From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id C480D1A03D6 for ; Wed, 11 Feb 2015 14:04:06 +1100 (AEDT) Message-ID: <1423623845.12568.1.camel@ellerman.id.au> Subject: Re: [RFC][PATCH 1/3] powerpc: Don't force ENOSYS as error on syscall fail From: Michael Ellerman To: Bogdan Purcareata Date: Wed, 11 Feb 2015 14:04:05 +1100 In-Reply-To: <1423468516-8688-2-git-send-email-bogdan.purcareata@freescale.com> References: <1423468516-8688-1-git-send-email-bogdan.purcareata@freescale.com> <1423468516-8688-2-git-send-email-bogdan.purcareata@freescale.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: linux-kernel@vger.kernel.org, pmoore@redhat.com, paulus@samba.org, strosake@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 2015-02-09 at 07:55 +0000, Bogdan Purcareata wrote: > In certain scenarios - e.g. seccomp filtering with ERRNO as default action - > the system call fails for other reasons than the syscall not being available. > The seccomp filter can be configured to store a user-defined error code on > return from a blacklisted syscall. > > The RFC is this: are there currently any user-space scenarios where it is > required that the system call return ENOSYS as error code on failure, no matter > the circumstances? I don't want to break userspace requirements. I have not > added code to force this error code in situations different than > secure_computing failure, in order to keep overhead at a minimum. > > Signed-off-by: Bogdan Purcareata > --- > arch/powerpc/kernel/entry_32.S | 3 ++- > arch/powerpc/kernel/entry_64.S | 2 +- > 2 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S > index 59848e5..52e48dd 100644 > --- a/arch/powerpc/kernel/entry_32.S > +++ b/arch/powerpc/kernel/entry_32.S > @@ -425,7 +425,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX) > b 1b > #endif /* CONFIG_44x */ > > -66: li r3,-ENOSYS > +66: > +# li r3,-ENOSYS > b ret_from_syscall > > .globl ret_from_fork > diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S > index e6bfe8e..80db02e 100644 > --- a/arch/powerpc/kernel/entry_64.S > +++ b/arch/powerpc/kernel/entry_64.S > @@ -269,7 +269,7 @@ syscall_dotrace: > b .Lsyscall_dotrace_cont > > syscall_enosys: > - li r3,-ENOSYS > +# li r3,-ENOSYS > b syscall_exit So what happens if you call this with a syscall number that's out of bounds? cheers