[PATCH AUTOSEL 5.5 438/542] bpf, btf: Always output invariant hit in pahole DWARF to BTF transform

[Sasha Levin]

From: Chris Down <chris@xxxxxxxxxxxxxx>

[ Upstream commit 2a67a6ccb01f21b854715d86ff6432a18b97adb3 ]

When trying to compile with CONFIG_DEBUG_INFO_BTF enabled, I got this
error:

    % make -s
    Failed to generate BTF for vmlinux
    Try to disable CONFIG_DEBUG_INFO_BTF
    make[3]: *** [vmlinux] Error 1

Compiling again without -s shows the true error (that pahole is
missing), but since this is fatal, we should show the error
unconditionally on stderr as well, not silence it using the `info`
function. With this patch:

    % make -s
    BTF: .tmp_vmlinux.btf: pahole (pahole) is not available
    Failed to generate BTF for vmlinux
    Try to disable CONFIG_DEBUG_INFO_BTF
    make[3]: *** [vmlinux] Error 1

Signed-off-by: Chris Down <chris@xxxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
Link: https://lore.kernel.org/bpf/20200122000110.GA310073@xxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 scripts/link-vmlinux.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 4363799403561..408b5c0b99b1b 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -108,13 +108,13 @@ gen_btf()
 	local bin_arch
 
 	if ! [ -x "$(command -v ${PAHOLE})" ]; then
-		info "BTF" "${1}: pahole (${PAHOLE}) is not available"
+		echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
 		return 1
 	fi
 
 	pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 	if [ "${pahole_ver}" -lt "113" ]; then
-		info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
+		echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
 		return 1
 	fi
 
-- 
2.20.1