[PATCH v2] btf: warn but return no error for NULL btf from __register_btf_kfunc_id_set()
__register_btf_kfunc_id_set() assumes .BTF to be part of the module's .ko file if CONFIG_DEBUG_INFO_BTF is enabled. If that's not the case, the function prints an error message and return an error. As a result, such modules cannot be loaded.
However, the section could be stripped out during a build process. It would be better to let the modules loaded, because their basic functionalities have no problem[1], though the BTF functionalities will not be supported. Make the function to lower the level of the message from error to warn, and return no error.
[1] https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/
Reported-by: Alexander Egorenkov Alexander.Egorenkov@ibm.com Link: https://lore.kernel.org/bpf/87y228q66f.fsf@oc8242746057.ibm.com/ Suggested-by: Kumar Kartikeya Dwivedi memxor@gmail.com Link: https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/ Fixes: c446fdacb10d ("bpf: fix register_btf_kfunc_id_set for !CONFIG_DEBUG_INFO_BTF") Cc: stable@vger.kernel.org # 5.18.x Signed-off-by: SeongJae Park sj@kernel.org Acked-by: Jiri Olsa jolsa@kernel.org --- Changes from v1 (https://lore.kernel.org/all/20230626181120.7086-1-sj@kernel.org/) - Fix Fixes: tag (Jiri Olsa) - Add 'Acked-by: ' from Jiri Olsa
kernel/bpf/btf.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6b682b8e4b50..d683f034996f 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7848,14 +7848,10 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
btf = btf_get_module_btf(kset->owner); if (!btf) { - if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) { - pr_err("missing vmlinux BTF, cannot register kfuncs\n"); - return -ENOENT; - } - if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) { - pr_err("missing module BTF, cannot register kfuncs\n"); - return -ENOENT; - } + if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) + pr_warn("missing vmlinux BTF, cannot register kfuncs\n"); + if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) + pr_warn("missing module BTF, cannot register kfuncs\n"); return 0; } if (IS_ERR(btf))
On 6/28/23 6:46 PM, SeongJae Park wrote:
__register_btf_kfunc_id_set() assumes .BTF to be part of the module's .ko file if CONFIG_DEBUG_INFO_BTF is enabled. If that's not the case, the function prints an error message and return an error. As a result, such modules cannot be loaded.
However, the section could be stripped out during a build process. It would be better to let the modules loaded, because their basic functionalities have no problem[1], though the BTF functionalities will not be supported. Make the function to lower the level of the message from error to warn, and return no error.
[1] https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/
Reported-by: Alexander Egorenkov Alexander.Egorenkov@ibm.com Link: https://lore.kernel.org/bpf/87y228q66f.fsf@oc8242746057.ibm.com/ Suggested-by: Kumar Kartikeya Dwivedi memxor@gmail.com Link: https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/ Fixes: c446fdacb10d ("bpf: fix register_btf_kfunc_id_set for !CONFIG_DEBUG_INFO_BTF") Cc: stable@vger.kernel.org # 5.18.x Signed-off-by: SeongJae Park sj@kernel.org Acked-by: Jiri Olsa jolsa@kernel.org
I presume this one is targeted at bpf (rather than bpf-next) tree, right?
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6b682b8e4b50..d683f034996f 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7848,14 +7848,10 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook, btf = btf_get_module_btf(kset->owner); if (!btf) {
if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {pr_err("missing vmlinux BTF, cannot register kfuncs\n");return -ENOENT;}
Why the above one needs to be changed? Do you also run into this case? vmlinux BTF should be built-in in this case. I understand it's rather the one below for BTF + modules instead, no?
if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {pr_err("missing module BTF, cannot register kfuncs\n");return -ENOENT;}
if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF))pr_warn("missing vmlinux BTF, cannot register kfuncs\n");if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))pr_warn("missing module BTF, cannot register kfuncs\n");
Hi Daniel,
On Fri, 30 Jun 2023 16:53:38 +0200 Daniel Borkmann daniel@iogearbox.net wrote:
On 6/28/23 6:46 PM, SeongJae Park wrote:
__register_btf_kfunc_id_set() assumes .BTF to be part of the module's .ko file if CONFIG_DEBUG_INFO_BTF is enabled. If that's not the case, the function prints an error message and return an error. As a result, such modules cannot be loaded.
However, the section could be stripped out during a build process. It would be better to let the modules loaded, because their basic functionalities have no problem[1], though the BTF functionalities will not be supported. Make the function to lower the level of the message from error to warn, and return no error.
[1] https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/
Reported-by: Alexander Egorenkov Alexander.Egorenkov@ibm.com Link: https://lore.kernel.org/bpf/87y228q66f.fsf@oc8242746057.ibm.com/ Suggested-by: Kumar Kartikeya Dwivedi memxor@gmail.com Link: https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/ Fixes: c446fdacb10d ("bpf: fix register_btf_kfunc_id_set for !CONFIG_DEBUG_INFO_BTF") Cc: stable@vger.kernel.org # 5.18.x Signed-off-by: SeongJae Park sj@kernel.org Acked-by: Jiri Olsa jolsa@kernel.org
I presume this one is targeted at bpf (rather than bpf-next) tree, right?
You're correct. It's not urgent for us, but I would prefer it to be merged into all affected kernels as early as possible.
