diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 8aa32cb140b9..8bbd0b20136a 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -84,6 +84,7 @@ struct jit_ctx { u64 user_vm_start; u64 arena_vm_start; bool fp_used; + bool write; }; struct bpf_plt { @@ -97,7 +98,7 @@ struct bpf_plt { static inline void emit(const u32 insn, struct jit_ctx *ctx) { - if (ctx->image != NULL) + if (ctx->image != NULL && ctx->write) ctx->image[ctx->idx] = cpu_to_le32(insn); ctx->idx++; @@ -182,14 +183,47 @@ static inline void emit_addr_mov_i64(const int reg, const u64 val, } } -static inline void emit_call(u64 target, struct jit_ctx *ctx) +static bool should_emit_indirect_call(long target, const struct jit_ctx *ctx) { - u8 tmp = bpf2a64[TMP_REG_1]; + long offset; + /* when ctx->ro_image is not allocated or the target is unknown, + * emit indirect call + */ + if (!ctx->ro_image || !target) + return true; + + offset = target - (long)&ctx->ro_image[ctx->idx]; + return offset < -SZ_128M || offset >= SZ_128M; +} + +static void emit_direct_call(u64 target, struct jit_ctx *ctx) +{ + u32 insn; + unsigned long pc; + + pc = (unsigned long)&ctx->ro_image[ctx->idx]; + insn = aarch64_insn_gen_branch_imm(pc, target, AARCH64_INSN_BRANCH_LINK); + emit(insn, ctx); +} + +static void emit_indirect_call(u64 target, struct jit_ctx *ctx) +{ + u8 tmp; + + tmp = bpf2a64[TMP_REG_1]; emit_addr_mov_i64(tmp, target, ctx); emit(A64_BLR(tmp), ctx); } +static void emit_call(u64 target, struct jit_ctx *ctx) +{ + if (should_emit_indirect_call((long)target, ctx)) + emit_indirect_call(target, ctx); + else + emit_direct_call(target, ctx); +} + static inline int bpf2a64_offset(int bpf_insn, int off, const struct jit_ctx *ctx) { @@ -1649,13 +1683,11 @@ static int build_body(struct jit_ctx *ctx, bool extra_pass) const struct bpf_insn *insn = &prog->insnsi[i]; int ret; - if (ctx->image == NULL) - ctx->offset[i] = ctx->idx; + ctx->offset[i] = ctx->idx; ret = build_insn(insn, ctx, extra_pass); if (ret > 0) { i++; - if (ctx->image == NULL) - ctx->offset[i] = ctx->idx; + ctx->offset[i] = ctx->idx; continue; } if (ret) @@ -1666,8 +1698,7 @@ static int build_body(struct jit_ctx *ctx, bool extra_pass) * the last element with the offset after the last * instruction (end of program) */ - if (ctx->image == NULL) - ctx->offset[i] = ctx->idx; + ctx->offset[i] = ctx->idx; return 0; } @@ -1721,6 +1752,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) struct jit_ctx ctx; u8 *image_ptr; u8 *ro_image_ptr; + int body_idx; + int exentry_idx; if (!prog->jit_requested) return orig_prog; @@ -1768,8 +1801,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) ctx.user_vm_start = bpf_arena_get_user_vm_start(prog->aux->arena); ctx.arena_vm_start = bpf_arena_get_kern_vm_start(prog->aux->arena); - /* - * 1. Initial fake pass to compute ctx->idx and ctx->offset. + /* Pass 1: Estimate the maximum image size. * * BPF line info needs ctx->offset[i] to be the offset of * instruction[i] in jited image, so build prologue first. @@ -1792,7 +1824,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) extable_size = prog->aux->num_exentries * sizeof(struct exception_table_entry); - /* Now we know the actual image size. */ + /* Now we know the maximum image size. */ prog_size = sizeof(u32) * ctx.idx; /* also allocate space for plt target */ extable_offset = round_up(prog_size + PLT_TARGET_SIZE, extable_align); @@ -1805,7 +1837,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) goto out_off; } - /* 2. Now, the actual pass. */ + /* Pass 2: Determine jited position and result for each instruction */ /* * Use the image(RW) for writing the JITed instructions. But also save @@ -1821,30 +1853,56 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) skip_init_ctx: ctx.idx = 0; ctx.exentry_idx = 0; + ctx.write = true; build_prologue(&ctx, was_classic); + /* Record exentry_idx and body_idx before first build_body */ + exentry_idx = ctx.exentry_idx; + body_idx = ctx.idx; + /* Dont write body instructions to memory for now */ + ctx.write = false; + if (build_body(&ctx, extra_pass)) { prog = orig_prog; goto out_free_hdr; } + ctx.epilogue_offset = ctx.idx; + ctx.exentry_idx = exentry_idx; + ctx.idx = body_idx; + ctx.write = true; + + /* Pass 3: Adjust jump offset and write final image */ + if (build_body(&ctx, extra_pass) || + WARN_ON_ONCE(ctx.idx != ctx.epilogue_offset)) { + prog = orig_prog; + goto out_free_hdr; + } + build_epilogue(&ctx); build_plt(&ctx); - /* 3. Extra pass to validate JITed code. */ + /* Extra pass to validate JITed code. */ if (validate_ctx(&ctx)) { prog = orig_prog; goto out_free_hdr; } + /* update the real prog size */ + prog_size = sizeof(u32) * ctx.idx; + /* And we're done. */ if (bpf_jit_enable > 1) bpf_jit_dump(prog->len, prog_size, 2, ctx.image); if (!prog->is_func || extra_pass) { - if (extra_pass && ctx.idx != jit_data->ctx.idx) { - pr_err_once("multi-func JIT bug %d != %d\n", + /* The jited image may shrink since the jited result for + * BPF_CALL to subprog may be changed from indirect call + * to direct call. + */ + if (extra_pass && ctx.idx > jit_data->ctx.idx) { + pr_err_once("multi-func JIT bug %d > %d\n", ctx.idx, jit_data->ctx.idx); prog->bpf_func = NULL; prog->jited = 0; @@ -2315,6 +2373,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *ro_image, .image = image, .ro_image = ro_image, .idx = 0, + .write = true, }; nregs = btf_func_model_nregs(m);