linux-kernel - Re: [PATCH] include/linux/bpf.h - fix missing prototype warnings...

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Message-ID: <5ff21ff7-fd7e-5e90-86a6-d06f9ab4fa3d@iogearbox.net>
Date:   Thu, 31 Jan 2019 10:39:02 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     valdis.kletnieks@...edu, Alexei Starovoitov <ast@...nel.org>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] include/linux/bpf.h - fix missing prototype warnings...

On 01/29/2019 07:04 AM, valdis.kletnieks@...edu wrote:
> Compiling with W=1 generates warnings:
> 
>   CC      kernel/bpf/core.o
> kernel/bpf/core.c:721:12: warning: no previous prototype for ?bpf_jit_alloc_exec_limit? [-Wmissing-prototypes]
>   721 | u64 __weak bpf_jit_alloc_exec_limit(void)
>       |            ^~~~~~~~~~~~~~~~~~~~~~~~
> kernel/bpf/core.c:757:14: warning: no previous prototype for ?bpf_jit_alloc_exec? [-Wmissing-prototypes]
>   757 | void *__weak bpf_jit_alloc_exec(unsigned long size)
>       |              ^~~~~~~~~~~~~~~~~~
> kernel/bpf/core.c:762:13: warning: no previous prototype for ?bpf_jit_free_exec? [-Wmissing-prototypes]
>   762 | void __weak bpf_jit_free_exec(void *addr)
>       |             ^~~~~~~~~~~~~~~~~
> 
> All three are weak functions that archs can override, although none do so
> currently.  Provide prototypes for when a new arch provides its own.
> 
> Signed-off-by: Valdis Kletnieks <valdis.kletnieks@...edu>

Applied all 3 to bpf-next, thanks Valdis!

> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 3851529062ec..99e55313123f 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -472,6 +472,10 @@ _out:							\
>  #define BPF_PROG_RUN_ARRAY_CHECK(array, ctx, func)	\
>  	__BPF_PROG_RUN_ARRAY(array, ctx, func, true)
>  
> +u64 __weak bpf_jit_alloc_exec_limit(void);
> +void *__weak bpf_jit_alloc_exec(unsigned long size);
> +void __weak bpf_jit_free_exec(void *addr);
> +

(I moved these to include/linux/filter.h while applying where we have all the
 other prototypes from JIT core already.)

>  #ifdef CONFIG_BPF_SYSCALL
>  DECLARE_PER_CPU(int, bpf_prog_active);
>  
>