tcg/mips: Support unaligned access for softmmu

We can use the routines just added for user-only to emit
unaligned accesses in softmmu mode too.

Tested-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tcg/mips/tcg-target.c.inc

@@ -1134,8 +1134,10 @@ static void tcg_out_tlb_load(TCGContext *s, TCGReg base, TCGReg addrl,
                              tcg_insn_unit *label_ptr[2], bool is_load)
 {
     MemOp opc = get_memop(oi);
-    unsigned s_bits = opc & MO_SIZE;
     unsigned a_bits = get_alignment_bits(opc);
+    unsigned s_bits = opc & MO_SIZE;
+    unsigned a_mask = (1 << a_bits) - 1;
+    unsigned s_mask = (1 << s_bits) - 1;
     int mem_index = get_mmuidx(oi);
     int fast_off = TLB_MASK_TABLE_OFS(mem_index);
     int mask_off = fast_off + offsetof(CPUTLBDescFast, mask);
@@ -1143,7 +1145,7 @@ static void tcg_out_tlb_load(TCGContext *s, TCGReg base, TCGReg addrl,
     int add_off = offsetof(CPUTLBEntry, addend);
     int cmp_off = (is_load ? offsetof(CPUTLBEntry, addr_read)
                    : offsetof(CPUTLBEntry, addr_write));
-    target_ulong mask;
+    target_ulong tlb_mask;
 
     /* Load tlb_mask[mmu_idx] and tlb_table[mmu_idx].  */
     tcg_out_ld(s, TCG_TYPE_PTR, TCG_TMP0, TCG_AREG0, mask_off);
@@ -1157,27 +1159,13 @@ static void tcg_out_tlb_load(TCGContext *s, TCGReg base, TCGReg addrl,
     /* Add the tlb_table pointer, creating the CPUTLBEntry address in TMP3.  */
     tcg_out_opc_reg(s, ALIAS_PADD, TCG_TMP3, TCG_TMP3, TCG_TMP1);
 
-    /* We don't currently support unaligned accesses.
-       We could do so with mips32r6.  */
-    if (a_bits < s_bits) {
-        a_bits = s_bits;
-    }
-
-    /* Mask the page bits, keeping the alignment bits to compare against.  */
-    mask = (target_ulong)TARGET_PAGE_MASK | ((1 << a_bits) - 1);
-
     /* Load the (low-half) tlb comparator.  */
     if (TCG_TARGET_REG_BITS < TARGET_LONG_BITS) {
-        tcg_out_ld(s, TCG_TYPE_I32, TCG_TMP0, TCG_TMP3, cmp_off + LO_OFF);
+        tcg_out_ldst(s, OPC_LW, TCG_TMP0, TCG_TMP3, cmp_off + LO_OFF);
-        tcg_out_movi(s, TCG_TYPE_I32, TCG_TMP1, mask);
     } else {
         tcg_out_ldst(s, (TARGET_LONG_BITS == 64 ? OPC_LD
                          : TCG_TARGET_REG_BITS == 64 ? OPC_LWU : OPC_LW),
                      TCG_TMP0, TCG_TMP3, cmp_off);
-        tcg_out_movi(s, TCG_TYPE_TL, TCG_TMP1, mask);
-        /* No second compare is required here;
-           load the tlb addend for the fast path.  */
-        tcg_out_ld(s, TCG_TYPE_PTR, TCG_TMP2, TCG_TMP3, add_off);
     }
 
     /* Zero extend a 32-bit guest address for a 64-bit host. */
@@ -1185,7 +1173,25 @@ static void tcg_out_tlb_load(TCGContext *s, TCGReg base, TCGReg addrl,
         tcg_out_ext32u(s, base, addrl);
         addrl = base;
     }
-    tcg_out_opc_reg(s, OPC_AND, TCG_TMP1, TCG_TMP1, addrl);
+
+    /*
+     * Mask the page bits, keeping the alignment bits to compare against.
+     * For unaligned accesses, compare against the end of the access to
+     * verify that it does not cross a page boundary.
+     */
+    tlb_mask = (target_ulong)TARGET_PAGE_MASK | a_mask;
+    tcg_out_movi(s, TCG_TYPE_I32, TCG_TMP1, tlb_mask);
+    if (a_mask >= s_mask) {
+        tcg_out_opc_reg(s, OPC_AND, TCG_TMP1, TCG_TMP1, addrl);
+    } else {
+        tcg_out_opc_imm(s, ALIAS_PADDI, TCG_TMP2, addrl, s_mask - a_mask);
+        tcg_out_opc_reg(s, OPC_AND, TCG_TMP1, TCG_TMP1, TCG_TMP2);
+    }
+
+    if (TCG_TARGET_REG_BITS >= TARGET_LONG_BITS) {
+        /* Load the tlb addend for the fast path.  */
+        tcg_out_ld(s, TCG_TYPE_PTR, TCG_TMP2, TCG_TMP3, add_off);
+    }
 
     label_ptr[0] = s->code_ptr;
     tcg_out_opc_br(s, OPC_BNE, TCG_TMP1, TCG_TMP0);
@@ -1193,7 +1199,7 @@ static void tcg_out_tlb_load(TCGContext *s, TCGReg base, TCGReg addrl,
     /* Load and test the high half tlb comparator.  */
     if (TCG_TARGET_REG_BITS < TARGET_LONG_BITS) {
         /* delay slot */
-        tcg_out_ld(s, TCG_TYPE_I32, TCG_TMP0, TCG_TMP3, cmp_off + HI_OFF);
+        tcg_out_ldst(s, OPC_LW, TCG_TMP0, TCG_TMP3, cmp_off + HI_OFF);
 
