Messages in this thread Patch in this message | | | From | Wang Nan <> | Subject | [RFC PATCH v10 01/50] bpf: Use correct #ifdef controller for trace_call_bpf() | Date | Wed, 1 Jul 2015 02:13:49 +0000 |
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Commit e1abf2cc8d5d80b41c4419368ec743ccadbb131e ("bpf: Fix the build on BPF_SYSCALL=y && !CONFIG_TRACING kernels, make it more configurable") updated the building condition of bpf_trace.o from CONFIG_BPF_SYSCALL to CONFIG_BPF_EVENTS, but the corresponding #ifdef controller in ftrace_event.h for trace_call_bpf() is not changed. Which, in theory, is incorrect.
With current Kconfigs, we can create a .config with CONFIG_BPF_SYSCALL=y and CONFIG_BPF_EVENTS=n by unselecting CONFIG_KPROBE_EVENT and selecting CONFIG_BPF_SYSCALL. With these options, trace_call_bpf() will be defined as an extern function, but if anyone calls it a symbol missing error will be trigger since bpf_trace.o is not build.
This patch changes the #ifdef controller for trace_call_bpf() from CONFIG_BPF_SYSCALL to CONFIG_BPF_EVENTS. I'll show its correctness:
Before this patch:
BPF_SYSCALL BPF_EVENTS trace_call_bpf bpf_trace.o y y normal compiled n n inline not compiled y n normal not compiled (incorrect) n y impossible (BPF_EVENTS depends on BPF_SYSCALL)
After this patch:
BPF_SYSCALL BPF_EVENTS trace_call_bpf bpf_trace.o y y normal compiled n n inline not compiled y n inline not compiled (fixed) n y impossible (BPF_EVENTS depends on BPF_SYSCALL)
So this patch doesn't break thing. QED.
Signed-off-by: Wang Nan <wangnan0@huawei.com> --- include/linux/ftrace_event.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index f9ecf63..ec48c92 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -553,7 +553,7 @@ event_trigger_unlock_commit_regs(struct ftrace_event_file *file, event_triggers_post_call(file, tt); } -#ifdef CONFIG_BPF_SYSCALL +#ifdef CONFIG_BPF_EVENTS unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx); #else static inline unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx) -- 1.8.3.4
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