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Re: [PATCH v2 1/3] Consolidate vDSO macros and usage


On 04/20/2015 11:47 AM, Adhemerval Zanella wrote:
> This patch consolidate the Linux vDSO define and usage across all ports
> that uses it.  The common vDSO definitions and calling through
> {INLINE/INTERNAL}_VSYSCALL macros are moved to a common header
> sysdep-vdso.h and vDSO name declaration and prototype is defined
> using a common macro.
> 
> Also PTR_{MANGLE,DEMANGLE} is added to ports that does not use them
> for vDSO calls (aarch64, powerpc, s390, and tile).

Obviously we can expect this patch to result in changes to generated
code for ports which did not use pointer mangling before.  But what
about the others?  It looks to me like the generated code for s390, i386
and x86_64 should not change, is that right?

[...]

> 	* sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h
> 	(INLINE_VSYSCALL): Remove macro.
> 	(INTERNAL_VSYSCALL): Remove macro.
> 	(INTERNAL_VSYSCALL_NCS): Define using INTERNAL_VSYSCALL_NCS_TYPE.

Does continuing to use the "NCS" term in vDSO-related code make sense?
As best I can tell, "NCS" refers to support for non-constant syscall
numbers, as in INTERNAL_SYSCALL_NCS.  I have found its current usage in
powerpc et al. confusing -- INTERNAL_VSYSCALL_NCS does not have the same
relationship to INTERNAL_VSYSCALL as INTERNAL_SYSCALL_NCS has to
INTERNAL_SYSCALL.



> diff --git a/sysdeps/unix/sysv/linux/sysdep-vdso.h b/sysdeps/unix/sysv/linux/sysdep-vdso.h
> new file mode 100644
> index 0000000..70458d1
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/sysdep-vdso.h
> @@ -0,0 +1,98 @@
> +/* vDSO common definition for Linux.
> +   Copyright (C) 2015 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +G

   ^ Typo?


> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */


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