| Message ID | 20221126111147.199366-2-changbin.du@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | bpftool: improve error handing for missing .BTF section | expand |
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 > >
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; }
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(+)