[PATCH bpf-next 2/2] arm64, bpf: support more atomic operations

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Atomics for eBPF patch series adds support for atomic[64]_fetch_add,
atomic[64]_[fetch_]{and,or,xor} and atomic[64]_{xchg|cmpxchg}, but
it only add support for x86-64, so support these atomic operations
for arm64 as well.

Basically the implementation procedure is almost mechanical translation
of code snippets in atomic_ll_sc.h & atomic_lse.h & cmpxchg.h located
under arch/arm64/include/asm. An extra temporary register is needed
for (BPF_ADD | BPF_FETCH) to save the value of src register, instead of
adding TMP_REG_4 just use BPF_REG_AX instead.

For cpus_have_cap(ARM64_HAS_LSE_ATOMICS) case and no-LSE-ATOMICS case,
both ./test_verifier and "./test_progs -t atomic" are exercised and
passed correspondingly.

Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
 arch/arm64/include/asm/insn.h |  45 +++++--
 arch/arm64/lib/insn.c         | 155 +++++++++++++++++++++---
 arch/arm64/net/bpf_jit.h      |  43 ++++++-
 arch/arm64/net/bpf_jit_comp.c | 216 +++++++++++++++++++++++++++-------
 4 files changed, 394 insertions(+), 65 deletions(-)

diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index 6b776c8667b2..1416d636f1af 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -280,6 +280,23 @@ enum aarch64_insn_adr_type {
 	AARCH64_INSN_ADR_TYPE_ADR,
 };
 
+enum aarch64_insn_mem_atomic_op {
+	AARCH64_INSN_MEM_ATOMIC_ADD,
+	AARCH64_INSN_MEM_ATOMIC_BIC,
+	AARCH64_INSN_MEM_ATOMIC_EOR,
+	AARCH64_INSN_MEM_ATOMIC_ORR,
+	AARCH64_INSN_MEM_ATOMIC_SWP,
+};
+
+enum aarch64_insn_mem_order_type {
+	AARCH64_INSN_MEM_ORDER_NONE,
+	AARCH64_INSN_MEM_ORDER_LOAD_ACQ_STORE_REL,
+};
+
+enum aarch64_insn_mb_type {
+	AARCH64_INSN_MB_ISH,
+};
+
 #define	__AARCH64_INSN_FUNCS(abbr, mask, val)				\
 static __always_inline bool aarch64_insn_is_##abbr(u32 code)		\
 {									\
@@ -303,6 +320,11 @@ __AARCH64_INSN_FUNCS(store_post,	0x3FE00C00, 0x38000400)
 __AARCH64_INSN_FUNCS(load_post,	0x3FE00C00, 0x38400400)
 __AARCH64_INSN_FUNCS(str_reg,	0x3FE0EC00, 0x38206800)
 __AARCH64_INSN_FUNCS(ldadd,	0x3F20FC00, 0x38200000)
+__AARCH64_INSN_FUNCS(ldclr,	0x3F20FC00, 0x38201000)
+__AARCH64_INSN_FUNCS(ldeor,	0x3F20FC00, 0x38202000)
+__AARCH64_INSN_FUNCS(ldset,	0x3F20FC00, 0x38203000)
+__AARCH64_INSN_FUNCS(swp,	0x3F20FC00, 0x38208000)
+__AARCH64_INSN_FUNCS(cas,	0x3FA07C00, 0x08A07C00)
 __AARCH64_INSN_FUNCS(ldr_reg,	0x3FE0EC00, 0x38606800)
 __AARCH64_INSN_FUNCS(ldr_lit,	0xBF000000, 0x18000000)
 __AARCH64_INSN_FUNCS(ldrsw_lit,	0xFF000000, 0x98000000)
@@ -474,13 +496,21 @@ u32 aarch64_insn_gen_load_store_ex(enum aarch64_insn_register reg,
 				   enum aarch64_insn_register state,
 				   enum aarch64_insn_size_type size,
 				   enum aarch64_insn_ldst_type type);
-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);
-u32 aarch64_insn_gen_stadd(enum aarch64_insn_register address,
-			   enum aarch64_insn_register value,
-			   enum aarch64_insn_size_type size);
+u32 aarch64_insn_gen_store_release_ex(enum aarch64_insn_register reg,
+				      enum aarch64_insn_register base,
+				      enum aarch64_insn_register state,
+				      enum aarch64_insn_size_type size);
+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 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 aarch64_insn_gen_add_sub_imm(enum aarch64_insn_register dst,
 				 enum aarch64_insn_register src,
 				 int imm, enum aarch64_insn_variant variant,
@@ -541,6 +571,7 @@ u32 aarch64_insn_gen_prefetch(enum aarch64_insn_register base,
 			      enum aarch64_insn_prfm_type type,
 			      enum aarch64_insn_prfm_target target,
 			      enum aarch64_insn_prfm_policy policy);
+u32 aarch64_insn_gen_dmb(enum aarch64_insn_mb_type type);
 s32 aarch64_get_branch_offset(u32 insn);
 u32 aarch64_set_branch_offset(u32 insn, s32 offset);
 
