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Message-Id: <20250611053625.352091-3-duanchenghao@kylinos.cn>
Date: Wed, 11 Jun 2025 13:36:22 +0800
From: Chenghao Duan <duanchenghao@...inos.cn>
To: loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org
Cc: Chenghao Duan <duanchenghao@...inos.cn>,
George Guo <guodongtai@...inos.cn>,
Youling Tang <tangyouling@...inos.cn>
Subject: [PATCH v1 2/5] LoongArch: BPF: The operation commands needed to add a trampoline
Add instrctions:
emit_NOP
emit_BREAK
Add branch jump function:
larch_insn_gen_beq
larch_insn_gen_bne
Add instruction copy function: larch_insn_text_copy
The implementation of larch_insn_text_copy uses the fixmap
FIX_TEXT_POKE0.
Signed-off-by: George Guo <guodongtai@...inos.cn>
Signed-off-by: Youling Tang <tangyouling@...inos.cn>
Signed-off-by: Chenghao Duan <duanchenghao@...inos.cn>
---
arch/loongarch/include/asm/inst.h | 19 +++++++
arch/loongarch/kernel/inst.c | 85 +++++++++++++++++++++++++++++++
2 files changed, 104 insertions(+)
diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index 3089785ca..dd6e07781 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)
{
@@ -778,6 +781,22 @@ static inline void emit_##NAME(union loongarch_instruction *insn, \
DEF_EMIT_REG3SA2_FORMAT(alsld, alsld_op)
+#define DEF_EMIT_NOP(NAME) \
+static inline void emit_##NAME(union loongarch_instruction *insn) \
+{ \
+ insn->word = INSN_NOP; \
+}
+
+DEF_EMIT_NOP(NOP)
+
+#define DEF_EMIT_BREAK(NAME) \
+static inline void emit_##NAME(union loongarch_instruction *insn) \
+{ \
+ insn->word = INSN_BREAK; \
+}
+
+DEF_EMIT_BREAK(BREAK)
+
struct pt_regs;
void emulate_load_store_insn(struct pt_regs *regs, void __user *addr, unsigned int *pc);
diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c
index 14d7d700b..a47dc3575 100644
--- a/arch/loongarch/kernel/inst.c
+++ b/arch/loongarch/kernel/inst.c
@@ -10,6 +10,33 @@
static DEFINE_RAW_SPINLOCK(patch_lock);
+static bool is_image_text(unsigned long addr)
+{
+ return core_kernel_text(addr);
+}
+
+static void *patch_map(void *addr, int fixmap)
+{
+ unsigned long uintaddr = (uintptr_t)addr;
+ bool image = is_image_text(uintaddr);
+ struct page *page;
+ phys_addr_t phys;
+
+ if (image)
+ phys = __pa_symbol(addr);
+ else {
+ page = vmalloc_to_page(addr);
+ phys = page_to_phys(page) + offset_in_page(addr);
+ }
+
+ return (void *)set_fixmap_offset(fixmap, phys);
+}
+
+static void patch_unmap(int fixmap)
+{
+ clear_fixmap(fixmap);
+}
+
void simu_pc(struct pt_regs *regs, union loongarch_instruction insn)
{
unsigned long pc = regs->csr_era;
@@ -218,6 +245,36 @@ 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 *waddr;
+ void *ptr;
+ int ret = 0;
+
+ 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);
+
+ waddr = patch_map(ptr, FIX_TEXT_POKE0);
+ ret = copy_to_kernel_nofault(waddr, src + wlen, size);
+ patch_unmap(FIX_TEXT_POKE0);
+
+ if (ret) {
+ pr_err("%s: operation failed\n", __func__);
+ break;
+ }
+ wlen += size;
+ }
+ raw_spin_unlock_irqrestore(&patch_lock, flags);
+
+ return ret;
+}
+
u32 larch_insn_gen_nop(void)
{
return INSN_NOP;
@@ -336,3 +393,31 @@ 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;
+}
--
2.25.1
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