* Re: [Qemu-devel] [PATCH] linux-user: add memfd_create
2019-08-16 21:10 [Qemu-devel] [PATCH] linux-user: add memfd_create Shu-Chun Weng via Qemu-devel
@ 2019-08-18 21:57 ` Philippe Mathieu-Daudé
2019-08-19 7:12 ` Marc-André Lureau
` (2 subsequent siblings)
3 siblings, 0 replies; 10+ messages in thread
From: Philippe Mathieu-Daudé @ 2019-08-18 21:57 UTC (permalink / raw)
To: Shu-Chun Weng, Riku Voipio, Laurent Vivier
Cc: arunkaly, Marc-André Lureau, qemu-devel
Cc'ing Marc-André
On 8/16/19 11:10 PM, Shu-Chun Weng via Qemu-devel 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 | 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);
>
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [Qemu-devel] [PATCH] linux-user: add memfd_create
2019-08-16 21:10 [Qemu-devel] [PATCH] linux-user: add memfd_create Shu-Chun Weng via Qemu-devel
2019-08-18 21:57 ` Philippe Mathieu-Daudé
@ 2019-08-19 7:12 ` Marc-André Lureau
2019-08-19 11:56 ` Peter Maydell
2019-09-10 8:16 ` Laurent Vivier
3 siblings, 0 replies; 10+ messages in thread
From: Marc-André Lureau @ 2019-08-19 7:12 UTC (permalink / raw)
To: Shu-Chun Weng; +Cc: arunkaly, Riku Voipio, Laurent Vivier, QEMU
On Sat, Aug 17, 2019 at 1:28 AM Shu-Chun Weng via Qemu-devel
<qemu-devel@nongnu.org> 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>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
> 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
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [Qemu-devel] [PATCH] linux-user: add memfd_create
2019-08-16 21:10 [Qemu-devel] [PATCH] linux-user: add memfd_create Shu-Chun Weng via Qemu-devel
2019-08-18 21:57 ` Philippe Mathieu-Daudé
2019-08-19 7:12 ` Marc-André Lureau
@ 2019-08-19 11:56 ` Peter Maydell
2019-08-19 18:08 ` [Qemu-devel] [PATCH v2] " Shu-Chun Weng via Qemu-devel
` (2 more replies)
2019-09-10 8:16 ` Laurent Vivier
3 siblings, 3 replies; 10+ messages in thread
From: Peter Maydell @ 2019-08-19 11:56 UTC (permalink / raw)
To: Shu-Chun Weng; +Cc: arunkaly, Riku Voipio, Laurent Vivier, QEMU Developers
On Fri, 16 Aug 2019 at 22:28, Shu-Chun Weng via Qemu-devel
<qemu-devel@nongnu.org> 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 | 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));
I think here you may need to call
fd_trans_unregister(ret);
since memfd_create() returns a file descriptor.
(This call unregisters any pre-existing hooks for "we need
to mangle the data for reads/writes of this file descriptor",
in case the fd was previously being used for a file descriptor
type that needed that.) This is what eg NR_open does.
Laurent -- do I have this right? It's not entirely clear
to me that we could ever be in a situation where a syscall
like open or memfd_create returns an fd that's got an fd_trans
hook active, because that would imply we'd failed to delete
the hook on fd-close somehow. Is this just a belt-and-braces
bit of coding ?