diff --git a/arch/arm64/lib/insn.c b/arch/arm64/lib/insn.c
index fccfe363e567..2a7dde58c44b 100644
--- a/arch/arm64/lib/insn.c
+++ b/arch/arm64/lib/insn.c
@@ -328,6 +328,29 @@ static u32 aarch64_insn_encode_ldst_size(enum aarch64_insn_size_type type,
 	return insn;
 }
 
+static u32 aarch64_insn_encode_ldst_order(enum aarch64_insn_mem_order_type type,
+					  u32 insn)
+{
+	u32 order;
+
+	switch (type) {
+	case AARCH64_INSN_MEM_ORDER_NONE:
+		order = 0;
+		break;
+	case AARCH64_INSN_MEM_ORDER_LOAD_ACQ_STORE_REL:
+		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;
+}
+
 static inline long branch_imm_common(unsigned long pc, unsigned long addr,
 				     long range)
 {
@@ -603,12 +626,49 @@ 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)
+u32 aarch64_insn_gen_store_release_ex(enum aarch64_insn_register reg,
+				      enum aarch64_insn_register base,
+				      enum aarch64_insn_register state,
+				      enum aarch64_insn_size_type size)
+{
+	u32 insn = aarch64_insn_gen_load_store_ex(reg, base, state, size,
+						  AARCH64_INSN_LDST_STORE_EX);
+
+	if (insn == AARCH64_BREAK_FAULT)
+		return insn;
+
+	return insn | BIT(15);
+}
+
+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 = aarch64_insn_get_ldadd_value();
+	u32 insn;
+
+	switch (op) {
+	case AARCH64_INSN_MEM_ATOMIC_ADD:
+		insn = aarch64_insn_get_ldadd_value();
+		break;
+	case AARCH64_INSN_MEM_ATOMIC_BIC:
+		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_ORR:
+		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 +681,8 @@ 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);
 
@@ -631,16 +693,60 @@ 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_LOAD_ACQ_STORE_REL:
+		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);
 }
 
 static u32 aarch64_insn_encode_prfm_imm(enum aarch64_insn_prfm_type type,
@@ -1456,3 +1562,24 @@ 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_ISH:
+		opt = 0xb;
+		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;
+}
diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h
index cc0cf0f5c7c3..308f96587861 100644
--- a/arch/arm64/net/bpf_jit.h
+++ b/arch/arm64/net/bpf_jit.h
@@ -88,10 +88,41 @@
 /* [Rn] = Rt; (atomic) Rs = [state] */
 #define A64_STXR(sf, Rt, Rn, Rs) \
 	A64_LSX(sf, Rt, Rn, Rs, STORE_EX)
+/* smp_mb(); [Rn] = Rt; (atomic) Rs = [state] */
+#define A64_STLXR(sf, Rt, Rn, Rs) \
+	aarch64_insn_gen_store_release_ex(Rt, Rn, Rs, A64_SIZE(sf))
 
-/* LSE atomics */
-#define A64_STADD(sf, Rn, Rs) \
-	aarch64_insn_gen_stadd(Rn, Rs, A64_SIZE(sf))
+/*
+ * LSE atomics
+ *
+ * ST{ADD,CLR,SET,EOR} is simply encoded as an alias for
+ * LDD{ADD,CLR,SET,EOR} with XZR as the destination register.
+ */
+#define A64_ST_OP(sf, Rn, Rs, op) \
+	aarch64_insn_gen_atomic_ld_op(A64_ZR, Rn, Rs, \
+		A64_SIZE(sf), AARCH64_INSN_MEM_ATOMIC_##op, \
+		AARCH64_INSN_MEM_ORDER_NONE)
+/* [Rn] <op>= Rs */
+#define A64_STADD(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, ADD)
+#define A64_STCLR(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, BIC)
+#define A64_STEOR(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, EOR)
+#define A64_STSET(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, ORR)
+
+#define A64_LD_OP_AL(sf, Rt, Rn, Rs, op) \
+	aarch64_insn_gen_atomic_ld_op(Rt, Rn, Rs, \
+		A64_SIZE(sf), AARCH64_INSN_MEM_ATOMIC_##op, \
+		AARCH64_INSN_MEM_ORDER_LOAD_ACQ_STORE_REL)
+/* Rt = [Rn]; [Rn] <op>= Rs */
+#define A64_LDADDAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, ADD)
+#define A64_LDCLRAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, BIC)
+#define A64_LDEORAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, EOR)
+#define A64_LDSETAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, ORR)
+/* Rt = [Rn]; [Rn] = Rs */
+#define A64_SWPAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, SWP)
+/* Rs = CAS(Rn, Rs, Rt) */
+#define A64_CASAL(sf, Rt, Rn, Rs) \
+	aarch64_insn_gen_cas(Rt, Rn, Rs, A64_SIZE(sf), \
+		AARCH64_INSN_MEM_ORDER_LOAD_ACQ_STORE_REL)
 
