With the previous commit adding common attribute support for
BPF_MAP_CREATE, users can now retrieve detailed error messages when map
creation fails via the log_buf field.
Introduce struct bpf_syscall_common_attr_opts with the following fields:
log_buf, log_size, log_level, and log_true_size.
Extend bpf_map_create_opts with a new field common_attr_opts, allowing
users to capture and inspect log messages on map creation failures.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
tools/lib/bpf/bpf.c | 15 ++++++++++++++-
tools/lib/bpf/bpf.h | 17 ++++++++++++++++-
2 files changed, 30 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index d44e667aaf02..d65df1b7b2be 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -207,6 +207,9 @@ int bpf_map_create(enum bpf_map_type map_type,
const struct bpf_map_create_opts *opts)
{
const size_t attr_sz = offsetofend(union bpf_attr, excl_prog_hash_size);
+ const size_t common_attr_sz = sizeof(struct bpf_common_attr);
+ struct bpf_syscall_common_attr_opts *common_attr_opts;
+ struct bpf_common_attr common_attr;
union bpf_attr attr;
int fd;
@@ -240,7 +243,17 @@ int bpf_map_create(enum bpf_map_type map_type,
attr.excl_prog_hash = ptr_to_u64(OPTS_GET(opts, excl_prog_hash, NULL));
attr.excl_prog_hash_size = OPTS_GET(opts, excl_prog_hash_size, 0);
- fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz);
+ common_attr_opts = OPTS_GET(opts, common_attr_opts, NULL);
+ if (common_attr_opts && feat_supported(NULL, FEAT_EXTENDED_SYSCALL)) {
+ memset(&common_attr, 0, common_attr_sz);
+ common_attr.log_buf = ptr_to_u64(OPTS_GET(common_attr_opts, log_buf, NULL));
+ common_attr.log_size = OPTS_GET(common_attr_opts, log_size, 0);
+ common_attr.log_level = OPTS_GET(common_attr_opts, log_level, 0);
+ fd = sys_bpf_ext_fd(BPF_MAP_CREATE, &attr, attr_sz, &common_attr, common_attr_sz);
+ OPTS_SET(common_attr_opts, log_true_size, common_attr.log_true_size);
+ } else {
+ fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz);
+ }
return libbpf_err_errno(fd);
}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 2c8e88ddb674..c4a26e6b71ea 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -37,6 +37,18 @@ extern "C" {
LIBBPF_API int libbpf_set_memlock_rlim(size_t memlock_bytes);
+struct bpf_syscall_common_attr_opts {
+ size_t sz; /* size of this struct for forward/backward compatibility */
+
+ char *log_buf;
+ __u32 log_size;
+ __u32 log_level;
+ __u32 log_true_size;
+
+ size_t :0;
+};
+#define bpf_syscall_common_attr_opts__last_field log_true_size
+
struct bpf_map_create_opts {
size_t sz; /* size of this struct for forward/backward compatibility */
@@ -57,9 +69,12 @@ struct bpf_map_create_opts {
const void *excl_prog_hash;
__u32 excl_prog_hash_size;
+
+ struct bpf_syscall_common_attr_opts *common_attr_opts;
+
size_t :0;
};
-#define bpf_map_create_opts__last_field excl_prog_hash_size
+#define bpf_map_create_opts__last_field common_attr_opts
LIBBPF_API int bpf_map_create(enum bpf_map_type map_type,
const char *map_name,
--
2.52.0On Mon, Jan 12, 2026 at 6:59 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>
> With the previous commit adding common attribute support for
> BPF_MAP_CREATE, users can now retrieve detailed error messages when map
> creation fails via the log_buf field.
>
> Introduce struct bpf_syscall_common_attr_opts with the following fields:
> log_buf, log_size, log_level, and log_true_size.
>
> Extend bpf_map_create_opts with a new field common_attr_opts, allowing
> users to capture and inspect log messages on map creation failures.
