On Thu, Jul 23, 2015 at 03:36:39AM +0200, Marc-André Lureau wrote:
> Implement memfd_create() fallback if not available in system libc.
> memfd_create() is still not included in glibc today, atlhough it's been
> available since Linux 3.17 in Oct 2014.
>
> memfd has numerous advantages over traditional shm/mmap for ipc memory
> sharing with fd handler, which we are going to make use of for
> vhost-user logging memory in following patches.
>
> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> ---
> include/qemu/osdep.h | 59
> ++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 59 insertions(+)
>
> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> index 3247364..adc138b 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -6,6 +6,7 @@
> #include <stddef.h>
> #include <stdbool.h>
> #include <stdint.h>
> +#include <unistd.h>
> #include <sys/types.h>
> #ifdef __OpenBSD__
> #include <sys/signal.h>
> @@ -20,6 +21,64 @@
>
> #include <sys/time.h>
>
> +#ifdef CONFIG_LINUX
> +
> +#ifndef F_LINUX_SPECIFIC_BASE
> +#define F_LINUX_SPECIFIC_BASE 1024
> +#endif
> +
> +#ifndef F_ADD_SEALS
> +#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9)
> +#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10)
> +
> +#define F_SEAL_SEAL 0x0001 /* prevent further seals from being set */
> +#define F_SEAL_SHRINK 0x0002 /* prevent file from shrinking */
> +#define F_SEAL_GROW 0x0004 /* prevent file from growing */
> +#define F_SEAL_WRITE 0x0008 /* prevent writes */
> +#endif
These are from include/uapi/linux/fcntl.h,
they should be imported into linux-headers I think.
> +
> +#ifndef MFD_ALLOW_SEALING
> +#define MFD_ALLOW_SEALING 0x0002U
> +#endif
> +
> +#ifndef MFD_CLOEXEC
> +#define MFD_CLOEXEC 0x0001U
> +#endif
> +
> +#ifndef __NR_memfd_create
> +# if defined __x86_64__
> +# define __NR_memfd_create 319
> +# elif defined __arm__
> +# define __NR_memfd_create 385
> +# elif defined __aarch64__
> +# define __NR_memfd_create 279
> +# elif defined _MIPS_SIM
> +# if _MIPS_SIM == _MIPS_SIM_ABI32
> +# define __NR_memfd_create 4354
> +# endif
> +# if _MIPS_SIM == _MIPS_SIM_NABI32
> +# define __NR_memfd_create 6318
> +# endif
> +# if _MIPS_SIM == _MIPS_SIM_ABI64
> +# define __NR_memfd_create 5314
> +# endif
What's defining all these macros?
> +# elif defined __i386__
> +# define __NR_memfd_create 356
> +# else
> +# warning "__NR_memfd_create unknown for your architecture"
> +# define __NR_memfd_create 0xffffffff
> +# endif
> +#endif
> +
> +#ifndef CONFIG_MEMFD
> +static inline int memfd_create(const char *name, unsigned int flags)
> +{
> + return syscall(__NR_memfd_create, name, flags);
> +}
> +#endif
How about making these non-inline?
I think we need stubs for non-posix systems, right?
> +
> +#endif /* LINUX */
> +
> #if defined(CONFIG_SOLARIS) && CONFIG_SOLARIS_VERSION < 10
> /* [u]int_fast*_t not in <sys/int_types.h> */
> typedef unsigned char uint_fast8_t;
> --
> 2.4.3