 /* Add/subtract (immediate) */
 #define A64_ADDSUB_IMM(sf, Rd, Rn, imm12, type) \
@@ -196,6 +227,9 @@
 #define A64_ANDS(sf, Rd, Rn, Rm) A64_LOGIC_SREG(sf, Rd, Rn, Rm, AND_SETFLAGS)
 /* Rn & Rm; set condition flags */
 #define A64_TST(sf, Rn, Rm) A64_ANDS(sf, A64_ZR, Rn, Rm)
+/* Rd = ~Rm (alias of ORN with A64_ZR as Rn) */
+#define A64_MVN(sf, Rd, Rm)  \
+	A64_LOGIC_SREG(sf, Rd, A64_ZR, Rm, ORN)
 
 /* Logical (immediate) */
 #define A64_LOGIC_IMM(sf, Rd, Rn, imm, type) ({ \
@@ -219,4 +253,7 @@
 #define A64_BTI_J  A64_HINT(AARCH64_INSN_HINT_BTIJ)
 #define A64_BTI_JC A64_HINT(AARCH64_INSN_HINT_BTIJC)
 
+/* DMB */
+#define A64_DMB_ISH aarch64_insn_gen_dmb(AARCH64_INSN_MB_ISH)
+
 #endif /* _BPF_JIT_H */
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 74f9a9b6a053..79e2c2c4c733 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -27,6 +27,17 @@
 #define TCALL_CNT (MAX_BPF_JIT_REG + 2)
 #define TMP_REG_3 (MAX_BPF_JIT_REG + 3)
 
+#define check_imm(bits, imm) do {				\
+	if ((((imm) > 0) && ((imm) >> (bits))) ||		\
+	    (((imm) < 0) && (~(imm) >> (bits)))) {		\
+		pr_info("[%2d] imm=%d(0x%x) out of range\n",	\
+			i, imm, imm);				\
+		return -EINVAL;					\
+	}							\
+} while (0)
+#define check_imm19(imm) check_imm(19, imm)
+#define check_imm26(imm) check_imm(26, imm)
+
 /* Map BPF registers to A64 registers */
 static const int bpf2a64[] = {
 	/* return value from in-kernel function, and exit value from eBPF */
@@ -329,6 +340,163 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
 #undef jmp_offset
 }
 
