arch/loongarch/net/bpf_jit.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * BPF JIT compiler for LoongArch
  *
  * Copyright (C) 2022 Loongson Technology Corporation Limited
  */
 #include <linux/bitfield.h>
 #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;
 	int num_exentries;
 	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_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;
 }
	/* SPDX-License-Identifier: GPL-2.0-only */
	/*
	* BPF JIT compiler for LoongArch
	*
	* Copyright (C) 2022 Loongson Technology Corporation Limited
	*/
	#include <linux/bitfield.h>
	#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;
	int num_exentries;
	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_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;
	}