Re: [PATCH V3 2/3] ARM: net: bpf_jit: make code generation less dependenton struct sk_filter.

[Daniel Borkmann]

On 04/26/2013 09:26 PM, Andrew Morton wrote:
> On Fri, 26 Apr 2013 16:04:44 +0200 Arnd Bergmann <arnd@xxxxxxxx> wrote:
> > On Wednesday 24 April 2013 19:27:08 Nicolas Schichan wrote:
> > > @@ -858,7 +858,7 @@ b_epilogue:
> > >   }
> > >
> > >
> > > -void bpf_jit_compile(struct sk_filter *fp)
> > > +static void __bpf_jit_compile(struct jit_ctx *out_ctx)
> > >   {
> > >          struct jit_ctx ctx;
> > >          unsigned tmp_idx;
> > > @@ -867,11 +867,10 @@ void bpf_jit_compile(struct sk_filter *fp)
> > >          if (!bpf_jit_enable)
> > >                  return;
> > >
> > > -       memset(&ctx, 0, sizeof(ctx));
> > > -       ctx.skf         = fp;
> > > +       ctx = *out_ctx;
> > >          ctx.ret0_fp_idx = -1;
> > >
> > > -       ctx.offsets = kzalloc(4 * (ctx.skf->len + 1), GFP_KERNEL);
> > > +       ctx.offsets = kzalloc(4 * (ctx.prog_len + 1), GFP_KERNEL);
> > >          if (ctx.offsets == NULL)
> > >                  return;
> > >
> > > @@ -921,13 +920,26 @@ void bpf_jit_compile(struct sk_filter *fp)
> > >                  print_hex_dump(KERN_INFO, "BPF JIT code: ",
> > >                                 DUMP_PREFIX_ADDRESS, 16, 4, ctx.target,
> > >                                 alloc_size, false);
> > > -
> > > -       fp->bpf_func = (void *)ctx.target;
> > >   out:
> > >          kfree(ctx.offsets);
> > > +
> > > +       *out_ctx = ctx;
> > >          return;
> >
> > This part of the patch, in combination with 79617801e "filter: bpf_jit_comp:
> > refactor and unify BPF JIT image dump output" is now causing build errors
> > in linux-next:
> >
> > arch/arm/net/bpf_jit_32.c: In function '__bpf_jit_compile':
> > arch/arm/net/bpf_jit_32.c:930:16: error: 'fp' undeclared (first use in this function)
> >     bpf_jit_dump(fp->len, alloc_size, 2, ctx.target);
>
> Thanks, I did this.  There may be a smarter way...

I think also seccomp_jit_compile() would need this change then, otherwise the build
with CONFIG_SECCOMP_FILTER_JIT might break.

I can fix this up for you if not already applied. I presume it's against
linux-next tree?

> --- a/arch/arm/net/bpf_jit_32.c~arm-net-bpf_jit-make-code-generation-less-dependent-on-struct-sk_filter-fix
> +++ a/arch/arm/net/bpf_jit_32.c
> @@ -858,7 +858,7 @@ b_epilogue:
>   }
>
>
> -static void __bpf_jit_compile(struct jit_ctx *out_ctx)
> +static void __bpf_jit_compile(struct sk_filter *fp, struct jit_ctx *out_ctx)
>   {
>   	struct jit_ctx ctx;
>   	unsigned tmp_idx;
> @@ -934,7 +934,7 @@ void bpf_jit_compile(struct sk_filter *f
>   	ctx.prog_len = fp->len;
>   	ctx.prog_insns = fp->insns;
>
> -	__bpf_jit_compile(&ctx);
> +	__bpf_jit_compile(fp, &ctx);
>   	if (ctx.target)
>   		fp->bpf_func = (void *)ctx.target;
>   }
> _
>
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