+static int emit_lse_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
+{
+	const u8 code = insn->code;
+	const u8 dst = bpf2a64[insn->dst_reg];
+	const u8 src = bpf2a64[insn->src_reg];
+	const u8 tmp = bpf2a64[TMP_REG_1];
+	const u8 tmp2 = bpf2a64[TMP_REG_2];
+	const bool isdw = BPF_SIZE(code) == BPF_DW;
+	const s16 off = insn->off;
+	u8 reg;
+
+	if (!off) {
+		reg = dst;
+	} else {
+		emit_a64_mov_i(1, tmp, off, ctx);
+		emit(A64_ADD(1, tmp, tmp, dst), ctx);
+		reg = tmp;
+	}
+
+	switch (insn->imm) {
+	/* lock *(u32/u64 *)(dst_reg + off) <op>= src_reg */
+	case BPF_ADD:
+		emit(A64_STADD(isdw, reg, src), ctx);
+		break;
+	case BPF_AND:
+		emit(A64_MVN(isdw, tmp2, src), ctx);
+		emit(A64_STCLR(isdw, reg, tmp2), ctx);
+		break;
+	case BPF_OR:
+		emit(A64_STSET(isdw, reg, src), ctx);
+		break;
+	case BPF_XOR:
+		emit(A64_STEOR(isdw, reg, src), ctx);
+		break;
+	/* src_reg = atomic_fetch_add(dst_reg + off, src_reg) */
+	case BPF_ADD | BPF_FETCH:
+		emit(A64_LDADDAL(isdw, src, reg, src), ctx);
+		break;
+	case BPF_AND | BPF_FETCH:
+		emit(A64_MVN(isdw, tmp2, src), ctx);
+		emit(A64_LDCLRAL(isdw, src, reg, tmp2), ctx);
+		break;
+	case BPF_OR | BPF_FETCH:
+		emit(A64_LDSETAL(isdw, src, reg, src), ctx);
+		break;
+	case BPF_XOR | BPF_FETCH:
+		emit(A64_LDEORAL(isdw, src, reg, src), ctx);
+		break;
+	/* src_reg = atomic_xchg(dst_reg + off, src_reg); */
+	case BPF_XCHG:
+		emit(A64_SWPAL(isdw, src, reg, src), ctx);
+		break;
+	/* r0 = atomic_cmpxchg(dst_reg + off, r0, src_reg); */
+	case BPF_CMPXCHG:
+		emit(A64_CASAL(isdw, src, reg, bpf2a64[BPF_REG_0]), ctx);
+		break;
+	default:
+		pr_err_once("unknown atomic op code %02x\n", insn->imm);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int emit_ll_sc_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
+{
+	const u8 code = insn->code;
+	const u8 dst = bpf2a64[insn->dst_reg];
+	const u8 src = bpf2a64[insn->src_reg];
+	const u8 tmp = bpf2a64[TMP_REG_1];
+	const u8 tmp2 = bpf2a64[TMP_REG_2];
+	const u8 tmp3 = bpf2a64[TMP_REG_3];
+	const int i = insn - ctx->prog->insnsi;
+	const s32 imm = insn->imm;
+	const s16 off = insn->off;
+	const bool isdw = BPF_SIZE(code) == BPF_DW;
+	u8 reg;
+	s32 jmp_offset;
+
+	if (!off) {
+		reg = dst;
+	} else {
+		emit_a64_mov_i(1, tmp, off, ctx);
+		emit(A64_ADD(1, tmp, tmp, dst), ctx);
+		reg = tmp;
+	}
+
+	if (imm == BPF_ADD || imm == BPF_AND ||
+	    imm == BPF_OR || imm == BPF_XOR) {
+		/* lock *(u32/u64 *)(dst_reg + off) <op>= src_reg */
+		emit(A64_LDXR(isdw, tmp2, reg), ctx);
+		if (imm == BPF_ADD)
+			emit(A64_ADD(isdw, tmp2, tmp2, src), ctx);
+		else if (imm == BPF_AND)
+			emit(A64_AND(isdw, tmp2, tmp2, src), ctx);
+		else if (imm == BPF_OR)
+			emit(A64_ORR(isdw, tmp2, tmp2, src), ctx);
+		else
+			emit(A64_EOR(isdw, tmp2, tmp2, src), ctx);
+		emit(A64_STXR(isdw, tmp2, reg, tmp3), ctx);
+		jmp_offset = -3;
+		check_imm19(jmp_offset);
+		emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
+	} else if (imm == (BPF_ADD | BPF_FETCH) ||
+		   imm == (BPF_AND | BPF_FETCH) ||
+		   imm == (BPF_OR | BPF_FETCH) ||
+		   imm == (BPF_XOR | BPF_FETCH)) {
+		/* src_reg = atomic_fetch_add(dst_reg + off, src_reg) */
+		const u8 ax = bpf2a64[BPF_REG_AX];
+
+		emit(A64_MOV(isdw, ax, src), ctx);
+		emit(A64_LDXR(isdw, src, reg), ctx);
+		if (imm == (BPF_ADD | BPF_FETCH))
+			emit(A64_ADD(isdw, tmp2, src, ax), ctx);
+		else if (imm == (BPF_AND | BPF_FETCH))
+			emit(A64_AND(isdw, tmp2, src, ax), ctx);
+		else if (imm == (BPF_OR | BPF_FETCH))
+			emit(A64_ORR(isdw, tmp2, src, ax), ctx);
+		else
+			emit(A64_EOR(isdw, tmp2, src, ax), ctx);
+		emit(A64_STLXR(isdw, tmp2, reg, tmp3), ctx);
+		jmp_offset = -3;
+		check_imm19(jmp_offset);
+		emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
+		emit(A64_DMB_ISH, ctx);
+	} else if (imm == BPF_XCHG) {
+		/* src_reg = atomic_xchg(dst_reg + off, src_reg); */
+		emit(A64_MOV(isdw, tmp2, src), ctx);
+		emit(A64_LDXR(isdw, src, reg), ctx);
+		emit(A64_STLXR(isdw, tmp2, reg, tmp3), ctx);
+		jmp_offset = -2;
+		check_imm19(jmp_offset);
+		emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
+		emit(A64_DMB_ISH, ctx);
+	} else if (imm == BPF_CMPXCHG) {
+		/* r0 = atomic_cmpxchg(dst_reg + off, r0, src_reg); */
+		const u8 r0 = bpf2a64[BPF_REG_0];
+
+		emit(A64_MOV(isdw, tmp2, r0), ctx);
+		emit(A64_LDXR(isdw, r0, reg), ctx);
+		emit(A64_EOR(isdw, tmp3, r0, tmp2), ctx);
+		jmp_offset = 4;
+		check_imm19(jmp_offset);
+		emit(A64_CBNZ(isdw, tmp3, jmp_offset), ctx);
+		emit(A64_STLXR(isdw, src, reg, tmp3), ctx);
+		jmp_offset = -4;
+		check_imm19(jmp_offset);
+		emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
+		emit(A64_DMB_ISH, ctx);
+	} else {
+		pr_err_once("unknown atomic op code %02x\n", imm);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static void build_epilogue(struct jit_ctx *ctx)
 {
 	const u8 r0 = bpf2a64[BPF_REG_0];
@@ -434,29 +602,16 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
 	const u8 src = bpf2a64[insn->src_reg];
 	const u8 tmp = bpf2a64[TMP_REG_1];
 	const u8 tmp2 = bpf2a64[TMP_REG_2];
-	const u8 tmp3 = bpf2a64[TMP_REG_3];
 	const s16 off = insn->off;
 	const s32 imm = insn->imm;
 	const int i = insn - ctx->prog->insnsi;
 	const bool is64 = BPF_CLASS(code) == BPF_ALU64 ||
 			  BPF_CLASS(code) == BPF_JMP;
-	const bool isdw = BPF_SIZE(code) == BPF_DW;
-	u8 jmp_cond, reg;
+	u8 jmp_cond;
 	s32 jmp_offset;
 	u32 a64_insn;
 	int ret;
 
