From f84192ee00b7d8b3c38545d3a61d4191f80cc81a Mon Sep 17 00:00:00 2001 From: Sandipan Das Date: Thu, 24 May 2018 12:26:50 +0530 Subject: [PATCH] tools: bpftool: resolve calls without using imm field Currently, we resolve the callee's address for a JITed function call by using the imm field of the call instruction as an offset from __bpf_call_base. If bpf_jit_kallsyms is enabled, we further use this address to get the callee's kernel symbol's name. For some architectures, such as powerpc64, the imm field is not large enough to hold this offset. So, instead of assigning this offset to the imm field, the verifier now assigns the subprog id. Also, a list of kernel symbol addresses for all the JITed functions is provided in the program info. We now use the imm field as an index for this list to lookup a callee's symbol's address and resolve its name. Suggested-by: Daniel Borkmann Signed-off-by: Sandipan Das Reviewed-by: Jakub Kicinski Signed-off-by: Daniel Borkmann --- tools/bpf/bpftool/prog.c | 24 ++++++++++++++++++++++++ tools/bpf/bpftool/xlated_dumper.c | 10 +++++++++- tools/bpf/bpftool/xlated_dumper.h | 2 ++ 3 files changed, 35 insertions(+), 1 deletion(-) diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index 9bdfdf2d3fbe..e05ab58d39e2 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -420,7 +420,9 @@ static int do_show(int argc, char **argv) static int do_dump(int argc, char **argv) { + unsigned long *func_ksyms = NULL; struct bpf_prog_info info = {}; + unsigned int nr_func_ksyms; struct dump_data dd = {}; __u32 len = sizeof(info); unsigned int buf_size; @@ -496,10 +498,22 @@ static int do_dump(int argc, char **argv) return -1; } + nr_func_ksyms = info.nr_jited_ksyms; + if (nr_func_ksyms) { + func_ksyms = malloc(nr_func_ksyms * sizeof(__u64)); + if (!func_ksyms) { + p_err("mem alloc failed"); + close(fd); + goto err_free; + } + } + memset(&info, 0, sizeof(info)); *member_ptr = ptr_to_u64(buf); *member_len = buf_size; + info.jited_ksyms = ptr_to_u64(func_ksyms); + info.nr_jited_ksyms = nr_func_ksyms; err = bpf_obj_get_info_by_fd(fd, &info, &len); close(fd); @@ -513,6 +527,11 @@ static int do_dump(int argc, char **argv) goto err_free; } + if (info.nr_jited_ksyms > nr_func_ksyms) { + p_err("too many addresses returned"); + goto err_free; + } + if ((member_len == &info.jited_prog_len && info.jited_prog_insns == 0) || (member_len == &info.xlated_prog_len && @@ -558,6 +577,9 @@ static int do_dump(int argc, char **argv) dump_xlated_cfg(buf, *member_len); } else { kernel_syms_load(&dd); + dd.nr_jited_ksyms = info.nr_jited_ksyms; + dd.jited_ksyms = (__u64 *) info.jited_ksyms; + if (json_output) dump_xlated_json(&dd, buf, *member_len, opcodes); else @@ -566,10 +588,12 @@ static int do_dump(int argc, char **argv) } free(buf); + free(func_ksyms); return 0; err_free: free(buf); + free(func_ksyms); return -1; } diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c index 7a3173b76c16..efdc8fecf2bb 100644 --- a/tools/bpf/bpftool/xlated_dumper.c +++ b/tools/bpf/bpftool/xlated_dumper.c @@ -174,7 +174,11 @@ static const char *print_call_pcrel(struct dump_data *dd, unsigned long address, const struct bpf_insn *insn) { - if (sym) + if (!dd->nr_jited_ksyms) + /* Do not show address for interpreted programs */ + snprintf(dd->scratch_buff, sizeof(dd->scratch_buff), + "%+d", insn->off); + else if (sym) snprintf(dd->scratch_buff, sizeof(dd->scratch_buff), "%+d#%s", insn->off, sym->name); else @@ -203,6 +207,10 @@ static const char *print_call(void *private_data, unsigned long address = dd->address_call_base + insn->imm; struct kernel_sym *sym; + if (insn->src_reg == BPF_PSEUDO_CALL && + (__u32) insn->imm < dd->nr_jited_ksyms) + address = dd->jited_ksyms[insn->imm]; + sym = kernel_syms_search(dd, address); if (insn->src_reg == BPF_PSEUDO_CALL) return print_call_pcrel(dd, sym, address, insn); diff --git a/tools/bpf/bpftool/xlated_dumper.h b/tools/bpf/bpftool/xlated_dumper.h index b34affa7ef2d..eafbb49c8d0b 100644 --- a/tools/bpf/bpftool/xlated_dumper.h +++ b/tools/bpf/bpftool/xlated_dumper.h @@ -49,6 +49,8 @@ struct dump_data { unsigned long address_call_base; struct kernel_sym *sym_mapping; __u32 sym_count; + __u64 *jited_ksyms; + __u32 nr_jited_ksyms; char scratch_buff[SYM_MAX_NAME + 8]; };