2020-09-07 18:07:34

by Gerald Schaefer

Subject: [RFC PATCH v2 3/3] mm: make generic pXd_addr_end() macros inline functions

From: Alexander Gordeev <[email protected]>

Since pXd_addr_end() macros take pXd page-table entry as a
parameter it makes sense to check the entry type on compile.
Even though most archs do not make use of page-table entries
in pXd_addr_end() calls, checking the type in traversal code
paths could help to avoid subtle bugs.

Signed-off-by: Alexander Gordeev <[email protected]>
Signed-off-by: Gerald Schaefer <[email protected]>
---
include/linux/pgtable.h | 36 ++++++++++++++++++++----------------
1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 67ebc22cf83d..d9e7d16c2263 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -656,31 +656,35 @@ static inline int arch_unmap_one(struct mm_struct *mm,
*/

#ifndef pgd_addr_end
-#define pgd_addr_end(pgd, addr, end) \
-({ unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK; \
- (__boundary - 1 < (end) - 1)? __boundary: (end); \
-})
+#define pgd_addr_end pgd_addr_end
+static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
+{ unsigned long __boundary = (addr + PGDIR_SIZE) & PGDIR_MASK;
+ return (__boundary - 1 < end - 1) ? __boundary : end;
+}
#endif

#ifndef p4d_addr_end
-#define p4d_addr_end(p4d, addr, end) \
-({ unsigned long __boundary = ((addr) + P4D_SIZE) & P4D_MASK; \
- (__boundary - 1 < (end) - 1)? __boundary: (end); \
-})
+#define p4d_addr_end p4d_addr_end
+static inline unsigned long p4d_addr_end(p4d_t p4d, unsigned long addr, unsigned long end)
+{ unsigned long __boundary = (addr + P4D_SIZE) & P4D_MASK;
+ return (__boundary - 1 < end - 1) ? __boundary : end;
+}
#endif

#ifndef pud_addr_end
-#define pud_addr_end(pud, addr, end) \
-({ unsigned long __boundary = ((addr) + PUD_SIZE) & PUD_MASK; \
- (__boundary - 1 < (end) - 1)? __boundary: (end); \
-})
+#define pud_addr_end pud_addr_end
+static inline unsigned long pud_addr_end(pud_t pud, unsigned long addr, unsigned long end)
+{ unsigned long __boundary = (addr + PUD_SIZE) & PUD_MASK;
+ return (__boundary - 1 < end - 1) ? __boundary : end;
+}
#endif

#ifndef pmd_addr_end
-#define pmd_addr_end(pmd, addr, end) \
-({ unsigned long __boundary = ((addr) + PMD_SIZE) & PMD_MASK; \
- (__boundary - 1 < (end) - 1)? __boundary: (end); \
-})
+#define pmd_addr_end pmd_addr_end
+static inline unsigned long pmd_addr_end(pmd_t pmd, unsigned long addr, unsigned long end)
+{ unsigned long __boundary = (addr + PMD_SIZE) & PMD_MASK;
+ return (__boundary - 1 < end - 1) ? __boundary : end;
+}
#endif

/*
--
2.17.1

2020-09-07 20:17:46

by Mike Rapoport

Subject: Re: [RFC PATCH v2 3/3] mm: make generic pXd_addr_end() macros inline functions

Hi,

Some style comments below.

On Mon, Sep 07, 2020 at 08:00:58PM +0200, Gerald Schaefer wrote:
> From: Alexander Gordeev <[email protected]>
>
> Since pXd_addr_end() macros take pXd page-table entry as a
> parameter it makes sense to check the entry type on compile.
> Even though most archs do not make use of page-table entries
> in pXd_addr_end() calls, checking the type in traversal code
> paths could help to avoid subtle bugs.
>
> Signed-off-by: Alexander Gordeev <[email protected]>
> Signed-off-by: Gerald Schaefer <[email protected]>
> ---
> include/linux/pgtable.h | 36 ++++++++++++++++++++----------------
> 1 file changed, 20 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 67ebc22cf83d..d9e7d16c2263 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -656,31 +656,35 @@ static inline int arch_unmap_one(struct mm_struct *mm,
> */
>
> #ifndef pgd_addr_end
> -#define pgd_addr_end(pgd, addr, end) \
> -({ unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define pgd_addr_end pgd_addr_end
> +static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + PGDIR_SIZE) & PGDIR_MASK;

The code should be on a separate line from the curly brace.
Besides, since this is not a macro anymore, I think it would be nicer to
use 'boundary' without underscores.
This applies to the changes below as well.

> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> #ifndef p4d_addr_end
> -#define p4d_addr_end(p4d, addr, end) \
> -({ unsigned long __boundary = ((addr) + P4D_SIZE) & P4D_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define p4d_addr_end p4d_addr_end
> +static inline unsigned long p4d_addr_end(p4d_t p4d, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + P4D_SIZE) & P4D_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> #ifndef pud_addr_end
> -#define pud_addr_end(pud, addr, end) \
> -({ unsigned long __boundary = ((addr) + PUD_SIZE) & PUD_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define pud_addr_end pud_addr_end
> +static inline unsigned long pud_addr_end(pud_t pud, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + PUD_SIZE) & PUD_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> #ifndef pmd_addr_end
> -#define pmd_addr_end(pmd, addr, end) \
> -({ unsigned long __boundary = ((addr) + PMD_SIZE) & PMD_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define pmd_addr_end pmd_addr_end
> +static inline unsigned long pmd_addr_end(pmd_t pmd, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + PMD_SIZE) & PMD_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> /*
> --
> 2.17.1
>

--
Sincerely yours,
Mike.

