| Message ID | 20190816211049.57317-1-scw@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | linux-user: add memfd_create | expand |
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); >
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 > >
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
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
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
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);
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(-)