From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <54DCDFD5.9090202@siemens.com> Date: Thu, 12 Feb 2015 18:16:05 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <5491B5E9.4030200@siemens.com> <5491C2CA.7000906@xenomai.org> <5491C179.2000600@siemens.com> <5491CB3F.2050509@xenomai.org> <5491CC27.6080909@siemens.com> <5491D196.3040309@xenomai.org> <54D0E961.4060705@xenomai.org> <54DCD68F.5020005@siemens.com> <54DCDC98.5070402@siemens.com> <54DCDDC7.5060700@xenomai.org> In-Reply-To: <54DCDDC7.5060700@xenomai.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai] Mayday mechanism broken on x86-64 - simpler approach feasible? List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philippe Gerum , Xenomai On 2015-02-12 18:07, Philippe Gerum wrote: > On 02/12/2015 06:02 PM, Jan Kiszka wrote: >> On 2015-02-12 17:36, Jan Kiszka wrote: >>>> As I mentioned earlier, I'd rather fix the MAYDAY implementation for >>>> x86_64 instead of forking the implementation between MMU-enabled and >>>> MMU-less architectures, also affecting powerpc, arm and x86_32 in the >>>> same move. Fortunately, the current implementation allows very specific >>>> tweaks to be applied on a per-architecture basis. This one fixes the >>>> issue for Cobalt on x86_64, and could be easily backported to 2.6.x: >>>> >>>> http://git.xenomai.org/xenomai-3.git/commit/?h=next&id=6db20901963d634b9786467c711c2ba526db48a2 >>> >>> Looks almost good - except for the detail that some bits of the >>> instruction pointer are lost on return from the syscall (int vs. long >>> return type). Patches in the making. >> >> Will take longer - I need to convert all cobalt syscalls. >> >> We have a sleeping bug there, though likely not seen in practice, with >> syscalls returning values > INT_MAX (size_t...). The problem is that >> handle_head/root_syscall only forwarded 32-bits so far. >> > > You mean this, and all the implications of it? > > diff --git a/kernel/cobalt/posix/syscall.c b/kernel/cobalt/posix/syscall.c > index 6a9a02c..99b86a4 100644 > --- a/kernel/cobalt/posix/syscall.c > +++ b/kernel/cobalt/posix/syscall.c > @@ -73,9 +73,9 @@ > /* Shorthand for oneway trap - does not return to call site. */ > #define __xn_exec_oneway __xn_exec_norestart > > -typedef int (*cobalt_syshand)(unsigned long arg1, unsigned long arg2, > - unsigned long arg3, unsigned long arg4, > - unsigned long arg5); > +typedef long (*cobalt_syshand)(unsigned long arg1, unsigned long arg2, > + unsigned long arg3, unsigned long arg4, > + unsigned long arg5); > > static void prepare_for_signal(struct task_struct *p, > struct xnthread *thread, > Exactly. Just done with the mechanics, crossing fingers it won't break things subtly. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux