* [PATCH net-next] bpf/tracing: fix kernel/events/core.c compilation error
@ 2017-12-13 7:42 Yonghong Song
2017-12-13 15:44 ` Daniel Borkmann
0 siblings, 1 reply; 4+ messages in thread
From: Yonghong Song @ 2017-12-13 7:42 UTC (permalink / raw)
To: ast, daniel, sfr, netdev; +Cc: kernel-team
Commit f371b304f12e ("bpf/tracing: allow user space to
query prog array on the same tp") introduced a perf
ioctl command to query prog array attached to the
same perf tracepoint. The commit introduced a
compilation error when either CONFIG_BPF_SYSCALL or
CONFIG_EVENT_TRACING is not defined:
kernel/events/core.o: In function `perf_ioctl':
core.c:(.text+0x98c4): undefined reference to `bpf_event_query_prog_array'
This patch fixed this error.
Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Yonghong Song <yhs@fb.com>
---
include/linux/bpf.h | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 93e15b9..8dbbfd7 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -254,7 +254,6 @@ typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src,
u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);
-int bpf_event_query_prog_array(struct perf_event *event, void __user *info);
int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr);
@@ -558,6 +557,15 @@ static inline int sock_map_prog(struct bpf_map *map,
}
#endif
+#if defined(CONFIG_EVENT_TRACING) && defined(CONFIG_BPF_SYSCALL)
+int bpf_event_query_prog_array(struct perf_event *event, void __user *info);
+#else
+static inline int bpf_event_query_prog_array(struct perf_event *event, void __user *info)
+{
+ return -EOPNOTSUPP;
+}
+#endif
+
/* verifier prototypes for helper functions called from eBPF programs */
extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
extern const struct bpf_func_proto bpf_map_update_elem_proto;
--
2.9.5
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH net-next] bpf/tracing: fix kernel/events/core.c compilation error
2017-12-13 7:42 [PATCH net-next] bpf/tracing: fix kernel/events/core.c compilation error Yonghong Song
@ 2017-12-13 15:44 ` Daniel Borkmann
2017-12-13 15:50 ` Alexei Starovoitov
0 siblings, 1 reply; 4+ messages in thread
From: Daniel Borkmann @ 2017-12-13 15:44 UTC (permalink / raw)
To: Yonghong Song, ast, sfr, netdev; +Cc: kernel-team
On 12/13/2017 08:42 AM, Yonghong Song wrote:
> Commit f371b304f12e ("bpf/tracing: allow user space to
> query prog array on the same tp") introduced a perf
> ioctl command to query prog array attached to the
> same perf tracepoint. The commit introduced a
> compilation error when either CONFIG_BPF_SYSCALL or
> CONFIG_EVENT_TRACING is not defined:
> kernel/events/core.o: In function `perf_ioctl':
> core.c:(.text+0x98c4): undefined reference to `bpf_event_query_prog_array'
>
> This patch fixed this error.
>
> Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp")
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Signed-off-by: Yonghong Song <yhs@fb.com>
Looking at _perf_ioctl(), we also have perf_event_set_bpf_prog()
there. It's basically under CONFIG_EVENT_TRACING, which later calls
perf_event_attach_bpf_prog() which is under CONFIG_BPF_EVENTS, so
where we have the dummy handler returning -EOPNOTSUPP when BPF
events is not set. bpf_trace.c is only built when CONFIG_BPF_EVENTS
is set and that by itself depends on BPF_SYSCALL already. So it would
be more correct to do the same thing here ...
#if defined(CONFIG_EVENT_TRACING) && defined(CONFIG_BPF_EVENTS)
[...]
> ---
> include/linux/bpf.h | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 93e15b9..8dbbfd7 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -254,7 +254,6 @@ typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src,
>
> u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
> void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);
> -int bpf_event_query_prog_array(struct perf_event *event, void __user *info);
>
> int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
> union bpf_attr __user *uattr);
> @@ -558,6 +557,15 @@ static inline int sock_map_prog(struct bpf_map *map,
> }
> #endif
>
> +#if defined(CONFIG_EVENT_TRACING) && defined(CONFIG_BPF_SYSCALL)
> +int bpf_event_query_prog_array(struct perf_event *event, void __user *info);
> +#else
> +static inline int bpf_event_query_prog_array(struct perf_event *event, void __user *info)
> +{
> + return -EOPNOTSUPP;
> +}
> +#endif
> +
> /* verifier prototypes for helper functions called from eBPF programs */
> extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
> extern const struct bpf_func_proto bpf_map_update_elem_proto;
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH net-next] bpf/tracing: fix kernel/events/core.c compilation error
2017-12-13 15:44 ` Daniel Borkmann
@ 2017-12-13 15:50 ` Alexei Starovoitov
2017-12-13 17:26 ` Yonghong Song
0 siblings, 1 reply; 4+ messages in thread
From: Alexei Starovoitov @ 2017-12-13 15:50 UTC (permalink / raw)
To: Daniel Borkmann, Yonghong Song, sfr, netdev; +Cc: kernel-team
On 12/13/17 7:44 AM, Daniel Borkmann wrote:
> On 12/13/2017 08:42 AM, Yonghong Song wrote:
>> Commit f371b304f12e ("bpf/tracing: allow user space to
>> query prog array on the same tp") introduced a perf
>> ioctl command to query prog array attached to the
>> same perf tracepoint. The commit introduced a
>> compilation error when either CONFIG_BPF_SYSCALL or
>> CONFIG_EVENT_TRACING is not defined:
>> kernel/events/core.o: In function `perf_ioctl':
>> core.c:(.text+0x98c4): undefined reference to `bpf_event_query_prog_array'
>>
>> This patch fixed this error.
>>
>> Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp")
>> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
>> Signed-off-by: Yonghong Song <yhs@fb.com>
>
> Looking at _perf_ioctl(), we also have perf_event_set_bpf_prog()
> there. It's basically under CONFIG_EVENT_TRACING, which later calls
> perf_event_attach_bpf_prog() which is under CONFIG_BPF_EVENTS, so
> where we have the dummy handler returning -EOPNOTSUPP when BPF
> events is not set. bpf_trace.c is only built when CONFIG_BPF_EVENTS
> is set and that by itself depends on BPF_SYSCALL already. So it would
> be more correct to do the same thing here ...
>
> #if defined(CONFIG_EVENT_TRACING) && defined(CONFIG_BPF_EVENTS)
> [...]
+1
#ifdef CONFIG_BPF_EVENTS
works, whereas CONFIG_EVENT_TRACING probably not, since kprobe
can be disabled independently which will turn off BPF_EVENTS
and body of bpf_event_query_prog_array() will be gone.
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH net-next] bpf/tracing: fix kernel/events/core.c compilation error
2017-12-13 15:50 ` Alexei Starovoitov
@ 2017-12-13 17:26 ` Yonghong Song
0 siblings, 0 replies; 4+ messages in thread
From: Yonghong Song @ 2017-12-13 17:26 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, sfr, netdev; +Cc: kernel-team
On 12/13/17 7:50 AM, Alexei Starovoitov wrote:
> On 12/13/17 7:44 AM, Daniel Borkmann wrote:
>> On 12/13/2017 08:42 AM, Yonghong Song wrote:
>>> Commit f371b304f12e ("bpf/tracing: allow user space to
>>> query prog array on the same tp") introduced a perf
>>> ioctl command to query prog array attached to the
>>> same perf tracepoint. The commit introduced a
>>> compilation error when either CONFIG_BPF_SYSCALL or
>>> CONFIG_EVENT_TRACING is not defined:
>>> kernel/events/core.o: In function `perf_ioctl':
>>> core.c:(.text+0x98c4): undefined reference to
>>> `bpf_event_query_prog_array'
>>>
>>> This patch fixed this error.
>>>
>>> Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog
>>> array on the same tp")
>>> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
>>> Signed-off-by: Yonghong Song <yhs@fb.com>
>>
>> Looking at _perf_ioctl(), we also have perf_event_set_bpf_prog()
>> there. It's basically under CONFIG_EVENT_TRACING, which later calls
>> perf_event_attach_bpf_prog() which is under CONFIG_BPF_EVENTS, so
>> where we have the dummy handler returning -EOPNOTSUPP when BPF
>> events is not set. bpf_trace.c is only built when CONFIG_BPF_EVENTS
>> is set and that by itself depends on BPF_SYSCALL already. So it would
>> be more correct to do the same thing here ...
>>
>> #if defined(CONFIG_EVENT_TRACING) && defined(CONFIG_BPF_EVENTS)
>> [...]
>
> +1
> #ifdef CONFIG_BPF_EVENTS
> works, whereas CONFIG_EVENT_TRACING probably not, since kprobe
> can be disabled independently which will turn off BPF_EVENTS
> and body of bpf_event_query_prog_array() will be gone.
I tested to enable/disable uprobe/kprobe/both and my patch works.
But I did not test enable a non uprobe/kprobe tracing event
(e.g., CONFIG_FUNCTION_TRACER) where CONFIG_TRACING and
CONFIG_EVENT_TRACING is on but CONFIG_UPROBES_EVENT/CONFIG_KPROBES_EVENT
is off and then my patch breaks.
Looks like
#ifdef CONFIG_BPF_EVENTS
is suffice.
This config will enable to include bpf_trace.c with the real definition.
It will depend on KPROBE_EVENTS or UPROBE_EVENTS and either
of them will enable CONFIG_TRACING and then CONFIG_EVENT_TRACING.
Will resubmit the patch after testing.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-12-13 7:42 [PATCH net-next] bpf/tracing: fix kernel/events/core.c compilation error Yonghong Song
2017-12-13 15:44 ` Daniel Borkmann
2017-12-13 15:50 ` Alexei Starovoitov
2017-12-13 17:26 ` Yonghong Song
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