Commit 326f578f authored May 09, 2013 by Paolo Bonzini Committed by Gleb Natapov May 09, 2013

KVM: emulator: emulate SALC



This is an almost-undocumented instruction available in 32-bit mode.
I say "almost" undocumented because AMD documents it in their opcode
maps just to say that it is unavailable in 64-bit mode (sections
"A.2.1 One-Byte Opcodes" and "B.3 Invalid and Reassigned Instructions
in 64-Bit Mode").

It is roughly equivalent to "sbb %al, %al" except it does not
set the flags.  Use fastop to emulate it, but do not use the opcode
directly because it would fail if the host is 64-bit!

Reported-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: stable@vger.kernel.org # 3.9
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

parent 7fa57952

arch/x86/kvm/emulate.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -535,6 +535,9 @@ FOP_SETCC(setle)
		FOP_SETCC(setnle)
		FOP_END;

		FOP_START(salc) "pushf; sbb %al, %al; popf \n\t" FOP_RET
		FOP_END;

		#define __emulate_1op_rax_rdx(ctxt, _op, _suffix, _ex) \
		do { \
		unsigned long _tmp; \
		@@ -3961,7 +3964,8 @@ static const struct opcode opcode_table[256] = {
		G(Src2One \| ByteOp, group2), G(Src2One, group2),
		G(Src2CL \| ByteOp, group2), G(Src2CL, group2),
		I(DstAcc \| SrcImmUByte \| No64, em_aam),
		I(DstAcc \| SrcImmUByte \| No64, em_aad), N,
		I(DstAcc \| SrcImmUByte \| No64, em_aad),
		F(DstAcc \| ByteOp \| No64, em_salc),
		I(DstAcc \| SrcXLat \| ByteOp, em_mov),
		/* 0xD8 - 0xDF */
		N, E(0, &escape_d9), N, E(0, &escape_db), N, E(0, &escape_dd), N, N,

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