1 files changed, 303 insertions, 0 deletions
diff --git a/arch/loongarch/net/bpf_jit.h b/arch/loongarch/net/bpf_jit.h
new file mode 100644
index 000000000..684b22f54
--- /dev/null
+++ b/arch/loongarch/net/bpf_jit.h
@@ -0,0 +1,303 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * BPF JIT compiler for LoongArch
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <asm/cacheflush.h>
+#include <asm/inst.h>
+
+struct jit_ctx {
+	const struct bpf_prog *prog;
+	unsigned int idx;
+	unsigned int flags;
+	unsigned int epilogue_offset;
+	u32 *offset;
+	union loongarch_instruction *image;
+	u32 stack_size;
+};
+
+struct jit_data {
+	struct bpf_binary_header *header;
+	u8 *image;
+	struct jit_ctx ctx;
+};
+
+#define emit_insn(ctx, func, ...)						\
+do {										\
+	if (ctx->image != NULL) {						\
+		union loongarch_instruction *insn = &ctx->image[ctx->idx];	\
+		emit_##func(insn, ##__VA_ARGS__);				\
+	}									\
+	ctx->idx++;								\
+} while (0)
+
+#define is_signed_imm12(val)	signed_imm_check(val, 12)
+#define is_signed_imm14(val)	signed_imm_check(val, 14)
+#define is_signed_imm16(val)	signed_imm_check(val, 16)
+#define is_signed_imm26(val)	signed_imm_check(val, 26)
+#define is_signed_imm32(val)	signed_imm_check(val, 32)
+#define is_signed_imm52(val)	signed_imm_check(val, 52)
+#define is_unsigned_imm12(val)	unsigned_imm_check(val, 12)
+
+static inline int bpf2la_offset(int bpf_insn, int off, const struct jit_ctx *ctx)
+{
+	/* BPF JMP offset is relative to the next instruction */
+	bpf_insn++;
+	/*
+	 * Whereas LoongArch branch instructions encode the offset
+	 * from the branch itself, so we must subtract 1 from the
+	 * instruction offset.
+	 */
+	return (ctx->offset[bpf_insn + off] - (ctx->offset[bpf_insn] - 1));
+}
+
+static inline int epilogue_offset(const struct jit_ctx *ctx)
+{
+	int from = ctx->idx;
+	int to = ctx->epilogue_offset;
+
+	return (to - from);
+}
+
+/* Zero-extend 32 bits into 64 bits */
+static inline void emit_zext_32(struct jit_ctx *ctx, enum loongarch_gpr reg, bool is32)
+{
+	if (!is32)
+		return;
+
+	emit_insn(ctx, lu32id, reg, 0);
+}
+
+/* Signed-extend 32 bits into 64 bits */
+static inline void emit_sext_32(struct jit_ctx *ctx, enum loongarch_gpr reg, bool is32)
+{
+	if (!is32)
+		return;
+
+	emit_insn(ctx, addiw, reg, reg, 0);
+}
+
+static inline void move_addr(struct jit_ctx *ctx, enum loongarch_gpr rd, u64 addr)
+{
+	u64 imm_11_0, imm_31_12, imm_51_32, imm_63_52;
+
+	/* lu12iw rd, imm_31_12 */
+	imm_31_12 = (addr >> 12) & 0xfffff;
+	emit_insn(ctx, lu12iw, rd, imm_31_12);
+
+	/* ori rd, rd, imm_11_0 */
+	imm_11_0 = addr & 0xfff;
+	emit_insn(ctx, ori, rd, rd, imm_11_0);
+
+	/* lu32id rd, imm_51_32 */
+	imm_51_32 = (addr >> 32) & 0xfffff;
+	emit_insn(ctx, lu32id, rd, imm_51_32);
