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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] x86emul: address x86_insn_is_mem_{access, write}() omissions
commit e28d13eeb65c25c0bd56e8bfa83c7473047d778d
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri May 29 17:28:04 2020 +0200
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri May 29 17:28:04 2020 +0200
x86emul: address x86_insn_is_mem_{access,write}() omissions
First of all explain in comments what the functions' purposes are. Then
make them actually match their comments.
Note that fc6fa977be54 ("x86emul: extend x86_insn_is_mem_write()
coverage") didn't actually fix the function's behavior for {,V}STMXCSR:
Both are covered by generic code higher up in the function, due to
x86_decode_twobyte() already doing suitable adjustments. And VSTMXCSR
wouldn't have been covered anyway without a further X86EMUL_OPC_VEX()
case label. Keep the inner case label in a comment for reference.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
xen/arch/x86/x86_emulate/x86_emulate.c | 126 ++++++++++++++++++++++++++++++---
1 file changed, 118 insertions(+), 8 deletions(-)
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c
b/xen/arch/x86/x86_emulate/x86_emulate.c
index fa24b1d725..080732b75b 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -11474,25 +11474,87 @@ x86_insn_operand_ea(const struct x86_emulate_state
*state,
return state->ea.mem.off;
}
+/*
+ * This function means to return 'true' for all supported insns with explicit
+ * accesses to memory. This means also insns which don't have an explicit
+ * memory operand (like POP), but it does not mean e.g. segment selector
+ * loads, where the descriptor table access is considered an implicit one.
+ */
bool
x86_insn_is_mem_access(const struct x86_emulate_state *state,
const struct x86_emulate_ctxt *ctxt)
{
+ if ( mode_64bit() && state->not_64bit )
+ return false;
+
if ( state->ea.type == OP_MEM )
- return ctxt->opcode != 0x8d /* LEA */ &&
- (ctxt->opcode != X86EMUL_OPC(0x0f, 0x01) ||
- (state->modrm_reg & 7) != 7) /* INVLPG */;
+ {
+ switch ( ctxt->opcode )
+ {
+ case 0x8d: /* LEA */
+ case X86EMUL_OPC(0x0f, 0x0d): /* PREFETCH */
+ case X86EMUL_OPC(0x0f, 0x18)
+ ... X86EMUL_OPC(0x0f, 0x1f): /* NOP space */
+ case X86EMUL_OPC_66(0x0f, 0x18)
+ ... X86EMUL_OPC_66(0x0f, 0x1f): /* NOP space */
+ case X86EMUL_OPC_F3(0x0f, 0x18)
+ ... X86EMUL_OPC_F3(0x0f, 0x1f): /* NOP space */
+ case X86EMUL_OPC_F2(0x0f, 0x18)
+ ... X86EMUL_OPC_F2(0x0f, 0x1f): /* NOP space */
+ case X86EMUL_OPC(0x0f, 0xb9): /* UD1 */
+ case X86EMUL_OPC(0x0f, 0xff): /* UD0 */
+ return false;
+
+ case X86EMUL_OPC(0x0f, 0x01):
+ return (state->modrm_reg & 7) != 7; /* INVLPG */
+
+ case X86EMUL_OPC(0x0f, 0xae):
+ return (state->modrm_reg & 7) != 7; /* CLFLUSH */
+
+ case X86EMUL_OPC_66(0x0f, 0xae):
+ return (state->modrm_reg & 7) < 6; /* CLWB, CLFLUSHOPT */
+ }
+
+ return true;
+ }
switch ( ctxt->opcode )
{
+ case 0x06 ... 0x07: /* PUSH / POP %es */
+ case 0x0e: /* PUSH %cs */
+ case 0x16 ... 0x17: /* PUSH / POP %ss */
+ case 0x1e ... 0x1f: /* PUSH / POP %ds */
+ case 0x50 ... 0x5f: /* PUSH / POP reg */
+ case 0x60 ... 0x61: /* PUSHA / POPA */
+ case 0x68: case 0x6a: /* PUSH imm */
case 0x6c ... 0x6f: /* INS / OUTS */
+ case 0x8f: /* POP r/m */
+ case 0x9a: /* CALL (far, direct) */
+ case 0x9c ... 0x9d: /* PUSHF / POPF */
case 0xa4 ... 0xa7: /* MOVS / CMPS */
case 0xaa ... 0xaf: /* STOS / LODS / SCAS */
+ case 0xc2 ... 0xc3: /* RET (near) */
+ case 0xc8 ... 0xc9: /* ENTER / LEAVE */
+ case 0xca ... 0xcb: /* RET (far) */
case 0xd7: /* XLAT */
+ case 0xe8: /* CALL (near, direct) */
+ case X86EMUL_OPC(0x0f, 0xa0): /* PUSH %fs */
+ case X86EMUL_OPC(0x0f, 0xa1): /* POP %fs */
+ case X86EMUL_OPC(0x0f, 0xa8): /* PUSH %gs */
+ case X86EMUL_OPC(0x0f, 0xa9): /* POP %gs */
CASE_SIMD_PACKED_INT_VEX(0x0f, 0xf7): /* MASKMOV{Q,DQU} */
/* VMASKMOVDQU */
return true;
+ case 0xff:
+ switch ( state->modrm_reg & 7 )
+ {
+ case 2: /* CALL (near, indirect) */
+ case 6: /* PUSH r/m */
+ return true;
+ }
+ break;
+
case X86EMUL_OPC(0x0f, 0x01):
/* Cover CLZERO. */
return (state->modrm_rm & 7) == 4 && (state->modrm_reg & 7) == 7;
@@ -11501,10 +11563,20 @@ x86_insn_is_mem_access(const struct x86_emulate_state
*state,
return false;
}
+/*
+ * This function means to return 'true' for all supported insns with explicit
+ * writes to memory. This means also insns which don't have an explicit
+ * memory operand (like PUSH), but it does not mean e.g. segment selector
+ * loads, where the (possible) descriptor table write is considered an
+ * implicit access.
