[PATCH bpf-next v2 8/9] bpf, trace, net: prepare CONFIG_DEBUG_INFO_BTF checks for a tristate
From: Jay Wang
Date: Fri Sep 25 2026 - 17:18:54 EST
The next patch makes CONFIG_DEBUG_INFO_BTF a tristate. With =m, Kconfig
defines CONFIG_DEBUG_INFO_BTF_MODULE instead of CONFIG_DEBUG_INFO_BTF,
so every check that must hold for both =y and =m has to be written for
it:
- #ifdef CONFIG_DEBUG_INFO_BTF becomes #if IS_ENABLED(...) where the
generated BTF and its id tables must be the same for =y and =m: the
.BTF_ids tables (btf_ids.h), the BTF type tags (compiler_types.h), and
the tracepoint and syscall BTF ids (trace_events.h, trace_syscalls.c).
Leaving them would silently produce empty id sets with =m.
- obj-$(CONFIG_DEBUG_INFO_BTF) and include-$(CONFIG_DEBUG_INFO_BTF)
become $(subst m,y,...) where the object is built into the kernel
regardless: sysfs_btf.o, the netfilter and xfrm kfunc objects, and
scripts/Makefile.btf. Otherwise =m would try to build them as
modules (xfrm_state_bpf.o fails modpost for lack of MODULE_LICENSE)
or skip the BTF generation flags.
No functional change: CONFIG_DEBUG_INFO_BTF is still a bool, for which
IS_ENABLED() and #ifdef agree and $(subst m,y,y) is y.
Signed-off-by: Jay Wang <wanjay@xxxxxxxxxx>
---
Makefile | 3 ++-
include/linux/btf_ids.h | 2 +-
include/linux/compiler_types.h | 2 +-
include/trace/trace_events.h | 2 +-
kernel/bpf/Makefile | 2 +-
kernel/trace/trace_syscalls.c | 6 +++---
net/netfilter/Makefile | 6 +++---
net/xfrm/Makefile | 4 ++--
8 files changed, 14 insertions(+), 13 deletions(-)
diff --git a/Makefile b/Makefile
index 66654fa71655..3a1b4a8fb424 100644
--- a/Makefile
+++ b/Makefile
@@ -1208,7 +1208,8 @@ endif
# include additional Makefiles when needed
include-y := scripts/Makefile.warn
include-$(CONFIG_DEBUG_INFO) += scripts/Makefile.debug
-include-$(CONFIG_DEBUG_INFO_BTF)+= scripts/Makefile.btf
+# CONFIG_DEBUG_INFO_BTF is a tristate; BTF is generated for both y and m
+include-$(subst m,y,$(CONFIG_DEBUG_INFO_BTF)) += scripts/Makefile.btf
include-$(CONFIG_KASAN) += scripts/Makefile.kasan
include-$(CONFIG_KCSAN) += scripts/Makefile.kcsan
include-$(CONFIG_KMSAN) += scripts/Makefile.kmsan
diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
index 8b5a9ee92513..c665afff100e 100644
--- a/include/linux/btf_ids.h
+++ b/include/linux/btf_ids.h
@@ -22,7 +22,7 @@ struct btf_id_set8 {
} pairs[];
};
-#ifdef CONFIG_DEBUG_INFO_BTF
+#if IS_ENABLED(CONFIG_DEBUG_INFO_BTF)
#include <linux/compiler.h> /* for __PASTE */
#include <linux/compiler_attributes.h> /* for __maybe_unused */
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index c5921f139007..a90a99849cee 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -34,7 +34,7 @@
* Skipped when running bindgen due to a libclang issue;
* see https://github.com/rust-lang/rust-bindgen/issues/2244.
*/
-#if defined(CONFIG_DEBUG_INFO_BTF) && defined(CONFIG_PAHOLE_HAS_BTF_TAG) && \
+#if IS_ENABLED(CONFIG_DEBUG_INFO_BTF) && defined(CONFIG_PAHOLE_HAS_BTF_TAG) && \
__has_attribute(btf_type_tag) && !defined(__BINDGEN__)
# define BTF_TYPE_TAG(value) __attribute__((btf_type_tag(#value)))
#else
diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h
index 93011f800d0f..2a0098929771 100644
--- a/include/trace/trace_events.h
+++ b/include/trace/trace_events.h
@@ -398,7 +398,7 @@ static inline notrace int trace_event_get_offsets_##call( \
#define _TRACE_PERF_INIT(call)
#endif /* CONFIG_PERF_EVENTS */
-#if defined(CONFIG_BPF_EVENTS) && defined(CONFIG_DEBUG_INFO_BTF)
+#if defined(CONFIG_BPF_EVENTS) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)
/*
* Per-template BTF id list, populated at link time by resolve_btfids:
* [0] FUNC __bpf_trace_<call> (the BPF dispatcher)
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index 9a92c348bbda..7d745b602b80 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -41,7 +41,7 @@ ifeq ($(CONFIG_INET),y)