         /* Load the tlb addend for the fast path.  */
         tcg_out_ld(s, TCG_TYPE_PTR, TCG_TMP2, TCG_TMP3, add_off);
@@ -1515,8 +1521,7 @@ static void tcg_out_qemu_ld_direct(TCGContext *s, TCGReg lo, TCGReg hi,
     }
 }
 
-static void __attribute__((unused))
+static void tcg_out_qemu_ld_unalign(TCGContext *s, TCGReg lo, TCGReg hi,
-tcg_out_qemu_ld_unalign(TCGContext *s, TCGReg lo, TCGReg hi,
                                     TCGReg base, MemOp opc, bool is_64)
 {
     const MIPSInsn lw1 = MIPS_BE ? OPC_LWL : OPC_LWR;
@@ -1645,8 +1650,8 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, bool is_64)
 #if defined(CONFIG_SOFTMMU)
     tcg_insn_unit *label_ptr[2];
 #else
-    unsigned a_bits, s_bits;
 #endif
+    unsigned a_bits, s_bits;
     TCGReg base = TCG_REG_A0;
 
     data_regl = *args++;
@@ -1655,10 +1660,20 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, bool is_64)
     addr_regh = (TCG_TARGET_REG_BITS < TARGET_LONG_BITS ? *args++ : 0);
     oi = *args++;
     opc = get_memop(oi);
+    a_bits = get_alignment_bits(opc);
+    s_bits = opc & MO_SIZE;
 
+    /*
+     * R6 removes the left/right instructions but requires the
+     * system to support misaligned memory accesses.
+     */
 #if defined(CONFIG_SOFTMMU)
     tcg_out_tlb_load(s, base, addr_regl, addr_regh, oi, label_ptr, 1);
-    tcg_out_qemu_ld_direct(s, data_regl, data_regh, base, opc, is_64);
+    if (use_mips32r6_instructions || a_bits >= s_bits) {
+        tcg_out_qemu_ld_direct(s, data_regl, data_regh, base, opc, is_64);
+    } else {
+        tcg_out_qemu_ld_unalign(s, data_regl, data_regh, base, opc, is_64);
+    }
     add_qemu_ldst_label(s, 1, oi,
                         (is_64 ? TCG_TYPE_I64 : TCG_TYPE_I32),
                         data_regl, data_regh, addr_regl, addr_regh,
@@ -1675,12 +1690,6 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, bool is_64)
     } else {
         tcg_out_opc_reg(s, ALIAS_PADD, base, TCG_GUEST_BASE_REG, addr_regl);
     }
-    a_bits = get_alignment_bits(opc);
-    s_bits = opc & MO_SIZE;
-    /*
-     * R6 removes the left/right instructions but requires the
-     * system to support misaligned memory accesses.
-     */
     if (use_mips32r6_instructions) {
         if (a_bits) {
             tcg_out_test_alignment(s, true, addr_regl, addr_regh, a_bits);
@@ -1760,8 +1769,7 @@ static void tcg_out_qemu_st_direct(TCGContext *s, TCGReg lo, TCGReg hi,
     }
 }
 
-static void __attribute__((unused))
+static void tcg_out_qemu_st_unalign(TCGContext *s, TCGReg lo, TCGReg hi,
-tcg_out_qemu_st_unalign(TCGContext *s, TCGReg lo, TCGReg hi,
                                     TCGReg base, MemOp opc)
 {
     const MIPSInsn sw1 = MIPS_BE ? OPC_SWL : OPC_SWR;
@@ -1841,9 +1849,8 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, bool is_64)
     MemOp opc;
 #if defined(CONFIG_SOFTMMU)
     tcg_insn_unit *label_ptr[2];
-#else
-    unsigned a_bits, s_bits;
 #endif
+    unsigned a_bits, s_bits;
     TCGReg base = TCG_REG_A0;
 
     data_regl = *args++;
@@ -1852,10 +1859,20 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, bool is_64)
     addr_regh = (TCG_TARGET_REG_BITS < TARGET_LONG_BITS ? *args++ : 0);
     oi = *args++;
     opc = get_memop(oi);
+    a_bits = get_alignment_bits(opc);
+    s_bits = opc & MO_SIZE;
 
+    /*
+     * R6 removes the left/right instructions but requires the
+     * system to support misaligned memory accesses.
+     */
 #if defined(CONFIG_SOFTMMU)
     tcg_out_tlb_load(s, base, addr_regl, addr_regh, oi, label_ptr, 0);
-    tcg_out_qemu_st_direct(s, data_regl, data_regh, base, opc);
+    if (use_mips32r6_instructions || a_bits >= s_bits) {
+        tcg_out_qemu_st_direct(s, data_regl, data_regh, base, opc);
+    } else {
+        tcg_out_qemu_st_unalign(s, data_regl, data_regh, base, opc);
+    }
     add_qemu_ldst_label(s, 0, oi,
                         (is_64 ? TCG_TYPE_I64 : TCG_TYPE_I32),
                         data_regl, data_regh, addr_regl, addr_regh,
@@ -1872,12 +1889,6 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, bool is_64)
     } else {
         tcg_out_opc_reg(s, ALIAS_PADD, base, TCG_GUEST_BASE_REG, addr_regl);
     }
-    a_bits = get_alignment_bits(opc);
-    s_bits = opc & MO_SIZE;
-    /*
-     * R6 removes the left/right instructions but requires the
-     * system to support misaligned memory accesses.
-     */
     if (use_mips32r6_instructions) {
         if (a_bits) {
             tcg_out_test_alignment(s, true, addr_regl, addr_regh, a_bits);