+
+	/* lu52id rd, rd, imm_63_52 */
+	imm_63_52 = (addr >> 52) & 0xfff;
+	emit_insn(ctx, lu52id, rd, rd, imm_63_52);
+}
+
+static inline void move_imm(struct jit_ctx *ctx, enum loongarch_gpr rd, long imm, bool is32)
+{
+	long imm_11_0, imm_31_12, imm_51_32, imm_63_52, imm_51_0, imm_51_31;
+
+	/* or rd, $zero, $zero */
+	if (imm == 0) {
+		emit_insn(ctx, or, rd, LOONGARCH_GPR_ZERO, LOONGARCH_GPR_ZERO);
+		return;
+	}
+
+	/* addiw rd, $zero, imm_11_0 */
+	if (is_signed_imm12(imm)) {
+		emit_insn(ctx, addiw, rd, LOONGARCH_GPR_ZERO, imm);
+		goto zext;
+	}
+
+	/* ori rd, $zero, imm_11_0 */
+	if (is_unsigned_imm12(imm)) {
+		emit_insn(ctx, ori, rd, LOONGARCH_GPR_ZERO, imm);
+		goto zext;
+	}
+
+	/* lu52id rd, $zero, imm_63_52 */
+	imm_63_52 = (imm >> 52) & 0xfff;
+	imm_51_0 = imm & 0xfffffffffffff;
+	if (imm_63_52 != 0 && imm_51_0 == 0) {
+		emit_insn(ctx, lu52id, rd, LOONGARCH_GPR_ZERO, imm_63_52);
+		return;
+	}
+
+	/* lu12iw rd, imm_31_12 */
+	imm_31_12 = (imm >> 12) & 0xfffff;
+	emit_insn(ctx, lu12iw, rd, imm_31_12);
+
+	/* ori rd, rd, imm_11_0 */
+	imm_11_0 = imm & 0xfff;
+	if (imm_11_0 != 0)
+		emit_insn(ctx, ori, rd, rd, imm_11_0);
+
+	if (!is_signed_imm32(imm)) {
+		if (imm_51_0 != 0) {
+			/*
+			 * If bit[51:31] is all 0 or all 1,
+			 * it means bit[51:32] is sign extended by lu12iw,
+			 * no need to call lu32id to do a new filled operation.
+			 */
+			imm_51_31 = (imm >> 31) & 0x1fffff;
+			if (imm_51_31 != 0 && imm_51_31 != 0x1fffff) {
+				/* lu32id rd, imm_51_32 */
+				imm_51_32 = (imm >> 32) & 0xfffff;
+				emit_insn(ctx, lu32id, rd, imm_51_32);
+			}
+		}
+
+		/* lu52id rd, rd, imm_63_52 */
+		if (!is_signed_imm52(imm))
+			emit_insn(ctx, lu52id, rd, rd, imm_63_52);
+	}
+
+zext:
+	emit_zext_32(ctx, rd, is32);
+}
+
+static inline void move_reg(struct jit_ctx *ctx, enum loongarch_gpr rd,
+			    enum loongarch_gpr rj)
+{
+	emit_insn(ctx, or, rd, rj, LOONGARCH_GPR_ZERO);
+}
+
+static inline int invert_jmp_cond(u8 cond)
+{
+	switch (cond) {
+	case BPF_JEQ:
+		return BPF_JNE;
+	case BPF_JNE:
+	case BPF_JSET:
+		return BPF_JEQ;
+	case BPF_JGT:
+		return BPF_JLE;
+	case BPF_JGE:
+		return BPF_JLT;
+	case BPF_JLT:
+		return BPF_JGE;
+	case BPF_JLE:
+		return BPF_JGT;
+	case BPF_JSGT:
+		return BPF_JSLE;
+	case BPF_JSGE:
+		return BPF_JSLT;
+	case BPF_JSLT:
+		return BPF_JSGE;
+	case BPF_JSLE:
+		return BPF_JSGT;
+	}
+	return -1;
+}
+
+static inline void cond_jmp_offset(struct jit_ctx *ctx, u8 cond, enum loongarch_gpr rj,
+				   enum loongarch_gpr rd, int jmp_offset)
+{
+	switch (cond) {
+	case BPF_JEQ:
+		/* PC += jmp_offset if rj == rd */
+		emit_insn(ctx, beq, rj, rd, jmp_offset);
+		return;
+	case BPF_JNE:
+	case BPF_JSET:
+		/* PC += jmp_offset if rj != rd */