thanks
-- PMM
^ permalink raw reply [flat|nested] 10+ messages in thread* [Qemu-devel] [PATCH v2] linux-user: add memfd_create
2019-08-19 11:56 ` Peter Maydell
@ 2019-08-19 18:08 ` Shu-Chun Weng via Qemu-devel
2019-08-19 18:09 ` [Qemu-devel] [PATCH v3] " Shu-Chun Weng via Qemu-devel
2019-08-23 16:42 ` [Qemu-devel] [PATCH] " Laurent Vivier
2 siblings, 0 replies; 10+ messages in thread
From: Shu-Chun Weng via Qemu-devel @ 2019-08-19 18:08 UTC (permalink / raw)
To: marcandre.lureau
Cc: arunkaly, Shu-Chun Weng, riku.voipio, qemu-devel, laurent
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 | 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
^ permalink raw reply related [flat|nested] 10+ messages in thread* [Qemu-devel] [PATCH v3] linux-user: add memfd_create
2019-08-19 11:56 ` Peter Maydell
2019-08-19 18:08 ` [Qemu-devel] [PATCH v2] " Shu-Chun Weng via Qemu-devel
@ 2019-08-19 18:09 ` Shu-Chun Weng via Qemu-devel
2019-08-23 16:48 ` Laurent Vivier
2019-09-10 16:49 ` Laurent Vivier
2019-08-23 16:42 ` [Qemu-devel] [PATCH] " Laurent Vivier
2 siblings, 2 replies; 10+ messages in thread
From: Shu-Chun Weng via Qemu-devel @ 2019-08-19 18:09 UTC (permalink / raw)
To: marcandre.lureau
Cc: arunkaly, Shu-Chun Weng, riku.voipio, qemu-devel, laurent
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(-)
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);
--
2.23.0.rc1.153.gdeed80330f-goog
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [Qemu-devel] [PATCH v3] linux-user: add memfd_create
2019-08-19 18:09 ` [Qemu-devel] [PATCH v3] " Shu-Chun Weng via Qemu-devel
@ 2019-08-23 16:48 ` Laurent Vivier
2019-09-10 16:49 ` Laurent Vivier
1 sibling, 0 replies; 10+ messages in thread
From: Laurent Vivier @ 2019-08-23 16:48 UTC (permalink / raw)
To: Shu-Chun Weng, marcandre.lureau; +Cc: arunkaly, riku.voipio, qemu-devel
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>
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [Qemu-devel] [PATCH v3] linux-user: add memfd_create
2019-08-19 18:09 ` [Qemu-devel] [PATCH v3] " Shu-Chun Weng via Qemu-devel
2019-08-23 16:48 ` Laurent Vivier
@ 2019-09-10 16:49 ` Laurent Vivier
1 sibling, 0 replies; 10+ messages in thread
From: Laurent Vivier @ 2019-09-10 16:49 UTC (permalink / raw)
To: Shu-Chun Weng; +Cc: arunkaly, riku.voipio, marcandre.lureau, qemu-devel
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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] [PATCH] linux-user: add memfd_create
2019-08-19 11:56 ` Peter Maydell
2019-08-19 18:08 ` [Qemu-devel] [PATCH v2] " Shu-Chun Weng via Qemu-devel
2019-08-19 18:09 ` [Qemu-devel] [PATCH v3] " Shu-Chun Weng via Qemu-devel
@ 2019-08-23 16:42 ` Laurent Vivier
2 siblings, 0 replies; 10+ messages in thread
From: Laurent Vivier @ 2019-08-23 16:42 UTC (permalink / raw)
To: Peter Maydell, Shu-Chun Weng; +Cc: arunkaly, Riku Voipio, QEMU Developers
Le 19/08/2019 à 13:56, Peter Maydell a écrit :
> On Fri, 16 Aug 2019 at 22:28, Shu-Chun Weng via Qemu-devel
> <qemu-devel@nongnu.org> 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 | 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));
>
> I think here you may need to call
> fd_trans_unregister(ret);
>
> since memfd_create() returns a file descriptor.
> (This call unregisters any pre-existing hooks for "we need
> to mangle the data for reads/writes of this file descriptor",
> in case the fd was previously being used for a file descriptor
> type that needed that.) This is what eg NR_open does.
>
> Laurent -- do I have this right? It's not entirely clear
> to me that we could ever be in a situation where a syscall
> like open or memfd_create returns an fd that's got an fd_trans
> hook active, because that would imply we'd failed to delete
> the hook on fd-close somehow. Is this just a belt-and-braces
> bit of coding ?
Exactly.
It's in case we missed one fd close and then to be sure an existing "fd
translator" will not mess with data of the new one.
Thanks,
Laurent
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] [PATCH] linux-user: add memfd_create
2019-08-16 21:10 [Qemu-devel] [PATCH] linux-user: add memfd_create Shu-Chun Weng via Qemu-devel
` (2 preceding siblings ...)
2019-08-19 11:56 ` Peter Maydell
@ 2019-09-10 8:16 ` Laurent Vivier
3 siblings, 0 replies; 10+ messages in thread
From: Laurent Vivier @ 2019-09-10 8:16 UTC (permalink / raw)
To: Shu-Chun Weng, Riku Voipio; +Cc: arunkaly, qemu-devel
Le 16/08/2019 à 23:10, 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>
> ---
> 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);
>
Applied to my linux-user branch.
Thanks,
Laurent
^ permalink raw reply [flat|nested] 10+ messages in thread