tcg/i386: Support raising sigbus for user-only

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tcg/i386/tcg-target.c.inc

@@ -22,6 +22,7 @@
  * THE SOFTWARE.
  */
 
+#include "../tcg-ldst.c.inc"
 #include "../tcg-pool.c.inc"
 
 #ifdef CONFIG_DEBUG_TCG
@@ -421,6 +422,7 @@ static bool tcg_target_const_match(int64_t val, TCGType type, int ct)
 #define OPC_VZEROUPPER  (0x77 | P_EXT)
 #define OPC_XCHG_ax_r32	(0x90)
 
+#define OPC_GRP3_Eb     (0xf6)
 #define OPC_GRP3_Ev     (0xf7)
 #define OPC_GRP5        (0xff)
 #define OPC_GRP14       (0x73 | P_EXT | P_DATA16)
@@ -444,6 +446,7 @@ static bool tcg_target_const_match(int64_t val, TCGType type, int ct)
 #define SHIFT_SAR 7
 
 /* Group 3 opcode extensions for 0xf6, 0xf7.  To be used with OPC_GRP3.  */
+#define EXT3_TESTi 0
 #define EXT3_NOT   2
 #define EXT3_NEG   3
 #define EXT3_MUL   4
@@ -1606,8 +1609,6 @@ static void tcg_out_nopn(TCGContext *s, int n)
 }
 
 #if defined(CONFIG_SOFTMMU)
-#include "../tcg-ldst.c.inc"
-
 /* helper signature: helper_ret_ld_mmu(CPUState *env, target_ulong addr,
  *                                     int mmu_idx, uintptr_t ra)
  */
@@ -1916,7 +1917,84 @@ static bool tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *l)
     tcg_out_jmp(s, qemu_st_helpers[opc & (MO_BSWAP | MO_SIZE)]);
     return true;
 }
-#elif TCG_TARGET_REG_BITS == 32
+#else
+
+static void tcg_out_test_alignment(TCGContext *s, bool is_ld, TCGReg addrlo,
+                                   TCGReg addrhi, unsigned a_bits)
+{
+    unsigned a_mask = (1 << a_bits) - 1;
+    TCGLabelQemuLdst *label;
+
+    /*
+     * We are expecting a_bits to max out at 7, so we can usually use testb.
+     * For i686, we have to use testl for %esi/%edi.
+     */
+    if (a_mask <= 0xff && (TCG_TARGET_REG_BITS == 64 || addrlo < 4)) {
+        tcg_out_modrm(s, OPC_GRP3_Eb | P_REXB_RM, EXT3_TESTi, addrlo);
+        tcg_out8(s, a_mask);
+    } else {
+        tcg_out_modrm(s, OPC_GRP3_Ev, EXT3_TESTi, addrlo);
+        tcg_out32(s, a_mask);
+    }
+
+    /* jne slow_path */
+    tcg_out_opc(s, OPC_JCC_long + JCC_JNE, 0, 0, 0);
+
+    label = new_ldst_label(s);
+    label->is_ld = is_ld;
+    label->addrlo_reg = addrlo;
+    label->addrhi_reg = addrhi;
+    label->raddr = tcg_splitwx_to_rx(s->code_ptr + 4);
+    label->label_ptr[0] = s->code_ptr;
+
+    s->code_ptr += 4;
+}
+
+static bool tcg_out_fail_alignment(TCGContext *s, TCGLabelQemuLdst *l)
+{
+    /* resolve label address */
+    tcg_patch32(l->label_ptr[0], s->code_ptr - l->label_ptr[0] - 4);
+
+    if (TCG_TARGET_REG_BITS == 32) {
+        int ofs = 0;
+
+        tcg_out_st(s, TCG_TYPE_PTR, TCG_AREG0, TCG_REG_ESP, ofs);
+        ofs += 4;
+
+        tcg_out_st(s, TCG_TYPE_I32, l->addrlo_reg, TCG_REG_ESP, ofs);
+        ofs += 4;
+        if (TARGET_LONG_BITS == 64) {
+            tcg_out_st(s, TCG_TYPE_I32, l->addrhi_reg, TCG_REG_ESP, ofs);
+            ofs += 4;
+        }
+
+        tcg_out_pushi(s, (uintptr_t)l->raddr);
+    } else {
+        tcg_out_mov(s, TCG_TYPE_TL, tcg_target_call_iarg_regs[1],
+                    l->addrlo_reg);
+        tcg_out_mov(s, TCG_TYPE_PTR, tcg_target_call_iarg_regs[0], TCG_AREG0);
+
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_RAX, (uintptr_t)l->raddr);
+        tcg_out_push(s, TCG_REG_RAX);
+    }
+
+    /* "Tail call" to the helper, with the return address back inline. */
+    tcg_out_jmp(s, (const void *)(l->is_ld ? helper_unaligned_ld
+                                  : helper_unaligned_st));
+    return true;
+}
+
+static bool tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *l)
+{
+    return tcg_out_fail_alignment(s, l);
+}
+
+static bool tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *l)
+{
+    return tcg_out_fail_alignment(s, l);
+}
+
+#if TCG_TARGET_REG_BITS == 32
 # define x86_guest_base_seg     0
 # define x86_guest_base_index   -1
 # define x86_guest_base_offset  guest_base
@@ -1950,6 +2028,7 @@ static inline int setup_guest_base_seg(void)
     return 0;
 }
 # endif
+#endif
 #endif /* SOFTMMU */
 
 static void tcg_out_qemu_ld_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
@@ -2059,6 +2138,8 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, bool is64)
 #if defined(CONFIG_SOFTMMU)
     int mem_index;
     tcg_insn_unit *label_ptr[2];
+#else
+    unsigned a_bits;
 #endif
 
     datalo = *args++;
@@ -2081,6 +2162,11 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, bool is64)
     add_qemu_ldst_label(s, true, is64, oi, datalo, datahi, addrlo, addrhi,
                         s->code_ptr, label_ptr);
 #else
+    a_bits = get_alignment_bits(opc);
+    if (a_bits) {
+        tcg_out_test_alignment(s, true, addrlo, addrhi, a_bits);
+    }
+
     tcg_out_qemu_ld_direct(s, datalo, datahi, addrlo, x86_guest_base_index,
                            x86_guest_base_offset, x86_guest_base_seg,
                            is64, opc);
@@ -2148,6 +2234,8 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, bool is64)
 #if defined(CONFIG_SOFTMMU)
     int mem_index;
     tcg_insn_unit *label_ptr[2];
+#else
+    unsigned a_bits;
 #endif
 
     datalo = *args++;
@@ -2170,6 +2258,11 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, bool is64)
     add_qemu_ldst_label(s, false, is64, oi, datalo, datahi, addrlo, addrhi,
                         s->code_ptr, label_ptr);
 #else
+    a_bits = get_alignment_bits(opc);
+    if (a_bits) {
+        tcg_out_test_alignment(s, false, addrlo, addrhi, a_bits);
+    }
+
     tcg_out_qemu_st_direct(s, datalo, datahi, addrlo, x86_guest_base_index,
                            x86_guest_base_offset, x86_guest_base_seg, opc);
 #endif

tcg/i386/tcg-target.h

@@ -232,9 +232,7 @@ static inline void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_rx,
 
 #define TCG_TARGET_HAS_MEMORY_BSWAP  have_movbe
 
-#ifdef CONFIG_SOFTMMU
 #define TCG_TARGET_NEED_LDST_LABELS
-#endif
 #define TCG_TARGET_NEED_POOL_LABELS
 
 #endif