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Re: [PATCH] Linux: Add memfd_create system call wrapper
On 12/11/2017 12:51, Florian Weimer wrote:
> On 11/12/2017 10:04 AM, Florian Weimer wrote:
>> If that's not acceptable, we should probably not add <sys/memfd.h> at
>> all, but replicate the UAPI constants in <sys/mman.h>.
>>
>> I see that this also affects the test. So we probably should go the
>> <sys/mman.h> route.
>
> I had already taken care of that, I forgot. Anyway, the attached patch has the <sys/mman.h> variant of the system call wrapper.
>
> Thanks,
> Florian
>
> memfd.patch
>
>
> The system call is somewhat obscure because it is closely related
> to file descriptor sealing. However, it is also the recommended
> way to create alias mappings, which is why it has more general use.
>
> No emulation is provided. Except for the name of the
> /proc/self/fd links, it would be possible to implement an
> approximation using O_TMPFILE and tmpfs, but this does not appear
> to be worth the added complexity.
>
> 2017-11-12 Florian Weimer <fweimer@redhat.com>
>
> Linux: Add memfd_create system call wrapper
> * sysdeps/unix/sysv/linux/Makefile [misc] (tests): Add
> tst-memfd_create.
> * sysdeps/unix/sysv/linux/bits/mman-linux.h [__USE_GNU]
> (MFD_CLOEXEC, MFD_ALLOW_SEALING): Define.
> [__USE_GNU] (memfd_create): Declare.
> * sysdeps/unix/sysv/linux/Versions (GLIBC_2.27): Add memfd_create.
> * sysdeps/unix/sysv/linux/syscalls.list (memfd_create): Add.
> * sysdeps/unix/sysv/linux/tst-memfd_create.c: New file.
> * sysdeps/unix/sysv/linux/**.abilist: Update.
> * manual/llio.texi (Memory-mapped I/O): Document memfd_create.
LGTM with just an update below.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
>
> diff --git a/NEWS b/NEWS
> index b7281621f4..eca0c00a9b 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -35,6 +35,9 @@ Major new features:
> are the same interfaces added in version 2.26 for some platforms where
> this format is supported but is not the format of long double.
>
> +* glibc now provides the <sys/memfd.h> header file and the memfd_create
> + system call.
> +
> Deprecated and removed features, and other changes affecting compatibility:
>
> * On GNU/Linux, the obsolete Linux constant PTRACE_SEIZE_DEVEL is no longer
Ok.
> diff --git a/manual/llio.texi b/manual/llio.texi
> index 10ad546723..59eb3af711 100644
> --- a/manual/llio.texi
> +++ b/manual/llio.texi
> @@ -1775,6 +1775,40 @@ the given @var{name} previously created by @code{shm_open}.
> On failure @code{errno} is set.
> @end deftypefn
>
> +@deftypefn Function int memfd_create (const char *@var{name}, unsigned int flags)
> +@standards{Linux, sys/mman.h}
> +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
> +The @code{memfd_create} function returns a file descriptor which can be
> +used to create memory mappings using the @code{mmap} function. It is
> +similar to the @code{shm_open} function in the sense that these mappings
> +are not backed by actual files. However, the descriptor return by
> +@code{memfd_create} does not correspond to a named object; the
> +@var{name} argument is used for informative purposes only. The
> +descriptor can be passed between processes (for example, over local
> +domain sockets), and mappings at the same offset refer to the same
> +memory, or the descriptor can be used to create alias mappings within
> +the same process.
> +
> +The descriptor initially refers to a zero-length file. Before mappings
> +can be created which are backed by memory, the file size needs to be
> +increased with the @code{ftruncate} function. @xref{File Size}.
> +
> +The @var{flags} argument can be a combination of the following flags:
> +
> +@table @code
> +@item MFD_CLOEXEC
> +The descriptor is created with the @code{O_CLOEXEC} flag.
> +
> +@item MFD_ALLOW_SEALING
> +The descriptor supports the addition of seals using the @code{fcntl}
> +function.
> +@end table
> +
> +The @code{memfd_create} function is specific to Linux.
