From: Andrii Nakryiko andrii@kernel.org
mainline inclusion from mainline-5.12-rc1 commit 284d2587ea8a96f97ca519a3de683ff226e9e2b3 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Add support for searching for ksym externs not just in vmlinux BTF, but across all module BTFs, similarly to how it's done for CO-RE relocations. Kernels that expose module BTFs through sysfs are assumed to support new ldimm64 instruction extension with BTF FD provided in insn[1].imm field, so no extra feature detection is performed.
Signed-off-by: Andrii Nakryiko andrii@kernel.org Signed-off-by: Alexei Starovoitov ast@kernel.org Acked-by: Yonghong Song yhs@fb.com Acked-by: Hao Luo haoluo@google.com Link: https://lore.kernel.org/bpf/20210112075520.4103414-7-andrii@kernel.org (cherry picked from commit 284d2587ea8a96f97ca519a3de683ff226e9e2b3) Signed-off-by: Wang Yufen wangyufen@huawei.com --- tools/lib/bpf/libbpf.c | 50 +++++++++++++++++++++++++++--------------- 1 file changed, 32 insertions(+), 18 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index a0a1b7c99f2f..668103ebd5cb 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -395,7 +395,8 @@ struct extern_desc { unsigned long long addr;
/* target btf_id of the corresponding kernel var. */ - int vmlinux_btf_id; + int kernel_btf_obj_fd; + int kernel_btf_id;
/* local btf_id of the ksym extern's type. */ __u32 type_id; @@ -6217,7 +6218,8 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog) } else /* EXT_KSYM */ { if (ext->ksym.type_id) { /* typed ksyms */ insn[0].src_reg = BPF_PSEUDO_BTF_ID; - insn[0].imm = ext->ksym.vmlinux_btf_id; + insn[0].imm = ext->ksym.kernel_btf_id; + insn[1].imm = ext->ksym.kernel_btf_obj_fd; } else { /* typeless ksyms */ insn[0].imm = (__u32)ext->ksym.addr; insn[1].imm = ext->ksym.addr >> 32; @@ -7377,7 +7379,8 @@ static int bpf_object__read_kallsyms_file(struct bpf_object *obj) static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) { struct extern_desc *ext; - int i, id; + struct btf *btf; + int i, j, id, btf_fd, err;
for (i = 0; i < obj->nr_extern; i++) { const struct btf_type *targ_var, *targ_type; @@ -7389,10 +7392,25 @@ static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) if (ext->type != EXT_KSYM || !ext->ksym.type_id) continue;
- id = btf__find_by_name_kind(obj->btf_vmlinux, ext->name, - BTF_KIND_VAR); + btf = obj->btf_vmlinux; + btf_fd = 0; + id = btf__find_by_name_kind(btf, ext->name, BTF_KIND_VAR); + if (id == -ENOENT) { + err = load_module_btfs(obj); + if (err) + return err; + + for (j = 0; j < obj->btf_module_cnt; j++) { + btf = obj->btf_modules[j].btf; + /* we assume module BTF FD is always >0 */ + btf_fd = obj->btf_modules[j].fd; + id = btf__find_by_name_kind(btf, ext->name, BTF_KIND_VAR); + if (id != -ENOENT) + break; + } + } if (id <= 0) { - pr_warn("extern (ksym) '%s': failed to find BTF ID in vmlinux BTF.\n", + pr_warn("extern (ksym) '%s': failed to find BTF ID in kernel BTF(s).\n", ext->name); return -ESRCH; } @@ -7401,24 +7419,19 @@ static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) local_type_id = ext->ksym.type_id;
/* find target type_id */ - targ_var = btf__type_by_id(obj->btf_vmlinux, id); - targ_var_name = btf__name_by_offset(obj->btf_vmlinux, - targ_var->name_off); - targ_type = skip_mods_and_typedefs(obj->btf_vmlinux, - targ_var->type, - &targ_type_id); + targ_var = btf__type_by_id(btf, id); + targ_var_name = btf__name_by_offset(btf, targ_var->name_off); + targ_type = skip_mods_and_typedefs(btf, targ_var->type, &targ_type_id);
ret = bpf_core_types_are_compat(obj->btf, local_type_id, - obj->btf_vmlinux, targ_type_id); + btf, targ_type_id); if (ret <= 0) { const struct btf_type *local_type; const char *targ_name, *local_name;
local_type = btf__type_by_id(obj->btf, local_type_id); - local_name = btf__name_by_offset(obj->btf, - local_type->name_off); - targ_name = btf__name_by_offset(obj->btf_vmlinux, - targ_type->name_off); + local_name = btf__name_by_offset(obj->btf, local_type->name_off); + targ_name = btf__name_by_offset(btf, targ_type->name_off);
pr_warn("extern (ksym) '%s': incompatible types, expected [%d] %s %s, but kernel has [%d] %s %s\n", ext->name, local_type_id, @@ -7428,7 +7441,8 @@ static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) }
ext->is_set = true; - ext->ksym.vmlinux_btf_id = id; + ext->ksym.kernel_btf_obj_fd = btf_fd; + ext->ksym.kernel_btf_id = id; pr_debug("extern (ksym) '%s': resolved to [%d] %s %s\n", ext->name, id, btf_kind_str(targ_var), targ_var_name); }