diff options
| -rw-r--r-- | tools/lib/bpf/bpf_gen_internal.h | 1 | ||||
| -rw-r--r-- | tools/lib/bpf/gen_loader.c | 48 |
2 files changed, 45 insertions, 4 deletions
diff --git a/tools/lib/bpf/bpf_gen_internal.h b/tools/lib/bpf/bpf_gen_internal.h index f42a55efd559..615400391e57 100644 --- a/tools/lib/bpf/bpf_gen_internal.h +++ b/tools/lib/bpf/bpf_gen_internal.h @@ -15,6 +15,7 @@ struct bpf_gen { void *data_cur; void *insn_start; void *insn_cur; + ssize_t cleanup_label; __u32 nr_progs; __u32 nr_maps; int log_level; diff --git a/tools/lib/bpf/gen_loader.c b/tools/lib/bpf/gen_loader.c index 0fc54b1ca311..8df718a6b142 100644 --- a/tools/lib/bpf/gen_loader.c +++ b/tools/lib/bpf/gen_loader.c @@ -101,8 +101,36 @@ static void emit2(struct bpf_gen *gen, struct bpf_insn insn1, struct bpf_insn in void bpf_gen__init(struct bpf_gen *gen, int log_level) { + size_t stack_sz = sizeof(struct loader_stack); + int i; + gen->log_level = log_level; + /* save ctx pointer into R6 */ emit(gen, BPF_MOV64_REG(BPF_REG_6, BPF_REG_1)); + + /* bzero stack */ + emit(gen, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10)); + emit(gen, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -stack_sz)); + emit(gen, BPF_MOV64_IMM(BPF_REG_2, stack_sz)); + emit(gen, BPF_MOV64_IMM(BPF_REG_3, 0)); + emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel)); + + /* jump over cleanup code */ + emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, + /* size of cleanup code below */ + (stack_sz / 4) * 3 + 2)); + + /* remember the label where all error branches will jump to */ + gen->cleanup_label = gen->insn_cur - gen->insn_start; + /* emit cleanup code: close all temp FDs */ + for (i = 0; i < stack_sz; i += 4) { + emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, -stack_sz + i)); + emit(gen, BPF_JMP_IMM(BPF_JSLE, BPF_REG_1, 0, 1)); + emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_close)); + } + /* R7 contains the error code from sys_bpf. Copy it into R0 and exit. */ + emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_7)); + emit(gen, BPF_EXIT_INSN()); } static int add_data(struct bpf_gen *gen, const void *data, __u32 size) @@ -187,12 +215,24 @@ static void emit_sys_bpf(struct bpf_gen *gen, int cmd, int attr, int attr_size) emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0)); } +static bool is_simm16(__s64 value) +{ + return value == (__s64)(__s16)value; +} + static void emit_check_err(struct bpf_gen *gen) { - emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 2)); - emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_7)); - /* TODO: close intermediate FDs in case of error */ - emit(gen, BPF_EXIT_INSN()); + __s64 off = -(gen->insn_cur - gen->insn_start - gen->cleanup_label) / 8 - 1; + + /* R7 contains result of last sys_bpf command. + * if (R7 < 0) goto cleanup; + */ + if (is_simm16(off)) { + emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, off)); + } else { + gen->error = -ERANGE; + emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, -1)); + } } /* reg1 and reg2 should not be R1 - R5. They can be R0, R6 - R10 */ |