Re: [Qemu-devel] [PATCH] linux-user: add memfd_create

[Marc-André Lureau]

On Sat, Aug 17, 2019 at 1:28 AM Shu-Chun Weng via Qemu-devel
<address@hidden> wrote:
>
> Add support for the memfd_create syscall. If the host does not have the
> libc wrapper, translate to a direct syscall with NC-macro.
>
> Buglink: https://bugs.launchpad.net/qemu/+bug/1734792
> Signed-off-by: Shu-Chun Weng <address@hidden>

Reviewed-by: Marc-André Lureau <address@hidden>

> ---
>  include/qemu/memfd.h |  4 ++++
>  linux-user/syscall.c | 11 +++++++++++
>  util/memfd.c         |  2 +-
>  3 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/include/qemu/memfd.h b/include/qemu/memfd.h
> index d551c28b68..975b6bdb77 100644
> --- a/include/qemu/memfd.h
> +++ b/include/qemu/memfd.h
> @@ -32,6 +32,10 @@
>  #define MFD_HUGE_SHIFT 26
>  #endif
>
> +#if defined CONFIG_LINUX && !defined CONFIG_MEMFD
> +int memfd_create(const char *name, unsigned int flags);
> +#endif
> +
>  int qemu_memfd_create(const char *name, size_t size, bool hugetlb,
>                        uint64_t hugetlbsize, unsigned int seals, Error 
> **errp);
>  bool qemu_memfd_alloc_check(void);
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 8367cb138d..b506c1f40e 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -20,6 +20,7 @@
>  #include "qemu/osdep.h"
>  #include "qemu/cutils.h"
>  #include "qemu/path.h"
> +#include "qemu/memfd.h"
>  #include <elf.h>
>  #include <endian.h>
>  #include <grp.h>
> @@ -11938,6 +11939,16 @@ static abi_long do_syscall1(void *cpu_env, int num, 
> abi_long arg1,
>          /* PowerPC specific.  */
>          return do_swapcontext(cpu_env, arg1, arg2, arg3);
>  #endif
> +#ifdef TARGET_NR_memfd_create
> +    case TARGET_NR_memfd_create:
> +        p = lock_user_string(arg1);
> +        if (!p) {
> +            return -TARGET_EFAULT;
> +        }
> +        ret = get_errno(memfd_create(p, arg2));
> +        unlock_user(p, arg1, 0);
> +        return ret;
> +#endif
>
>      default:
>          qemu_log_mask(LOG_UNIMP, "Unsupported syscall: %d\n", num);
> diff --git a/util/memfd.c b/util/memfd.c
> index 00334e5b21..4a3c07e0be 100644
> --- a/util/memfd.c
> +++ b/util/memfd.c
> @@ -35,7 +35,7 @@
>  #include <sys/syscall.h>
>  #include <asm/unistd.h>
>
> -static int memfd_create(const char *name, unsigned int flags)
> +int memfd_create(const char *name, unsigned int flags)
>  {
>  #ifdef __NR_memfd_create
>      return syscall(__NR_memfd_create, name, flags);
> --
> 2.23.0.rc1.153.gdeed80330f-goog
>
>


-- 
Marc-André Lureau