diff mbox series

[v3] linux-user: add memfd_create

Message ID 20190819180947.180725-1-scw@google.com (mailing list archive)
State New, archived
Headers show
Series [v3] linux-user: add memfd_create | expand

Commit Message

Zhijian Li (Fujitsu)" via Aug. 19, 2019, 6:09 p.m. UTC
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 <scw@google.com>
---
 include/qemu/memfd.h |  4 ++++
 linux-user/syscall.c | 12 ++++++++++++
 util/memfd.c         |  2 +-
 3 files changed, 17 insertions(+), 1 deletion(-)

Comments

Laurent Vivier Aug. 23, 2019, 4:48 p.m. UTC | #1
Le 19/08/2019 à 20:09, Shu-Chun Weng via Qemu-devel a écrit :
> 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 <scw@google.com>
> ---

Please, next time, to help review, add an history here, something like:

v3: add fd_trans_unregister()
v2: no change

And don't send new versions as a reply to the previous ones.

>  include/qemu/memfd.h |  4 ++++
>  linux-user/syscall.c | 12 ++++++++++++
>  util/memfd.c         |  2 +-
>  3 files changed, 17 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..f3f9311e9c 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 +11939,17 @@ 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));
> +        fd_trans_unregister(ret);
> +        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);
> 

Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Laurent Vivier Sept. 10, 2019, 4:49 p.m. UTC | #2
On 19/08/2019 20:09, Shu-Chun Weng 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 <scw@google.com>
> ---
>  include/qemu/memfd.h |  4 ++++
>  linux-user/syscall.c | 12 ++++++++++++
>  util/memfd.c         |  2 +-
>  3 files changed, 17 insertions(+), 1 deletion(-)

A nice follow up to this patch would be to implement the file-sealing
APIs provided by fnctl (see memfd_create(2) and fcntl(2), File sealing).

Thanks,
Laurent
diff mbox series

Patch

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..f3f9311e9c 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 +11939,17 @@  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));
+        fd_trans_unregister(ret);
+        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);