Messages in this thread | | | Subject | Re: [PATCH 4.4 12/23] ARC: [arcompact] handle unaligned access delay slot corner case | From | Ben Hutchings <> | Date | Fri, 10 Feb 2017 12:51:48 +0000 |
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On Tue, 2017-01-31 at 06:37 +0100, Greg Kroah-Hartman wrote: > 4.4-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Vineet Gupta <vgupta@synopsys.com> > > commit 9aed02feae57bf7a40cb04ea0e3017cb7a998db4 upstream. > > After emulating an unaligned access in delay slot of a branch, we > pretend as the delay slot never happened - so return back to actual > branch target (or next PC if branch was not taken). > > Curently we did this by handling STATUS32.DE, we also need to clear the > BTA.T bit, which is disregarded when returning from original misaligned > exception, but could cause weirdness if it took the interrupt return > path (in case interrupt was acive too) > > One ARC700 customer ran into this when enabling unaligned access fixup > for kernel mode accesses as well > > Signed-off-by: Vineet Gupta <vgupta@synopsys.com> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > --- > arch/arc/kernel/unaligned.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > --- a/arch/arc/kernel/unaligned.c > +++ b/arch/arc/kernel/unaligned.c > @@ -241,8 +241,9 @@ int misaligned_fixup(unsigned long addre > if (state.fault) > goto fault; > > + /* clear any remanants of delay slot */ > if (delay_mode(regs)) { > - regs->ret = regs->bta; > + regs->ret = regs->bta ~1U;
Unless you're doing something terrible with macros, this is missing an & operator. I doubt this even compiled (looks like it's only used in some ARC configurations).
Ben.
> regs->status32 &= ~STATUS_DE_MASK; > } else { > regs->ret += state.instr_len;
-- Ben Hutchings It's easier to fight for one's principles than to live up to them.
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