Commit a835d38d authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Alexei Starovoitov

tools/bpf/runqslower: Fix override option for VMLINUX_BTF

The runqslower tool refuses to build without a file to read vmlinux BTF
from. The build fails with an error message to override the location by
setting the VMLINUX_BTF variable if autodetection fails. However, the
Makefile doesn't actually work with that override - the error message is
still emitted.

Fix this by including the value of VMLINUX_BTF in the expansion, and only
emitting the error message if the *result* is empty. Also permit running
'make clean' even though no VMLINUX_BTF is set.

Fixes: 9c01546d ("tools/bpf: Add runqslower tool to tools/bpf")
Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/157952560237.1683545.17771785178857224877.stgit@toke.dk
parent b2e5e93a
......@@ -10,13 +10,9 @@ CFLAGS := -g -Wall
# Try to detect best kernel BTF source
KERNEL_REL := $(shell uname -r)
ifneq ("$(wildcard /sys/kernel/btf/vmlinux)","")
VMLINUX_BTF := /sys/kernel/btf/vmlinux
else ifneq ("$(wildcard /boot/vmlinux-$(KERNEL_REL))","")
VMLINUX_BTF := /boot/vmlinux-$(KERNEL_REL)
else
$(error "Can't detect kernel BTF, use VMLINUX_BTF to specify it explicitly")
endif
VMLINUX_BTF_PATHS := /sys/kernel/btf/vmlinux /boot/vmlinux-$(KERNEL_REL)
VMLINUX_BTF_PATH := $(or $(VMLINUX_BTF),$(firstword \
$(wildcard $(VMLINUX_BTF_PATHS))))
abs_out := $(abspath $(OUTPUT))
ifeq ($(V),1)
......@@ -67,9 +63,14 @@ $(OUTPUT):
$(call msg,MKDIR,$@)
$(Q)mkdir -p $(OUTPUT)
$(OUTPUT)/vmlinux.h: $(VMLINUX_BTF) | $(OUTPUT) $(BPFTOOL)
$(OUTPUT)/vmlinux.h: $(VMLINUX_BTF_PATH) | $(OUTPUT) $(BPFTOOL)
$(call msg,GEN,$@)
$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
$(Q)if [ ! -e "$(VMLINUX_BTF_PATH)" ] ; then \
echo "Couldn't find kernel BTF; set VMLINUX_BTF to" \
"specify its location." >&2; \
exit 1;\
fi
$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@
$(OUTPUT)/libbpf.a: | $(OUTPUT)
$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) \
......
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