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Re: [Qemu-devel] [PATCH] i386: hvf: Fix register refs if REX is present
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH] i386: hvf: Fix register refs if REX is present |
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Date: |
Thu, 18 Oct 2018 16:33:20 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 |
On 18/10/2018 15:44, Roman Bolshakov wrote:
> According to Intel(R)64 and IA-32 Architectures Software Developer's
> Manual, the following one-byte registers should be fetched when REX
> prefix is present (sorted by reg encoding index):
> AL, CL, DL, BL, SPL, BPL, SIL, DIL, R8L - R15L
>
> The first 8 are fetched if REX.R is zero, the last 8 if non-zero.
>
> The following registers should be fetched for instructions without REX
> prefix (also sorted by reg encoding index):
> AL, CL, DL, BL, AH, CH, DH, BH
>
> Current emulation code doesn't handle accesses to SPL, BPL, SIL, DIL
> when REX is present, thefore an instruction 40883e "mov %dil,(%rsi)" is
> decoded as "mov %bh,(%rsi)".
>
> That caused an infinite loop in vp_reset:
> https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg03293.html
>
> Signed-off-by: Roman Bolshakov <address@hidden>
Queued, thanks.
Paolo
> target/i386/hvf/x86_decode.c | 67 ++++++++++++++++++++----------------
> target/i386/hvf/x86_decode.h | 6 ++--
> 2 files changed, 42 insertions(+), 31 deletions(-)
>
> diff --git a/target/i386/hvf/x86_decode.c b/target/i386/hvf/x86_decode.c
> index 2d7540fe7c..2e33b69541 100644
> --- a/target/i386/hvf/x86_decode.c
> +++ b/target/i386/hvf/x86_decode.c
> @@ -113,7 +113,8 @@ static void decode_modrm_reg(CPUX86State *env, struct
> x86_decode *decode,
> {
> op->type = X86_VAR_REG;
> op->reg = decode->modrm.reg;
> - op->ptr = get_reg_ref(env, op->reg, decode->rex.r, decode->operand_size);
> + op->ptr = get_reg_ref(env, op->reg, decode->rex.rex, decode->rex.r,
> + decode->operand_size);
> }
>
> static void decode_rax(CPUX86State *env, struct x86_decode *decode,
> @@ -121,7 +122,8 @@ static void decode_rax(CPUX86State *env, struct
> x86_decode *decode,
> {
> op->type = X86_VAR_REG;
> op->reg = R_EAX;
> - op->ptr = get_reg_ref(env, op->reg, 0, decode->operand_size);
> + op->ptr = get_reg_ref(env, op->reg, decode->rex.rex, 0,
> + decode->operand_size);
> }
>
> static inline void decode_immediate(CPUX86State *env, struct x86_decode
> *decode,
> @@ -263,16 +265,16 @@ static void decode_incgroup(CPUX86State *env, struct
> x86_decode *decode)
> {
> decode->op[0].type = X86_VAR_REG;
> decode->op[0].reg = decode->opcode[0] - 0x40;
> - decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.b,
> - decode->operand_size);
> + decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.rex,
> + decode->rex.b, decode->operand_size);
> }
>
> static void decode_decgroup(CPUX86State *env, struct x86_decode *decode)
> {
> decode->op[0].type = X86_VAR_REG;
> decode->op[0].reg = decode->opcode[0] - 0x48;
> - decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.b,
> - decode->operand_size);
> + decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.rex,
> + decode->rex.b, decode->operand_size);
> }
>
> static void decode_incgroup2(CPUX86State *env, struct x86_decode *decode)
> @@ -288,16 +290,16 @@ static void decode_pushgroup(CPUX86State *env, struct
> x86_decode *decode)
> {
