmd
> > > headers, P*D_SHIFT is guarded by an #indef __ASSEMBLY__ in those files.
> > > 
> > > Something like below appears to fix this, though I'm not particularly
> > > fond of guarding the ARM64_MEMSTART_* definitions by #ifndef
> > > __ASSEMBLY__ for no apparent reason (could add a comment though):
> > > 
> > > -----------------------8<---------------------------
> > > diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
> > > index 577773870b66..fcea7e87a6ca 100644
> > > --- a/arch/arm64/include/asm/kernel-pgtable.h
> > > +++ b/arch/arm64/include/asm/kernel-pgtable.h
> > > @@ -118,6 +118,8 @@
> > >   #define SWAPPER_RX_MMUFLAGS	(SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
> > >   #endif
> > > +#ifndef __ASSEMBLY__
> > > +
> > >   /*
> > >    * To make optimal use of block mappings when laying out the linear
> > >    * mapping, round down the base of physical memory to a size that can
> > > @@ -145,4 +147,6 @@
> > >   #define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
> > >   #endif
> > > +#endif /* __ASSEMBLY__ */
> > > +
> > >   #endif	/* __ASM_KERNEL_PGTABLE_H */
> > > diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
> > > index e4944d517c99..22b36f2d5d93 100644
> > > --- a/arch/arm64/include/asm/pgtable-hwdef.h
> > > +++ b/arch/arm64/include/asm/pgtable-hwdef.h
> > > @@ -6,6 +6,7 @@
> > >   #define __ASM_PGTABLE_HWDEF_H
> > >   #include <asm/memory.h>
> > > +#include <asm/pgtable-types.h>
> > >   /*
> > >    * Number of page-table levels required to address 'va_bits' wide
> > > diff --git a/arch/arm64/include/asm/pgtable-types.h b/arch/arm64/include/asm/pgtable-types.h
> > > index b8f158ae2527..ae86e66fdb11 100644
> > > --- a/arch/arm64/include/asm/pgtable-types.h
> > > +++ b/arch/arm64/include/asm/pgtable-types.h
> > > @@ -11,6 +11,8 @@
> > >   #include <asm/types.h>
> > > +#ifndef __ASSEMBLY__
> > > +
> > >   typedef u64 pteval_t;
> > >   typedef u64 pmdval_t;
> > >   typedef u64 pudval_t;
> > > @@ -44,6 +46,8 @@ typedef struct { pteval_t pgprot; } pgprot_t;
> > >   #define pgprot_val(x)	((x).pgprot)
> > >   #define __pgprot(x)	((pgprot_t) { (x) } )
> > > +#endif /* __ASSEMBLY__ */
> > > +
> > >   #if CONFIG_PGTABLE_LEVELS == 2
> > >   #include <asm-generic/pgtable-nopmd.h>
> > >   #elif CONFIG_PGTABLE_LEVELS == 3
> > > -----------------------8<---------------------------
> > > 
> > > To avoid guarding the ARM64_MEMSTART_* definitions, we could instead
> > > move the P*D_SHIFT definitions in asm-generic/pgtable-nop*d.h outside
> > > the #ifndef __ASSEMBLY__ block.
> > 
> > OR could ARM64_MEMSTART_SHIFT and ARM64_MEMSTART_ALIGN computation blocks
> > be moved inside arch/arm64/mm/init.c, where it is used exclusively. Seems
> > to be solving the problem as well.

That's fine by me, better than adding the #ifndef __ASSEMBLY__ around
them.

> This method can avoid the current compilation warning, but does not
> solve the problem that PUD_SHIFT and PMD_SHIFT undefined in fact, and
> it is contrary to XXX_SHIFT should always be defined. Maybe it would
> be more appropriate to solve this issue directly.

For .c files, we can solve this by including asm/pgtable-types.h in
asm/pgtable-hwdef.h. This still leaves P*D_SHIFT undefined for .S files
since the generic nop*d.h headers guard the shifts with !__ASSEMBLY__
but do we really care about this? I haven't seen any other warning of
P*D_SHIFT not being defined. If you do want to solve these, just go and
change the generic headers to take the shift out of the asm guard. I
don't think it's worth it.

-- 
Catalin

Re: [PATCH -next v2] arm64: fix build warning for ARM64_MEMSTART_SHIFT

[zhangjianhua (E)]

