[PATCH v2 06/11] kernel: backport build fix for tools/resolve_btfids

[Stijn Tintel]

Building tools/resolve_btfids requires libelf and zlib. Without this
build fix, the kernel build system will not find these dependencies.

Signed-off-by: Stijn Tintel <stijn at linux-ipv6.be>
---
 ...resolve_btfids-Build-with-host-flags.patch | 54 +++++++++++++++++++
 ...resolve_btfids-Build-with-host-flags.patch | 54 +++++++++++++++++++
 2 files changed, 108 insertions(+)
 create mode 100644 target/linux/generic/backport-5.10/200-v5.18-tools-resolve_btfids-Build-with-host-flags.patch
 create mode 100644 target/linux/generic/backport-5.15/200-v5.18-tools-resolve_btfids-Build-with-host-flags.patch

diff --git a/target/linux/generic/backport-5.10/200-v5.18-tools-resolve_btfids-Build-with-host-flags.patch b/target/linux/generic/backport-5.10/200-v5.18-tools-resolve_btfids-Build-with-host-flags.patch
new file mode 100644
index 0000000000..489575fb35
--- /dev/null
+++ b/target/linux/generic/backport-5.10/200-v5.18-tools-resolve_btfids-Build-with-host-flags.patch
@@ -0,0 +1,54 @@
+From cdbc4e3399ed8cdcf234a85f7a2482b622379e82 Mon Sep 17 00:00:00 2001
+From: Connor O'Brien <connoro at google.com>
+Date: Wed, 12 Jan 2022 00:25:03 +0000
+Subject: [PATCH] tools/resolve_btfids: Build with host flags
+
+resolve_btfids is built using $(HOSTCC) and $(HOSTLD) but does not
+pick up the corresponding flags. As a result, host-specific settings
+(such as a sysroot specified via HOSTCFLAGS=--sysroot=..., or a linker
+specified via HOSTLDFLAGS=-fuse-ld=...) will not be respected.
+
+Fix this by setting CFLAGS to KBUILD_HOSTCFLAGS and LDFLAGS to
+KBUILD_HOSTLDFLAGS.
+
+Also pass the cflags through to libbpf via EXTRA_CFLAGS to ensure that
+the host libbpf is built with flags consistent with resolve_btfids.
+
+Signed-off-by: Connor O'Brien <connoro at google.com>
+Signed-off-by: Andrii Nakryiko <andrii at kernel.org>
+Acked-by: Song Liu <songliubraving at fb.com>
+Link: https://lore.kernel.org/bpf/20220112002503.115968-1-connoro@google.com
+(cherry picked from commit 0e3a1c902ffb56e9fe4416f0cd382c97b09ecbf6)
+Signed-off-by: Stijn Tintel <stijn at linux-ipv6.be>
+---
+ tools/bpf/resolve_btfids/Makefile | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
+index af9f9d3534c9..e727058bfe15 100644
+--- a/tools/bpf/resolve_btfids/Makefile
++++ b/tools/bpf/resolve_btfids/Makefile
+@@ -23,6 +23,8 @@ CC       = $(HOSTCC)
+ LD       = $(HOSTLD)
+ ARCH     = $(HOSTARCH)
+ RM      ?= rm
++CFLAGS  := $(KBUILD_HOSTCFLAGS)
++LDFLAGS := $(KBUILD_HOSTLDFLAGS)
+ 
+ OUTPUT ?= $(srctree)/tools/bpf/resolve_btfids/
+ 
+@@ -45,9 +47,9 @@ $(SUBCMDOBJ): fixdep FORCE | $(OUTPUT)/libsubcmd
+ 	$(Q)$(MAKE) -C $(SUBCMD_SRC) OUTPUT=$(abspath $(dir $@))/ $(abspath $@)
+ 
+ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(OUTPUT)/libbpf
+-	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC)  OUTPUT=$(abspath $(dir $@))/ $(abspath $@)
