Before the change on `i686-linux` `systemd` build failed as:
$ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
After the change it fails as:
$ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
libbpf: ELF section #9 has inconsistent alignment in src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
Now it's slightly easier to figure out what is wrong with an ELF file.
CC: Alexei Starovoitov <[email protected]>
CC: Daniel Borkmann <[email protected]>
CC: Andrii Nakryiko <[email protected]>
CC: Martin KaFai Lau <[email protected]>
CC: Song Liu <[email protected]>
CC: Yonghong Song <[email protected]>
CC: John Fastabend <[email protected]>
CC: KP Singh <[email protected]>
CC: Stanislav Fomichev <[email protected]>
CC: Hao Luo <[email protected]>
CC: Jiri Olsa <[email protected]>
CC: [email protected]
Signed-off-by: Sergei Trofimovich <[email protected]>
---
tools/lib/bpf/linker.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index 5ced96d99f8c..71bb4916b762 100644
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -719,13 +719,22 @@ static int linker_sanity_check_elf(struct src_obj *obj)
return -EINVAL;
}
- if (sec->shdr->sh_addralign && !is_pow_of_2(sec->shdr->sh_addralign))
+ if (sec->shdr->sh_addralign && !is_pow_of_2(sec->shdr->sh_addralign)) {
+ pr_warn("ELF section #%zu alignment is non pow-of-2 alignment in %s\n",
+ sec->sec_idx, obj->filename);
return -EINVAL;
- if (sec->shdr->sh_addralign != sec->data->d_align)
+ }
+ if (sec->shdr->sh_addralign != sec->data->d_align) {
+ pr_warn("ELF section #%zu has inconsistent alignment in %s\n",
+ sec->sec_idx, obj->filename);
return -EINVAL;
+ }
- if (sec->shdr->sh_size != sec->data->d_size)
+ if (sec->shdr->sh_size != sec->data->d_size) {
+ pr_warn("ELF section #%zu has inconsistent section size in %s\n",
+ sec->sec_idx, obj->filename);
return -EINVAL;
+ }
switch (sec->shdr->sh_type) {
case SHT_SYMTAB:
--
2.42.0
On Thu, 2023-12-07 at 18:09 +0000, Sergei Trofimovich wrote:
> Before the change on `i686-linux` `systemd` build failed as:
>
> $ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
> Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
>
> After the change it fails as:
>
> $ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
> libbpf: ELF section #9 has inconsistent alignment in src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
> Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
>
> Now it's slightly easier to figure out what is wrong with an ELF file.
Hi Sergei,
Thank you for adding these prints.
Could you please make a few adjustments, as noted below.
Also, please add "libbpf:" prefix in subject and mention
linker_sanity_check_elf in it, e.g.:
libbpf: add pr_warn() for EINVAL cases in linker_sanity_check_elf
or something like that.
[...]
> diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
> index 5ced96d99f8c..71bb4916b762 100644
> --- a/tools/lib/bpf/linker.c
> +++ b/tools/lib/bpf/linker.c
> @@ -719,13 +719,22 @@ static int linker_sanity_check_elf(struct src_obj *obj)
> return -EINVAL;
> }
>
> - if (sec->shdr->sh_addralign && !is_pow_of_2(sec->shdr->sh_addralign))
> + if (sec->shdr->sh_addralign && !is_pow_of_2(sec->shdr->sh_addralign)) {
> + pr_warn("ELF section #%zu alignment is non pow-of-2 alignment in %s\n",
> + sec->sec_idx, obj->filename);
Could you please also print values for shdr->sh_addralign here?
And also print shdr->sh_addralign/data->d_align, shdr->sh_size/data->d_size
in corresponding pr_warn() calls below.
> return -EINVAL;
> - if (sec->shdr->sh_addralign != sec->data->d_align)
> + }
> + if (sec->shdr->sh_addralign != sec->data->d_align) {
> + pr_warn("ELF section #%zu has inconsistent alignment in %s\n",
> + sec->sec_idx, obj->filename);
> return -EINVAL;
> + }
>
> - if (sec->shdr->sh_size != sec->data->d_size)
> + if (sec->shdr->sh_size != sec->data->d_size) {
> + pr_warn("ELF section #%zu has inconsistent section size in %s\n",
> + sec->sec_idx, obj->filename);
> return -EINVAL;
> + }
>
> switch (sec->shdr->sh_type) {
> case SHT_SYMTAB:
A few lines below this one there is:
case SHT_PROGBITS:
if (sec->shdr->sh_flags & SHF_EXECINSTR) {
if (sec->shdr->sh_size % sizeof(struct bpf_insn) != 0)
return -EINVAL;
}
break;
Could you please add pr_warn() there as well?
Before the change on `i686-linux` `systemd` build failed as:
$ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
After the change it fails as:
$ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
libbpf: ELF section #9 has inconsistent alignment addr=8 != d=4 in src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
Now it's slightly easier to figure out what is wrong with an ELF file.
