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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2 4/4] x86/emul: Improvements to internal users of decode_register()
Most users of decode_register() can be replaced with decode_gpr() right away.
For the few sites which do care about possibly using the legacy byteop
encoding, rename decode_register() to decode_gpr_byteop(), and adjust its 'int
highbyte_regs' parameter to the more correct 'bool legacy_byteop'.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
v2:
* s/highbyte/legacy_byteop/ across the patch
* Keep decode_gpr_byteop() returning void. It doesn't affect any usecases
---
xen/arch/x86/x86_emulate/x86_emulate.c | 69 +++++++++++++++-------------------
1 file changed, 30 insertions(+), 39 deletions(-)
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 3766b7a..2444417 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1957,9 +1957,8 @@ const uint8_t cpu_user_regs_gpr_offsets[] = {
#endif
};
-void *
-decode_register(
- uint8_t modrm_reg, struct cpu_user_regs *regs, int highbyte_regs)
+static void *decode_gpr_byteop(
+ struct cpu_user_regs *regs, unsigned int modrm_reg, bool legacy_byteop)
{
static const uint8_t byteop_offsets[] = {
offsetof(struct cpu_user_regs, al),
@@ -1972,7 +1971,7 @@ decode_register(
offsetof(struct cpu_user_regs, bh),
};
- if ( !highbyte_regs )
+ if ( !legacy_byteop )
return decode_gpr(regs, modrm_reg);
/* Check that the array is a power of two. */
@@ -1987,10 +1986,11 @@ decode_register(
return (void *)regs + byteop_offsets[modrm_reg];
}
-static void *decode_vex_gpr(unsigned int vex_reg, struct cpu_user_regs *regs,
- const struct x86_emulate_ctxt *ctxt)
+static unsigned long *decode_vex_gpr(
+ unsigned int vex_reg, struct cpu_user_regs *regs,
+ const struct x86_emulate_ctxt *ctxt)
{
- return decode_register(~vex_reg & (mode_64bit() ? 0xf : 7), regs, 0);
+ return decode_gpr(regs, ~vex_reg & (mode_64bit() ? 0xf : 7));
}
static bool is_aligned(enum x86_segment seg, unsigned long offs,
@@ -2799,8 +2799,7 @@ x86_decode(
sib_index = ((sib >> 3) & 7) | ((rex_prefix << 2) & 8);
sib_base = (sib & 7) | ((rex_prefix << 3) & 8);
if ( sib_index != 4 && !(d & vSIB) )
- ea.mem.off = *(long *)decode_register(sib_index,
- state->regs, 0);
+ ea.mem.off = *decode_gpr(state->regs, sib_index);
ea.mem.off <<= (sib >> 6) & 3;
if ( (modrm_mod == 0) && ((sib_base & 7) == 5) )
ea.mem.off += insn_fetch_type(int32_t);
@@ -2819,15 +2818,13 @@ x86_decode(
ea.mem.off += state->regs->r(bp);
}
else
- ea.mem.off += *(long *)decode_register(sib_base,
- state->regs, 0);
+ ea.mem.off += *decode_gpr(state->regs, sib_base);
}
else
{
generate_exception_if(d & vSIB, EXC_UD);
modrm_rm |= (rex_prefix & 1) << 3;
- ea.mem.off = *(long *)decode_register(modrm_rm,
- state->regs, 0);
+ ea.mem.off = *decode_gpr(state->regs, modrm_rm);
if ( (modrm_rm == 5) && (modrm_mod != 0) )
ea.mem.seg = x86_seg_ss;
}
@@ -3052,8 +3049,7 @@ x86_emulate(
generate_exception_if(state->not_64bit && mode_64bit(), EXC_UD);
if ( ea.type == OP_REG )
- ea.reg = decode_register(modrm_rm, &_regs,
- (d & ByteOp) && !rex_prefix);
+ ea.reg = decode_gpr_byteop(&_regs, modrm_rm, (d & ByteOp) &&
!rex_prefix);
memset(mmvalp, 0xaa /* arbitrary */, sizeof(*mmvalp));
@@ -3067,13 +3063,13 @@ x86_emulate(
src.type = OP_REG;
if ( d & ByteOp )
{
- src.reg = decode_register(modrm_reg, &_regs, (rex_prefix == 0));
+ src.reg = decode_gpr_byteop(&_regs, modrm_reg, !rex_prefix);
src.val = *(uint8_t *)src.reg;
src.bytes = 1;
}
else
{
- src.reg = decode_register(modrm_reg, &_regs, 0);
+ src.reg = decode_gpr(&_regs, modrm_reg);
switch ( (src.bytes = op_bytes) )
{
case 2: src.val = *(uint16_t *)src.reg; break;
@@ -3143,13 +3139,13 @@ x86_emulate(
dst.type = OP_REG;
if ( d & ByteOp )
{
- dst.reg = decode_register(modrm_reg, &_regs, (rex_prefix == 0));
+ dst.reg = decode_gpr_byteop(&_regs, modrm_reg, !rex_prefix);
dst.val = *(uint8_t *)dst.reg;
dst.bytes = 1;
}
else
{
- dst.reg = decode_register(modrm_reg, &_regs, 0);
