Modify the automatic generator of the light skeleton by adding three calls to bpf_preload_set_ops() for registering and unregistering a preload method, two in load_skel() (set and unset if there is an error) and one in free_objs_and_skel().
Regenerate the light skeleton of the already preloaded eBPF program iterators_bpf, which will now use the new registration method, and directly call load_skel() and free_objs_and_skel() in the init and fini module entrypoints.
Finally, allow users to specify a customized list of eBPF programs to preload with the CONFIG_BPF_PRELOAD_LIST option in the kernel configuration, at build time, or with new kernel option bpf_preload_list=, at run-time.
By default, set CONFIG_BPF_PRELOAD_LIST to 'bpf_preload', so that the current preloading behavior is kept unchanged.
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- .../admin-guide/kernel-parameters.txt | 8 ++++++ kernel/bpf/inode.c | 16 ++++++++++-- kernel/bpf/preload/Kconfig | 25 +++++++++++++------ kernel/bpf/preload/bpf_preload_kern.c | 20 ++------------- .../bpf/preload/iterators/iterators.lskel.h | 9 +++++-- tools/bpf/bpftool/gen.c | 15 ++++++++--- 6 files changed, 60 insertions(+), 33 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 9927564db88e..732d83764e6e 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -482,6 +482,14 @@ bgrt_disable [ACPI][X86] Disable BGRT to avoid flickering OEM logo.
+ bpf_preload_list= [BPF] + Specify a list of eBPF programs to preload. + Format: obj_name1,obj_name2,... + Default: bpf_preload + + Specify the list of eBPF programs to preload when the + bpf filesystem is mounted. + bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) bttv.radio= Most important insmod options are available as kernel args too. diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 619cdef0ba54..c1941c65ce95 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -22,7 +22,14 @@ #include <linux/bpf_trace.h> #include <linux/bpf_preload.h>
-static char *bpf_preload_list_str; +static char *bpf_preload_list_str = CONFIG_BPF_PRELOAD_LIST; + +static int __init bpf_preload_list_setup(char *str) +{ + bpf_preload_list_str = str; + return 1; +} +__setup("bpf_preload_list=", bpf_preload_list_setup);
static void *bpf_any_get(void *raw, enum bpf_type type) { @@ -732,7 +739,12 @@ static bool bpf_preload_list_mod_get(void) struct bpf_preload_ops_item *cur; bool ret = false;
- ret |= bpf_preload_mod_get("bpf_preload", &bpf_preload_ops); + /* + * Keep the legacy registration method, but do not attempt to load + * bpf_preload.ko, as it switched to the new registration method. + */ + if (bpf_preload_ops) + ret |= bpf_preload_mod_get("bpf_preload", &bpf_preload_ops);
list_for_each_entry(cur, &preload_list, list) ret |= bpf_preload_mod_get(cur->obj_name, &cur->ops); diff --git a/kernel/bpf/preload/Kconfig b/kernel/bpf/preload/Kconfig index c9d45c9d6918..f878e537b0ff 100644 --- a/kernel/bpf/preload/Kconfig +++ b/kernel/bpf/preload/Kconfig @@ -4,7 +4,7 @@ config USERMODE_DRIVER default n
menuconfig BPF_PRELOAD - bool "Preload BPF file system with kernel specific program and map iterators" + bool "Preload eBPF programs" depends on BPF depends on BPF_SYSCALL # The dependency on !COMPILE_TEST prevents it from being enabled @@ -12,15 +12,26 @@ menuconfig BPF_PRELOAD depends on !COMPILE_TEST select USERMODE_DRIVER help - This builds kernel module with several embedded BPF programs that are - pinned into BPF FS mount point as human readable files that are - useful in debugging and introspection of BPF programs and maps. + This enables preloading eBPF programs chosen from the kernel + configuration or from the kernel option bpf_preload_list=.