>
> Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
> ---
> tools/lib/bpf/bpf.c | 15 ++++++++++++++-
> tools/lib/bpf/bpf.h | 17 ++++++++++++++++-
> 2 files changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index d44e667aaf02..d65df1b7b2be 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -207,6 +207,9 @@ int bpf_map_create(enum bpf_map_type map_type,
> const struct bpf_map_create_opts *opts)
> {
> const size_t attr_sz = offsetofend(union bpf_attr, excl_prog_hash_size);
> + const size_t common_attr_sz = sizeof(struct bpf_common_attr);
> + struct bpf_syscall_common_attr_opts *common_attr_opts;
> + struct bpf_common_attr common_attr;
> union bpf_attr attr;
> int fd;
>
> @@ -240,7 +243,17 @@ int bpf_map_create(enum bpf_map_type map_type,
> attr.excl_prog_hash = ptr_to_u64(OPTS_GET(opts, excl_prog_hash, NULL));
> attr.excl_prog_hash_size = OPTS_GET(opts, excl_prog_hash_size, 0);
>
> - fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz);
> + common_attr_opts = OPTS_GET(opts, common_attr_opts, NULL);
> + if (common_attr_opts && feat_supported(NULL, FEAT_EXTENDED_SYSCALL)) {
> + memset(&common_attr, 0, common_attr_sz);
> + common_attr.log_buf = ptr_to_u64(OPTS_GET(common_attr_opts, log_buf, NULL));
> + common_attr.log_size = OPTS_GET(common_attr_opts, log_size, 0);
> + common_attr.log_level = OPTS_GET(common_attr_opts, log_level, 0);
> + fd = sys_bpf_ext_fd(BPF_MAP_CREATE, &attr, attr_sz, &common_attr, common_attr_sz);
> + OPTS_SET(common_attr_opts, log_true_size, common_attr.log_true_size);
> + } else {
> + fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz);
OPTS_SET(log_true_size) to zero here, maybe?
> + }
> return libbpf_err_errno(fd);
> }
>
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index 2c8e88ddb674..c4a26e6b71ea 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -37,6 +37,18 @@ extern "C" {
>
> LIBBPF_API int libbpf_set_memlock_rlim(size_t memlock_bytes);
>
> +struct bpf_syscall_common_attr_opts {
> + size_t sz; /* size of this struct for forward/backward compatibility */
> +
> + char *log_buf;
> + __u32 log_size;
> + __u32 log_level;
> + __u32 log_true_size;
> +
> + size_t :0;
> +};
> +#define bpf_syscall_common_attr_opts__last_field log_true_size
see below, let's drop this struct and just add these 4 fields directly
to bpf_map_create_opts
> +
> struct bpf_map_create_opts {
> size_t sz; /* size of this struct for forward/backward compatibility */
>
> @@ -57,9 +69,12 @@ struct bpf_map_create_opts {
>
> const void *excl_prog_hash;
> __u32 excl_prog_hash_size;
> +
> + struct bpf_syscall_common_attr_opts *common_attr_opts;
maybe let's just add those log_xxx fields here directly? This whole
extra bpf_syscall_common_attr_opts pointer and struct seems like a
cumbersome API.
> +
> size_t :0;
> };
> -#define bpf_map_create_opts__last_field excl_prog_hash_size
> +#define bpf_map_create_opts__last_field common_attr_opts
>
> LIBBPF_API int bpf_map_create(enum bpf_map_type map_type,
> const char *map_name,
> --
> 2.52.0
>
On 2026/1/16 09:03, Andrii Nakryiko wrote:
> On Mon, Jan 12, 2026 at 6:59 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>>
>> With the previous commit adding common attribute support for
>> BPF_MAP_CREATE, users can now retrieve detailed error messages when map
>> creation fails via the log_buf field.
>>
>> Introduce struct bpf_syscall_common_attr_opts with the following fields:
>> log_buf, log_size, log_level, and log_true_size.
>>
>> Extend bpf_map_create_opts with a new field common_attr_opts, allowing
>> users to capture and inspect log messages on map creation failures.
