Commit 1ae7a84e authored by Jiayuan Chen's avatar Jiayuan Chen Committed by Alexei Starovoitov
Browse files

bpftool: Add support for custom BTF path in prog load/loadall 



This patch exposes the btf_custom_path feature to bpftool, allowing users
to specify a custom BTF file when loading BPF programs using prog load or
prog loadall commands.

The argument 'btf_custom_path' in libbpf is used for those kernels that
don't have CONFIG_DEBUG_INFO_BTF enabled but still want to perform CO-RE
relocations.

Suggested-by: default avatarQuentin Monnet <qmo@kernel.org>
Reviewed-by: default avatarQuentin Monnet <qmo@kernel.org>
Signed-off-by: default avatarJiayuan Chen <jiayuan.chen@linux.dev>
Link: https://lore.kernel.org/r/20250516144708.298652-1-jiayuan.chen@linux.dev


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 92de53d2

tools/bpf/bpftool/Documentation/bpftool-prog.rst

+8 −2
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ PROG COMMANDS 
| **bpftool** **prog dump xlated** *PROG* [{ **file** *FILE* | [**opcodes**] [**linum**] [**visual**] }]

| **bpftool** **prog dump jited**  *PROG* [{ **file** *FILE* | [**opcodes**] [**linum**] }]

| **bpftool** **prog pin** *PROG* *FILE*

| **bpftool** **prog** { **load** | **loadall** } *OBJ* *PATH* [**type** *TYPE*] [**map** { **idx** *IDX* | **name** *NAME* } *MAP*] [{ **offload_dev** | **xdpmeta_dev** } *NAME*] [**pinmaps** *MAP_DIR*] [**autoattach**]

| **bpftool** **prog** { **load** | **loadall** } *OBJ* *PATH* [**type** *TYPE*] [**map** { **idx** *IDX* | **name** *NAME* } *MAP*] [{ **offload_dev** | **xdpmeta_dev** } *NAME*] [**pinmaps** *MAP_DIR*] [**autoattach**] [**kernel_btf** *BTF_FILE*]

| **bpftool** **prog attach** *PROG* *ATTACH_TYPE* [*MAP*]

| **bpftool** **prog detach** *PROG* *ATTACH_TYPE* [*MAP*]

| **bpftool** **prog tracelog**
@@ -127,7 +127,7 @@ bpftool prog pin *PROG* *FILE* 
    Note: *FILE* must be located in *bpffs* mount. It must not contain a dot

    character ('.'), which is reserved for future extensions of *bpffs*.



bpftool prog { load | loadall } *OBJ* *PATH* [type *TYPE*] [map { idx *IDX* | name *NAME* } *MAP*] [{ offload_dev | xdpmeta_dev } *NAME*] [pinmaps *MAP_DIR*] [autoattach]

bpftool prog { load | loadall } *OBJ* *PATH* [type *TYPE*] [map { idx *IDX* | name *NAME* } *MAP*] [{ offload_dev | xdpmeta_dev } *NAME*] [pinmaps *MAP_DIR*] [autoattach] [kernel_btf *BTF_FILE*]

    Load bpf program(s) from binary *OBJ* and pin as *PATH*. **bpftool prog

    load** pins only the first program from the *OBJ* as *PATH*. **bpftool prog

    loadall** pins all programs from the *OBJ* under *PATH* directory. **type**
@@ -153,6 +153,12 @@ bpftool prog { load | loadall } *OBJ* *PATH* [type *TYPE*] [map { idx *IDX* | na 
    program does not support autoattach, bpftool falls back to regular pinning

    for that program instead.



    The **kernel_btf** option allows specifying an external BTF file to replace

    the system's own vmlinux BTF file for CO-RE relocations. Note that any

    other feature relying on BTF (such as fentry/fexit programs, struct_ops)

    requires the BTF file for the actual kernel running on the host, often

    exposed at /sys/kernel/btf/vmlinux.



    Note: *PATH* must be located in *bpffs* mount. It must not contain a dot

    character ('.'), which is reserved for future extensions of *bpffs*.

tools/bpf/bpftool/bash-completion/bpftool

+2 −2
Original line number Diff line number Diff line
@@ -505,13 +505,13 @@ _bpftool() 
                            _bpftool_get_map_names

                            return 0

                            ;;

                        pinned|pinmaps)

                        pinned|pinmaps|kernel_btf)

                            _filedir

                            return 0

                            ;;

                        *)

                            COMPREPLY=( $( compgen -W "map" -- "$cur" ) )

                            _bpftool_once_attr 'type pinmaps autoattach'

                            _bpftool_once_attr 'type pinmaps autoattach kernel_btf'

                            _bpftool_one_of_list 'offload_dev xdpmeta_dev'

                            return 0

                            ;;

tools/bpf/bpftool/prog.c

+11 −1
Original line number Diff line number Diff line
@@ -1681,8 +1681,17 @@ static int load_with_options(int argc, char **argv, bool first_prog_only) 
		} else if (is_prefix(*argv, "autoattach")) {

			auto_attach = true;

			NEXT_ARG();

		} else if (is_prefix(*argv, "kernel_btf")) {

			NEXT_ARG();



			if (!REQ_ARGS(1))

				goto err_free_reuse_maps;



			open_opts.btf_custom_path = GET_ARG();

		} else {

			p_err("expected no more arguments, 'type', 'map' or 'dev', got: '%s'?",

			p_err("expected no more arguments, "

			      "'type', 'map', 'offload_dev', 'xdpmeta_dev', 'pinmaps', "

			      "'autoattach', or 'kernel_btf', got: '%s'?",

			      *argv);

			goto err_free_reuse_maps;

		}
@@ -2474,6 +2483,7 @@ static int do_help(int argc, char **argv) 
		"                         [map { idx IDX | name NAME } MAP]\\\n"

		"                         [pinmaps MAP_DIR]\n"

		"                         [autoattach]\n"

		"                         [kernel_btf BTF_FILE]\n"

		"       %1$s %2$s attach PROG ATTACH_TYPE [MAP]\n"

		"       %1$s %2$s detach PROG ATTACH_TYPE [MAP]\n"

		"       %1$s %2$s run PROG \\\n"