[PATCH bpf-next v3 8/9] bpf, trace, net: prepare CONFIG_DEBUG_INFO_BTF checks for a tristate

[Jay Wang]

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.

 - "depends on !DEBUG_INFO_BTF" becomes "depends on DEBUG_INFO_BTF=n"
   for RUST and GENDWARFKSYMS: with =m the BTF is generated as with =y,
   so the pahole restrictions they express still apply, but !m is m,
   which a bool option takes as y.

No functional change: CONFIG_DEBUG_INFO_BTF is still a bool, for which
IS_ENABLED() and #ifdef agree, $(subst m,y,y) is y and "=n" is "!".

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 +-
 init/Kconfig                   | 2 +-
 kernel/bpf/Makefile            | 2 +-
 kernel/module/Kconfig          | 2 +-
 kernel/trace/trace_syscalls.c  | 6 +++---
 net/netfilter/Makefile         | 6 +++---
 net/xfrm/Makefile              | 4 ++--
 10 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/Makefile b/Makefile
index 751a08643bf8..f561516e1735 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/init/Kconfig b/init/Kconfig
index 8583d9f06c52..9f9562f813c5 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2257,7 +2257,7 @@ config RUST
 	depends on !MODVERSIONS || GENDWARFKSYMS
 	depends on !GCC_PLUGIN_RANDSTRUCT
 	depends on !RANDSTRUCT
-	depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO)
+	depends on DEBUG_INFO_BTF=n || (PAHOLE_HAS_LANG_EXCLUDE && !LTO)
 	depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
 	select CFI_ICALL_NORMALIZE_INTEGERS if CFI
 	depends on !KASAN || CC_IS_CLANG
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index c1f9b0d3468d..0b7db88f1bed 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/module/Kconfig b/kernel/module/Kconfig
index 43b1bb01fd27..da49cb984b0d 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -197,7 +197,7 @@ config GENDWARFKSYMS
 	# X86, requires pahole before commit 47dcb534e253 ("btf_encoder: Stop
 	# indexing symbols for VARs") or after commit 9810758003ce ("btf_encoder:
 	# Verify 0 address DWARF variables are in ELF section").
-	depends on !X86 || !DEBUG_INFO_BTF || PAHOLE_VERSION < 128 || PAHOLE_VERSION > 129
+	depends on !X86 || DEBUG_INFO_BTF=n || PAHOLE_VERSION < 128 || PAHOLE_VERSION > 129
 	help
 	  Calculate symbol versions from DWARF debugging information using
 	  gendwarfksyms. Requires DEBUG_INFO to be enabled.
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