Re: [Qemu-devel] [PATCH] linux-user: add memfd_create
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
> ---
> 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
> #include
> #include
> @@ -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
> #include
>
> -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
Re: [Qemu-devel] [PATCH] linux-user: add memfd_create
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
> 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
>> ---
>> 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
>> #include
>> #include
>> @@ -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
Re: [Qemu-devel] [PATCH] linux-user: add memfd_create
On Fri, 16 Aug 2019 at 22:28, 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
> ---
> 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
> #include
> #include
> @@ -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
Re: [Qemu-devel] [PATCH] linux-user: add memfd_create
On Sat, Aug 17, 2019 at 1:28 AM 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
Reviewed-by: Marc-André Lureau
> ---
> 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
> #include
> #include
> @@ -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
> #include
>
> -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
Re: [Qemu-devel] [PATCH] linux-user: add memfd_create
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
> ---
> 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
> #include
> #include
> @@ -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
> #include
>
> -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);
>
[Qemu-devel] [PATCH] linux-user: add memfd_create
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
---
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
#include
#include
@@ -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
#include
-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
