[CRIU] [PATCH 7/7] ppc64/aarch64: Dynamically define PAGE_SIZE

[Mike Rapoport]

On Mon, Mar 26, 2018 at 02:07:02PM +0100, Dmitry Safonov wrote:
> On ppc64/aarch64 Linux can be set to use Large pages, so the PAGE_SIZE
> isn't build-time constant anymore. Define it through _SC_PAGESIZE.
> 
> There are different sizes for a page on ppc64:
> : #if defined(CONFIG_PPC_256K_PAGES)
> : #define PAGE_SHIFT              18
> : #elif defined(CONFIG_PPC_64K_PAGES)
> : #define PAGE_SHIFT              16
> : #elif defined(CONFIG_PPC_16K_PAGES)
> : #define PAGE_SHIFT              14
> : #else
> : #define PAGE_SHIFT              12
> : #endif
> 
> And on aarch64 there are default sizes and possibly someone can set his
> own PAGE_SHIFT:
> : config ARM64_PAGE_SHIFT
> :         int
> :         default 16 if ARM64_64K_PAGES
> :         default 14 if ARM64_16K_PAGES
> :         default 12
> 
> On the downside - each time we need PAGE_SIZE, we're doing libc
> function call on aarch64/ppc64.
> 
> Fixes: #415
> 
> Tested-by: Adrian Reber <areber at redhat.com>
> Signed-off-by: Dmitry Safonov <dima at arista.com>
> ---
>  include/common/arch/aarch64/asm/page.h | 23 +++++++++++------------
>  include/common/arch/ppc64/asm/page.h   | 25 ++++++++++---------------
>  2 files changed, 21 insertions(+), 27 deletions(-)
> 
> diff --git a/include/common/arch/aarch64/asm/page.h b/include/common/arch/aarch64/asm/page.h
> index 4126c8474a7d..a4d98aa21fb7 100644
> --- a/include/common/arch/aarch64/asm/page.h
> +++ b/include/common/arch/aarch64/asm/page.h
> @@ -4,22 +4,21 @@
>  #define ARCH_HAS_LONG_PAGES
> 
>  #ifndef CR_NOGLIBC
> -#include <unistd.h>
> +#include <string.h> /* ffsl() */
> +#include <unistd.h> /* _SC_PAGESIZE */
> 
> -#ifndef PAGE_SHIFT
> -# define PAGE_SHIFT	12
> -#endif
> -
> -#ifndef PAGE_SIZE
> -# define PAGE_SIZE	(1UL << PAGE_SHIFT)
> -#endif
> +#define page_size()	sysconf(_SC_PAGESIZE)

Maybe we could save a couple of cycles with

static unsigned long __page_size;
static inline page_size(void)
{
	if (!__page_size)
		__page_size = sysconf(_SC_PAGESIZE);
	return _page_size;
}
 

> -#ifndef PAGE_MASK
> -# define PAGE_MASK	(~(PAGE_SIZE - 1))
> -#endif
> +/*
> + * Don't add ifdefs for PAGE_SIZE: if any header defines it as a constant
> + * on aarch64, then we need refrain using PAGE_SIZE in criu and use
> + * page_size() across sources (as it may differ on aarch64).
> + */
> +#define PAGE_SIZE	page_size()
> +#define PAGE_MASK	(~(PAGE_SIZE - 1))
> +#define PAGE_SHIFT	(ffsl(page_size()) - 1)
> 
>  #define PAGE_PFN(addr)	((addr) / PAGE_SIZE)
> -#define page_size()	sysconf(_SC_PAGESIZE)
> 
>  #else /* CR_NOGLIBC */
> 
> diff --git a/include/common/arch/ppc64/asm/page.h b/include/common/arch/ppc64/asm/page.h
> index a95af55ef8a0..f2e1dcaeb616 100644
> --- a/include/common/arch/ppc64/asm/page.h
> +++ b/include/common/arch/ppc64/asm/page.h
> @@ -4,26 +4,21 @@
>  #define ARCH_HAS_LONG_PAGES
> 
>  #ifndef CR_NOGLIBC
> -#include <unistd.h>
> +#include <string.h> /* ffsl() */
> +#include <unistd.h> /* _SC_PAGESIZE */
> +
> +#define page_size()	sysconf(_SC_PAGESIZE)
> 
>  /*
> - * Default config for Pseries is to use 64K pages.
> - * See kernel file arch/powerpc/configs/pseries_*defconfig
> + * Don't add ifdefs for PAGE_SIZE: if any header defines it as a constant
> + * on ppc64, then we need refrain using PAGE_SIZE in criu and use
> + * page_size() across sources (as it may differ on ppc64).
>   */
> -#ifndef PAGE_SHIFT
> -# define PAGE_SHIFT	16
> -#endif
> -
> -#ifndef PAGE_SIZE
> -# define PAGE_SIZE	(1UL << PAGE_SHIFT)
> -#endif
> -
> -#ifndef PAGE_MASK
> -# define PAGE_MASK	(~(PAGE_SIZE - 1))
> -#endif
> +#define PAGE_SIZE	page_size()
> +#define PAGE_MASK	(~(PAGE_SIZE - 1))
> +#define PAGE_SHIFT	(ffsl(page_size()) - 1)
> 
>  #define PAGE_PFN(addr)	((addr) / PAGE_SIZE)
> -#define page_size()	sysconf(_SC_PAGESIZE)
> 
>  #else /* CR_NOGLIBC */
> 
> -- 
> 2.13.6
> 

-- 
Sincerely yours,
Mike.