[PATCH v2 09/50] target/i386: Assert !VM86 for x86_64 user-only

From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: pbonzini@redhat.com, f4bug@amsat.org, ehabkost@redhat.com,
	cfontana@suse.de
Subject: [PATCH v2 09/50] target/i386: Assert !VM86 for x86_64 user-only
Date: Fri, 14 May 2021 10:13:01 -0500	[thread overview]
Message-ID: <20210514151342.384376-10-richard.henderson@linaro.org> (raw)
In-Reply-To: <20210514151342.384376-1-richard.henderson@linaro.org>

For i386-linux-user, we can enter vm86 mode via the vm86(2) syscall.
That syscall explicitly returns to 32-bit mode, and the syscall does
not exist for a 64-bit x86_64 executable.

Since we're adding an accessor macro, pull the value directly out of
flags otherwise.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/i386/tcg/translate.c | 40 ++++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 18 deletions(-)

diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index b8cb7163ee..27806f35f9 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -116,7 +116,6 @@ typedef struct DisasContext {
 #endif
     int addseg; /* non zero if either DS/ES/SS have a non zero base */
     int f_st;   /* currently unused */
-    int vm86;   /* vm86 mode */
     int tf;     /* TF cpu flag */
     int jmp_opt; /* use direct block chaining for direct jumps */
     int repz_opt; /* optimize jumps within repz instructions */
@@ -159,6 +158,11 @@ typedef struct DisasContext {
 #define CPL(S)    ((S)->cpl)
 #define IOPL(S)   ((S)->iopl)
 #endif
+#if defined(CONFIG_USER_ONLY) && defined(TARGET_X86_64)
+#define VM86(S)   false
+#else
+#define VM86(S)   (((S)->flags & HF_VM_MASK) != 0)
+#endif
 
 static void gen_eob(DisasContext *s);
 static void gen_jr(DisasContext *s, TCGv dest);
@@ -631,7 +635,7 @@ static void gen_check_io(DisasContext *s, MemOp ot, target_ulong cur_eip,
 {
     target_ulong next_eip;
 