在 2023/7/25 18:15, Catalin Marinas 写道:
> On Tue, Jul 25, 2023 at 04:47:46PM +0800, zhangjianhua (E) wrote:
>> 在 2023/7/25 12:22, Anshuman Khandual 写道:
>>> On 7/24/23 20:41, Catalin Marinas wrote:
>>>> On Mon, Jul 24, 2023 at 05:27:51PM +0000, Zhang Jianhua wrote:
>>>>> When building with W=1, the following warning occurs.
>>>>>
>>>>> arch/arm64/include/asm/kernel-pgtable.h:129:41: error: "PUD_SHIFT" is not defined, evaluates to 0 [-Werror=undef]
>>>>>     129 | #define ARM64_MEMSTART_SHIFT            PUD_SHIFT
>>>>>         |                                         ^~~~~~~~~
>>>>> arch/arm64/include/asm/kernel-pgtable.h:142:5: note: in expansion of macro ‘ARM64_MEMSTART_SHIFT’
>>>>>     142 | #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
>>>>>         |     ^~~~~~~~~~~~~~~~~~~~
>>>> Another thing that's missing here is that the warning is probably when
>>>> this file is included from asm-offests.h or some .S file.
>>>>
>>>>> diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
>>>>> index 577773870b66..51bdce66885d 100644
>>>>> --- a/arch/arm64/include/asm/kernel-pgtable.h
>>>>> +++ b/arch/arm64/include/asm/kernel-pgtable.h
>>>>> @@ -125,12 +125,14 @@
>>>>>     * (64k granule), or a multiple that can be mapped using contiguous bits
>>>>>     * in the page tables: 32 * PMD_SIZE (16k granule)
>>>>>     */
>>>>> -#if defined(CONFIG_ARM64_4K_PAGES)
>>>>> +#if defined(CONFIG_ARM64_4K_PAGES) && defined(PUD_SHIFT)
>>>>>    #define ARM64_MEMSTART_SHIFT		PUD_SHIFT
>>>> That's not the correct fix since PUD_SHIFT should always be defined.
>>>> When CONFIG_PGTABLE_LEVELS == 3, pgtable-types.h includes
>>>> asm-generic/pgtable-nopud.h and this defines PUD_SHIFT. We either got
>>> Right, PUD_SHIFT is always defined irrespective of page table levels.
>>>
>>>> ARM64_MEMSTART_SHIFT defined in the wrong file or kernel-pgtable.h does
>>>> not pull the relevant headers (either directly or via an included
>>>> header). Even if kernel-pgtable.h ends up including the nopud/nopmd
>>>> headers, P*D_SHIFT is guarded by an #indef __ASSEMBLY__ in those files.
>>>>
>>>> Something like below appears to fix this, though I'm not particularly
>>>> fond of guarding the ARM64_MEMSTART_* definitions by #ifndef
>>>> __ASSEMBLY__ for no apparent reason (could add a comment though):
>>>>
>>>> -----------------------8<---------------------------
>>>> diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
>>>> index 577773870b66..fcea7e87a6ca 100644
>>>> --- a/arch/arm64/include/asm/kernel-pgtable.h
>>>> +++ b/arch/arm64/include/asm/kernel-pgtable.h
>>>> @@ -118,6 +118,8 @@
>>>>    #define SWAPPER_RX_MMUFLAGS	(SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
>>>>    #endif
>>>> +#ifndef __ASSEMBLY__
>>>> +
>>>>    /*
>>>>     * To make optimal use of block mappings when laying out the linear
>>>>     * mapping, round down the base of physical memory to a size that can
>>>> @@ -145,4 +147,6 @@
>>>>    #define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
>>>>    #endif
>>>> +#endif /* __ASSEMBLY__ */
>>>> +
>>>>    #endif	/* __ASM_KERNEL_PGTABLE_H */
>>>> diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
>>>> index e4944d517c99..22b36f2d5d93 100644
>>>> --- a/arch/arm64/include/asm/pgtable-hwdef.h
>>>> +++ b/arch/arm64/include/asm/pgtable-hwdef.h
>>>> @@ -6,6 +6,7 @@
>>>>    #define __ASM_PGTABLE_HWDEF_H
>>>>    #include <asm/memory.h>
>>>> +#include <asm/pgtable-types.h>
>>>>    /*
>>>>     * Number of page-table levels required to address 'va_bits' wide
>>>> diff --git a/arch/arm64/include/asm/pgtable-types.h b/arch/arm64/include/asm/pgtable-types.h
>>>> index b8f158ae2527..ae86e66fdb11 100644
>>>> --- a/arch/arm64/include/asm/pgtable-types.h
>>>> +++ b/arch/arm64/include/asm/pgtable-types.h
>>>> @@ -11,6 +11,8 @@
>>>>    #include <asm/types.h>
>>>> +#ifndef __ASSEMBLY__
>>>> +
>>>>    typedef u64 pteval_t;
>>>>    typedef u64 pmdval_t;
>>>>    typedef u64 pudval_t;
>>>> @@ -44,6 +46,8 @@ typedef struct { pteval_t pgprot; } pgprot_t;
>>>>    #define pgprot_val(x)	((x).pgprot)
>>>>    #define __pgprot(x)	((pgprot_t) { (x) } )
>>>> +#endif /* __ASSEMBLY__ */
>>>> +
>>>>    #if CONFIG_PGTABLE_LEVELS == 2
>>>>    #include <asm-generic/pgtable-nopmd.h>
>>>>    #elif CONFIG_PGTABLE_LEVELS == 3
>>>> -----------------------8<---------------------------
>>>>
>>>> To avoid guarding the ARM64_MEMSTART_* definitions, we could instead
>>>> move the P*D_SHIFT definitions in asm-generic/pgtable-nop*d.h outside
>>>> the #ifndef __ASSEMBLY__ block.
>>> OR could ARM64_MEMSTART_SHIFT and ARM64_MEMSTART_ALIGN computation blocks
>>> be moved inside arch/arm64/mm/init.c, where it is used exclusively. Seems
>>> to be solving the problem as well.
> That's fine by me, better than adding the #ifndef __ASSEMBLY__ around
> them.
>
>> This method can avoid the current compilation warning, but does not
>> solve the problem that PUD_SHIFT and PMD_SHIFT undefined in fact, and
>> it is contrary to XXX_SHIFT should always be defined. Maybe it would
>> be more appropriate to solve this issue directly.
> For .c files, we can solve this by including asm/pgtable-types.h in
> asm/pgtable-hwdef.h. This still leaves P*D_SHIFT undefined for .S files
> since the generic nop*d.h headers guard the shifts with !__ASSEMBLY__
> but do we really care about this? I haven't seen any other warning of
> P*D_SHIFT not being defined. If you do want to solve these, just go and
> change the generic headers to take the shift out of the asm guard. I
> don't think it's worth it.
OK, agree, I will send a new patch for Anshuman's method.