+		emit_insn(ctx, bne, rj, rd, jmp_offset);
+		return;
+	case BPF_JGT:
+		/* PC += jmp_offset if rj > rd (unsigned) */
+		emit_insn(ctx, bltu, rd, rj, jmp_offset);
+		return;
+	case BPF_JLT:
+		/* PC += jmp_offset if rj < rd (unsigned) */
+		emit_insn(ctx, bltu, rj, rd, jmp_offset);
+		return;
+	case BPF_JGE:
+		/* PC += jmp_offset if rj >= rd (unsigned) */
+		emit_insn(ctx, bgeu, rj, rd, jmp_offset);
+		return;
+	case BPF_JLE:
+		/* PC += jmp_offset if rj <= rd (unsigned) */
+		emit_insn(ctx, bgeu, rd, rj, jmp_offset);
+		return;
+	case BPF_JSGT:
+		/* PC += jmp_offset if rj > rd (signed) */
+		emit_insn(ctx, blt, rd, rj, jmp_offset);
+		return;
+	case BPF_JSLT:
+		/* PC += jmp_offset if rj < rd (signed) */
+		emit_insn(ctx, blt, rj, rd, jmp_offset);
+		return;
+	case BPF_JSGE:
+		/* PC += jmp_offset if rj >= rd (signed) */
+		emit_insn(ctx, bge, rj, rd, jmp_offset);
+		return;
+	case BPF_JSLE:
+		/* PC += jmp_offset if rj <= rd (signed) */
+		emit_insn(ctx, bge, rd, rj, jmp_offset);
+		return;
+	}
+}
+
+static inline void cond_jmp_offs26(struct jit_ctx *ctx, u8 cond, enum loongarch_gpr rj,
+				   enum loongarch_gpr rd, int jmp_offset)
+{
+	cond = invert_jmp_cond(cond);
+	cond_jmp_offset(ctx, cond, rj, rd, 2);
+	emit_insn(ctx, b, jmp_offset);
+}
+
+static inline void uncond_jmp_offs26(struct jit_ctx *ctx, int jmp_offset)
+{
+	emit_insn(ctx, b, jmp_offset);
+}
+
+static inline int emit_cond_jmp(struct jit_ctx *ctx, u8 cond, enum loongarch_gpr rj,
+				enum loongarch_gpr rd, int jmp_offset)
+{
+	/*
+	 * A large PC-relative jump offset may overflow the immediate field of
+	 * the native conditional branch instruction, triggering a conversion
+	 * to use an absolute jump instead, this jump sequence is particularly
+	 * nasty. For now, use cond_jmp_offs26() directly to keep it simple.
+	 * In the future, maybe we can add support for far branching, the branch
+	 * relaxation requires more than two passes to converge, the code seems
+	 * too complex to understand, not quite sure whether it is necessary and
+	 * worth the extra pain. Anyway, just leave it as it is to enhance code
+	 * readability now.
+	 */
+	if (is_signed_imm26(jmp_offset)) {
+		cond_jmp_offs26(ctx, cond, rj, rd, jmp_offset);
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static inline int emit_uncond_jmp(struct jit_ctx *ctx, int jmp_offset)
+{
+	if (is_signed_imm26(jmp_offset)) {
+		uncond_jmp_offs26(ctx, jmp_offset);
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static inline int emit_tailcall_jmp(struct jit_ctx *ctx, u8 cond, enum loongarch_gpr rj,
+				    enum loongarch_gpr rd, int jmp_offset)
+{
+	if (is_signed_imm16(jmp_offset)) {
+		cond_jmp_offset(ctx, cond, rj, rd, jmp_offset);
+		return 0;
+	}
+
+	return -EINVAL;
+}