-#define check_imm(bits, imm) do {				\
-	if ((((imm) > 0) && ((imm) >> (bits))) ||		\
-	    (((imm) < 0) && (~(imm) >> (bits)))) {		\
-		pr_info("[%2d] imm=%d(0x%x) out of range\n",	\
-			i, imm, imm);				\
-		return -EINVAL;					\
-	}							\
-} while (0)
-#define check_imm19(imm) check_imm(19, imm)
-#define check_imm26(imm) check_imm(26, imm)
-
 	switch (code) {
 	/* dst = src */
 	case BPF_ALU | BPF_MOV | BPF_X:
@@ -891,33 +1046,12 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
 
 	case BPF_STX | BPF_ATOMIC | BPF_W:
 	case BPF_STX | BPF_ATOMIC | BPF_DW:
-		if (insn->imm != BPF_ADD) {
-			pr_err_once("unknown atomic op code %02x\n", insn->imm);
-			return -EINVAL;
-		}
-
-		/* STX XADD: lock *(u32 *)(dst + off) += src
-		 * and
-		 * STX XADD: lock *(u64 *)(dst + off) += src
-		 */
-
-		if (!off) {
-			reg = dst;
-		} else {
-			emit_a64_mov_i(1, tmp, off, ctx);
-			emit(A64_ADD(1, tmp, tmp, dst), ctx);
-			reg = tmp;
-		}
-		if (cpus_have_cap(ARM64_HAS_LSE_ATOMICS)) {
-			emit(A64_STADD(isdw, reg, src), ctx);
-		} else {
-			emit(A64_LDXR(isdw, tmp2, reg), ctx);
-			emit(A64_ADD(isdw, tmp2, tmp2, src), ctx);
-			emit(A64_STXR(isdw, tmp2, reg, tmp3), ctx);
-			jmp_offset = -3;
-			check_imm19(jmp_offset);
-			emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
-		}
+		if (cpus_have_cap(ARM64_HAS_LSE_ATOMICS))
+			ret = emit_lse_atomic(insn, ctx);
+		else
+			ret = emit_ll_sc_atomic(insn, ctx);
+		if (ret)
+			return ret;
 		break;
 
 	default:
-- 
2.27.0




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