2020-09-08 05:20:42

by Christophe Leroy

Subject: Re: [RFC PATCH v2 3/3] mm: make generic pXd_addr_end() macros inline functions

Le 07/09/2020 à 20:00, Gerald Schaefer a écrit :
> From: Alexander Gordeev <[email protected]>
>
> Since pXd_addr_end() macros take pXd page-table entry as a
> parameter it makes sense to check the entry type on compile.
> Even though most archs do not make use of page-table entries
> in pXd_addr_end() calls, checking the type in traversal code
> paths could help to avoid subtle bugs.
>
> Signed-off-by: Alexander Gordeev <[email protected]>
> Signed-off-by: Gerald Schaefer <[email protected]>
> ---
> include/linux/pgtable.h | 36 ++++++++++++++++++++----------------
> 1 file changed, 20 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 67ebc22cf83d..d9e7d16c2263 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -656,31 +656,35 @@ static inline int arch_unmap_one(struct mm_struct *mm,
> */
>
> #ifndef pgd_addr_end
> -#define pgd_addr_end(pgd, addr, end) \
> -({ unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define pgd_addr_end pgd_addr_end

I think that #define is pointless, usually there is no such #define for
the default case.

> +static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + PGDIR_SIZE) & PGDIR_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}

Please use the standard layout, ie entry { and exit } alone on their
line, and space between local vars declaration and the rest.

Also remove the leading __ in front of var names as it's not needed once
it is not macros anymore.

f_name()
{
some_local_var;

do_something();
}

> #endif
>
> #ifndef p4d_addr_end
> -#define p4d_addr_end(p4d, addr, end) \
> -({ unsigned long __boundary = ((addr) + P4D_SIZE) & P4D_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define p4d_addr_end p4d_addr_end
> +static inline unsigned long p4d_addr_end(p4d_t p4d, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + P4D_SIZE) & P4D_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> #ifndef pud_addr_end
> -#define pud_addr_end(pud, addr, end) \
> -({ unsigned long __boundary = ((addr) + PUD_SIZE) & PUD_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define pud_addr_end pud_addr_end
> +static inline unsigned long pud_addr_end(pud_t pud, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + PUD_SIZE) & PUD_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> #ifndef pmd_addr_end
> -#define pmd_addr_end(pmd, addr, end) \
> -({ unsigned long __boundary = ((addr) + PMD_SIZE) & PMD_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define pmd_addr_end pmd_addr_end
> +static inline unsigned long pmd_addr_end(pmd_t pmd, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + PMD_SIZE) & PMD_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> /*
>

2020-09-08 17:23:34

by Christophe Leroy

Subject: Re: [RFC PATCH v2 3/3] mm: make generic pXd_addr_end() macros inline functions

Le 08/09/2020 à 17:48, Alexander Gordeev a écrit :
> On Tue, Sep 08, 2020 at 07:19:38AM +0200, Christophe Leroy wrote:
>
> [...]
>
>>> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
>>> index 67ebc22cf83d..d9e7d16c2263 100644
>>> --- a/include/linux/pgtable.h
>>> +++ b/include/linux/pgtable.h
>>> @@ -656,31 +656,35 @@ static inline int arch_unmap_one(struct mm_struct *mm,
>>> */
>>> #ifndef pgd_addr_end
>>> -#define pgd_addr_end(pgd, addr, end) \
>>> -({ unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK; \
>>> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
>>> -})
>>> +#define pgd_addr_end pgd_addr_end
>>
>> I think that #define is pointless, usually there is no such #define
>> for the default case.
>
> Default pgd_addr_end() gets overriden on s390 (arch/s390/include/asm/pgtable.h):
>
> #define pgd_addr_end pgd_addr_end
> static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
> {
> return rste_addr_end_folded(pgd_val(pgd), addr, end);
> }

Yes, there in s390 the #define is needed to hit the #ifndef pgd_addr_end
that's in include/linux/pgtable.h

But in include/linux/pgtable.h, there is no need of an #define
pgd_addr_end pgd_addr_end I think

>
>>> +static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
>>> +{ unsigned long __boundary = (addr + PGDIR_SIZE) & PGDIR_MASK;
>>> + return (__boundary - 1 < end - 1) ? __boundary : end;
>>> +}


Christophe

2020-09-08 19:45:40

by Alexander Gordeev

Subject: Re: [RFC PATCH v2 3/3] mm: make generic pXd_addr_end() macros inline functions

On Tue, Sep 08, 2020 at 07:19:38AM +0200, Christophe Leroy wrote:

[...]

> >diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> >index 67ebc22cf83d..d9e7d16c2263 100644
> >--- a/include/linux/pgtable.h
> >+++ b/include/linux/pgtable.h
> >@@ -656,31 +656,35 @@ static inline int arch_unmap_one(struct mm_struct *mm,
> > */
> > #ifndef pgd_addr_end
> >-#define pgd_addr_end(pgd, addr, end) \
> >-({ unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK; \
> >- (__boundary - 1 < (end) - 1)? __boundary: (end); \
> >-})
> >+#define pgd_addr_end pgd_addr_end
>
> I think that #define is pointless, usually there is no such #define
> for the default case.

Default pgd_addr_end() gets overriden on s390 (arch/s390/include/asm/pgtable.h):

#define pgd_addr_end pgd_addr_end
static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
{
return rste_addr_end_folded(pgd_val(pgd), addr, end);
}

> >+static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
> >+{ unsigned long __boundary = (addr + PGDIR_SIZE) & PGDIR_MASK;
> >+ return (__boundary - 1 < end - 1) ? __boundary : end;
> >+}