linux-kernel - [PATCH v2 1/4] LoongArch: BPF: The operation commands needed to add a trampoline

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Message-Id: <20250618105048.1510560-2-duanchenghao@kylinos.cn>
Date: Wed, 18 Jun 2025 18:50:45 +0800
From: Chenghao Duan <duanchenghao@...inos.cn>
To: ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org,
	yangtiezhu@...ngson.cn,
	hengqi.chen@...il.com,
	chenhuacai@...nel.org
Cc: martin.lau@...ux.dev,
	eddyz87@...il.com,
	song@...nel.org,
	yonghong.song@...ux.dev,
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	kernel@...0n.name,
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	youling.tang@...ux.dev,
	jianghaoran@...inos.cn,
	Youling Tang <tangyouling@...inos.cn>
Subject: [PATCH v2 1/4] LoongArch: BPF: The operation commands needed to add a trampoline

Add branch jump function:
larch_insn_gen_beq
larch_insn_gen_bne

Add instruction copy function: larch_insn_text_copy

Co-developed-by: George Guo <guodongtai@...inos.cn>
Signed-off-by: George Guo <guodongtai@...inos.cn>
Co-developed-by: Youling Tang <tangyouling@...inos.cn>
Signed-off-by: Youling Tang <tangyouling@...inos.cn>
Signed-off-by: Chenghao Duan <duanchenghao@...inos.cn>
---
 arch/loongarch/include/asm/inst.h |  3 ++
 arch/loongarch/kernel/inst.c      | 57 +++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index 3089785ca..88bb73e46 100644
--- a/arch/loongarch/include/asm/inst.h
+++ b/arch/loongarch/include/asm/inst.h
@@ -497,6 +497,7 @@ void arch_simulate_insn(union loongarch_instruction insn, struct pt_regs *regs);
 int larch_insn_read(void *addr, u32 *insnp);
 int larch_insn_write(void *addr, u32 insn);
 int larch_insn_patch_text(void *addr, u32 insn);
+int larch_insn_text_copy(void *dst, void *src, size_t len);
 
 u32 larch_insn_gen_nop(void);
 u32 larch_insn_gen_b(unsigned long pc, unsigned long dest);
@@ -511,6 +512,8 @@ u32 larch_insn_gen_lu12iw(enum loongarch_gpr rd, int imm);
 u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm);
 u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm);
 u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm);
+u32 larch_insn_gen_beq(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm);
+u32 larch_insn_gen_bne(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm);
 
 static inline bool signed_imm_check(long val, unsigned int bit)
 {
diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c
index 14d7d700b..7423b0772 100644
--- a/arch/loongarch/kernel/inst.c
+++ b/arch/loongarch/kernel/inst.c
@@ -4,6 +4,7 @@
  */
 #include <linux/sizes.h>
 #include <linux/uaccess.h>
+#include <linux/set_memory.h>
 
 #include <asm/cacheflush.h>
 #include <asm/inst.h>
@@ -218,6 +219,34 @@ int larch_insn_patch_text(void *addr, u32 insn)
 	return ret;
 }
 
+int larch_insn_text_copy(void *dst, void *src, size_t len)
+{
+	unsigned long flags;
+	size_t wlen = 0;
+	size_t size;
+	void *ptr;
+	int ret = 0;
+
+	set_memory_rw((unsigned long)dst, round_up(len, PAGE_SIZE) / PAGE_SIZE);
+	raw_spin_lock_irqsave(&patch_lock, flags);
+	while (wlen < len) {
+		ptr = dst + wlen;
+		size = min_t(size_t, PAGE_SIZE - offset_in_page(ptr),
+			     len - wlen);
+
+		ret = copy_to_kernel_nofault(ptr, src + wlen, size);
+		if (ret) {
+			pr_err("%s: operation failed\n", __func__);
+			break;
+		}
+		wlen += size;
+	}
+	raw_spin_unlock_irqrestore(&patch_lock, flags);
+	set_memory_rox((unsigned long)dst, round_up(len, PAGE_SIZE) / PAGE_SIZE);
+
+	return ret;
+}
+
 u32 larch_insn_gen_nop(void)
 {
 	return INSN_NOP;
@@ -336,3 +365,31 @@ u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm)
 
 	return insn.word;
 }
+
+u32 larch_insn_gen_beq(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm)
+{
+	union loongarch_instruction insn;
+
+	if ((imm & 3) || imm < -SZ_128K || imm >= SZ_128K) {
+		pr_warn("The generated beq instruction is out of range.\n");
+		return INSN_BREAK;
+	}
+
+	emit_beq(&insn, rd, rj, imm >> 2);
+
+	return insn.word;
+}
+
+u32 larch_insn_gen_bne(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm)
+{
+	union loongarch_instruction insn;
+
+	if ((imm & 3) || imm < -SZ_128K || imm >= SZ_128K) {
+		pr_warn("The generated bne instruction is out of range.\n");
+		return INSN_BREAK;
+	}
+
+	emit_bne(&insn, rj, rd, imm >> 2);
+
+	return insn.word;
+}
-- 
2.43.0