> +
> +@end deftypefn
> +
> +
> @node Waiting for I/O
> @section Waiting for Input or Output
> @cindex waiting for input or output
Linux 4.14 (749df87bd7be) added a new flag MFD_HUGETLB. I think ww should add
and document it.
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index bf76b8773d..f974ac446b 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -43,7 +43,8 @@ sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
> bits/siginfo-arch.h bits/siginfo-consts-arch.h
>
> tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
> - tst-quota tst-sync_file_range test-errno-linux tst-sysconf-iov_max
> + tst-quota tst-sync_file_range test-errno-linux tst-sysconf-iov_max \
> + tst-memfd_create
>
> # Generate the list of SYS_* macros for the system calls (__NR_*
> # macros). The file syscall-names.list contains all possible system
Ok.
> diff --git a/sysdeps/unix/sysv/linux/Versions b/sysdeps/unix/sysv/linux/Versions
> index d3dbcde8c9..6f2fe516d7 100644
> --- a/sysdeps/unix/sysv/linux/Versions
> +++ b/sysdeps/unix/sysv/linux/Versions
> @@ -166,6 +166,9 @@ libc {
> GLIBC_2.15 {
> process_vm_readv; process_vm_writev;
> }
> + GLIBC_2.27 {
> + memfd_create;
> + }
> GLIBC_PRIVATE {
> # functions used in other libraries
> __syscall_rt_sigqueueinfo;
Ok.
> diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> index ed598aedac..140ca28abc 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> @@ -2106,6 +2106,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.27 strfromf128 F
> GLIBC_2.27 strtof128 F
> GLIBC_2.27 strtof128_l F
> diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
> index 4e57f36bcf..f698e1b2f4 100644
> --- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
> @@ -2017,6 +2017,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.27 strfromf128 F
> GLIBC_2.27 strtof128 F
> GLIBC_2.27 strtof128_l F
> diff --git a/sysdeps/unix/sysv/linux/arm/libc.abilist b/sysdeps/unix/sysv/linux/arm/libc.abilist
> index 5b70e1bfc9..8a8af3e3e4 100644
> --- a/sysdeps/unix/sysv/linux/arm/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/arm/libc.abilist
> @@ -107,6 +107,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.4 GLIBC_2.4 A
> GLIBC_2.4 _Exit F
> GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
> diff --git a/sysdeps/unix/sysv/linux/bits/mman-linux.h b/sysdeps/unix/sysv/linux/bits/mman-linux.h
> index b091181960..396829482a 100644
> --- a/sysdeps/unix/sysv/linux/bits/mman-linux.h
> +++ b/sysdeps/unix/sysv/linux/bits/mman-linux.h
> @@ -109,3 +109,18 @@
> # define MCL_ONFAULT 4 /* Lock all pages that are
> faulted in. */
> #endif
> +
> +#ifdef __USE_GNU
> +/* Flags for memfd_create. */
> +# define MFD_CLOEXEC 1U
> +# define MFD_ALLOW_SEALING 2U
> +
> +__BEGIN_DECLS
> +
> +/* Create a new memory file descriptor. NAME is a name for debugging.
> + FLAGS is a combination of the MFD_* constants. */
> +int memfd_create (const char *__name, unsigned int __flags) __THROW;
> +
> +__END_DECLS
> +
> +#endif /* __USE_GNU */
As before I think we should include MFD_HUGETLB.
> diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
> index 6a2500a8b3..5b81a6cd7d 100644
> --- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
> @@ -1871,6 +1871,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 __ctype_b_loc F
> GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
> index 9ab4e3642a..51ead9e867 100644
> --- a/sysdeps/unix/sysv/linux/i386/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
> @@ -2036,6 +2036,7 @@ GLIBC_2.26 wcstof128_l F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 __ctype_b_loc F
> GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
> index 81bb623fe8..78b4ee8d40 100644
> --- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
> @@ -1900,6 +1900,7 @@ GLIBC_2.26 wcstof128_l F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 __ctype_b_loc F
> GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
> index 5a33b57390..d9c97779e4 100644
> --- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
> @@ -108,6 +108,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.4 GLIBC_2.4 A
> GLIBC_2.4 _Exit F
> GLIBC_2.4 _IO_2_1_stderr_ D 0x98
> diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
> index 50a86e74fa..4acbf7eeed 100644
> --- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
> @@ -1985,6 +1985,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 __ctype_b_loc F
> GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/microblaze/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
> index 250ef305c3..93f02f08ce 100644
> --- a/sysdeps/unix/sysv/linux/microblaze/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
> @@ -2106,3 +2106,4 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
> index 87a1dc4ad7..795e85de70 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
> @@ -1960,6 +1960,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 __ctype_b_loc F
> GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
> index f2b35f250e..dc714057b7 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
> @@ -1958,6 +1958,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 __ctype_b_loc F
> GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
> index ade654dbea..ce7bc9b175 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
> @@ -1956,6 +1956,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.27 strfromf128 F
> GLIBC_2.27 strtof128 F
> GLIBC_2.27 strtof128_l F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
> index 56032c3f82..3fdd85eace 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
> @@ -1951,6 +1951,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.27 strfromf128 F
> GLIBC_2.27 strtof128 F
> GLIBC_2.27 strtof128_l F
> diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
> index c599dd9212..3e0bcb2a5c 100644
> --- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
> @@ -2147,3 +2147,4 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
> index 385409aa6e..375c69d9d1 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
> @@ -1989,6 +1989,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 __ctype_b_loc F
> GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
> index e99cb454b5..a88172a906 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
> @@ -1994,6 +1994,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 __ctype_b_loc F
> GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
> index 173672ab5e..fa026a332c 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
> @@ -2201,3 +2201,4 @@ GLIBC_2.26 wcstof128_l F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
> index 8a654436ab..838f395d78 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
> @@ -108,6 +108,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 _Exit F
> GLIBC_2.3 _IO_2_1_stderr_ D 0xe0
> diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
> index dbd411ceb1..41b79c496a 100644
> --- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
> @@ -1989,6 +1989,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.27 strfromf128 F
> GLIBC_2.27 strtof128 F
> GLIBC_2.27 strtof128_l F
> diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
> index 5617784ca0..68251a0e69 100644
> --- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
> @@ -1890,6 +1890,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.27 strfromf128 F
> GLIBC_2.27 strtof128 F
> GLIBC_2.27 strtof128_l F
> diff --git a/sysdeps/unix/sysv/linux/sh/libc.abilist b/sysdeps/unix/sysv/linux/sh/libc.abilist
> index 0f840e6e88..bc1aae275e 100644
> --- a/sysdeps/unix/sysv/linux/sh/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/sh/libc.abilist
> @@ -1875,6 +1875,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 __ctype_b_loc F
> GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
> index bb7e1042c7..93e6d092ac 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
> @@ -1982,6 +1982,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.27 strfromf128 F
> GLIBC_2.27 strtof128 F
> GLIBC_2.27 strtof128_l F
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
> index 4053b0a51c..b11d6764d4 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
> @@ -1919,6 +1919,7 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.27 strfromf128 F
> GLIBC_2.27 strtof128 F
> GLIBC_2.27 strtof128_l F
> diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
> index 8bfb080d80..40c4fbb9ea 100644
> --- a/sysdeps/unix/sysv/linux/syscalls.list
> +++ b/sysdeps/unix/sysv/linux/syscalls.list
> @@ -109,3 +109,4 @@ setns EXTRA setns i:ii setns
>
> process_vm_readv EXTRA process_vm_readv i:ipipii process_vm_readv
> process_vm_writev EXTRA process_vm_writev i:ipipii process_vm_writev
> +memfd_create EXTRA memfd_create i:si memfd_create
> diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
> index 38a96d3a02..e9eb4ff7bd 100644
> --- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
> @@ -2113,3 +2113,4 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
> index 572b917d7d..8f08e909cd 100644
> --- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
> @@ -2113,3 +2113,4 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> diff --git a/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
> index 38a96d3a02..e9eb4ff7bd 100644
> --- a/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
> @@ -2113,3 +2113,4 @@ GLIBC_2.26 reallocarray F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> diff --git a/sysdeps/unix/sysv/linux/tst-memfd_create.c b/sysdeps/unix/sysv/linux/tst-memfd_create.c
> new file mode 100644
> index 0000000000..fd173ff71d
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-memfd_create.c
> @@ -0,0 +1,121 @@
> +/* Test for the memfd_create system call.