>>
>> Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
>> ---
>> tools/lib/bpf/bpf.c | 15 ++++++++++++++-
>> tools/lib/bpf/bpf.h | 17 ++++++++++++++++-
>> 2 files changed, 30 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
>> index d44e667aaf02..d65df1b7b2be 100644
>> --- a/tools/lib/bpf/bpf.c
>> +++ b/tools/lib/bpf/bpf.c
>> @@ -207,6 +207,9 @@ int bpf_map_create(enum bpf_map_type map_type,
>> const struct bpf_map_create_opts *opts)
>> {
>> const size_t attr_sz = offsetofend(union bpf_attr, excl_prog_hash_size);
>> + const size_t common_attr_sz = sizeof(struct bpf_common_attr);
>> + struct bpf_syscall_common_attr_opts *common_attr_opts;
>> + struct bpf_common_attr common_attr;
>> union bpf_attr attr;
>> int fd;
>>
>> @@ -240,7 +243,17 @@ int bpf_map_create(enum bpf_map_type map_type,
>> attr.excl_prog_hash = ptr_to_u64(OPTS_GET(opts, excl_prog_hash, NULL));
>> attr.excl_prog_hash_size = OPTS_GET(opts, excl_prog_hash_size, 0);
>>
>> - fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz);
>> + common_attr_opts = OPTS_GET(opts, common_attr_opts, NULL);
>> + if (common_attr_opts && feat_supported(NULL, FEAT_EXTENDED_SYSCALL)) {
>> + memset(&common_attr, 0, common_attr_sz);
>> + common_attr.log_buf = ptr_to_u64(OPTS_GET(common_attr_opts, log_buf, NULL));
>> + common_attr.log_size = OPTS_GET(common_attr_opts, log_size, 0);
>> + common_attr.log_level = OPTS_GET(common_attr_opts, log_level, 0);
>> + fd = sys_bpf_ext_fd(BPF_MAP_CREATE, &attr, attr_sz, &common_attr, common_attr_sz);
>> + OPTS_SET(common_attr_opts, log_true_size, common_attr.log_true_size);
>> + } else {
>> + fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz);
>
> OPTS_SET(log_true_size) to zero here, maybe?
>
Unnecessary, but ok to do it.
>> + }
>> return libbpf_err_errno(fd);
>> }
>>
>> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
>> index 2c8e88ddb674..c4a26e6b71ea 100644
>> --- a/tools/lib/bpf/bpf.h
>> +++ b/tools/lib/bpf/bpf.h
>> @@ -37,6 +37,18 @@ extern "C" {
>>
>> LIBBPF_API int libbpf_set_memlock_rlim(size_t memlock_bytes);
>>
>> +struct bpf_syscall_common_attr_opts {
>> + size_t sz; /* size of this struct for forward/backward compatibility */
>> +
>> + char *log_buf;
>> + __u32 log_size;
>> + __u32 log_level;
>> + __u32 log_true_size;
>> +
>> + size_t :0;
>> +};
>> +#define bpf_syscall_common_attr_opts__last_field log_true_size
>
> see below, let's drop this struct and just add these 4 fields directly
> to bpf_map_create_opts
>
>> +
>> struct bpf_map_create_opts {
>> size_t sz; /* size of this struct for forward/backward compatibility */
>>
>> @@ -57,9 +69,12 @@ struct bpf_map_create_opts {
>>
>> const void *excl_prog_hash;
>> __u32 excl_prog_hash_size;
>> +
>> + struct bpf_syscall_common_attr_opts *common_attr_opts;
>
> maybe let's just add those log_xxx fields here directly? This whole
> extra bpf_syscall_common_attr_opts pointer and struct seems like a
> cumbersome API.
>
Oops... This struct was suggested by the v3 discussion [1].
This struct was used to report 'log_true_size' without changing
'bpf_map_create()' API.
Links
[1]
https://lore.kernel.org/bpf/CAEf4Bzaw9cboFSf1OXmD84S7pKaeyj=bcQg_diUzGwAkFsjUgg@mail.gmail.com/
Thanks,
Leon
>> +
>> size_t :0;
>> };
>> -#define bpf_map_create_opts__last_field excl_prog_hash_size
>> +#define bpf_map_create_opts__last_field common_attr_opts
>>
>> LIBBPF_API int bpf_map_create(enum bpf_map_type map_type,
>> const char *map_name,
>> --
>> 2.52.0
>>
On Fri, Jan 16, 2026 at 6:17 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>
>
>
> On 2026/1/16 09:03, Andrii Nakryiko wrote:
> > On Mon, Jan 12, 2026 at 6:59 AM Leon Hwang <leon.hwang@linux.dev> wrote:
> >>
> >> With the previous commit adding common attribute support for
> >> BPF_MAP_CREATE, users can now retrieve detailed error messages when map
> >> creation fails via the log_buf field.
> >>
> >> Introduce struct bpf_syscall_common_attr_opts with the following fields:
> >> log_buf, log_size, log_level, and log_true_size.
> >>
> >> Extend bpf_map_create_opts with a new field common_attr_opts, allowing
> >> users to capture and inspect log messages on map creation failures.
