Messages in this thread |  | | | Date | Tue, 4 Dec 2007 14:43:29 -0800 (PST) | | From | Linus Torvalds <> | | Subject | Re: [PATCH] fix for futex_wait signal stack corruption |
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On Tue, 4 Dec 2007, Steven Rostedt wrote: > > Seems that arg3 is not used here and since the timer is 64 bits, we can > store the bottom 32 bits in arg2 and the top in arg3 (this will work for > both 32 and 64 bit archs).
Yes. That should work fine.
The restart logic sometimes results in odd calling conventions, and quite frankly, we could just change how "restart_block" looks too. There is nothing that says that it has to be
unsigned long arg0, arg1, arg2, arg3
and that particular layout was just picked on a whim. The only issue is:
- we don't want the restart block to be *too* large, since it's part of the thread info. - but we need to have enough room for all the system calls that want to use the restart block, and preferably in a reasonable format.
So far, using "unsigned long" has been good enough, in that it's big enough for a pointer and all normal arguments, but if something really deeply wants another format or a guaranteed 64-bit word regardless of architecture, we could make one or more of the arguments be "u64" instead.
But in this case, since there is already unused argument space, I think that doing the "32 high bits + 32 low bits" is probably the best option.
Linus
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