[PATCH bpf-next v5 0/3] bpf, btf: Add DEBUG_INFO_BTF checks for __register_bpf_struct_ops

[PATCH bpf-next v5 0/3] bpf, btf: Add DEBUG_INFO_BTF checks for __register_bpf_struct_ops

[Geliang Tang]

From: Geliang Tang <tanggeliang@kylinos.cn>

v5:
 - drop CONFIG_MODULE_ALLOW_BTF_MISMATCH check as Martin suggested.

v4:
 - add a new patch to fix error checks for btf_get_module_btf.
 - rename the helper to check_btf_kconfigs.

v3:
 - fix this build error:
kernel/bpf/btf.c:7750:11: error: incomplete definition of type 'struct module'

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202402040934.Fph0XeEo-lkp@intel.com/

v2:
 - add register_check_missing_btf helper as Jiri suggested.

Geliang Tang (3):
  bpf, btf: Fix return value of register_btf_id_dtor_kfuncs
  bpf, btf: Add check_btf_kconfigs helper
  bpf, btf: Check btf for register_bpf_struct_ops

 kernel/bpf/btf.c | 39 ++++++++++++++++++---------------------
 1 file changed, 18 insertions(+), 21 deletions(-)

-- 
2.40.1

[PATCH bpf-next v5 1/3] bpf, btf: Fix return value of register_btf_id_dtor_kfuncs

[Geliang Tang]

From: Geliang Tang <tanggeliang@kylinos.cn>

The same as __register_btf_kfunc_id_set(), to let the modules with
stripped btf section loaded, this patch changes the return value of
register_btf_id_dtor_kfuncs() too from -ENOENT to 0 when btf is NULL.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 kernel/bpf/btf.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index f7725cb6e564..16eb937eca46 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -8219,10 +8219,8 @@ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_c
 			pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n");
 			return -ENOENT;
 		}
-		if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {
-			pr_err("missing module BTF, cannot register dtor kfuncs\n");
-			return -ENOENT;
-		}
+		if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
+			pr_warn("missing module BTF, cannot register dtor kfuncs\n");
 		return 0;
 	}
 	if (IS_ERR(btf))
-- 
2.40.1

[PATCH bpf-next v5 2/3] bpf, btf: Add check_btf_kconfigs helper

[Geliang Tang]

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch extracts duplicate code on error path when btf_get_module_btf()
returns NULL from the functions __register_btf_kfunc_id_set() and
register_btf_id_dtor_kfuncs() into a new helper named check_btf_kconfigs()
to check CONFIG_DEBUG_INFO_BTF and CONFIG_DEBUG_INFO_BTF_MODULES in it.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 kernel/bpf/btf.c | 33 +++++++++++++++------------------
 1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 16eb937eca46..e318df7f0071 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -7738,6 +7738,17 @@ static struct btf *btf_get_module_btf(const struct module *module)
 	return btf;
 }
 
+static int check_btf_kconfigs(const struct module *module)
+{
+	if (!module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
+		pr_err("missing vmlinux BTF, cannot register kfuncs\n");
+		return -ENOENT;
+	}
+	if (module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
+		pr_warn("missing module BTF, cannot register kfuncs\n");
+	return 0;
+}
+
 BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
 {
 	struct btf *btf = NULL;
@@ -8098,15 +8109,8 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
 	int ret, i;
 
 	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_warn("missing module BTF, cannot register kfuncs\n");
-		return 0;
-	}
+	if (!btf)
+		return check_btf_kconfigs(kset->owner);
 	if (IS_ERR(btf))
 		return PTR_ERR(btf);
 
@@ -8214,15 +8218,8 @@ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_c
 	int ret;
 
 	btf = btf_get_module_btf(owner);
-	if (!btf) {
-		if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
-			pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n");
-			return -ENOENT;
-		}
-		if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
-			pr_warn("missing module BTF, cannot register dtor kfuncs\n");
-		return 0;
-	}
+	if (!btf)
+		return check_btf_kconfigs(owner);
 	if (IS_ERR(btf))
 		return PTR_ERR(btf);
 
-- 
2.40.1

Re: [PATCH bpf-next v5 2/3] bpf, btf: Add check_btf_kconfigs helper

[Jiri Olsa]

On Thu, Feb 08, 2024 at 02:24:22PM +0800, Geliang Tang wrote:
> From: Geliang Tang <tanggeliang@kylinos.cn>
> 
> This patch extracts duplicate code on error path when btf_get_module_btf()
> returns NULL from the functions __register_btf_kfunc_id_set() and
> register_btf_id_dtor_kfuncs() into a new helper named check_btf_kconfigs()
> to check CONFIG_DEBUG_INFO_BTF and CONFIG_DEBUG_INFO_BTF_MODULES in it.
> 
> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
> ---
>  kernel/bpf/btf.c | 33 +++++++++++++++------------------
>  1 file changed, 15 insertions(+), 18 deletions(-)
> 
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index 16eb937eca46..e318df7f0071 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -7738,6 +7738,17 @@ static struct btf *btf_get_module_btf(const struct module *module)
>  	return btf;
>  }
>  
> +static int check_btf_kconfigs(const struct module *module)
> +{
> +	if (!module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
> +		pr_err("missing vmlinux BTF, cannot register kfuncs\n");
> +		return -ENOENT;
> +	}
> +	if (module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
> +		pr_warn("missing module BTF, cannot register kfuncs\n");
> +	return 0;
> +}
> +
>  BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
>  {
>  	struct btf *btf = NULL;
> @@ -8098,15 +8109,8 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
>  	int ret, i;
>  
>  	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_warn("missing module BTF, cannot register kfuncs\n");
> -		return 0;
> -	}
> +	if (!btf)
> +		return check_btf_kconfigs(kset->owner);
>  	if (IS_ERR(btf))
>  		return PTR_ERR(btf);
>  
> @@ -8214,15 +8218,8 @@ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_c
>  	int ret;
>  
>  	btf = btf_get_module_btf(owner);
> -	if (!btf) {
> -		if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
> -			pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n");
> -			return -ENOENT;
> -		}
> -		if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
> -			pr_warn("missing module BTF, cannot register dtor kfuncs\n");

