Changbin Du (2): libbpf: show more info about missing ".BTF" section makefiles: do not generate empty vmlinux.h
samples/bpf/Makefile | 2 +- tools/bpf/bpftool/Makefile | 2 +- tools/bpf/runqslower/Makefile | 2 +- tools/lib/bpf/btf.c | 12 ++++++++++++ tools/perf/Makefile.perf | 2 +- tools/testing/selftests/bpf/Makefile | 2 +- 6 files changed, 17 insertions(+), 5 deletions(-)
Show more information about why failed instead of just saying "No such file or directory".
Now will print below info: libbpf: can not find '.BTF' section libbpf: is CONFIG_DEBUG_INFO_BTF enabled for kernel? Error: failed to load BTF from /home/changbin/work/linux/vmlinux: No such file or directory
Signed-off-by: Changbin Du changbin.du@gmail.com --- tools/lib/bpf/btf.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index d88647da2c7f..3f661d991808 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -906,6 +906,15 @@ struct btf *btf__new(const void *data, __u32 size) return libbpf_ptr(btf_new(data, size, NULL)); }
+static bool is_vmlinux(const char *path) +{ + size_t path_len = strlen(path); + size_t suffix_len = strlen("vmlinux"); + + return (path_len >= suffix_len) && + (!memcmp(path + path_len - suffix_len, "vmlinux", suffix_len)); +} + static struct btf *btf_parse_elf(const char *path, struct btf *base_btf, struct btf_ext **btf_ext) { @@ -990,6 +999,9 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf, err = 0;
if (!btf_data) { + pr_warn("can not find '%s' section\n", BTF_ELF_SEC); + if (is_vmlinux(path)) + pr_warn("is CONFIG_DEBUG_INFO_BTF enabled for kernel?\n"); err = -ENOENT; goto done; }
On Sat, Nov 26, 2022 at 3:13 AM Changbin Du changbin.du@gmail.com wrote:
Show more information about why failed instead of just saying "No such file or directory".
Now will print below info: libbpf: can not find '.BTF' section libbpf: is CONFIG_DEBUG_INFO_BTF enabled for kernel? Error: failed to load BTF from /home/changbin/work/linux/vmlinux: No such file or directory
Signed-off-by: Changbin Du changbin.du@gmail.com
tools/lib/bpf/btf.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index d88647da2c7f..3f661d991808 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -906,6 +906,15 @@ struct btf *btf__new(const void *data, __u32 size) return libbpf_ptr(btf_new(data, size, NULL)); }
+static bool is_vmlinux(const char *path) +{
size_t path_len = strlen(path);size_t suffix_len = strlen("vmlinux");return (path_len >= suffix_len) &&(!memcmp(path + path_len - suffix_len, "vmlinux", suffix_len));+}
static struct btf *btf_parse_elf(const char *path, struct btf *base_btf, struct btf_ext **btf_ext) { @@ -990,6 +999,9 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf, err = 0;
if (!btf_data) {
pr_warn("can not find '%s' section\n", BTF_ELF_SEC);if (is_vmlinux(path))pr_warn("is CONFIG_DEBUG_INFO_BTF enabled for kernel?\n");
this is generic piece of BTF loading code in libbpf, it knows nothing and should know nothing about vmlinux and CONFIG_DEBUG_INFO_BTF, this is not the right place to add such suggestions.
Check bpf_object__load_vmlinux_btf(), libbpf emits vmlinux-specific error there: "Error loading vmlinux BTF". If we need to mention CONFIG_DEBUG_INFO_BTF anywhere, that would be the place to do that.
err = -ENOENT; goto done; }-- 2.37.2
On Mon, Nov 28, 2022 at 09:59:00PM -0800, Andrii Nakryiko wrote:
On Sat, Nov 26, 2022 at 3:13 AM Changbin Du changbin.du@gmail.com wrote:
Show more information about why failed instead of just saying "No such file or directory".
