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ARC: [arcompact] handle unaligned access delay slot corner case

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commit 9aed02feae 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>
This commit is contained in:
Vineet Gupta
2017-01-27 10:45:27 -08:00
committed by Greg Kroah-Hartman
parent 42ad766367
commit acb63c8b57
1 changed files with 2 additions and 1 deletions
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3
arch/arc/kernel/unaligned.c
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@@ -241,8 +241,9 @@ int misaligned_fixup(unsigned long address, struct pt_regs *regs,
if (state.fault)
goto fault;
/* clear any remanants of delay slot */
if (delay_mode(regs)) {
regs->ret = regs->bta;
regs->ret = regs->bta ~1U;
regs->status32 &= ~STATUS_DE_MASK;
} else {
regs->ret += state.instr_len;