> >>
> >> Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
> >> ---
> >> tools/lib/bpf/bpf.c | 15 ++++++++++++++-
> >> tools/lib/bpf/bpf.h | 17 ++++++++++++++++-
> >> 2 files changed, 30 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> >> index d44e667aaf02..d65df1b7b2be 100644
> >> --- a/tools/lib/bpf/bpf.c
> >> +++ b/tools/lib/bpf/bpf.c
> >> @@ -207,6 +207,9 @@ int bpf_map_create(enum bpf_map_type map_type,
> >> const struct bpf_map_create_opts *opts)
> >> {
> >> const size_t attr_sz = offsetofend(union bpf_attr, excl_prog_hash_size);
> >> + const size_t common_attr_sz = sizeof(struct bpf_common_attr);
> >> + struct bpf_syscall_common_attr_opts *common_attr_opts;
> >> + struct bpf_common_attr common_attr;
> >> union bpf_attr attr;
> >> int fd;
> >>
> >> @@ -240,7 +243,17 @@ int bpf_map_create(enum bpf_map_type map_type,
> >> attr.excl_prog_hash = ptr_to_u64(OPTS_GET(opts, excl_prog_hash, NULL));
> >> attr.excl_prog_hash_size = OPTS_GET(opts, excl_prog_hash_size, 0);
> >>
> >> - fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz);
> >> + common_attr_opts = OPTS_GET(opts, common_attr_opts, NULL);
> >> + if (common_attr_opts && feat_supported(NULL, FEAT_EXTENDED_SYSCALL)) {
> >> + memset(&common_attr, 0, common_attr_sz);
> >> + common_attr.log_buf = ptr_to_u64(OPTS_GET(common_attr_opts, log_buf, NULL));
> >> + common_attr.log_size = OPTS_GET(common_attr_opts, log_size, 0);
> >> + common_attr.log_level = OPTS_GET(common_attr_opts, log_level, 0);
> >> + fd = sys_bpf_ext_fd(BPF_MAP_CREATE, &attr, attr_sz, &common_attr, common_attr_sz);
> >> + OPTS_SET(common_attr_opts, log_true_size, common_attr.log_true_size);
> >> + } else {
> >> + fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz);
> >
> > OPTS_SET(log_true_size) to zero here, maybe?
> >
>
> Unnecessary, but ok to do it.
>
> >> + }
> >> return libbpf_err_errno(fd);
> >> }
> >>
> >> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> >> index 2c8e88ddb674..c4a26e6b71ea 100644
> >> --- a/tools/lib/bpf/bpf.h
> >> +++ b/tools/lib/bpf/bpf.h
> >> @@ -37,6 +37,18 @@ extern "C" {
> >>
> >> LIBBPF_API int libbpf_set_memlock_rlim(size_t memlock_bytes);
> >>
> >> +struct bpf_syscall_common_attr_opts {
> >> + size_t sz; /* size of this struct for forward/backward compatibility */
> >> +
> >> + char *log_buf;
> >> + __u32 log_size;
> >> + __u32 log_level;
> >> + __u32 log_true_size;
> >> +
> >> + size_t :0;
> >> +};
> >> +#define bpf_syscall_common_attr_opts__last_field log_true_size
> >
> > see below, let's drop this struct and just add these 4 fields directly
> > to bpf_map_create_opts
> >
> >> +
> >> struct bpf_map_create_opts {
> >> size_t sz; /* size of this struct for forward/backward compatibility */
> >>
> >> @@ -57,9 +69,12 @@ struct bpf_map_create_opts {
> >>
> >> const void *excl_prog_hash;
> >> __u32 excl_prog_hash_size;
> >> +
> >> + struct bpf_syscall_common_attr_opts *common_attr_opts;
> >
> > maybe let's just add those log_xxx fields here directly? This whole
> > extra bpf_syscall_common_attr_opts pointer and struct seems like a
> > cumbersome API.
> >
>
> Oops... This struct was suggested by the v3 discussion [1].
>
> This struct was used to report 'log_true_size' without changing
> 'bpf_map_create()' API.
>
Ah, I already forgot. log_true_size being an output parameter here...
Sigh. I don't like the verboseness of bpf_syscall_common_attr_opts and
"common_attr_opts" and all that stuff...
What if we make it struct bpf_log_opts {} and keep it log-specific?
> Links
> [1]
> https://lore.kernel.org/bpf/CAEf4Bzaw9cboFSf1OXmD84S7pKaeyj=bcQg_diUzGwAkFsjUgg@mail.gmail.com/
>
> Thanks,
> Leon
>
> >> +
> >> size_t :0;
> >> };
> >> -#define bpf_map_create_opts__last_field excl_prog_hash_size
> >> +#define bpf_map_create_opts__last_field common_attr_opts
> >>
> >> LIBBPF_API int bpf_map_create(enum bpf_map_type map_type,
> >> const char *map_name,
> >> --
> >> 2.52.0
> >>
>
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