From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55415) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bWhwT-0002Mn-Ub for qemu-devel@nongnu.org; Mon, 08 Aug 2016 06:37:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bWhwQ-0000hh-Ha for qemu-devel@nongnu.org; Mon, 08 Aug 2016 06:37:57 -0400 Received: from mail-wm0-x242.google.com ([2a00:1450:400c:c09::242]:35505) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bWhwQ-0000hO-7l for qemu-devel@nongnu.org; Mon, 08 Aug 2016 06:37:54 -0400 Received: by mail-wm0-x242.google.com with SMTP id i5so14593659wmg.2 for ; Mon, 08 Aug 2016 03:37:54 -0700 (PDT) Date: Mon, 8 Aug 2016 11:37:50 +0100 From: Stefan Hajnoczi Message-ID: <20160808103750.GA30105@stefanha-x1.localdomain> References: <1468340586-19304-1-git-send-email-pl@kamp.de> <1468340586-19304-2-git-send-email-pl@kamp.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="X1bOJ3K7DJ5YkBrT" Content-Disposition: inline In-Reply-To: <1468340586-19304-2-git-send-email-pl@kamp.de> Subject: Re: [Qemu-devel] [PATCH V5 1/6] oslib-posix: add helpers for stack alloc and free List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: qemu-devel@nongnu.org, kwolf@redhat.com, peter.maydell@linaro.org, mst@redhat.com, armbru@redhat.com, dgilbert@redhat.com, mreitz@redhat.com, pbonzini@redhat.com, rth@twiddle.net --X1bOJ3K7DJ5YkBrT Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jul 12, 2016 at 06:23:01PM +0200, Peter Lieven wrote: > the allocated stack will be adjusted to the minimum supported stack size > by the OS and rounded up to be a multiple of the system pagesize. > Additionally an architecture dependent guard page is added to the stack > to catch stack overflows. >=20 > Signed-off-by: Peter Lieven > --- > include/sysemu/os-posix.h | 23 +++++++++++++++++++++++ > util/oslib-posix.c | 46 +++++++++++++++++++++++++++++++++++++++++= +++++ > 2 files changed, 69 insertions(+) >=20 > diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h > index 9c7dfdf..7630665 100644 > --- a/include/sysemu/os-posix.h > +++ b/include/sysemu/os-posix.h > @@ -60,4 +60,27 @@ int qemu_utimens(const char *path, const qemu_timespec= *times); > =20 > bool is_daemonized(void); > =20 > +/** > + * qemu_alloc_stack: > + * @sz: size of required stack in bytes > + * > + * Allocate memory that can be used as a stack, for instance for > + * coroutines. If the memory cannot be allocated, this function > + * will abort (like g_malloc()). > + * > + * The allocated stack must be freed with qemu_free_stack(). > + * > + * Returns: pointer to (the lowest address of) the stack memory. > + */ > +void *qemu_alloc_stack(size_t sz); > + > +/** > + * qemu_free_stack: > + * @stack: stack to free > + * @sz: size of stack in bytes > + * > + * Free a stack allocated via qemu_alloc_stack(). > + */ > +void qemu_free_stack(void *stack, size_t sz); > + > #endif > diff --git a/util/oslib-posix.c b/util/oslib-posix.c > index e2e1d4d..2303ca6 100644 > --- a/util/oslib-posix.c > +++ b/util/oslib-posix.c > @@ -497,3 +497,49 @@ pid_t qemu_fork(Error **errp) > } > return pid; > } > + > +static size_t adjust_stack_size(size_t sz) > +{ > +#ifdef _SC_THREAD_STACK_MIN > + /* avoid stacks smaller than _SC_THREAD_STACK_MIN */ > + sz =3D MAX(MAX(sysconf(_SC_THREAD_STACK_MIN), 0), sz); > +#endif > + /* adjust stack size to a multiple of the page size */ > + sz =3D ROUND_UP(sz, getpagesize()); > + return sz; > +} > + > +void *qemu_alloc_stack(size_t sz) > +{ > + void *ptr, *guardpage; > + size_t pagesz =3D getpagesize(); > + sz =3D adjust_stack_size(sz); > + > + ptr =3D mmap(NULL, sz, PROT_READ | PROT_WRITE, It's cleaner to count for the guard page separately and give the caller the sz bytes they expected: sz + pagesz > + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); > + if (ptr =3D=3D MAP_FAILED) { > + abort(); > + } > + > +#if defined(HOST_IA64) > + /* separate register stack */ > + guardpage =3D ptr + (((sz - pagesz) / 2) & ~pagesz); > +#elif defined(HOST_HPPA) > + /* stack grows up */ > + guardpage =3D ptr + sz - pagesz; > +#else > + /* stack grows down */ > + guardpage =3D ptr; > +#endif > + if (mprotect(guardpage, pagesz, PROT_NONE) !=3D 0) { > + abort(); > + } > + > + return ptr; > +} > + > +void qemu_free_stack(void *stack, size_t sz) > +{ > + sz =3D adjust_stack_size(sz); > + munmap(stack, sz); > +} > --=20 > 1.9.1 >=20 >=20 --X1bOJ3K7DJ5YkBrT Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJXqGD+AAoJEJykq7OBq3PIeXYH/jkrepGmc0nJoXQqexmFCvDD x5FwjkQc7MgcmPUGNochXJBcAKSm0dA8b3IUqWDSZCWld8NAxpbYbw5lxV3mY3zT 66ZO+bZOuOi3FE+GMbULhybDzNs4yYVMMdF+HetK3d+LFHdT6j8Xw6LLAlL5QRt4 Adly2qXMLysy44vrlGss9E4AU2Xky9a13bxDZ0DS12L3p44jJmUAzij/fFF/OajN dscXjfN+G9KgklLT5R236sxLEriRh2oiyoBf+jtR9buz/0e4MeDg6ds8lzg76p9Q COv18ocopcDVnEM5kzdU6Ae05z4Eaz1JcXnIQtZHHdLpCVgE83DEEgYYmqNgv34= =Tu8z -----END PGP SIGNATURE----- --X1bOJ3K7DJ5YkBrT--