arm64: insn: add encoders for atomic operations

It is a preparation patch for eBPF atomic supports under arm64. eBPF
needs support atomic[64]_fetch_add, atomic[64]_[fetch_]{and,or,xor} and
atomic[64]_{xchg|cmpxchg}. The ordering semantics of eBPF atomics are
the same with the implementations in linux kernel.

Add three helpers to support LDCLR/LDEOR/LDSET/SWP, CAS and DMB
instructions. STADD/STCLR/STEOR/STSET are simply encoded as aliases for
LDADD/LDCLR/LDEOR/LDSET with XZR as the destination register, so no extra
helper is added. atomic_fetch_add() and other atomic ops needs support for
STLXR instruction, so extend enum aarch64_insn_ldst_type to do that.

LDADD/LDEOR/LDSET/SWP and CAS instructions are only available when LSE
atomics is enabled, so just return AARCH64_BREAK_FAULT directly in
these newly-added helpers if CONFIG_ARM64_LSE_ATOMICS is disabled.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20220217072232.1186625-3-houtao1@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 171 insertions, 14 deletions

diff --git a/arch/arm64/lib/insn.c b/arch/arm64/lib/insn.c
index e485cd735261..5e90887deec4 100644
--- a/arch/arm64/lib/insn.c
+++ b/arch/arm64/lib/insn.c
@@ -578,10 +578,16 @@ u32 aarch64_insn_gen_load_store_ex(enum aarch64_insn_register reg,
 
 	switch (type) {
 	case AARCH64_INSN_LDST_LOAD_EX:
+	case AARCH64_INSN_LDST_LOAD_ACQ_EX:
 		insn = aarch64_insn_get_load_ex_value();
+		if (type == AARCH64_INSN_LDST_LOAD_ACQ_EX)
+			insn |= BIT(15);
 		break;
 	case AARCH64_INSN_LDST_STORE_EX:
+	case AARCH64_INSN_LDST_STORE_REL_EX:
 		insn = aarch64_insn_get_store_ex_value();
+		if (type == AARCH64_INSN_LDST_STORE_REL_EX)
+			insn |= BIT(15);
 		break;
 	default:
 		pr_err("%s: unknown load/store exclusive encoding %d\n", __func__, type);
@@ -603,12 +609,65 @@ u32 aarch64_insn_gen_load_store_ex(enum aarch64_insn_register reg,
 					    state);
 }
 
-u32 aarch64_insn_gen_ldadd(enum aarch64_insn_register result,
-			   enum aarch64_insn_register address,
-			   enum aarch64_insn_register value,
-			   enum aarch64_insn_size_type size)
+#ifdef CONFIG_ARM64_LSE_ATOMICS
+static u32 aarch64_insn_encode_ldst_order(enum aarch64_insn_mem_order_type type,
+					  u32 insn)
 {
-	u32 insn = aarch64_insn_get_ldadd_value();
+	u32 order;
+
+	switch (type) {
+	case AARCH64_INSN_MEM_ORDER_NONE:
+		order = 0;
+		break;
+	case AARCH64_INSN_MEM_ORDER_ACQ:
+		order = 2;
+		break;
+	case AARCH64_INSN_MEM_ORDER_REL:
+		order = 1;
+		break;
+	case AARCH64_INSN_MEM_ORDER_ACQREL:
+		order = 3;
+		break;
+	default:
+		pr_err("%s: unknown mem order %d\n", __func__, type);
+		return AARCH64_BREAK_FAULT;
+	}
+
+	insn &= ~GENMASK(23, 22);
+	insn |= order << 22;
+
+	return insn;
+}
+
+u32 aarch64_insn_gen_atomic_ld_op(enum aarch64_insn_register result,
+				  enum aarch64_insn_register address,
+				  enum aarch64_insn_register value,
+				  enum aarch64_insn_size_type size,
+				  enum aarch64_insn_mem_atomic_op op,
+				  enum aarch64_insn_mem_order_type order)
+{
+	u32 insn;
+
+	switch (op) {
+	case AARCH64_INSN_MEM_ATOMIC_ADD:
+		insn = aarch64_insn_get_ldadd_value();
+		break;
+	case AARCH64_INSN_MEM_ATOMIC_CLR:
+		insn = aarch64_insn_get_ldclr_value();
+		break;
+	case AARCH64_INSN_MEM_ATOMIC_EOR:
+		insn = aarch64_insn_get_ldeor_value();
+		break;
+	case AARCH64_INSN_MEM_ATOMIC_SET:
+		insn = aarch64_insn_get_ldset_value();
+		break;
+	case AARCH64_INSN_MEM_ATOMIC_SWP:
+		insn = aarch64_insn_get_swp_value();
+		break;
+	default:
+		pr_err("%s: unimplemented mem atomic op %d\n", __func__, op);
+		return AARCH64_BREAK_FAULT;
+	}
 
 	switch (size) {
 	case AARCH64_INSN_SIZE_32:
@@ -621,6 +680,8 @@ u32 aarch64_insn_gen_ldadd(enum aarch64_insn_register result,
 
 	insn = aarch64_insn_encode_ldst_size(size, insn);
 
