Re: [PATCH V3 2/3] ARM: net: bpf_jit: make code generation less dependent on 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 <a...@arndb.de> 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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