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From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au
Cc: paulus@samba.org, linux-kernel@vger.kernel.org
Subject: [PATCH] powerpc: Enabling sys_kcmp for CRIU
Date: Tue,  5 May 2015 17:30:21 +0200	[thread overview]
Message-ID: <1430839821-9259-1-git-send-email-ldufour@linux.vnet.ibm.com> (raw)

The commit 8170a83f15ee ("powerpc: Wireup the kcmp syscall to sys_ni") has
disabled the kcmp syscall for powerpc.  This has been done due to the use
of unsigned long parameters which may require a dedicated wrapper to handle
32bit process on top of 64bit kernel.  However in the kcmp() case, the 2
unsigned long parameters are currently only used to carry file descriptors
from user space to the kernel.  Since such a parameter is passed through
register, and file descriptor doesn't need to get extended, there is,
today, no need for a wrapper.

In the case there will be a need to pass address in or out of this system
call, then a wrapper could be required, it will then be to care of it.

As today this is not the case, it is safe to enable kcmp() on powerpc.

Cc: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/systbl.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/systbl.h b/arch/powerpc/include/asm/systbl.h
index 91062eef582f..b257f02ab6bf 100644
--- a/arch/powerpc/include/asm/systbl.h
+++ b/arch/powerpc/include/asm/systbl.h
@@ -358,7 +358,7 @@ SYSCALL_SPU(setns)
 COMPAT_SYS(process_vm_readv)
 COMPAT_SYS(process_vm_writev)
 SYSCALL(finit_module)
-SYSCALL(ni_syscall) /* sys_kcmp */
+SYSCALL(kcmp) /* sys_kcmp */
 SYSCALL_SPU(sched_setattr)
 SYSCALL_SPU(sched_getattr)
 SYSCALL_SPU(renameat2)
-- 
1.9.1

             reply	other threads:[~2015-05-05 15:30 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-05 15:30 Laurent Dufour [this message]
2015-05-11 10:31 ` powerpc: Enabling sys_kcmp for CRIU Michael Ellerman
2015-05-11 11:53   ` Laurent Dufour

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