+ */
bool
x86_insn_is_mem_write(const struct x86_emulate_state *state,
const struct x86_emulate_ctxt *ctxt)
{
+ if ( mode_64bit() && state->not_64bit )
+ return false;
+
switch ( state->desc & DstMask )
{
case DstMem:
@@ -11516,19 +11588,48 @@ x86_insn_is_mem_write(const struct x86_emulate_state
*state,
break;
default:
+ switch ( ctxt->opcode )
+ {
+ case 0x63: /* ARPL */
+ return !mode_64bit();
+ }
+
return false;
}
if ( state->modrm_mod == 3 )
- /* CLZERO is the odd one. */
- return ctxt->opcode == X86EMUL_OPC(0x0f, 0x01) &&
- (state->modrm_rm & 7) == 4 && (state->modrm_reg & 7) == 7;
+ {
+ switch ( ctxt->opcode )
+ {
+ case 0xff: /* Grp5 */
+ break;
+
+ case X86EMUL_OPC(0x0f, 0x01): /* CLZERO is the odd one. */
+ return (state->modrm_rm & 7) == 4 && (state->modrm_reg & 7) == 7;
+
+ default:
+ return false;
+ }
+ }
switch ( ctxt->opcode )
{
+ case 0x06: /* PUSH %es */
+ case 0x0e: /* PUSH %cs */
+ case 0x16: /* PUSH %ss */
+ case 0x1e: /* PUSH %ds */
+ case 0x50 ... 0x57: /* PUSH reg */
+ case 0x60: /* PUSHA */
+ case 0x68: case 0x6a: /* PUSH imm */
case 0x6c: case 0x6d: /* INS */
+ case 0x9a: /* CALL (far, direct) */
+ case 0x9c: /* PUSHF */
case 0xa4: case 0xa5: /* MOVS */
case 0xaa: case 0xab: /* STOS */
+ case 0xc8: /* ENTER */
+ case 0xe8: /* CALL (near, direct) */
+ case X86EMUL_OPC(0x0f, 0xa0): /* PUSH %fs */
+ case X86EMUL_OPC(0x0f, 0xa8): /* PUSH %gs */
case X86EMUL_OPC(0x0f, 0xab): /* BTS */
case X86EMUL_OPC(0x0f, 0xb3): /* BTR */
case X86EMUL_OPC(0x0f, 0xbb): /* BTC */
@@ -11586,6 +11687,16 @@ x86_insn_is_mem_write(const struct x86_emulate_state
*state,
}
break;
+ case 0xff:
+ switch ( state->modrm_reg & 7 )
+ {
+ case 2: /* CALL (near, indirect) */
+ case 3: /* CALL (far, indirect) */
+ case 6: /* PUSH r/m */
+ return true;
+ }
+ break;
+
case X86EMUL_OPC(0x0f, 0x01):
switch ( state->modrm_reg & 7 )
{
@@ -11600,7 +11711,7 @@ x86_insn_is_mem_write(const struct x86_emulate_state
*state,
switch ( state->modrm_reg & 7 )
{
case 0: /* FXSAVE */
- case 3: /* {,V}STMXCSR */
+ /* case 3: STMXCSR - handled above */
case 4: /* XSAVE */
case 6: /* XSAVEOPT */
return true;
@@ -11616,7 +11727,6 @@ x86_insn_is_mem_write(const struct x86_emulate_state
*state,
case 1: /* CMPXCHG{8,16}B */
case 4: /* XSAVEC */
case 5: /* XSAVES */
- case 7: /* VMPTRST */
return true;
}
break;
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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