nit, we do lose the 'dtor' from the message but I think it's ok,
for the patchset:

Acked-by: Jiri Olsa <jolsa@kernel.org>

jirka

> -		return 0;
> -	}
> +	if (!btf)
> +		return check_btf_kconfigs(owner);
>  	if (IS_ERR(btf))
>  		return PTR_ERR(btf);
>  
> -- 
> 2.40.1
> 

Re: [PATCH bpf-next v5 2/3] bpf, btf: Add check_btf_kconfigs helper

[Martin KaFai Lau]

On 2/8/24 2:07 AM, Jiri Olsa wrote:
>> +static int check_btf_kconfigs(const struct module *module)
>> +{
>> +	if (!module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
>> +		pr_err("missing vmlinux BTF, cannot register kfuncs\n");
>> +		return -ENOENT;
>> +	}
>> +	if (module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
>> +		pr_warn("missing module BTF, cannot register kfuncs\n");
>> +	return 0;
>> +}
>> +
>>   BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
>>   {
>>   	struct btf *btf = NULL;
>> @@ -8098,15 +8109,8 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
>>   	int ret, i;
>>   
>>   	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_warn("missing module BTF, cannot register kfuncs\n");
>> -		return 0;
>> -	}
>> +	if (!btf)
>> +		return check_btf_kconfigs(kset->owner);
>>   	if (IS_ERR(btf))
>>   		return PTR_ERR(btf);
>>   
>> @@ -8214,15 +8218,8 @@ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_c
>>   	int ret;
>>   
>>   	btf = btf_get_module_btf(owner);
>> -	if (!btf) {
>> -		if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
>> -			pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n");
>> -			return -ENOENT;
>> -		}
>> -		if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
>> -			pr_warn("missing module BTF, cannot register dtor kfuncs\n");
> nit, we do lose the 'dtor' from the message but I think it's ok,
> for the patchset:

I added "const char *feature" argument to check_btf_kconfigs(), so it is like 
check_btf_kconfigs(, "kfunc"), check_btf_kconfigs(, "dtor kfunc"), and 
check_btf_kconfigs(, "struct_ops"). Applied. Thanks.

[PATCH bpf-next v5 3/3] bpf, btf: Check btf for register_bpf_struct_ops

[Geliang Tang]

From: Geliang Tang <tanggeliang@kylinos.cn>

Similar to the handling in the functions __register_btf_kfunc_id_set()
and register_btf_id_dtor_kfuncs(), this patch uses the newly added
helper check_btf_kconfigs() and IS_ERR() to check the return value of
btf_get_module_btf().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 kernel/bpf/btf.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index e318df7f0071..c18b0f47f1f9 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -8882,7 +8882,9 @@ int __register_bpf_struct_ops(struct bpf_struct_ops *st_ops)
 
 	btf = btf_get_module_btf(st_ops->owner);
 	if (!btf)
-		return -EINVAL;
+		return check_btf_kconfigs(st_ops->owner);
+	if (IS_ERR(btf))
+		return PTR_ERR(btf);
 
 	log = kzalloc(sizeof(*log), GFP_KERNEL | __GFP_NOWARN);
 	if (!log) {
-- 
2.40.1

Re: [PATCH bpf-next v5 0/3] bpf, btf: Add DEBUG_INFO_BTF checks for __register_bpf_struct_ops

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Martin KaFai Lau <martin.lau@kernel.org>:

On Thu,  8 Feb 2024 14:24:20 +0800 you wrote:
> From: Geliang Tang <tanggeliang@kylinos.cn>
> 
> v5:
>  - drop CONFIG_MODULE_ALLOW_BTF_MISMATCH check as Martin suggested.
> 
> v4:
>  - add a new patch to fix error checks for btf_get_module_btf.
>  - rename the helper to check_btf_kconfigs.
> 
> [...]

Here is the summary with links:
  - [bpf-next,v5,1/3] bpf, btf: Fix return value of register_btf_id_dtor_kfuncs
    https://git.kernel.org/bpf/bpf-next/c/b9a395f0f7af
  - [bpf-next,v5,2/3] bpf, btf: Add check_btf_kconfigs helper
    https://git.kernel.org/bpf/bpf-next/c/9e60b0e02550
  - [bpf-next,v5,3/3] bpf, btf: Check btf for register_bpf_struct_ops
    https://git.kernel.org/bpf/bpf-next/c/947e56f82fd7

You are awesome, thank you!
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