linux-kernel - [PATCH bpf-next v1 5/8] arm64: insn: Add load-acquire and store-release instructions

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Message-ID: <7544131164e5a3ab1aa192e895c883106d8dd324.1737763916.git.yepeilin@google.com>
Date: Sat, 25 Jan 2025 02:19:00 +0000
From: Peilin Ye <yepeilin@...gle.com>
To: bpf@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc: Peilin Ye <yepeilin@...gle.com>, bpf@...f.org, Xu Kuohai <xukuohai@...weicloud.com>, 
	Eduard Zingerman <eddyz87@...il.com>, David Vernet <void@...ifault.com>, 
	Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
	Jiri Olsa <jolsa@...nel.org>, Jonathan Corbet <corbet@....net>, 
	"Paul E. McKenney" <paulmck@...nel.org>, Puranjay Mohan <puranjay@...nel.org>, 
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
	Quentin Monnet <qmo@...nel.org>, Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>, 
	Josh Don <joshdon@...gle.com>, Barret Rhoden <brho@...gle.com>, Neel Natu <neelnatu@...gle.com>, 
	Benjamin Segall <bsegall@...gle.com>, linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next v1 5/8] arm64: insn: Add load-acquire and
 store-release instructions

Add load-acquire ("load_acq", LDAR{,B,H}) and store-release
("store_rel", STLR{,B,H}) instructions.  Breakdown of encoding:

                                size        L   (Rs)  o0 (Rt2) Rn    Rt
             mask (0x3fdffc00): 00 111111 1 1 0 11111 1  11111 00000 00000
  value, load_acq (0x08dffc00): 00 001000 1 1 0 11111 1  11111 00000 00000
 value, store_rel (0x089ffc00): 00 001000 1 0 0 11111 1  11111 00000 00000

As suggested by Xu [1], include all Should-Be-One (SBO) bits ("Rs" and
"Rt2" fields) in the "mask" and "value" numbers.

It is worth noting that we are adding the "no offset" variant of STLR
instead of the "pre-index" variant, which has a different encoding.

Reference: Arm Architecture Reference Manual (ARM DDI 0487K.a,
           ID032224),

  * C6.2.161 LDAR
  * C6.2.353 STLR

[1] https://lore.kernel.org/bpf/4e6641ce-3f1e-4251-8daf-4dd4b77d08c4@huaweicloud.com/

Signed-off-by: Peilin Ye <yepeilin@...gle.com>
---
 arch/arm64/include/asm/insn.h |  8 ++++++++
 arch/arm64/lib/insn.c         | 28 ++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index 2d8316b3abaf..39577f1d079a 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -188,8 +188,10 @@ enum aarch64_insn_ldst_type {
 	AARCH64_INSN_LDST_STORE_PAIR_PRE_INDEX,
 	AARCH64_INSN_LDST_LOAD_PAIR_POST_INDEX,
 	AARCH64_INSN_LDST_STORE_PAIR_POST_INDEX,
+	AARCH64_INSN_LDST_LOAD_ACQ,
 	AARCH64_INSN_LDST_LOAD_EX,
 	AARCH64_INSN_LDST_LOAD_ACQ_EX,
+	AARCH64_INSN_LDST_STORE_REL,
 	AARCH64_INSN_LDST_STORE_EX,
 	AARCH64_INSN_LDST_STORE_REL_EX,
 	AARCH64_INSN_LDST_SIGNED_LOAD_IMM_OFFSET,
@@ -351,6 +353,8 @@ __AARCH64_INSN_FUNCS(ldr_imm,	0x3FC00000, 0x39400000)
 __AARCH64_INSN_FUNCS(ldr_lit,	0xBF000000, 0x18000000)
 __AARCH64_INSN_FUNCS(ldrsw_lit,	0xFF000000, 0x98000000)
 __AARCH64_INSN_FUNCS(exclusive,	0x3F800000, 0x08000000)
+__AARCH64_INSN_FUNCS(load_acq,  0x3FDFFC00, 0x08DFFC00)
+__AARCH64_INSN_FUNCS(store_rel, 0x3FDFFC00, 0x089FFC00)
 __AARCH64_INSN_FUNCS(load_ex,	0x3FC00000, 0x08400000)
 __AARCH64_INSN_FUNCS(store_ex,	0x3FC00000, 0x08000000)
 __AARCH64_INSN_FUNCS(mops,	0x3B200C00, 0x19000400)
@@ -602,6 +606,10 @@ u32 aarch64_insn_gen_load_store_pair(enum aarch64_insn_register reg1,
 				     int offset,
 				     enum aarch64_insn_variant variant,
 				     enum aarch64_insn_ldst_type type);
+u32 aarch64_insn_gen_load_acq_store_rel(enum aarch64_insn_register reg,
+					enum aarch64_insn_register base,
+					enum aarch64_insn_size_type size,
+					enum aarch64_insn_ldst_type type);
 u32 aarch64_insn_gen_load_store_ex(enum aarch64_insn_register reg,
 				   enum aarch64_insn_register base,
 				   enum aarch64_insn_register state,
diff --git a/arch/arm64/lib/insn.c b/arch/arm64/lib/insn.c
index b008a9b46a7f..f8b83f4d9171 100644
--- a/arch/arm64/lib/insn.c
+++ b/arch/arm64/lib/insn.c
@@ -540,6 +540,34 @@ u32 aarch64_insn_gen_load_store_pair(enum aarch64_insn_register reg1,
 					     offset >> shift);
 }
 
+u32 aarch64_insn_gen_load_acq_store_rel(enum aarch64_insn_register reg,
+					enum aarch64_insn_register base,
+					enum aarch64_insn_size_type size,
+					enum aarch64_insn_ldst_type type)
+{
+	u32 insn;
+
+	switch (type) {
+	case AARCH64_INSN_LDST_LOAD_ACQ:
+		insn = aarch64_insn_get_load_acq_value();
+		break;
+	case AARCH64_INSN_LDST_STORE_REL:
+		insn = aarch64_insn_get_store_rel_value();
+		break;
+	default:
+		pr_err("%s: unknown load-acquire/store-release encoding %d\n", __func__, type);
+		return AARCH64_BREAK_FAULT;
+	}
+
+	insn = aarch64_insn_encode_ldst_size(size, insn);
+
+	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RT, insn,
+					    reg);
+
+	return aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn,
+					    base);
+}
+
 u32 aarch64_insn_gen_load_store_ex(enum aarch64_insn_register reg,
 				   enum aarch64_insn_register base,
 				   enum aarch64_insn_register state,
-- 
2.48.1.262.g85cc9f2d1e-goog