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Commit c9eaf20f authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: x86 emulator: Implement zero-extended immediate decoding 



Absolute jumps use zero extended immediate operands.

Cc: stable@kernel.org
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent cb007648

arch/x86/kvm/x86_emulate.c

+15 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ 
#define SrcImmByte  (6<<4)	/* 8-bit sign-extended immediate operand. */

#define SrcOne      (7<<4)	/* Implied '1' */

#define SrcImmUByte (8<<4)      /* 8-bit unsigned immediate operand. */

#define SrcImmU     (9<<4)      /* Immediate operand, unsigned */

#define SrcMask     (0xf<<4)

/* Generic ModRM decode. */

#define ModRM       (1<<8)
@@ -1027,6 +1028,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
		c->src.type = OP_MEM;

		break;

	case SrcImm:

	case SrcImmU:

		c->src.type = OP_IMM;

		c->src.ptr = (unsigned long *)c->eip;

		c->src.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
@@ -1044,6 +1046,19 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
			c->src.val = insn_fetch(s32, 4, c->eip);

			break;

		}

		if ((c->d & SrcMask) == SrcImmU) {

			switch (c->src.bytes) {

			case 1:

				c->src.val &= 0xff;

				break;

			case 2:

				c->src.val &= 0xffff;

				break;

			case 4:

				c->src.val &= 0xffffffff;

				break;

			}

		}

		break;

	case SrcImmByte:

	case SrcImmUByte: