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-rw-r--r--arch/loongarch/net/bpf_jit.h282
1 files changed, 282 insertions, 0 deletions
diff --git a/arch/loongarch/net/bpf_jit.h b/arch/loongarch/net/bpf_jit.h
new file mode 100644
index 000000000000..e665ddb0aeb8
--- /dev/null
+++ b/arch/loongarch/net/bpf_jit.h
@@ -0,0 +1,282 @@
+/* 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_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;
+}