On Tue, 2007-05-08 at 16:07 +0200, Markus Osterried wrote:
> Hello Phillipe,
>
> in __t_start() in /ksrc/skins/psos+/syscall.c the pointer to the
> (user-space) tasks argument is directly used for the (kernel-space)
> t_start() call.
>
> u_long *argp;
> argp = (u_long *)__xn_reg_arg4(regs);
> return t_start((u_long)task, mode, startaddr, argp);
>
>
> I think the arguments must be copied to kernel-space, so isn't it better to
> do it this way?
>
> u_long arg[4];
> if (!__xn_access_ok
> (curr, VERIFY_READ, __xn_reg_arg4(regs), sizeof(u_long[4])))
> return -EFAULT;
> __xn_copy_from_user(curr, arg, (void __user *)__xn_reg_arg4(regs),
> sizeof(u_long[4]));
> return t_start((u_long)task, mode, startaddr, arg);
>
Actually, we currently don't need to know anything about the task args
from kernel space, since we only have to relay their address to the task
trampoline code in src/skins/psos/task.c. However, we must not try to
access those args from kernel space. The patch below fixes this bug.
Thanks for pointing this out.
--- ksrc/skins/psos+/task.c (revision 2395)
+++ ksrc/skins/psos+/task.c (working copy)
@@ -197,9 +197,6 @@
xnmode = psos_mode_to_xeno(mode);
- for (n = 0; n < 4; n++)
- task->args[n] = targs ? targs[n] : 0;
-
task->entry = startaddr;
#if defined(__KERNEL__) && defined(CONFIG_XENO_OPT_PERVASIVE)
@@ -214,10 +211,15 @@
XNPOD_ALL_CPUS, (void (*)(void *))startaddr,
targs);
else
#endif /* __KERNEL__ && CONFIG_XENO_OPT_PERVASIVE */
+ {
+ for (n = 0; n < 4; n++)
+ task->args[n] = targs ? targs[n] : 0;
+
xnpod_start_thread(&task->threadbase,
xnmode,
(int)((mode >> 8) & 0x7),
XNPOD_ALL_CPUS, &psostask_trampoline, task);
+ }
unlock_and_exit:
--
Philippe.
_______________________________________________
Xenomai-core mailing list
Xenomai-core@gna.org
https://mail.gna.org/listinfo/xenomai-core
