Subject: Re: [PATCH v5 0/5] mm: introduce memfd_secret system call to create "secret" memory areas

From: Qian Cai <[email-masked]>
Date: Fri, 18 Sep 2020 14:25:15 -0400

On Thu, 2020-09-17 at 09:27 -0400, Qian Cai wrote:
> On Wed, 2020-09-16 at 10:35 +0300, Mike Rapoport wrote:
> > From: Mike Rapoport <[email-masked]>
> > 
> > Hi,
> > 
> > This is an implementation of "secret" mappings backed by a file descriptor. 
> > I've dropped the boot time reservation patch for now as it is not strictly
> > required for the basic usage and can be easily added later either with or
> > without CMA.
> 
> On powerpc: https://gitlab.com/cailca/linux-mm/-/blob/master/powerpc.config
> 
> There is a compiling warning from the today's linux-next:
> 
> <stdin>:1532:2: warning: #warning syscall memfd_secret not implemented [-Wcpp]

This should silence the warning:

diff --git a/scripts/checksyscalls.sh b/scripts/checksyscalls.sh
index a18b47695f55..b7609958ee36 100755
--- a/scripts/checksyscalls.sh
+++ b/scripts/checksyscalls.sh
@@ -40,6 +40,10 @@ cat << EOF
 #define __IGNORE_setrlimit	/* setrlimit */
 #endif
 
+#ifndef __ARCH_WANT_MEMFD_SECRET
+#define __IGNORE_memfd_secret
+#endif
+
 /* Missing flags argument */
 #define __IGNORE_renameat	/* renameat2 */