Now will print below info: libbpf: can not find '.BTF' section libbpf: is CONFIG_DEBUG_INFO_BTF enabled for kernel? Error: failed to load BTF from /home/changbin/work/linux/vmlinux: No such file or directory
Signed-off-by: Changbin Du changbin.du@gmail.com
tools/lib/bpf/btf.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index d88647da2c7f..3f661d991808 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -906,6 +906,15 @@ struct btf *btf__new(const void *data, __u32 size) return libbpf_ptr(btf_new(data, size, NULL)); }
+static bool is_vmlinux(const char *path) +{
size_t path_len = strlen(path);size_t suffix_len = strlen("vmlinux");return (path_len >= suffix_len) &&(!memcmp(path + path_len - suffix_len, "vmlinux", suffix_len));+}
static struct btf *btf_parse_elf(const char *path, struct btf *base_btf, struct btf_ext **btf_ext) { @@ -990,6 +999,9 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf, err = 0;
if (!btf_data) {
pr_warn("can not find '%s' section\n", BTF_ELF_SEC);if (is_vmlinux(path))pr_warn("is CONFIG_DEBUG_INFO_BTF enabled for kernel?\n");this is generic piece of BTF loading code in libbpf, it knows nothing and should know nothing about vmlinux and CONFIG_DEBUG_INFO_BTF, this is not the right place to add such suggestions.
Check bpf_object__load_vmlinux_btf(), libbpf emits vmlinux-specific error there: "Error loading vmlinux BTF". If we need to mention CONFIG_DEBUG_INFO_BTF anywhere, that would be the place to do that.
Agreed. I think adding "can not find '.BTF' section" is enough to diagnose the problem. The standalone error msg "No such file or directory" is really weird.
err = -ENOENT; goto done; }-- 2.37.2
Remove the empty vmlinux.h if bpftool failed to dump btf info. The emptry vmlinux.h can hide real error when reading output of make.
Signed-off-by: Changbin Du changbin.du@gmail.com --- samples/bpf/Makefile | 2 +- tools/bpf/bpftool/Makefile | 2 +- tools/bpf/runqslower/Makefile | 2 +- tools/perf/Makefile.perf | 2 +- tools/testing/selftests/bpf/Makefile | 2 +- 5 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 727da3c5879b..ab4788b4883e 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -362,7 +362,7 @@ ifeq ($(VMLINUX_BTF),) $(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)",\ build the kernel or set VMLINUX_BTF or VMLINUX_H variable) endif - $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ + $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ || { rm $@; exit 1; } else $(Q)cp "$(VMLINUX_H)" $@ endif diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 4a95c017ad4c..d9d6f890884c 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -177,7 +177,7 @@ BUILD_BPF_SKELS := 1
$(OUTPUT)vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL_BOOTSTRAP) ifeq ($(VMLINUX_H),) - $(QUIET_GEN)$(BPFTOOL_BOOTSTRAP) btf dump file $< format c > $@ + $(QUIET_GEN)$(BPFTOOL_BOOTSTRAP) btf dump file $< format c > $@ || { rm $@; exit 1; } else $(Q)cp "$(VMLINUX_H)" $@ endif diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile index 8b3d87b82b7a..2d7911f4666b 100644 --- a/tools/bpf/runqslower/Makefile +++ b/tools/bpf/runqslower/Makefile @@ -77,7 +77,7 @@ ifeq ($(VMLINUX_H),) "specify its location." >&2; \ exit 1;\ fi - $(QUIET_GEN)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@ + $(QUIET_GEN)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@ || { rm $@; exit 1; } else $(Q)cp "$(VMLINUX_H)" $@ endif diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf index a432e59afc42..0546d408aa4e 100644 --- a/tools/perf/Makefile.perf +++ b/tools/perf/Makefile.perf @@ -1064,7 +1064,7 @@ VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
$(SKEL_OUT)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL) ifeq ($(VMLINUX_H),) - $(QUIET_GEN)$(BPFTOOL) btf dump file $< format c > $@ + $(QUIET_GEN)$(BPFTOOL) btf dump file $< format c > $@ || { rm $@; exit 1; } else $(Q)cp "$(VMLINUX_H)" $@ endif diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index e6cf21fad69f..9aa2475b4ac6 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -284,7 +284,7 @@ endif $(INCLUDE_DIR)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL) | $(INCLUDE_DIR) ifeq ($(VMLINUX_H),) $(call msg,GEN,,$@) - $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ + $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ || { rm $@; exit 1; } else $(call msg,CP,,$@) $(Q)cp "$(VMLINUX_H)" $@
On Sat, Nov 26, 2022 at 3:13 AM Changbin Du changbin.du@gmail.com wrote:
Remove the empty vmlinux.h if bpftool failed to dump btf info. The emptry vmlinux.h can hide real error when reading output of make.