> decode->op[0].type = X86_VAR_REG;
> decode->op[0].reg = decode->opcode[0] - 0x50;
> - decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.b,
> - decode->operand_size);
> + decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.rex,
> + decode->rex.b, decode->operand_size);
> }
>
> static void decode_popgroup(CPUX86State *env, struct x86_decode *decode)
> {
> decode->op[0].type = X86_VAR_REG;
> decode->op[0].reg = decode->opcode[0] - 0x58;
> - decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.b,
> - decode->operand_size);
> + decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.rex,
> + decode->rex.b, decode->operand_size);
> }
>
> static void decode_jxx(CPUX86State *env, struct x86_decode *decode)
> @@ -378,16 +380,16 @@ static void decode_xchgroup(CPUX86State *env, struct
> x86_decode *decode)
> {
> decode->op[0].type = X86_VAR_REG;
> decode->op[0].reg = decode->opcode[0] - 0x90;
> - decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.b,
> - decode->operand_size);
> + decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.rex,
> + decode->rex.b, decode->operand_size);
> }
>
> static void decode_movgroup(CPUX86State *env, struct x86_decode *decode)
> {
> decode->op[0].type = X86_VAR_REG;
> decode->op[0].reg = decode->opcode[0] - 0xb8;
> - decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.b,
> - decode->operand_size);
> + decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.rex,
> + decode->rex.b, decode->operand_size);
> decode_immediate(env, decode, &decode->op[1], decode->operand_size);
> }
>
> @@ -402,8 +404,8 @@ static void decode_movgroup8(CPUX86State *env, struct
> x86_decode *decode)
> {
> decode->op[0].type = X86_VAR_REG;
> decode->op[0].reg = decode->opcode[0] - 0xb0;
> - decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.b,
> - decode->operand_size);
> + decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.rex,
> + decode->rex.b, decode->operand_size);
> decode_immediate(env, decode, &decode->op[1], decode->operand_size);
> }
>
> @@ -412,7 +414,8 @@ static void decode_rcx(CPUX86State *env, struct
> x86_decode *decode,
> {
> op->type = X86_VAR_REG;
> op->reg = R_ECX;
> - op->ptr = get_reg_ref(env, op->reg, decode->rex.b, decode->operand_size);
> + op->ptr = get_reg_ref(env, op->reg, decode->rex.rex, decode->rex.b,
> + decode->operand_size);
> }
>
> struct decode_tbl {
> @@ -639,8 +642,8 @@ static void decode_bswap(CPUX86State *env, struct
> x86_decode *decode)
> {
> decode->op[0].type = X86_VAR_REG;
> decode->op[0].reg = decode->opcode[1] - 0xc8;
> - decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.b,
> - decode->operand_size);
> + decode->op[0].ptr = get_reg_ref(env, decode->op[0].reg, decode->rex.rex,
> + decode->rex.b, decode->operand_size);
> }
>
> static void decode_d9_4(CPUX86State *env, struct x86_decode *decode)
> @@ -1686,7 +1689,8 @@ calc_addr:
> }
> }
>
> -target_ulong get_reg_ref(CPUX86State *env, int reg, int is_extended, int
> size)
> +target_ulong get_reg_ref(CPUX86State *env, int reg, int rex, int is_extended,
> + int size)
> {
> target_ulong ptr = 0;
> int which = 0;
> @@ -1698,7 +1702,7 @@ target_ulong get_reg_ref(CPUX86State *env, int reg, int
> is_extended, int size)
>
> switch (size) {
> case 1:
> - if (is_extended || reg < 4) {
> + if (is_extended || reg < 4 || rex) {
> which = 1;
