Hi Yamada-san,
On Tue, Jan 8, 2019 at 12:41 AM Masahiro Yamada
<yamada.masahiro@xxxxxxxxxxxxx> wrote:
> Most architectures do not export shmparam.h to user-space.
>
> $ find arch -name shmparam.h | sort
> arch/alpha/include/asm/shmparam.h
> arch/arc/include/asm/shmparam.h
> arch/arm64/include/asm/shmparam.h
> arch/arm/include/asm/shmparam.h
> arch/csky/include/asm/shmparam.h
> arch/ia64/include/asm/shmparam.h
> arch/mips/include/asm/shmparam.h
> arch/nds32/include/asm/shmparam.h
> arch/nios2/include/asm/shmparam.h
> arch/parisc/include/asm/shmparam.h
> arch/powerpc/include/asm/shmparam.h
> arch/s390/include/asm/shmparam.h
> arch/sh/include/asm/shmparam.h
> arch/sparc/include/asm/shmparam.h
> arch/x86/include/asm/shmparam.h
> arch/xtensa/include/asm/shmparam.h
>
> Strangely, some users of the asm-generic wrapper export shmparam.h
>
> $ git grep 'generic-y += shmparam.h'
> arch/c6x/include/uapi/asm/Kbuild:generic-y += shmparam.h
> arch/h8300/include/uapi/asm/Kbuild:generic-y += shmparam.h
> arch/hexagon/include/uapi/asm/Kbuild:generic-y += shmparam.h
> arch/m68k/include/uapi/asm/Kbuild:generic-y += shmparam.h
> arch/microblaze/include/uapi/asm/Kbuild:generic-y += shmparam.h
> arch/openrisc/include/uapi/asm/Kbuild:generic-y += shmparam.h
> arch/riscv/include/asm/Kbuild:generic-y += shmparam.h
> arch/unicore32/include/uapi/asm/Kbuild:generic-y += shmparam.h
>
> The newly added riscv correctly creates the asm-generic wrapper
> in the kernel space, but the others (c6x, h8300, hexagon, m68k,
> microblaze, openrisc, unicore32) create the one in the uapi directory.
>
> Digging into the git history, now I guess fcc8487d477a ("uapi:
> export all headers under uapi directories") was the misconversion.
> Prior to that commit, no architecture exported to shmparam.h
> As its commit description said, that commit exported shmparam.h
> for c6x, h8300, hexagon, m68k, openrisc, unicore32.
>
> 83f0124ad81e ("microblaze: remove asm-generic wrapper headers")
> accidentally exported shmparam.h for microblaze.
>
> This commit unexports shmparam.h for those architectures.
>
> There is no more reason to export include/uapi/asm-generic/shmparam.h,
> so it has been moved to include/asm-generic/shmparam.h
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Thanks for your patch!
include/uapi/asm-generic/shmparam.h contains a single definition:
#define SHMLBA PAGE_SIZE /* attach addr a multiple of this */
So this definition is not used by userspace?
Note that it is refered to by include/uapi/linux/shm.h, albeit in a comment:
#define SHM_RND 020000 /* round attach address to SHMLBA
boundary */
Glibc provides its own definition in /usr/include/x86_64-linux-gnu/bits/shm.h
#define SHMLBA (__getpagesize ())
So probably this is safe.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