+	insn = aarch64_insn_encode_ldst_order(order, insn);
+
 	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RT, insn,
 					    result);
 
@@ -631,17 +692,68 @@ u32 aarch64_insn_gen_ldadd(enum aarch64_insn_register result,
 					    value);
 }
 
-u32 aarch64_insn_gen_stadd(enum aarch64_insn_register address,
-			   enum aarch64_insn_register value,
-			   enum aarch64_insn_size_type size)
+static u32 aarch64_insn_encode_cas_order(enum aarch64_insn_mem_order_type type,
+					 u32 insn)
 {
-	/*
-	 * STADD is simply encoded as an alias for LDADD with XZR as
-	 * the destination register.
-	 */
-	return aarch64_insn_gen_ldadd(AARCH64_INSN_REG_ZR, address,
-				      value, size);
+	u32 order;
+
+	switch (type) {
+	case AARCH64_INSN_MEM_ORDER_NONE:
+		order = 0;
+		break;
+	case AARCH64_INSN_MEM_ORDER_ACQ:
+		order = BIT(22);
+		break;
+	case AARCH64_INSN_MEM_ORDER_REL:
+		order = BIT(15);
+		break;
+	case AARCH64_INSN_MEM_ORDER_ACQREL:
+		order = BIT(15) | BIT(22);
+		break;
+	default:
+		pr_err("%s: unknown mem order %d\n", __func__, type);
+		return AARCH64_BREAK_FAULT;
+	}
+
+	insn &= ~(BIT(15) | BIT(22));
+	insn |= order;
+
+	return insn;
+}
+
+u32 aarch64_insn_gen_cas(enum aarch64_insn_register result,
+			 enum aarch64_insn_register address,
+			 enum aarch64_insn_register value,
+			 enum aarch64_insn_size_type size,
+			 enum aarch64_insn_mem_order_type order)
+{
+	u32 insn;
+
+	switch (size) {
+	case AARCH64_INSN_SIZE_32:
+	case AARCH64_INSN_SIZE_64:
+		break;
+	default:
+		pr_err("%s: unimplemented size encoding %d\n", __func__, size);
+		return AARCH64_BREAK_FAULT;
+	}
+
+	insn = aarch64_insn_get_cas_value();
+
+	insn = aarch64_insn_encode_ldst_size(size, insn);
+
+	insn = aarch64_insn_encode_cas_order(order, insn);
+
+	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RT, insn,
+					    result);
+
+	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn,
+					    address);
+
+	return aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RS, insn,
+					    value);
 }
+#endif
 
 static u32 aarch64_insn_encode_prfm_imm(enum aarch64_insn_prfm_type type,
 					enum aarch64_insn_prfm_target target,
@@ -1456,3 +1568,48 @@ u32 aarch64_insn_gen_extr(enum aarch64_insn_variant variant,
 	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn, Rn);
 	return aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RM, insn, Rm);
 }
+
+u32 aarch64_insn_gen_dmb(enum aarch64_insn_mb_type type)
+{
+	u32 opt;
+	u32 insn;
+
+	switch (type) {
+	case AARCH64_INSN_MB_SY:
+		opt = 0xf;
+		break;
+	case AARCH64_INSN_MB_ST:
+		opt = 0xe;
+		break;
+	case AARCH64_INSN_MB_LD:
+		opt = 0xd;
+		break;
+	case AARCH64_INSN_MB_ISH:
+		opt = 0xb;
+		break;
+	case AARCH64_INSN_MB_ISHST:
+		opt = 0xa;
+		break;
+	case AARCH64_INSN_MB_ISHLD:
+		opt = 0x9;
+		break;
+	case AARCH64_INSN_MB_NSH:
+		opt = 0x7;
+		break;
+	case AARCH64_INSN_MB_NSHST:
+		opt = 0x6;
+		break;
+	case AARCH64_INSN_MB_NSHLD:
+		opt = 0x5;
+		break;
+	default:
+		pr_err("%s: unknown dmb type %d\n", __func__, type);
+		return AARCH64_BREAK_FAULT;
+	}
+
+	insn = aarch64_insn_get_dmb_value();
+	insn &= ~GENMASK(11, 8);
+	insn |= (opt << 8);
+
+	return insn;
+}