| Message ID | 1437615403-13554-3-git-send-email-marcandre.lureau@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Thu, Jul 23, 2015 at 03:36:39AM +0200, Marc-André Lureau wrote: > Implement memfd_create() fallback if not available in system libc. > memfd_create() is still not included in glibc today, atlhough it's been > available since Linux 3.17 in Oct 2014. > > memfd has numerous advantages over traditional shm/mmap for ipc memory > sharing with fd handler, which we are going to make use of for > vhost-user logging memory in following patches. > > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> > --- > include/qemu/osdep.h | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 59 insertions(+) > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > index 3247364..adc138b 100644 > --- a/include/qemu/osdep.h > +++ b/include/qemu/osdep.h > @@ -6,6 +6,7 @@ > #include <stddef.h> > #include <stdbool.h> > #include <stdint.h> > +#include <unistd.h> > #include <sys/types.h> > #ifdef __OpenBSD__ > #include <sys/signal.h> > @@ -20,6 +21,64 @@ > > #include <sys/time.h> > > +#ifdef CONFIG_LINUX > + > +#ifndef F_LINUX_SPECIFIC_BASE > +#define F_LINUX_SPECIFIC_BASE 1024 > +#endif > + > +#ifndef F_ADD_SEALS > +#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9) > +#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10) > + > +#define F_SEAL_SEAL 0x0001 /* prevent further seals from being set */ > +#define F_SEAL_SHRINK 0x0002 /* prevent file from shrinking */ > +#define F_SEAL_GROW 0x0004 /* prevent file from growing */ > +#define F_SEAL_WRITE 0x0008 /* prevent writes */ > +#endif These are from include/uapi/linux/fcntl.h, they should be imported into linux-headers I think. > + > +#ifndef MFD_ALLOW_SEALING > +#define MFD_ALLOW_SEALING 0x0002U > +#endif > + > +#ifndef MFD_CLOEXEC > +#define MFD_CLOEXEC 0x0001U > +#endif > + > +#ifndef __NR_memfd_create > +# if defined __x86_64__ > +# define __NR_memfd_create 319 > +# elif defined __arm__ > +# define __NR_memfd_create 385 > +# elif defined __aarch64__ > +# define __NR_memfd_create 279 > +# elif defined _MIPS_SIM > +# if _MIPS_SIM == _MIPS_SIM_ABI32 > +# define __NR_memfd_create 4354 > +# endif > +# if _MIPS_SIM == _MIPS_SIM_NABI32 > +# define __NR_memfd_create 6318 > +# endif > +# if _MIPS_SIM == _MIPS_SIM_ABI64 > +# define __NR_memfd_create 5314 > +# endif What's defining all these macros? > +# elif defined __i386__ > +# define __NR_memfd_create 356 > +# else > +# warning "__NR_memfd_create unknown for your architecture" > +# define __NR_memfd_create 0xffffffff > +# endif > +#endif > + > +#ifndef CONFIG_MEMFD > +static inline int memfd_create(const char *name, unsigned int flags) > +{ > + return syscall(__NR_memfd_create, name, flags); > +} > +#endif How about making these non-inline? I think we need stubs for non-posix systems, right? > + > +#endif /* LINUX */ > + > #if defined(CONFIG_SOLARIS) && CONFIG_SOLARIS_VERSION < 10 > /* [u]int_fast*_t not in <sys/int_types.h> */ > typedef unsigned char uint_fast8_t; > -- > 2.4.3
On 23/07/2015 17:25, Michael S. Tsirkin wrote: > > +#ifdef CONFIG_LINUX > > + > > +#ifndef F_LINUX_SPECIFIC_BASE > > +#define F_LINUX_SPECIFIC_BASE 1024 > > +#endif > > + > > +#ifndef F_ADD_SEALS > > +#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9) > > +#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10) > > + > > +#define F_SEAL_SEAL 0x0001 /* prevent further seals from being set */ > > +#define F_SEAL_SHRINK 0x0002 /* prevent file from shrinking */ > > +#define F_SEAL_GROW 0x0004 /* prevent file from growing */ > > +#define F_SEAL_WRITE 0x0008 /* prevent writes */ > > +#endif > > These are from include/uapi/linux/fcntl.h, > they should be imported into linux-headers I think. linux-headers is usually used for virt-related features that we want in QEMU a few weeks before they are distributed upstream. Here, I think just including linux/fcntl.h is enough. >> +#ifndef __NR_memfd_create >> +# if defined __x86_64__ >> +# define __NR_memfd_create 319 >> +# elif defined __arm__ >> +# define __NR_memfd_create 385 >> +# elif defined __aarch64__ >> +# define __NR_memfd_create 279 >> +# elif defined _MIPS_SIM >> +# if _MIPS_SIM == _MIPS_SIM_ABI32 >> +# define __NR_memfd_create 4354 >> +# endif >> +# if _MIPS_SIM == _MIPS_SIM_NABI32 >> +# define __NR_memfd_create 6318 >> +# endif >> +# if _MIPS_SIM == _MIPS_SIM_ABI64 >> +# define __NR_memfd_create 5314 >> +# endif > > What's defining all these macros? They're in asm/unistd.h. I think that, instead of making qemu/osdep.h the new qemu-common.h, the wrappers added by patch 3 should be declared in a new header qemu/memfd.h. The implementation in util/memfd.c can include both linux/fcntl.h and asm/unistd.h. Paolo
Hi On Tue, Jul 28, 2015 at 10:11 AM, Paolo Bonzini <pbonzini@redhat.com> wrote: >> >> What's defining all these macros? > > They're in asm/unistd.h. > > I think that, instead of making qemu/osdep.h the new qemu-common.h, the > wrappers added by patch 3 should be declared in a new header > qemu/memfd.h. The implementation in util/memfd.c can include both > linux/fcntl.h and asm/unistd.h. > Ok, shouldn't it keep the inline function? this avoids future clash when upgrading glibc.