+ dst.reg = decode_gpr(&_regs, modrm_reg);
switch ( (dst.bytes = op_bytes) )
{
case 2: dst.val = *(uint16_t *)dst.reg; break;
@@ -3339,7 +3335,7 @@ x86_emulate(
case 0x40 ... 0x4f: /* inc/dec reg */
dst.type = OP_REG;
- dst.reg = decode_register(b & 7, &_regs, 0);
+ dst.reg = decode_gpr(&_regs, b & 7);
dst.bytes = op_bytes;
dst.val = *dst.reg;
if ( b & 8 )
@@ -3349,14 +3345,12 @@ x86_emulate(
break;
case 0x50 ... 0x57: /* push reg */
- src.val = *(unsigned long *)decode_register(
- (b & 7) | ((rex_prefix & 1) << 3), &_regs, 0);
+ src.val = *decode_gpr(&_regs, (b & 7) | ((rex_prefix & 1) << 3));
goto push;
case 0x58 ... 0x5f: /* pop reg */
dst.type = OP_REG;
- dst.reg = decode_register(
- (b & 7) | ((rex_prefix & 1) << 3), &_regs, 0);
+ dst.reg = decode_gpr(&_regs, (b & 7) | ((rex_prefix & 1) << 3));
dst.bytes = op_bytes;
if ( mode_64bit() && (dst.bytes == 4) )
dst.bytes = 8;
@@ -3370,7 +3364,7 @@ x86_emulate(
ea.val = _regs.esp;
for ( i = 0; i < 8; i++ )
{
- void *reg = decode_register(i, &_regs, 0);
+ void *reg = decode_gpr(&_regs, i);
if ( (rc = ops->write(x86_seg_ss, sp_pre_dec(op_bytes),
reg != &_regs.esp ? reg : &ea.val,
@@ -3382,7 +3376,7 @@ x86_emulate(
case 0x61: /* popa */
for ( i = 0; i < 8; i++ )
{
- void *reg = decode_register(7 - i, &_regs, 0);
+ void *reg = decode_gpr(&_regs, 7 - i);
if ( (rc = read_ulong(x86_seg_ss, sp_post_inc(op_bytes),
&dst.val, op_bytes, ctxt, ops)) != 0 )
@@ -3662,8 +3656,7 @@ x86_emulate(
case 0x91 ... 0x97: /* xchg reg,%%rax */
dst.type = OP_REG;
dst.bytes = op_bytes;
- dst.reg = decode_register(
- (b & 7) | ((rex_prefix & 1) << 3), &_regs, 0);
+ dst.reg = decode_gpr(&_regs, (b & 7) | ((rex_prefix & 1) << 3));
dst.val = *dst.reg;
goto xchg;
@@ -3895,14 +3888,13 @@ x86_emulate(
}
case 0xb0 ... 0xb7: /* mov imm8,r8 */
- dst.reg = decode_register(
- (b & 7) | ((rex_prefix & 1) << 3), &_regs, (rex_prefix == 0));
+ dst.reg = decode_gpr_byteop(&_regs, (b & 7) | ((rex_prefix & 1) << 3),
+ !rex_prefix);
dst.val = src.val;
break;
case 0xb8 ... 0xbf: /* mov imm{16,32,64},r{16,32,64} */
- dst.reg = decode_register(
- (b & 7) | ((rex_prefix & 1) << 3), &_regs, 0);
+ dst.reg = decode_gpr(&_regs, (b & 7) | ((rex_prefix & 1) << 3));
dst.val = src.val;
break;
@@ -5684,7 +5676,7 @@ x86_emulate(
opc[2] = 0xc3;
copy_REX_VEX(opc, rex_prefix, vex);
- ea.reg = decode_register(modrm_reg, &_regs, 0);
+ ea.reg = decode_gpr(&_regs, modrm_reg);
invoke_stub("", "", "=a" (*ea.reg), "+m" (fic.exn_raised)
: "c" (mmvalp), "m" (*mmvalp));
@@ -6461,7 +6453,7 @@ x86_emulate(
else
{
shift = src.val;
- src.reg = decode_register(modrm_reg, &_regs, 0);
+ src.reg = decode_gpr(&_regs, modrm_reg);
src.val = truncate_word(*src.reg, dst.bytes);
}
if ( (shift &= width - 1) == 0 )
@@ -6580,7 +6572,7 @@ x86_emulate(
fail_if(!ops->read_segment);
if ( (rc = ops->read_segment(seg, &sreg, ctxt)) != X86EMUL_OKAY )
goto done;
- dst.reg = decode_register(modrm_rm, &_regs, 0);
+ dst.reg = decode_gpr(&_regs, modrm_rm);
if ( !(modrm_reg & 2) )
{
/* rd{f,g}sbase */
@@ -6640,7 +6632,7 @@ x86_emulate(
case X86EMUL_OPC(0x0f, 0xb6): /* movzx rm8,r{16,32,64} */
/* Recompute DstReg as we may have decoded AH/BH/CH/DH. */
- dst.reg = decode_register(modrm_reg, &_regs, 0);
+ dst.reg = decode_gpr(&_regs, modrm_reg);
dst.bytes = op_bytes;
dst.val = (uint8_t)src.val;
break;
@@ -6732,7 +6724,7 @@ x86_emulate(
case X86EMUL_OPC(0x0f, 0xbe): /* movsx rm8,r{16,32,64} */
/* Recompute DstReg as we may have decoded AH/BH/CH/DH. */
- dst.reg = decode_register(modrm_reg, &_regs, 0);
+ dst.reg = decode_gpr(&_regs, modrm_reg);
dst.bytes = op_bytes;
dst.val = (int8_t)src.val;
break;
@@ -6957,8 +6949,7 @@ x86_emulate(
case X86EMUL_OPC(0x0f, 0xc8) ... X86EMUL_OPC(0x0f, 0xcf): /* bswap */
dst.type = OP_REG;
- dst.reg = decode_register(
- (b & 7) | ((rex_prefix & 1) << 3), &_regs, 0);
+ dst.reg = decode_gpr(&_regs, (b & 7) | ((rex_prefix & 1) << 3));
switch ( dst.bytes = op_bytes )
{
default: /* case 2: */
--
2.1.4
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