Re: [PATCH v10 1/3] arm64: Add __NR_* definitions for compat syscalls

From: AKASHI Takahiro
Date: Fri Jul 04 2014 - 07:05:58 EST


Arnd,

On 07/04/2014 07:06 PM, Arnd Bergmann wrote:
On Friday 04 July 2014 16:28:29 AKASHI Takahiro wrote:
From: Catalin Marinas <catalin.marinas@xxxxxxx>

This patch adds __NR_* definitions to asm/unistd32.h, moves the
__NR_compat_* definitions to asm/unistd.h and removes all the explicit
unistd32.h includes apart from the one building the compat syscall
table. The aim is to have the compat __NR_* definitions available but
without colliding with the native syscall definitions.

And adds more syscall definitions for 3.16.

Can you explain in more detail why you want to add those macros? I've
looked at all three patches in the series but can't find any code using
them.

Right. "unistd32.h" is not used by this patch, but by lib/compat_audit.c.
when I thought of adding audit support for arm64, there was duplicated code
of auditing compat system calls across many architectures.
lib/compat_audit.c fixes this issue but at the same time it also requires
__NR_* macros for a couple of compat system calls which arm64 didn't have.

In the first implementation, I generated an extra generated/asm/unistd_32.h
from the original asm/unist32.h by using a sed script. But Catalin suggested
(agreed?) to modify unistd32.h for this purpose.

See
http://lists.infradead.org/pipermail/linux-arm-kernel/2014-January/228992.html

Thanks,
-Takahiro AKASHI

I would expect that we don't need to define those macros at all for
compat mode, since they are meant primarily for user space (glibc)
compilation, which gets them from arch/arm/include/asm/unistd.h.

Arnd

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