if BPF_PRELOAD config BPF_PRELOAD_UMD - tristate "bpf_preload kernel module" + tristate "Preload BPF file system with kernel specific program and map iterators" default m help - This builds bpf_preload kernel module with embedded BPF programs for - introspection in bpffs. + This builds bpf_preload kernel module with several embedded BPF + programs that are pinned into BPF FS mount point as human readable + files that are useful in debugging and introspection of BPF programs + and maps. + +config BPF_PRELOAD_LIST + string "Ordered list of eBPF programs to preload" + default "bpf_preload" + help + A comma-separated list of eBPF programs to preload. Any eBPF program + left off this list will be ignored. This can be controlled at boot + with the "bpf_preload_list=" parameter. + + If unsure, leave this as the default. endif diff --git a/kernel/bpf/preload/bpf_preload_kern.c b/kernel/bpf/preload/bpf_preload_kern.c index 3839af367200..c6d97872225b 100644 --- a/kernel/bpf/preload/bpf_preload_kern.c +++ b/kernel/bpf/preload/bpf_preload_kern.c @@ -5,22 +5,6 @@ #include <linux/bpf_preload.h> #include "iterators/iterators.lskel.h"
-static int __init load(void) -{ - int err; - - err = load_skel(); - if (err) - return err; - bpf_preload_ops = &ops; - return err; -} - -static void __exit fini(void) -{ - bpf_preload_ops = NULL; - free_objs_and_skel(); -} -late_initcall(load); -module_exit(fini); +late_initcall(load_skel); +module_exit(free_objs_and_skel); MODULE_LICENSE("GPL"); diff --git a/kernel/bpf/preload/iterators/iterators.lskel.h b/kernel/bpf/preload/iterators/iterators.lskel.h index 7595fc283a65..5e999564cc7a 100644 --- a/kernel/bpf/preload/iterators/iterators.lskel.h +++ b/kernel/bpf/preload/iterators/iterators.lskel.h @@ -440,6 +440,8 @@ static struct iterators_bpf *skel;
static void free_objs_and_skel(void) { + bpf_preload_set_ops("bpf_preload", THIS_MODULE, NULL); + if (!IS_ERR_OR_NULL(dump_bpf_map_link)) bpf_link_put(dump_bpf_map_link); if (!IS_ERR_OR_NULL(dump_bpf_prog_link)) @@ -481,11 +483,14 @@ static struct bpf_preload_ops ops = {
static int load_skel(void) { - int err; + int err = -ENOMEM; + + if (!bpf_preload_set_ops("bpf_preload", THIS_MODULE, &ops)) + return 0;
skel = iterators_bpf__open(); if (!skel) - return -ENOMEM; + goto out;
err = iterators_bpf__load(skel); if (err) diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index 5593cbee1846..af939183f57a 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -700,7 +700,10 @@ static void codegen_preload_free(struct bpf_object *obj, const char *obj_name) \n\ static void free_objs_and_skel(void) \n\ { \n\ - "); + bpf_preload_set_ops("%s", THIS_MODULE, NULL); \n\ + \n\ + ", !strcmp(obj_name, "iterators_bpf") ? + "bpf_preload" : obj_name);
bpf_object__for_each_program(prog, obj) { codegen("\ @@ -864,11 +867,14 @@ static void codegen_preload_load(struct bpf_object *obj, const char *obj_name) \n\ static int load_skel(void) \n\ { \n\ - int err; \n\ + int err = -ENOMEM; \n\ + \n\ + if (!bpf_preload_set_ops("%2$s", THIS_MODULE, &ops)) \n\ + return 0; \n\ \n\ skel = %1$s__open(); \n\ if (!skel) \n\ - return -ENOMEM; \n\ + goto out; \n\ \n\ err = %1$s__load(skel); \n\ if (err) \n\ @@ -877,7 +883,8 @@ static void codegen_preload_load(struct bpf_object *obj, const char *obj_name) err = %1$s__attach(skel); \n\ if (err) \n\ goto out; \n\ - ", obj_name); + ", obj_name, !strcmp(obj_name, "iterators_bpf") ? + "bpf_preload" : obj_name);
bpf_object__for_each_program(prog, obj) { codegen("\