From: Vineet Gupta Date: Fri, 27 Jan 2017 18:45:27 +0000 (-0800) Subject: ARC: [arcompact] handle unaligned access delay slot corner case X-Git-Tag: v3.10.107~140 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b5882ec2fe3c937c863aab441e96b3f47f72f035;p=thirdparty%2Fkernel%2Fstable.git ARC: [arcompact] handle unaligned access delay slot corner case 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 Signed-off-by: Willy Tarreau --- diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c index 116d3e09b5b55..b13b422a885c2 100644 --- a/arch/arc/kernel/unaligned.c +++ b/arch/arc/kernel/unaligned.c @@ -228,8 +228,9 @@ 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;