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

From: Andrew Morton
Date: Fri Apr 26 2013 - 16:09:54 EST


On Fri, 26 Apr 2013 21:47:46 +0200 Daniel Borkmann <dborkman@xxxxxxxxxx> wrote:

> 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.

urgh, that tears it.

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

Yup, please send something.

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