wouldn't this be better handled by adding .DELETE_ON_ERROR: to bpftool's Makefile?
Signed-off-by: Changbin Du changbin.du@gmail.com
samples/bpf/Makefile | 2 +- tools/bpf/bpftool/Makefile | 2 +- tools/bpf/runqslower/Makefile | 2 +- tools/perf/Makefile.perf | 2 +- tools/testing/selftests/bpf/Makefile | 2 +- 5 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 727da3c5879b..ab4788b4883e 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -362,7 +362,7 @@ ifeq ($(VMLINUX_BTF),) $(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)",\ build the kernel or set VMLINUX_BTF or VMLINUX_H variable) endif
$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ || { rm $@; exit 1; }else $(Q)cp "$(VMLINUX_H)" $@ endif diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 4a95c017ad4c..d9d6f890884c 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -177,7 +177,7 @@ BUILD_BPF_SKELS := 1
$(OUTPUT)vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL_BOOTSTRAP) ifeq ($(VMLINUX_H),)
$(QUIET_GEN)$(BPFTOOL_BOOTSTRAP) btf dump file $< format c > $@
$(QUIET_GEN)$(BPFTOOL_BOOTSTRAP) btf dump file $< format c > $@ || { rm $@; exit 1; }else $(Q)cp "$(VMLINUX_H)" $@ endif diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile index 8b3d87b82b7a..2d7911f4666b 100644 --- a/tools/bpf/runqslower/Makefile +++ b/tools/bpf/runqslower/Makefile @@ -77,7 +77,7 @@ ifeq ($(VMLINUX_H),) "specify its location." >&2; \ exit 1;\ fi
$(QUIET_GEN)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@
$(QUIET_GEN)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@ || { rm $@; exit 1; }else $(Q)cp "$(VMLINUX_H)" $@ endif diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf index a432e59afc42..0546d408aa4e 100644 --- a/tools/perf/Makefile.perf +++ b/tools/perf/Makefile.perf @@ -1064,7 +1064,7 @@ VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
$(SKEL_OUT)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL) ifeq ($(VMLINUX_H),)
$(QUIET_GEN)$(BPFTOOL) btf dump file $< format c > $@
$(QUIET_GEN)$(BPFTOOL) btf dump file $< format c > $@ || { rm $@; exit 1; }else $(Q)cp "$(VMLINUX_H)" $@ endif diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index e6cf21fad69f..9aa2475b4ac6 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -284,7 +284,7 @@ endif $(INCLUDE_DIR)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL) | $(INCLUDE_DIR) ifeq ($(VMLINUX_H),) $(call msg,GEN,,$@)
$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ || { rm $@; exit 1; }else $(call msg,CP,,$@) $(Q)cp "$(VMLINUX_H)" $@ -- 2.37.2
On Mon, Nov 28, 2022 at 10:00:14PM -0800, Andrii Nakryiko wrote:
On Sat, Nov 26, 2022 at 3:13 AM Changbin Du changbin.du@gmail.com wrote:
Remove the empty vmlinux.h if bpftool failed to dump btf info. The emptry vmlinux.h can hide real error when reading output of make.
wouldn't this be better handled by adding .DELETE_ON_ERROR: to bpftool's Makefile?
yes, let me replace it.
linux-kselftest-mirror@lists.linaro.org
-
Andrii Nakryiko -
Changbin Du