Messages in this thread | | | Date | Mon, 15 Feb 2010 08:23:19 -0800 | From | "H. Peter Anvin" <> | Subject | Re: x86: get rid of the insane TIF_ABI_PENDING bit |
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On 02/15/2010 08:17 AM, Oleg Nesterov wrote: > >> +void set_personality_ia32(void) >> +{ >> + /* inherit personality from parent */ >> + >> + /* Make sure to be in 32bit mode */ >> + set_thread_flag(TIF_IA32); >> + >> + /* Prepare the first "return" to user space */ >> + current_thread_info()->status |= TS_COMPAT; > > Can't understand why we need TS_COMPAT. I assume this is correct, > this was copied from flush_thread(). > > What TS_COMPAT actually means? I thought it just means "the task > is inside 32-bit syscall".
Yes. In this case, though, it was a 64-bit syscall when the process did the exec, but it needs to "return" as if it came from a 32-bit syscall; that's why we set the TS_COMPAT bit.
> If a 64bit task execs a 32bit app, can't this TS_COMPAT break, say, > syscall_get_arguments() ? >
At that point (this is after the exec!) we don't get arguments anyway.
> Just curious, I don't really understand COMPAT issues anyway.
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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