@@ -402,6 +402,23 @@ double-word product T0. The later is returned in two single-word outputs.
Similar to mulu2, except the two inputs T1 and T2 are signed.
+********* Memory Barrier support
+
+* mb <$arg>
+
+Generate a target memory barrier instruction to ensure memory ordering as being
+enforced by a corresponding guest memory barrier instruction. The ordering
+enforced by the backend may be stricter than the ordering required by the guest.
+It cannot be weaker. This opcode takes a constant argument which is required to
+generate the appropriate barrier instruction. The backend should take care to
+emit the target barrier instruction only when necessary i.e., for SMP guests and
+when MTTCG is enabled.
+
+The guest translators should generate this opcode for all guest instructions
+which have ordering side effects.
+
+Please see docs/atomics.txt for more information on memory barriers.
+
********* 64-bit guest on 32-bit host support
The following opcodes are internal to TCG. Thus they are to be implemented by
@@ -148,6 +148,23 @@ void tcg_gen_op6(TCGContext *ctx, TCGOpcode opc, TCGArg a1, TCGArg a2,
tcg_emit_op(ctx, opc, pi);
}
+void tcg_gen_mb(TCGBar mb_type)
+{
+ bool emit_barriers = true;
+
+#ifndef CONFIG_USER_ONLY
+ /* TODO: When MTTCG is available for system mode, we will check
+ * the following condition and enable emit_barriers
+ * (qemu_tcg_mttcg_enabled() && smp_cpus > 1)
+ */
+ emit_barriers = false;
+#endif
+
+ if (emit_barriers) {
+ tcg_gen_op1(&tcg_ctx, INDEX_op_mb, mb_type);
+ }
+}
+
/* 32 bit ops */
void tcg_gen_addi_i32(TCGv_i32 ret, TCGv_i32 arg1, int32_t arg2)
@@ -261,6 +261,8 @@ static inline void tcg_gen_br(TCGLabel *l)
tcg_gen_op1(&tcg_ctx, INDEX_op_br, label_arg(l));
}
+void tcg_gen_mb(TCGBar);
+
/* Helper calls. */
/* 32 bit ops */
@@ -42,6 +42,8 @@ DEF(br, 0, 0, 1, TCG_OPF_BB_END)
# define IMPL64 TCG_OPF_64BIT
#endif
+DEF(mb, 0, 0, 1, 0)
+
DEF(mov_i32, 1, 1, 0, TCG_OPF_NOT_PRESENT)
DEF(movi_i32, 1, 0, 1, TCG_OPF_NOT_PRESENT)
DEF(setcond_i32, 1, 2, 1, 0)
@@ -465,6 +465,23 @@ static inline intptr_t QEMU_ARTIFICIAL GET_TCGV_PTR(TCGv_ptr t)
#define TCG_CALL_DUMMY_TCGV MAKE_TCGV_I32(-1)
#define TCG_CALL_DUMMY_ARG ((TCGArg)(-1))
+typedef enum {
+ /* Used to indicate the type of accesses on which ordering
+ is to be ensured. Modeled after SPARC barriers. */
+ TCG_MO_LD_LD = 0x01,
+ TCG_MO_ST_LD = 0x02,
+ TCG_MO_LD_ST = 0x04,
+ TCG_MO_ST_ST = 0x08,
+ TCG_MO_ALL = 0x0F, /* OR of the above */
+
+ /* Used to indicate the kind of ordering which is to be ensured by the
+ instruction. These types are derived from x86/aarch64 instructions.
+ It should be noted that these are different from C11 semantics. */
+ TCG_BAR_LDAQ = 0x10, /* Following ops will not come forward */
+ TCG_BAR_STRL = 0x20, /* Previous ops will not be delayed */
+ TCG_BAR_SC = 0x30, /* No ops cross barrier; OR of the above */
+} TCGBar;
+
/* Conditions. Note that these are laid out for easy manipulation by
the functions below:
bit 0 is used for inverting;