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6b682b8e4b50..d683f034996f 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7848,14 +7848,10 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook, btf = btf_get_module_btf(kset->owner); if (!btf) {
if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {pr_err("missing vmlinux BTF, cannot register kfuncs\n");return -ENOENT;}Why the above one needs to be changed? Do you also run into this case? vmlinux BTF should be built-in in this case. I understand it's rather the one below for BTF + modules instead, no?
Again, you're correct. This change is not really needed. I was interpreting Kumar's suggestion merely into code without thinking about his real meaning, sorry. I will restore this in the next spin.
Thanks, SJ
if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {pr_err("missing module BTF, cannot register kfuncs\n");return -ENOENT;}
if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF))pr_warn("missing vmlinux BTF, cannot register kfuncs\n");if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))pr_warn("missing module BTF, cannot register kfuncs\n");
On 6/30/23 9:48 PM, SeongJae Park wrote:
On Fri, 30 Jun 2023 16:53:38 +0200 Daniel Borkmann daniel@iogearbox.net wrote:
On 6/28/23 6:46 PM, SeongJae Park wrote:
__register_btf_kfunc_id_set() assumes .BTF to be part of the module's .ko file if CONFIG_DEBUG_INFO_BTF is enabled. If that's not the case, the function prints an error message and return an error. As a result, such modules cannot be loaded.
However, the section could be stripped out during a build process. It would be better to let the modules loaded, because their basic functionalities have no problem[1], though the BTF functionalities will not be supported. Make the function to lower the level of the message from error to warn, and return no error.
[1] https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/
Reported-by: Alexander Egorenkov Alexander.Egorenkov@ibm.com Link: https://lore.kernel.org/bpf/87y228q66f.fsf@oc8242746057.ibm.com/ Suggested-by: Kumar Kartikeya Dwivedi memxor@gmail.com Link: https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/ Fixes: c446fdacb10d ("bpf: fix register_btf_kfunc_id_set for !CONFIG_DEBUG_INFO_BTF") Cc: stable@vger.kernel.org # 5.18.x Signed-off-by: SeongJae Park sj@kernel.org Acked-by: Jiri Olsa jolsa@kernel.org
I presume this one is targeted at bpf (rather than bpf-next) tree, right?
You're correct. It's not urgent for us, but I would prefer it to be merged into all affected kernels as early as possible.
Ok, sounds good, bpf tree it is then.
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6b682b8e4b50..d683f034996f 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7848,14 +7848,10 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook, btf = btf_get_module_btf(kset->owner); if (!btf) {
if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {pr_err("missing vmlinux BTF, cannot register kfuncs\n");return -ENOENT;}Why the above one needs to be changed? Do you also run into this case? vmlinux BTF should be built-in in this case. I understand it's rather the one below for BTF + modules instead, no?
Again, you're correct. This change is not really needed. I was interpreting Kumar's suggestion merely into code without thinking about his real meaning, sorry. I will restore this in the next spin.
Perfect, I think after your v3 respin it should be good to land.
Thanks, Daniel
On Fri, 30 Jun 2023 22:52:24 +0200 Daniel Borkmann daniel@iogearbox.net wrote:
On 6/30/23 9:48 PM, SeongJae Park wrote:
On Fri, 30 Jun 2023 16:53:38 +0200 Daniel Borkmann daniel@iogearbox.net wrote:
On 6/28/23 6:46 PM, SeongJae Park wrote:
__register_btf_kfunc_id_set() assumes .BTF to be part of the module's .ko file if CONFIG_DEBUG_INFO_BTF is enabled. If that's not the case, the function prints an error message and return an error. As a result, such modules cannot be loaded.
However, the section could be stripped out during a build process. It would be better to let the modules loaded, because their basic functionalities have no problem[1], though the BTF functionalities will not be supported. Make the function to lower the level of the message from error to warn, and return no error.
[1] https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/
Reported-by: Alexander Egorenkov Alexander.Egorenkov@ibm.com Link: https://lore.kernel.org/bpf/87y228q66f.fsf@oc8242746057.ibm.com/ Suggested-by: Kumar Kartikeya Dwivedi memxor@gmail.com Link: https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/ Fixes: c446fdacb10d ("bpf: fix register_btf_kfunc_id_set for !CONFIG_DEBUG_INFO_BTF") Cc: stable@vger.kernel.org # 5.18.x Signed-off-by: SeongJae Park sj@kernel.org Acked-by: Jiri Olsa jolsa@kernel.org
I presume this one is targeted at bpf (rather than bpf-next) tree, right?
You're correct. It's not urgent for us, but I would prefer it to be merged into all affected kernels as early as possible.
Ok, sounds good, bpf tree it is then.
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6b682b8e4b50..d683f034996f 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7848,14 +7848,10 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook, btf = btf_get_module_btf(kset->owner); if (!btf) {
if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {pr_err("missing vmlinux BTF, cannot register kfuncs\n");return -ENOENT;}Why the above one needs to be changed? Do you also run into this case? vmlinux BTF should be built-in in this case. I understand it's rather the one below for BTF + modules instead, no?
Again, you're correct. This change is not really needed. I was interpreting Kumar's suggestion merely into code without thinking about his real meaning, sorry. I will restore this in the next spin.
Perfect, I think after your v3 respin it should be good to land.
Thank you! I will send it by tomorrow, to give people enough time to comment. If you don't want to wait, please let me know :)
Also, please note that this will not cleanly applicable on 6.1.y. I will provide the backport to stable@ as soon as this is merged into the mainline.
Thanks, SJ
Thanks, Daniel
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