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authorKumar Kartikeya Dwivedi <memxor@gmail.com>2021-11-22 20:17:40 +0530
committerAndrii Nakryiko <andrii@kernel.org>2021-12-02 13:39:46 -0800
commitd9847eb8be3d895b2b5f514fdf3885d47a0b92a2 (patch)
tree7265378e4f5c2cb960c01afc816f15de93b66d12
parent099f83aa2d06680d5987e43fed1afeda14b5037e (diff)
bpf: Make CONFIG_DEBUG_INFO_BTF depend upon CONFIG_BPF_SYSCALL
Vinicius Costa Gomes reported [0] that build fails when CONFIG_DEBUG_INFO_BTF is enabled and CONFIG_BPF_SYSCALL is disabled. This leads to btf.c not being compiled, and then no symbol being present in vmlinux for the declarations in btf.h. Since BTF is not useful without enabling BPF subsystem, disallow this combination. However, theoretically disabling both now could still fail, as the symbol for kfunc_btf_id_list variables is not available. This isn't a problem as the compiler usually optimizes the whole register/unregister call, but at lower optimization levels it can fail the build in linking stage. Fix that by adding dummy variables so that modules taking address of them still work, but the whole thing is a noop. [0]: https://lore.kernel.org/bpf/20211110205418.332403-1-vinicius.gomes@intel.com Fixes: 14f267d95fe4 ("bpf: btf: Introduce helpers for dynamic BTF set registration") Reported-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211122144742.477787-2-memxor@gmail.com
-rw-r--r--include/linux/btf.h14
-rw-r--r--kernel/bpf/btf.c9
-rw-r--r--lib/Kconfig.debug1
3 files changed, 13 insertions, 11 deletions
diff --git a/include/linux/btf.h b/include/linux/btf.h
index 203eef993d76..0e1b6281fd8f 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -245,7 +245,10 @@ struct kfunc_btf_id_set {
struct module *owner;
};
-struct kfunc_btf_id_list;
+struct kfunc_btf_id_list {
+ struct list_head list;
+ struct mutex mutex;
+};
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
void register_kfunc_btf_id_set(struct kfunc_btf_id_list *l,
@@ -254,6 +257,9 @@ void unregister_kfunc_btf_id_set(struct kfunc_btf_id_list *l,
struct kfunc_btf_id_set *s);
bool bpf_check_mod_kfunc_call(struct kfunc_btf_id_list *klist, u32 kfunc_id,
struct module *owner);
+
+extern struct kfunc_btf_id_list bpf_tcp_ca_kfunc_list;
+extern struct kfunc_btf_id_list prog_test_kfunc_list;
#else
static inline void register_kfunc_btf_id_set(struct kfunc_btf_id_list *l,
struct kfunc_btf_id_set *s)
@@ -268,13 +274,13 @@ static inline bool bpf_check_mod_kfunc_call(struct kfunc_btf_id_list *klist,
{
return false;
}
+
+static struct kfunc_btf_id_list bpf_tcp_ca_kfunc_list __maybe_unused;
+static struct kfunc_btf_id_list prog_test_kfunc_list __maybe_unused;
#endif
#define DEFINE_KFUNC_BTF_ID_SET(set, name) \
struct kfunc_btf_id_set name = { LIST_HEAD_INIT(name.list), (set), \
THIS_MODULE }
-extern struct kfunc_btf_id_list bpf_tcp_ca_kfunc_list;
-extern struct kfunc_btf_id_list prog_test_kfunc_list;
-
#endif
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index dbc3ad07e21b..ea3df9867cec 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6346,11 +6346,6 @@ BTF_ID_LIST_GLOBAL_SINGLE(btf_task_struct_ids, struct, task_struct)
/* BTF ID set registration API for modules */
-struct kfunc_btf_id_list {
- struct list_head list;
- struct mutex mutex;
-};
-
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
void register_kfunc_btf_id_set(struct kfunc_btf_id_list *l,
@@ -6389,8 +6384,6 @@ bool bpf_check_mod_kfunc_call(struct kfunc_btf_id_list *klist, u32 kfunc_id,
return false;
}
-#endif
-
#define DEFINE_KFUNC_BTF_ID_LIST(name) \
struct kfunc_btf_id_list name = { LIST_HEAD_INIT(name.list), \
__MUTEX_INITIALIZER(name.mutex) }; \
@@ -6398,3 +6391,5 @@ bool bpf_check_mod_kfunc_call(struct kfunc_btf_id_list *klist, u32 kfunc_id,
DEFINE_KFUNC_BTF_ID_LIST(bpf_tcp_ca_kfunc_list);
DEFINE_KFUNC_BTF_ID_LIST(prog_test_kfunc_list);
+
+#endif
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 9ef7ce18b4f5..596bb5e4790c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -316,6 +316,7 @@ config DEBUG_INFO_BTF
bool "Generate BTF typeinfo"
depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
+ depends on BPF_SYSCALL
help
Generate deduplicated BTF type information from DWARF debug info.
Turning this on expects presence of pahole tool, which will convert