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