++	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC)  OUTPUT=$(abspath $(dir $@))/ EXTRA_CFLAGS="$(CFLAGS)" $(abspath $@)
+ 
+-CFLAGS := -g \
++CFLAGS += -g \
+           -I$(srctree)/tools/include \
+           -I$(srctree)/tools/include/uapi \
+           -I$(LIBBPF_SRC) \
+-- 
+2.35.1
+
diff --git a/target/linux/generic/backport-5.15/200-v5.18-tools-resolve_btfids-Build-with-host-flags.patch b/target/linux/generic/backport-5.15/200-v5.18-tools-resolve_btfids-Build-with-host-flags.patch
new file mode 100644
index 0000000000..489575fb35
--- /dev/null
+++ b/target/linux/generic/backport-5.15/200-v5.18-tools-resolve_btfids-Build-with-host-flags.patch
@@ -0,0 +1,54 @@
+From cdbc4e3399ed8cdcf234a85f7a2482b622379e82 Mon Sep 17 00:00:00 2001
+From: Connor O'Brien <connoro at google.com>
+Date: Wed, 12 Jan 2022 00:25:03 +0000
+Subject: [PATCH] tools/resolve_btfids: Build with host flags
+
+resolve_btfids is built using $(HOSTCC) and $(HOSTLD) but does not
+pick up the corresponding flags. As a result, host-specific settings
+(such as a sysroot specified via HOSTCFLAGS=--sysroot=..., or a linker
+specified via HOSTLDFLAGS=-fuse-ld=...) will not be respected.
+
+Fix this by setting CFLAGS to KBUILD_HOSTCFLAGS and LDFLAGS to
+KBUILD_HOSTLDFLAGS.
+
+Also pass the cflags through to libbpf via EXTRA_CFLAGS to ensure that
+the host libbpf is built with flags consistent with resolve_btfids.
+
+Signed-off-by: Connor O'Brien <connoro at google.com>
+Signed-off-by: Andrii Nakryiko <andrii at kernel.org>
+Acked-by: Song Liu <songliubraving at fb.com>
+Link: https://lore.kernel.org/bpf/20220112002503.115968-1-connoro@google.com
+(cherry picked from commit 0e3a1c902ffb56e9fe4416f0cd382c97b09ecbf6)
+Signed-off-by: Stijn Tintel <stijn at linux-ipv6.be>
+---
+ tools/bpf/resolve_btfids/Makefile | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
+index af9f9d3534c9..e727058bfe15 100644
+--- a/tools/bpf/resolve_btfids/Makefile
++++ b/tools/bpf/resolve_btfids/Makefile
+@@ -23,6 +23,8 @@ CC       = $(HOSTCC)
+ LD       = $(HOSTLD)
+ ARCH     = $(HOSTARCH)
+ RM      ?= rm
++CFLAGS  := $(KBUILD_HOSTCFLAGS)
++LDFLAGS := $(KBUILD_HOSTLDFLAGS)
+ 
+ OUTPUT ?= $(srctree)/tools/bpf/resolve_btfids/
+ 
+@@ -45,9 +47,9 @@ $(SUBCMDOBJ): fixdep FORCE | $(OUTPUT)/libsubcmd
+ 	$(Q)$(MAKE) -C $(SUBCMD_SRC) OUTPUT=$(abspath $(dir $@))/ $(abspath $@)
+ 
+ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(OUTPUT)/libbpf
+-	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC)  OUTPUT=$(abspath $(dir $@))/ $(abspath $@)
++	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC)  OUTPUT=$(abspath $(dir $@))/ EXTRA_CFLAGS="$(CFLAGS)" $(abspath $@)
+ 
+-CFLAGS := -g \
++CFLAGS += -g \
+           -I$(srctree)/tools/include \
+           -I$(srctree)/tools/include/uapi \
+           -I$(LIBBPF_SRC) \
+-- 
+2.35.1
+
-- 
2.35.1