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    Subject[PATCH 05/42] KVM: x86 emulator: Add 'push/pop sreg' instructions
    Date
    From: Mohammed Gamal <m.gamal005@gmail.com>

    [avi: avoid buffer overflow]

    Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
    Signed-off-by: Avi Kivity <avi@redhat.com>
    ---
    arch/x86/kvm/emulate.c | 107 +++++++++++++++++++++++++++++++++++++++++++++---
    1 files changed, 101 insertions(+), 6 deletions(-)

    diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
    index 1be5cd6..1cdfec5 100644
    --- a/arch/x86/kvm/emulate.c
    +++ b/arch/x86/kvm/emulate.c
    @@ -92,19 +92,22 @@ static u32 opcode_table[256] = {
    /* 0x00 - 0x07 */
    ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
    ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
    - ByteOp | DstAcc | SrcImm, DstAcc | SrcImm, 0, 0,
    + ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
    + ImplicitOps | Stack, ImplicitOps | Stack,
    /* 0x08 - 0x0F */
    ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
    ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
    - 0, 0, 0, 0,
    + 0, 0, ImplicitOps | Stack, 0,
    /* 0x10 - 0x17 */
    ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
    ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
    - ByteOp | DstAcc | SrcImm, DstAcc | SrcImm, 0, 0,
    + ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
    + ImplicitOps | Stack, ImplicitOps | Stack,
    /* 0x18 - 0x1F */
    ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
    ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
    - ByteOp | DstAcc | SrcImm, DstAcc | SrcImm, 0, 0,
    + ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
    + ImplicitOps | Stack, ImplicitOps | Stack,
    /* 0x20 - 0x27 */
    ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
    ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
    @@ -244,11 +247,13 @@ static u32 twobyte_table[256] = {
    /* 0x90 - 0x9F */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    /* 0xA0 - 0xA7 */
    - 0, 0, 0, DstMem | SrcReg | ModRM | BitOp,
    + ImplicitOps | Stack, ImplicitOps | Stack,
    + 0, DstMem | SrcReg | ModRM | BitOp,
    DstMem | SrcReg | Src2ImmByte | ModRM,
    DstMem | SrcReg | Src2CL | ModRM, 0, 0,
    /* 0xA8 - 0xAF */
    - 0, 0, 0, DstMem | SrcReg | ModRM | BitOp,
    + ImplicitOps | Stack, ImplicitOps | Stack,
    + 0, DstMem | SrcReg | ModRM | BitOp,
    DstMem | SrcReg | Src2ImmByte | ModRM,
    DstMem | SrcReg | Src2CL | ModRM,
    ModRM, 0,
    @@ -1186,6 +1191,32 @@ static int emulate_pop(struct x86_emulate_ctxt *ctxt,
    return rc;
    }

    +static void emulate_push_sreg(struct x86_emulate_ctxt *ctxt, int seg)
    +{
    + struct decode_cache *c = &ctxt->decode;
    + struct kvm_segment segment;
    +
    + kvm_x86_ops->get_segment(ctxt->vcpu, &segment, seg);
    +
    + c->src.val = segment.selector;
    + emulate_push(ctxt);
    +}
    +
    +static int emulate_pop_sreg(struct x86_emulate_ctxt *ctxt,
    + struct x86_emulate_ops *ops, int seg)
    +{
    + struct decode_cache *c = &ctxt->decode;
    + unsigned long selector;
    + int rc;
    +
    + rc = emulate_pop(ctxt, ops, &selector, c->op_bytes);
    + if (rc != 0)
    + return rc;
    +
    + rc = kvm_load_segment_descriptor(ctxt->vcpu, (u16)selector, 1, seg);
    + return rc;
    +}
    +
    static inline int emulate_grp1a(struct x86_emulate_ctxt *ctxt,
    struct x86_emulate_ops *ops)
    {
    @@ -1707,18 +1738,66 @@ special_insn:
    add: /* add */
    emulate_2op_SrcV("add", c->src, c->dst, ctxt->eflags);
    break;
    + case 0x06: /* push es */
    + if (ctxt->mode == X86EMUL_MODE_PROT64)
    + goto cannot_emulate;
    +
    + emulate_push_sreg(ctxt, VCPU_SREG_ES);
    + break;
    + case 0x07: /* pop es */
    + if (ctxt->mode == X86EMUL_MODE_PROT64)
    + goto cannot_emulate;
    +
    + rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_ES);
    + if (rc != 0)
    + goto done;
    + break;
    case 0x08 ... 0x0d:
    or: /* or */
    emulate_2op_SrcV("or", c->src, c->dst, ctxt->eflags);
    break;
    + case 0x0e: /* push cs */
    + if (ctxt->mode == X86EMUL_MODE_PROT64)
    + goto cannot_emulate;
    +
    + emulate_push_sreg(ctxt, VCPU_SREG_CS);
    + break;
    case 0x10 ... 0x15:
    adc: /* adc */
    emulate_2op_SrcV("adc", c->src, c->dst, ctxt->eflags);
    break;
    + case 0x16: /* push ss */
    + if (ctxt->mode == X86EMUL_MODE_PROT64)
    + goto cannot_emulate;
    +
    + emulate_push_sreg(ctxt, VCPU_SREG_SS);
    + break;
    + case 0x17: /* pop ss */
    + if (ctxt->mode == X86EMUL_MODE_PROT64)
    + goto cannot_emulate;
    +
    + rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_SS);
    + if (rc != 0)
    + goto done;
    + break;
    case 0x18 ... 0x1d:
    sbb: /* sbb */
    emulate_2op_SrcV("sbb", c->src, c->dst, ctxt->eflags);
    break;
    + case 0x1e: /* push ds */
    + if (ctxt->mode == X86EMUL_MODE_PROT64)
    + goto cannot_emulate;
    +
    + emulate_push_sreg(ctxt, VCPU_SREG_DS);
    + break;
    + case 0x1f: /* pop ds */
    + if (ctxt->mode == X86EMUL_MODE_PROT64)
    + goto cannot_emulate;
    +
    + rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_DS);
    + if (rc != 0)
    + goto done;
    + break;
    case 0x20 ... 0x25:
    and: /* and */
    emulate_2op_SrcV("and", c->src, c->dst, ctxt->eflags);
    @@ -2297,6 +2376,14 @@ twobyte_insn:
    jmp_rel(c, c->src.val);
    c->dst.type = OP_NONE;
    break;
    + case 0xa0: /* push fs */
    + emulate_push_sreg(ctxt, VCPU_SREG_FS);
    + break;
    + case 0xa1: /* pop fs */
    + rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_FS);
    + if (rc != 0)
    + goto done;
    + break;
    case 0xa3:
    bt: /* bt */
    c->dst.type = OP_NONE;
    @@ -2308,6 +2395,14 @@ twobyte_insn:
    case 0xa5: /* shld cl, r, r/m */
    emulate_2op_cl("shld", c->src2, c->src, c->dst, ctxt->eflags);
    break;
    + case 0xa8: /* push gs */
    + emulate_push_sreg(ctxt, VCPU_SREG_GS);
    + break;
    + case 0xa9: /* pop gs */
    + rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_GS);
    + if (rc != 0)
    + goto done;
    + break;
    case 0xab:
    bts: /* bts */
    /* only subword offset */
    --
    1.6.5.2


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