The verification signature header generation requires converting a
binary certificate to a C array. Previously this only worked with xxd,
and a switch to hexdump has been done in commit b640d556a2b3
("selftests/bpf: Remove xxd util dependency").
hexdump is a more common utility program, yet it might not be installed
by default. When it is not installed, BPF selftests build without
errors, but tests_progs is unusable: it exits with the 255 code and
without any error messages. When manually reproducing the issue, it is
not too hard to find out that the generated verification_cert.h file is
incorrect, but that's time consuming. When digging the BPF selftests
build logs, this line can be seen amongst thousands others, but ignored:
/bin/sh: 2: hexdump: not found
Here, od is used with awk, instead of hexdump with sed. od is coming
from the core utils package, and this new od command produces the same
output when using od from GNU coreutils, uutils, and even busybox. This
is more portable, and it produces the same results as what was done
before with hexdump (without trailing whitespaces as a bonus).
Fixes: b640d556a2b3 ("selftests/bpf: Remove xxd util dependency")
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
---
Originally, I was going to add a check to stop the build if hexdump was
not available, but switching to 'od' seems to be a better solution while
not adding a new dependency.
Because test_progs was not reporting why it became unusable, I added a
Fixes tag to have this backported, to help others. Feel free to remove
it, or even drop the patch if you prefer to stick with hexdump.
---
tools/testing/selftests/bpf/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/Makefile
b/tools/testing/selftests/bpf/Makefile
index c6bf4dfb1495..5a618d14243e 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -723,7 +723,7 @@ $(VERIFICATION_CERT) $(PRIVATE_KEY): $(VERIFY_SIG_SETUP)
# Generates a header with C array declaration, containing
test_progs_verification_cert bytes
$(VERIFY_SIG_HDR): $(VERIFICATION_CERT)
$(Q)(echo "unsigned char test_progs_verification_cert[] = {"; \
- hexdump -v -e '12/1 " 0x%02x," "\n"' $< | sed 's/0x ,//g;
$$s/,$$//'; \
+ od -v -t 'xC' -w12 $< | awk 'NF > 1 {for (i=2; i<=NF; i++) { printf "
0x%s,", $$i }; printf "\n"}'; \
echo "};"; \
echo "unsigned int test_progs_verification_cert_len = $$(wc -c <
$<);") > $@
---
base-commit: 886bf921ecfc30f8f31341bc26560d8bf08b937b
change-id: 20260216-bpf-sft-hexdump-od-abd07a3bf026
Best regards,
--
Matthieu Baerts (NGI0) <[email protected]>