On 28/07/2015 12:58, Marc-André Lureau wrote: > Hi > > On Tue, Jul 28, 2015 at 10:11 AM, Paolo Bonzini <pbonzini@redhat.com> wrote: >>> >>> What's defining all these macros? >> >> They're in asm/unistd.h. >> >> I think that, instead of making qemu/osdep.h the new qemu-common.h, the >> wrappers added by patch 3 should be declared in a new header >> qemu/memfd.h. The implementation in util/memfd.c can include both >> linux/fcntl.h and asm/unistd.h. >> > > Ok, shouldn't it keep the inline function? this avoids future clash > when upgrading glibc. Can the inline function stay in util/memfd.c? Paolo
Hi
On Tue, Jul 28, 2015 at 1:50 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> Can the inline function stay in util/memfd.c?
I see little benefits in that, only the qemu_memfd_alloc helpers would
then be exported. Then the inline is probably unnecessary if moved in
the memfd.c.
On 28/07/2015 16:25, Marc-André Lureau wrote: > > Can the inline function stay in util/memfd.c? > I see little benefits in that, only the qemu_memfd_alloc helpers would > then be exported. Then the inline is probably unnecessary if moved in > the memfd.c. That's just a matter of taste, I agree. Paolo
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index 3247364..adc138b 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -6,6 +6,7 @@ #include <stddef.h> #include <stdbool.h> #include <stdint.h> +#include <unistd.h> #include <sys/types.h> #ifdef __OpenBSD__ #include <sys/signal.h> @@ -20,6 +21,64 @@ #include <sys/time.h> +#ifdef CONFIG_LINUX + +#ifndef F_LINUX_SPECIFIC_BASE +#define F_LINUX_SPECIFIC_BASE 1024 +#endif + +#ifndef F_ADD_SEALS +#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9) +#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10) + +#define F_SEAL_SEAL 0x0001 /* prevent further seals from being set */ +#define F_SEAL_SHRINK 0x0002 /* prevent file from shrinking */ +#define F_SEAL_GROW 0x0004 /* prevent file from growing */ +#define F_SEAL_WRITE 0x0008 /* prevent writes */ +#endif + +#ifndef MFD_ALLOW_SEALING +#define MFD_ALLOW_SEALING 0x0002U +#endif + +#ifndef MFD_CLOEXEC +#define MFD_CLOEXEC 0x0001U +#endif + +#ifndef __NR_memfd_create +# if defined __x86_64__ +# define __NR_memfd_create 319 +# elif defined __arm__ +# define __NR_memfd_create 385 +# elif defined __aarch64__ +# define __NR_memfd_create 279 +# elif defined _MIPS_SIM +# if _MIPS_SIM == _MIPS_SIM_ABI32 +# define __NR_memfd_create 4354 +# endif +# if _MIPS_SIM == _MIPS_SIM_NABI32 +# define __NR_memfd_create 6318 +# endif +# if _MIPS_SIM == _MIPS_SIM_ABI64 +# define __NR_memfd_create 5314 +# endif +# elif defined __i386__ +# define __NR_memfd_create 356 +# else +# warning "__NR_memfd_create unknown for your architecture" +# define __NR_memfd_create 0xffffffff +# endif +#endif + +#ifndef CONFIG_MEMFD +static inline int memfd_create(const char *name, unsigned int flags) +{ + return syscall(__NR_memfd_create, name, flags); +} +#endif + +#endif /* LINUX */ + #if defined(CONFIG_SOLARIS) && CONFIG_SOLARIS_VERSION < 10 /* [u]int_fast*_t not in <sys/int_types.h> */ typedef unsigned char uint_fast8_t;
Implement memfd_create() fallback if not available in system libc. memfd_create() is still not included in glibc today, atlhough it's been available since Linux 3.17 in Oct 2014. memfd has numerous advantages over traditional shm/mmap for ipc memory sharing with fd handler, which we are going to make use of for vhost-user logging memory in following patches. Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> --- include/qemu/osdep.h | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+)