-    if (PE(s) && (CPL(s) > IOPL(s) || s->vm86)) {
+    if (PE(s) && (CPL(s) > IOPL(s) || VM86(s))) {
         tcg_gen_trunc_tl_i32(s->tmp2_i32, s->T0);
         switch (ot) {
         case MO_8:
@@ -1309,7 +1313,7 @@ static bool check_cpl0(DisasContext *s)
 /* If vm86, check for iopl == 3; if not, raise #GP and return false. */
 static bool check_vm86_iopl(DisasContext *s)
 {
-    if (!s->vm86 || IOPL(s) == 3) {
+    if (!VM86(s) || IOPL(s) == 3) {
         return true;
     }
     gen_exception_gpf(s);
@@ -1319,7 +1323,7 @@ static bool check_vm86_iopl(DisasContext *s)
 /* Check for iopl allowing access; if not, raise #GP and return false. */
 static bool check_iopl(DisasContext *s)
 {
-    if (s->vm86 ? IOPL(s) == 3 : CPL(s) <= IOPL(s)) {
+    if (VM86(s) ? IOPL(s) == 3 : CPL(s) <= IOPL(s)) {
         return true;
     }
     gen_exception_gpf(s);
@@ -2359,7 +2363,7 @@ static inline void gen_op_movl_seg_T0_vm(DisasContext *s, X86Seg seg_reg)
    call this function with seg_reg == R_CS */
 static void gen_movl_seg_T0(DisasContext *s, X86Seg seg_reg)
 {
-    if (PE(s) && !s->vm86) {
+    if (PE(s) && !VM86(s)) {
         tcg_gen_trunc_tl_i32(s->tmp2_i32, s->T0);
         gen_helper_load_seg(cpu_env, tcg_const_i32(seg_reg), s->tmp2_i32);
         /* abort translation because the addseg value may change or
@@ -4615,7 +4619,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
     case 0xc4: /* 3-byte VEX */
         /* VEX prefixes cannot be used except in 32-bit mode.
            Otherwise the instruction is LES or LDS.  */
-        if (s->code32 && !s->vm86) {
+        if (s->code32 && !VM86(s)) {
             static const int pp_prefix[4] = {
                 0, PREFIX_DATA, PREFIX_REPZ, PREFIX_REPNZ
             };
@@ -5122,7 +5126,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
             gen_add_A0_im(s, 1 << ot);
             gen_op_ld_v(s, MO_16, s->T0, s->A0);
         do_lcall:
-            if (PE(s) && !s->vm86) {
+            if (PE(s) && !VM86(s)) {
                 tcg_gen_trunc_tl_i32(s->tmp2_i32, s->T0);
                 gen_helper_lcall_protected(cpu_env, s->tmp2_i32, s->T1,
                                            tcg_const_i32(dflag - 1),
@@ -5152,7 +5156,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
             gen_add_A0_im(s, 1 << ot);
             gen_op_ld_v(s, MO_16, s->T0, s->A0);
         do_ljmp:
-            if (PE(s) && !s->vm86) {
+            if (PE(s) && !VM86(s)) {
                 tcg_gen_trunc_tl_i32(s->tmp2_i32, s->T0);
                 gen_helper_ljmp_protected(cpu_env, s->tmp2_i32, s->T1,
                                           tcg_const_tl(s->pc - s->cs_base));
@@ -6585,7 +6589,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
     case 0xca: /* lret im */
         val = x86_ldsw_code(env, s);
     do_lret:
-        if (PE(s) && !s->vm86) {
+        if (PE(s) && !VM86(s)) {
             gen_update_cc_op(s);
             gen_jmp_im(s, pc_start - s->cs_base);
             gen_helper_lret_protected(cpu_env, tcg_const_i32(dflag - 1),
@@ -6611,7 +6615,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
         goto do_lret;
     case 0xcf: /* iret */
         gen_svm_check_intercept(s, pc_start, SVM_EXIT_IRET);
-        if (!PE(s) || s->vm86) {
+        if (!PE(s) || VM86(s)) {
             /* real mode or vm86 mode */
             if (!check_vm86_iopl(s)) {
                 break;
@@ -7315,7 +7319,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
         op = (modrm >> 3) & 7;
         switch(op) {
         case 0: /* sldt */
-            if (!PE(s) || s->vm86)
+            if (!PE(s) || VM86(s))
                 goto illegal_op;
             gen_svm_check_intercept(s, pc_start, SVM_EXIT_LDTR_READ);
             tcg_gen_ld32u_tl(s->T0, cpu_env,
@@ -7324,7 +7328,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
             gen_ldst_modrm(env, s, modrm, ot, OR_TMP0, 1);
             break;
         case 2: /* lldt */
-            if (!PE(s) || s->vm86)
+            if (!PE(s) || VM86(s))
                 goto illegal_op;
             if (check_cpl0(s)) {
                 gen_svm_check_intercept(s, pc_start, SVM_EXIT_LDTR_WRITE);
@@ -7334,7 +7338,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
             }
             break;
         case 1: /* str */
-            if (!PE(s) || s->vm86)
+            if (!PE(s) || VM86(s))
                 goto illegal_op;
             gen_svm_check_intercept(s, pc_start, SVM_EXIT_TR_READ);
             tcg_gen_ld32u_tl(s->T0, cpu_env,
@@ -7343,7 +7347,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
             gen_ldst_modrm(env, s, modrm, ot, OR_TMP0, 1);
             break;
         case 3: /* ltr */
-            if (!PE(s) || s->vm86)
+            if (!PE(s) || VM86(s))
                 goto illegal_op;
             if (check_cpl0(s)) {
                 gen_svm_check_intercept(s, pc_start, SVM_EXIT_TR_WRITE);
@@ -7354,7 +7358,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
             break;
         case 4: /* verr */
         case 5: /* verw */
-            if (!PE(s) || s->vm86)
+            if (!PE(s) || VM86(s))
                 goto illegal_op;
             gen_ldst_modrm(env, s, modrm, MO_16, OR_TMP0, 0);
             gen_update_cc_op(s);
@@ -7725,7 +7729,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
             TCGLabel *label1;
             TCGv t0, t1, t2, a0;
 
-            if (!PE(s) || s->vm86)
+            if (!PE(s) || VM86(s))
                 goto illegal_op;
             t0 = tcg_temp_local_new();
             t1 = tcg_temp_local_new();
@@ -7773,7 +7777,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
         {
             TCGLabel *label1;
             TCGv t0;
-            if (!PE(s) || s->vm86)
+            if (!PE(s) || VM86(s))
                 goto illegal_op;
             ot = dflag != MO_16 ? MO_32 : MO_16;
             modrm = x86_ldub_code(env, s);
@@ -8489,12 +8493,12 @@ static void i386_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cpu)
     g_assert(PE(dc) == ((flags & HF_PE_MASK) != 0));
     g_assert(CPL(dc) == cpl);
     g_assert(IOPL(dc) == iopl);
+    g_assert(VM86(dc) == ((flags & HF_VM_MASK) != 0));
 
     dc->code32 = (flags >> HF_CS32_SHIFT) & 1;
     dc->ss32 = (flags >> HF_SS32_SHIFT) & 1;
     dc->addseg = (flags >> HF_ADDSEG_SHIFT) & 1;
     dc->f_st = 0;
-    dc->vm86 = (flags >> VM_SHIFT) & 1;
     dc->tf = (flags >> TF_SHIFT) & 1;
     dc->cc_op = CC_OP_DYNAMIC;
     dc->cc_op_dirty = false;
-- 
2.25.1