obj-$(CONFIG_BPF_SYSCALL) += reuseport_array.o
endif
ifeq ($(CONFIG_SYSFS),y)
-obj-$(CONFIG_DEBUG_INFO_BTF) += sysfs_btf.o
+obj-$(subst m,y,$(CONFIG_DEBUG_INFO_BTF)) += sysfs_btf.o
endif
ifeq ($(CONFIG_BPF_JIT),y)
obj-$(CONFIG_BPF_SYSCALL) += bpf_struct_ops.o
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index e35744049e3f..7a0d59c308c2 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -1304,7 +1304,7 @@ struct trace_event_functions exit_syscall_print_funcs = {
.trace = print_syscall_exit,
};
-#if defined(CONFIG_BPF_EVENTS) && defined(CONFIG_DEBUG_INFO_BTF)
+#if defined(CONFIG_BPF_EVENTS) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)
/* BTF id lists for the shared sys_enter/sys_exit dispatcher tracepoints. */
BTF_ID_LIST(syscall_enter_btf_ids)
BTF_ID(func, __bpf_trace_sys_enter)
@@ -1321,7 +1321,7 @@ struct trace_event_class __refdata event_class_syscall_enter = {
.fields_array = syscall_enter_fields_array,
.get_fields = syscall_get_enter_fields,
.raw_init = init_syscall_trace,
-#if defined(CONFIG_BPF_EVENTS) && defined(CONFIG_DEBUG_INFO_BTF)
+#if defined(CONFIG_BPF_EVENTS) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)
.btf_ids = syscall_enter_btf_ids,
#endif
};
@@ -1336,7 +1336,7 @@ struct trace_event_class __refdata event_class_syscall_exit = {
},
.fields = LIST_HEAD_INIT(event_class_syscall_exit.fields),
.raw_init = init_syscall_trace,
-#if defined(CONFIG_BPF_EVENTS) && defined(CONFIG_DEBUG_INFO_BTF)
+#if defined(CONFIG_BPF_EVENTS) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)
.btf_ids = syscall_exit_btf_ids,
#endif
};
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 6bf74d488a29..a2c7f00794d2 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -18,7 +18,7 @@ nf_conntrack-$(CONFIG_NF_CT_PROTO_GRE) += nf_conntrack_proto_gre.o
ifeq ($(CONFIG_NF_CONNTRACK),m)
nf_conntrack-$(CONFIG_DEBUG_INFO_BTF_MODULES) += nf_conntrack_bpf.o
else ifeq ($(CONFIG_NF_CONNTRACK),y)
-nf_conntrack-$(CONFIG_DEBUG_INFO_BTF) += nf_conntrack_bpf.o
+nf_conntrack-$(subst m,y,$(CONFIG_DEBUG_INFO_BTF)) += nf_conntrack_bpf.o
endif
obj-$(CONFIG_NETFILTER) = netfilter.o
@@ -65,7 +65,7 @@ nf_nat-$(CONFIG_NF_NAT_OVS) += nf_nat_ovs.o
ifeq ($(CONFIG_NF_NAT),m)
nf_nat-$(CONFIG_DEBUG_INFO_BTF_MODULES) += nf_nat_bpf.o
else ifeq ($(CONFIG_NF_NAT),y)
-nf_nat-$(CONFIG_DEBUG_INFO_BTF) += nf_nat_bpf.o
+nf_nat-$(subst m,y,$(CONFIG_DEBUG_INFO_BTF)) += nf_nat_bpf.o
endif
# NAT helpers
@@ -147,7 +147,7 @@ nf_flow_table-$(CONFIG_NF_FLOW_TABLE_PROCFS) += nf_flow_table_procfs.o
ifeq ($(CONFIG_NF_FLOW_TABLE),m)
nf_flow_table-$(CONFIG_DEBUG_INFO_BTF_MODULES) += nf_flow_table_bpf.o
else ifeq ($(CONFIG_NF_FLOW_TABLE),y)
-nf_flow_table-$(CONFIG_DEBUG_INFO_BTF) += nf_flow_table_bpf.o
+nf_flow_table-$(subst m,y,$(CONFIG_DEBUG_INFO_BTF)) += nf_flow_table_bpf.o
endif
obj-$(CONFIG_NF_FLOW_TABLE_INET) += nf_flow_table_inet.o
diff --git a/net/xfrm/Makefile b/net/xfrm/Makefile
index 5a1787587cb3..b7f6e5046a0e 100644
--- a/net/xfrm/Makefile
+++ b/net/xfrm/Makefile
@@ -8,7 +8,7 @@ xfrm_interface-$(CONFIG_XFRM_INTERFACE) += xfrm_interface_core.o
ifeq ($(CONFIG_XFRM_INTERFACE),m)
xfrm_interface-$(CONFIG_DEBUG_INFO_BTF_MODULES) += xfrm_interface_bpf.o
else ifeq ($(CONFIG_XFRM_INTERFACE),y)
-xfrm_interface-$(CONFIG_DEBUG_INFO_BTF) += xfrm_interface_bpf.o
+xfrm_interface-$(subst m,y,$(CONFIG_DEBUG_INFO_BTF)) += xfrm_interface_bpf.o
endif
obj-$(CONFIG_XFRM) := xfrm_policy.o xfrm_state.o xfrm_hash.o \
@@ -23,4 +23,4 @@ obj-$(CONFIG_XFRM_IPCOMP) += xfrm_ipcomp.o
obj-$(CONFIG_XFRM_INTERFACE) += xfrm_interface.o
obj-$(CONFIG_XFRM_IPTFS) += xfrm_iptfs.o
obj-$(CONFIG_XFRM_ESPINTCP) += espintcp.o
-obj-$(CONFIG_DEBUG_INFO_BTF) += xfrm_state_bpf.o
+obj-$(subst m,y,$(CONFIG_DEBUG_INFO_BTF)) += xfrm_state_bpf.o
--
2.47.3