Commit 87c4b83e authored Jun 15, 2017 by Anton Blanchard Committed by Michael Ellerman Jul 12, 2017

powerpc: Fix emulation of mcrf in emulate_step()



The mcrf emulation code was using the CR field number directly as the shift
value, without taking into account that CR fields are numbered from 0-7 starting
at the high bits. That meant it was looking at the CR fields in the reverse
order.

Fixes: cf87c3f6 ("powerpc: Emulate icbi, mcrf and conditional-trap instructions")
Cc: stable@vger.kernel.org # v3.18+
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

parent 3f0bd8da

arch/powerpc/lib/sstep.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -683,8 +683,10 @@ int analyse_instr(struct instruction_op op, struct pt_regs regs,
		case 19:
		switch ((instr >> 1) & 0x3ff) {
		case 0: /* mcrf */
		rd = (instr >> 21) & 0x1c;
		ra = (instr >> 16) & 0x1c;
		rd = 7 - ((instr >> 23) & 0x7);
		ra = 7 - ((instr >> 18) & 0x7);
		rd *= 4;
		ra *= 4;
		val = (regs->ccr >> ra) & 0xf;
		regs->ccr = (regs->ccr & ~(0xfUL << rd)) \| (val << rd);
		goto instr_done;

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