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Commit 242aa00b authored by Anton Blanchard's avatar Anton Blanchard Committed by Greg Kroah-Hartman
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powerpc: Fix emulation of mcrf in emulate_step() 



commit 87c4b83e0fe234a1f0eed131ab6fa232036860d5 upstream.

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")
Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Acked-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 68fb479f

arch/powerpc/lib/sstep.c

+4 −2
Original line number Diff line number Diff line
@@ -687,8 +687,10 @@ int __kprobes 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;