CC: Alexei Starovoitov <[email protected]>
CC: Daniel Borkmann <[email protected]>
CC: Andrii Nakryiko <[email protected]>
CC: Martin KaFai Lau <[email protected]>
CC: Song Liu <[email protected]>
CC: Yonghong Song <[email protected]>
CC: John Fastabend <[email protected]>
CC: KP Singh <[email protected]>
CC: Stanislav Fomichev <[email protected]>
CC: Hao Luo <[email protected]>
CC: Jiri Olsa <[email protected]>
CC: Eduard Zingerman <[email protected]>
CC: [email protected]
Signed-off-by: Sergei Trofimovich <[email protected]>
---
tools/lib/bpf/linker.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
Change since v1:
Following Eduard's suggestion added one extra pr_warn() call around
section alignment and added compared values into warning messages.
diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index 5ced96d99f8c..52a2901e8bd0 100644
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -719,13 +719,25 @@ static int linker_sanity_check_elf(struct src_obj *obj)
return -EINVAL;
}
- if (sec->shdr->sh_addralign && !is_pow_of_2(sec->shdr->sh_addralign))
+ if (sec->shdr->sh_addralign && !is_pow_of_2(sec->shdr->sh_addralign)) {
+ pr_warn("ELF section #%zu alignment %llu is non pow-of-2 alignment in %s\n",
+ sec->sec_idx, (long long unsigned)sec->shdr->sh_addralign,
+ obj->filename);
return -EINVAL;
- if (sec->shdr->sh_addralign != sec->data->d_align)
+ }
+ if (sec->shdr->sh_addralign != sec->data->d_align) {
+ pr_warn("ELF section #%zu has inconsistent alignment addr=%llu != d=%llu in %s\n",
+ sec->sec_idx, (long long unsigned)sec->shdr->sh_addralign,
+ (long long unsigned)sec->data->d_align, obj->filename);
return -EINVAL;
+ }
- if (sec->shdr->sh_size != sec->data->d_size)
+ if (sec->shdr->sh_size != sec->data->d_size) {
+ pr_warn("ELF section #%zu has inconsistent section size sh=%llu != d=%llu in %s\n",
+ sec->sec_idx, (long long unsigned)sec->shdr->sh_size,
+ (long long unsigned)sec->data->d_size, obj->filename);
return -EINVAL;
+ }
switch (sec->shdr->sh_type) {
case SHT_SYMTAB:
@@ -737,8 +749,12 @@ static int linker_sanity_check_elf(struct src_obj *obj)
break;
case SHT_PROGBITS:
if (sec->shdr->sh_flags & SHF_EXECINSTR) {
- if (sec->shdr->sh_size % sizeof(struct bpf_insn) != 0)
+ if (sec->shdr->sh_size % sizeof(struct bpf_insn) != 0) {
+ pr_warn("ELF section #%zu has unexpected size alignment %llu in %s\n",
+ sec->sec_idx, (long long unsigned)sec->shdr->sh_size,
+ obj->filename);
return -EINVAL;
+ }
}
break;
case SHT_NOBITS:
--
2.42.0
On Fri, 2023-12-08 at 21:51 +0000, Sergei Trofimovich wrote:
> Before the change on `i686-linux` `systemd` build failed as:
>
> $ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
> Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
>
> After the change it fails as:
>
> $ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
> libbpf: ELF section #9 has inconsistent alignment addr=8 != d=4 in src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
> Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
>
> Now it's slightly easier to figure out what is wrong with an ELF file.
>
> CC: Alexei Starovoitov <[email protected]>
> CC: Daniel Borkmann <[email protected]>
> CC: Andrii Nakryiko <[email protected]>
> CC: Martin KaFai Lau <[email protected]>
> CC: Song Liu <[email protected]>
> CC: Yonghong Song <[email protected]>
> CC: John Fastabend <[email protected]>
> CC: KP Singh <[email protected]>
> CC: Stanislav Fomichev <[email protected]>
> CC: Hao Luo <[email protected]>
> CC: Jiri Olsa <[email protected]>
> CC: Eduard Zingerman <[email protected]>
> CC: [email protected]
> Signed-off-by: Sergei Trofimovich <[email protected]>
> ---
> tools/lib/bpf/linker.c | 24 ++++++++++++++++++++----
> 1 file changed, 20 insertions(+), 4 deletions(-)
> Change since v1:
> Following Eduard's suggestion added one extra pr_warn() call around
> section alignment and added compared values into warning messages.
Thank you for doing adjustments.
(Note: when I apply this patch locally full CC block is a part of the
commit message, this is usually omitted from commit messages).
Acked-by: Eduard Zingerman <[email protected]>
Hello:
This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <[email protected]>:
On Fri, 8 Dec 2023 21:51:00 +0000 you wrote:
> Before the change on `i686-linux` `systemd` build failed as:
>
> $ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
> Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
>
> After the change it fails as:
>
> [...]
Here is the summary with links:
- [v2] libbpf: add pr_warn() for EINVAL cases in linker_sanity_check_elf
https://git.kernel.org/bpf/bpf-next/c/32fa05839862
You are awesome, thank you!
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