> ptr = (target_ulong)&RL(env, reg);
> } else {
> @@ -1714,10 +1718,11 @@ target_ulong get_reg_ref(CPUX86State *env, int reg,
> int is_extended, int size)
> return ptr;
> }
>
> -target_ulong get_reg_val(CPUX86State *env, int reg, int is_extended, int
> size)
> +target_ulong get_reg_val(CPUX86State *env, int reg, int rex, int is_extended,
> + int size)
> {
> target_ulong val = 0;
> - memcpy(&val, (void *)get_reg_ref(env, reg, is_extended, size), size);
> + memcpy(&val, (void *)get_reg_ref(env, reg, rex, is_extended, size),
> size);
> return val;
> }
>
> @@ -1739,7 +1744,8 @@ static target_ulong get_sib_val(CPUX86State *env,
> struct x86_decode *decode,
> if (base_reg == R_ESP || base_reg == R_EBP) {
> *sel = R_SS;
> }
> - base = get_reg_val(env, decode->sib.base, decode->rex.b, addr_size);
> + base = get_reg_val(env, decode->sib.base, decode->rex.rex,
> + decode->rex.b, addr_size);
> }
>
> if (decode->rex.x) {
> @@ -1747,7 +1753,8 @@ static target_ulong get_sib_val(CPUX86State *env,
> struct x86_decode *decode,
> }
>
> if (index_reg != R_ESP) {
> - scaled_index = get_reg_val(env, index_reg, decode->rex.x, addr_size)
> <<
> + scaled_index = get_reg_val(env, index_reg, decode->rex.rex,
> + decode->rex.x, addr_size) <<
> decode->sib.scale;
> }
> return base + scaled_index;
> @@ -1776,7 +1783,8 @@ void calc_modrm_operand32(CPUX86State *env, struct
> x86_decode *decode,
> if (decode->modrm.rm == R_EBP || decode->modrm.rm == R_ESP) {
> seg = R_SS;
> }
> - ptr += get_reg_val(env, decode->modrm.rm, decode->rex.b, addr_size);
> + ptr += get_reg_val(env, decode->modrm.rm, decode->rex.rex,
> + decode->rex.b, addr_size);
> }
>
> if (X86_DECODE_CMD_LEA == decode->cmd) {
> @@ -1805,7 +1813,8 @@ void calc_modrm_operand64(CPUX86State *env, struct
> x86_decode *decode,
> } else if (0 == mod && 5 == rm) {
> ptr = RIP(env) + decode->len + (int32_t) offset;
> } else {
> - ptr = get_reg_val(env, src, decode->rex.b, 8) + (int64_t) offset;
> + ptr = get_reg_val(env, src, decode->rex.rex, decode->rex.b, 8) +
> + (int64_t) offset;
> }
>
> if (X86_DECODE_CMD_LEA == decode->cmd) {
> @@ -1822,8 +1831,8 @@ void calc_modrm_operand(CPUX86State *env, struct
> x86_decode *decode,
> if (3 == decode->modrm.mod) {
> op->reg = decode->modrm.reg;
> op->type = X86_VAR_REG;
> - op->ptr = get_reg_ref(env, decode->modrm.rm, decode->rex.b,
> - decode->operand_size);
> + op->ptr = get_reg_ref(env, decode->modrm.rm, decode->rex.rex,
> + decode->rex.b, decode->operand_size);
> return;
> }
>
> diff --git a/target/i386/hvf/x86_decode.h b/target/i386/hvf/x86_decode.h
> index 5ab6f31fa5..ef4bcab310 100644
> --- a/target/i386/hvf/x86_decode.h
> +++ b/target/i386/hvf/x86_decode.h
> @@ -303,8 +303,10 @@ uint64_t sign(uint64_t val, int size);
>
> uint32_t decode_instruction(CPUX86State *env, struct x86_decode *decode);
>
> -target_ulong get_reg_ref(CPUX86State *env, int reg, int is_extended, int
> size);
> -target_ulong get_reg_val(CPUX86State *env, int reg, int is_extended, int
> size);
> +target_ulong get_reg_ref(CPUX86State *env, int reg, int rex, int is_extended,
> + int size);
> +target_ulong get_reg_val(CPUX86State *env, int reg, int rex, int is_extended,
> + int size);
> void calc_modrm_operand(CPUX86State *env, struct x86_decode *decode,
> struct x86_decode_op *op);
> target_ulong decode_linear_addr(CPUX86State *env, struct x86_decode *decode,
>