In preparation to support preloading multiple eBPF programs, define a linked list of bpf_preload_ops_item structures. The new structure contains the object name from the eBPF program to preload (except for iterators_bpf whose kernel module name is bpf_preload, the object name and the kernel module name should match).
The new structure also contains a bpf_preload_ops structure declared in the light skeleton, with the preload method of the eBPF program.
The list of eBPF programs that can be preloaded can be specified in a subsequent patch from the kernel configuration or with the new option bpf_preload_list= in the kernel command line.
For now, bpf_preload is always preloaded, as it still relies on the old registration method consisting in setting the bpf_preload_ops global variable. That will change when bpf_preload will switch to the new registration method based on the linked list.
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- kernel/bpf/inode.c | 89 +++++++++++++++++++++++++++++++++++++--------- 1 file changed, 73 insertions(+), 16 deletions(-)
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index bb8762abbf3d..0a6e83d32360 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -685,35 +685,91 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) struct bpf_preload_ops *bpf_preload_ops; EXPORT_SYMBOL_GPL(bpf_preload_ops);
-static bool bpf_preload_mod_get(void) +struct bpf_preload_ops_item { + struct list_head list; + struct bpf_preload_ops *ops; + char *obj_name; +}; + +static LIST_HEAD(preload_list); +static DEFINE_MUTEX(bpf_preload_lock); + +static bool bpf_preload_mod_get(const char *obj_name, + struct bpf_preload_ops **ops) { - /* If bpf_preload.ko wasn't loaded earlier then load it now. - * When bpf_preload is built into vmlinux the module's __init + /* If the kernel preload module wasn't loaded earlier then load it now. + * When the preload code is built into vmlinux the module's __init * function will populate it. */ - if (!bpf_preload_ops) { - request_module("bpf_preload"); - if (!bpf_preload_ops) + if (!*ops) { + mutex_unlock(&bpf_preload_lock); + request_module(obj_name); + mutex_lock(&bpf_preload_lock); + if (!*ops) return false; } /* And grab the reference, so the module doesn't disappear while the * kernel is interacting with the kernel module and its UMD. */ - if (!try_module_get(bpf_preload_ops->owner)) { + if (!try_module_get((*ops)->owner)) { pr_err("bpf_preload module get failed.\n"); return false; } return true; }
-static void bpf_preload_mod_put(void) +static void bpf_preload_mod_put(struct bpf_preload_ops *ops) { - if (bpf_preload_ops) - /* now user can "rmmod bpf_preload" if necessary */ - module_put(bpf_preload_ops->owner); + if (ops) + /* now user can "rmmod <kernel module>" if necessary */ + module_put(ops->owner); }
-static DEFINE_MUTEX(bpf_preload_lock); +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); + + list_for_each_entry(cur, &preload_list, list) + ret |= bpf_preload_mod_get(cur->obj_name, &cur->ops); + + return ret; +} + +static int bpf_preload_list(struct dentry *parent) +{ + struct bpf_preload_ops_item *cur; + int err; + + if (bpf_preload_ops) { + err = bpf_preload_ops->preload(parent); + if (err) + return err; + } + + list_for_each_entry(cur, &preload_list, list) { + if (!cur->ops) + continue; + + err = cur->ops->preload(parent); + if (err) + return err; + } + + return 0; +} + +static void bpf_preload_list_mod_put(void) +{ + struct bpf_preload_ops_item *cur; + + list_for_each_entry(cur, &preload_list, list) + bpf_preload_mod_put(cur->ops); + + bpf_preload_mod_put(bpf_preload_ops); +}
static int populate_bpffs(struct dentry *parent) { @@ -724,12 +780,13 @@ static int populate_bpffs(struct dentry *parent) */ mutex_lock(&bpf_preload_lock);
- /* if bpf_preload.ko wasn't built into vmlinux then load it */ - if (!bpf_preload_mod_get()) + /* if kernel preload mods weren't built into vmlinux then load them */ + if (!bpf_preload_list_mod_get()) goto out;
- err = bpf_preload_ops->preload(parent); - bpf_preload_mod_put(); + err = bpf_preload_list(parent); + bpf_preload_list_mod_put(); + out: mutex_unlock(&bpf_preload_lock); return err;