> + Copyright (C) 2017 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <http://www.gnu.org/licenses/>. */
> +
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <support/check.h>
> +#include <support/support.h>
> +#include <support/test-driver.h>
> +#include <support/xunistd.h>
> +#include <sys/mman.h>
> +
> +/* Return true if the descriptor has the FD_CLOEXEC flag set. */
> +static bool
> +is_cloexec (int fd)
> +{
> + int flags = fcntl (fd, F_GETFD);
> + TEST_VERIFY (flags >= 0);
> + return flags & FD_CLOEXEC;
> +}
> +
> +/* Return the seals set on FD. */
> +static int
> +get_seals (int fd)
> +{
> + int flags = fcntl (fd, F_GET_SEALS);
> + TEST_VERIFY (flags >= 0);
> + return flags;
> +}
> +
> +/* Return true if the F_SEAL_SEAL flag is set on the descriptor. */
> +static bool
> +is_sealed (int fd)
> +{
> + return get_seals (fd) & F_SEAL_SEAL;
> +}
> +
> +static int
> +do_test (void)
> +{
> + /* Initialized by the first call to memfd_create to 0 (memfd_create
> + unsupported) or 1 (memfd_create is implemented in the kernel).
> + Subsequent iterations check that the success/failure state is
> + consistent. */
> + int supported = -1;
> +
> + for (int do_cloexec = 0; do_cloexec < 2; ++do_cloexec)
> + for (int do_sealing = 0; do_sealing < 2; ++do_sealing)
> + {
> + int flags = 0;
> + if (do_cloexec)
> + flags |= MFD_CLOEXEC;
> + if (do_sealing)
> + flags |= MFD_ALLOW_SEALING;
> + if (test_verbose > 0)
> + printf ("info: memfd_create with flags=0x%x\n", flags);
> + int fd = memfd_create ("tst-memfd_create", flags);
> + if (fd < 0)
> + {
> + if (errno == ENOSYS)
> + {
> + if (supported < 0)
> + {
> + printf ("warning: memfd_create is unsupported\n");
> + supported = 0;
> + continue;
> + }
> + TEST_VERIFY (supported == 0);
> + continue;
> + }
> + else
> + FAIL_EXIT1 ("memfd_create: %m");
> + }
> + if (supported < 0)
> + supported = 1;
> + TEST_VERIFY (supported > 0);
> +
> + char *fd_path = xasprintf ("/proc/self/fd/%d", fd);
> + char *link = xreadlink (fd_path);
> + if (test_verbose > 0)
> + printf ("info: memfd link: %s\n", link);
> + TEST_VERIFY (strcmp (link, "memfd:tst-memfd_create (deleted)"));
> + TEST_VERIFY (is_cloexec (fd) == do_cloexec);
> + TEST_VERIFY (is_sealed (fd) == !do_sealing);
> + if (do_sealing)
> + {
> + TEST_VERIFY (fcntl (fd, F_ADD_SEALS, F_SEAL_WRITE) == 0);
> + TEST_VERIFY (!is_sealed (fd));
> + TEST_VERIFY (get_seals (fd) & F_SEAL_WRITE);
> + TEST_VERIFY (fcntl (fd, F_ADD_SEALS, F_SEAL_SEAL) == 0);
> + TEST_VERIFY (is_sealed (fd));
> + }
> + xclose (fd);
> + free (fd_path);
> + free (link);
> + }
> +
> + if (supported == 0)
> + return EXIT_UNSUPPORTED;
> + return 0;
> +}
> +
> +#include <support/test-driver.c>
Ok.
> diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> index b83d25c2e3..0a4f7797ac 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> @@ -1877,6 +1877,7 @@ GLIBC_2.26 wcstof128_l F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
> GLIBC_2.3 GLIBC_2.3 A
> GLIBC_2.3 __ctype_b_loc F
> GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
> index cba1d59057..23f6a91429 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
> @@ -2120,3 +2120,4 @@ GLIBC_2.26 wcstof128_l F
> GLIBC_2.27 GLIBC_2.27 A
> GLIBC_2.27 glob F
> GLIBC_2.27 glob64 F
> +GLIBC_2.27 memfd_create F
>