linux-kernel - Re: [PATCH v14 09/10] arch, mm: wire up memfd

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Message-ID: <20201207160006.GG1112728@linux.ibm.com>
Date:   Mon, 7 Dec 2020 18:00:06 +0200
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     Qian Cai <qcai@...hat.com>
Cc:     Mike Rapoport <rppt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Christopher Lameter <cl@...ux.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        David Hildenbrand <david@...hat.com>,
        Elena Reshetova <elena.reshetova@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        James Bottomley <jejb@...ux.ibm.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Matthew Wilcox <willy@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Roman Gushchin <guro@...com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Shuah Khan <shuah@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tycho Andersen <tycho@...ho.ws>, Will Deacon <will@...nel.org>,
        linux-api@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-riscv@...ts.infradead.org,
        x86@...nel.org, Palmer Dabbelt <palmerdabbelt@...gle.com>
Subject: Re: [PATCH v14 09/10] arch, mm: wire up memfd_secret system call
 were relevant

On Mon, Dec 07, 2020 at 09:45:59AM -0500, Qian Cai wrote:
> On Thu, 2020-12-03 at 08:29 +0200, Mike Rapoport wrote:

...

> > diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> > index 6d55324363ab..f9d93fbf9b69 100644
> > --- a/include/linux/syscalls.h
> > +++ b/include/linux/syscalls.h
> > @@ -1010,6 +1010,7 @@ asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
> >  asmlinkage long sys_pidfd_getfd(int pidfd, int fd, unsigned int flags);
> >  asmlinkage long sys_watch_mount(int dfd, const char __user *path,
> >  				unsigned int at_flags, int watch_fd, int watch_id);
> > +asmlinkage long sys_memfd_secret(unsigned long flags);
> >  
> >  /*
> >   * Architecture-specific system calls
> > diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
> > index 5df46517260e..51151888f330 100644
> > --- a/include/uapi/asm-generic/unistd.h
> > +++ b/include/uapi/asm-generic/unistd.h
> > @@ -861,9 +861,13 @@ __SYSCALL(__NR_faccessat2, sys_faccessat2)
> >  __SYSCALL(__NR_process_madvise, sys_process_madvise)
> >  #define __NR_watch_mount 441
> >  __SYSCALL(__NR_watch_mount, sys_watch_mount)
> > +#ifdef __ARCH_WANT_MEMFD_SECRET
> > +#define __NR_memfd_secret 442
> > +__SYSCALL(__NR_memfd_secret, sys_memfd_secret)
> > +#endif
> 
> I can't see where was it defined for arm64 after it looks like Andrew has
> deleted the  above chunk. Thus, we have a warning using this .config:
> 
> https://cailca.coding.net/public/linux/mm/git/files/master/arm64.config
> 
> <stdin>:1539:2: warning: #warning syscall memfd_secret not implemented [-Wcpp]

I was under the impression that Andrew only removed the #ifdef...

Andrew, can you please restore syscall definition for memfd_secret() in
include/uapi/asm-generic/unistd.h?

> >  
> >  #undef __NR_syscalls
> > -#define __NR_syscalls 442
> > +#define __NR_syscalls 443
> >  
> >  /*
> >   * 32 bit systems traditionally used different
> > diff --git a/mm/secretmem.c b/mm/secretmem.c
> > index 7236f4d9458a..b8a32954ac68 100644
> > --- a/mm/secretmem.c
> > +++ b/mm/secretmem.c
> > @@ -415,6 +415,9 @@ static int __init secretmem_setup(char *str)
> >  	unsigned long reserved_size;
> >  	int err;
> >  
> > +	if (!can_set_direct_map())
> > +		return 0;
> > +
> >  	reserved_size = memparse(str, NULL);
> >  	if (!reserved_size)
> >  		return 0;
> > 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 */
> >  
> 

-- 
Sincerely yours,
Mike.