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Date: Sat, 25 Feb 2012 21:54:57 -0800 From: "H. Peter Anvin" <hpa@...or.com> To: Bobby Powers <bobbypowers@...il.com> CC: linux-kernel@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de, x86@...nel.org, hjl.tools@...il.com, Andi Kleen <andi@...stfloor.org> Subject: Re: [PATCH] x32: make sure TS_COMPAT is cleared for x32 tasks On 02/25/2012 08:25 PM, Bobby Powers wrote: > If a process has a non-x32 ia32 personality and changes to x32, the > process would keep its TS_COMPAT flag. x32 uses the presence of the > x32 flag on a syscall to determine compat status, so make sure > TS_COMPAT is cleared. > > Signed-off-by: Bobby Powers <bobbypowers@...il.com> > --- > arch/x86/kernel/process_64.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c > index e9ec8f1..a465973 100644 > --- a/arch/x86/kernel/process_64.c > +++ b/arch/x86/kernel/process_64.c > @@ -539,6 +539,9 @@ void set_personality_ia32(bool x32) > clear_thread_flag(TIF_IA32); > set_thread_flag(TIF_X32); > current->personality &= ~READ_IMPLIES_EXEC; > + /* is_compat_task() uses the presence of the x32 > + syscall bit flag to determine compat status */ > + current_thread_info()->status &= ~TS_COMPAT; > } else { > set_thread_flag(TIF_IA32); > clear_thread_flag(TIF_X32); I suspect we should also clear TS_COMPAT in set_personality_64() ... this is not x32-related, but would affect the behavior when execing a 64-bit task from an i386 compatibility task. I have no idea if it actually makes any difference, and clearly it can't have been too broken since noone has found a problem all these years, but it looks wrong... -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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