[PATCH] powerpc: Enabling sys_kcmp for CRIU

Laurent Dufour ldufour at linux.vnet.ibm.com
Wed May 6 01:30:21 AEST 2015

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 at bakeyournoodle.com>
Signed-off-by: Laurent Dufour <ldufour at 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)
-SYSCALL(ni_syscall) /* sys_kcmp */
+SYSCALL(kcmp) /* sys_kcmp */

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