[PATCH] net: export pkt_type_offset() helper

[PATCH] net: export pkt_type_offset() helper

[Denis Kirjanov]

Currently we have 2 pkt_type_offset functions doing
the same thing and spread across the architecture files.
Let's use the generic helper routine.

Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Daniel Borkmann <dborkman@redhat.com>
---
 arch/mips/net/bpf_jit.c      | 21 ---------------------
 arch/s390/net/bpf_jit_comp.c | 38 ++++----------------------------------
 include/linux/filter.h       |  7 +++++++
 net/core/filter.c            |  7 +------
 4 files changed, 12 insertions(+), 61 deletions(-)

diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
index 05a5661..08ff823 100644
--- a/arch/mips/net/bpf_jit.c
+++ b/arch/mips/net/bpf_jit.c
@@ -765,27 +765,6 @@ static u64 jit_get_skb_w(struct sk_buff *skb, unsigned offset)
 	return (u64)err << 32 | ntohl(ret);
 }
 
-#ifdef __BIG_ENDIAN_BITFIELD
-#define PKT_TYPE_MAX	(7 << 5)
-#else
-#define PKT_TYPE_MAX	7
-#endif
-static int pkt_type_offset(void)
-{
-	struct sk_buff skb_probe = {
-		.pkt_type = ~0,
-	};
-	u8 *ct = (u8 *)&skb_probe;
-	unsigned int off;
-
-	for (off = 0; off < sizeof(struct sk_buff); off++) {
-		if (ct[off] == PKT_TYPE_MAX)
-			return off;
-	}
-	pr_err_once("Please fix pkt_type_offset(), as pkt_type couldn't be found\n");
-	return -1;
-}
-
 static int build_body(struct jit_ctx *ctx)
 {
 	void *load_func[] = {jit_get_skb_b, jit_get_skb_h, jit_get_skb_w};
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 61e45b7..34383d1 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -223,37 +223,6 @@ static void bpf_jit_epilogue(struct bpf_jit *jit)
 	EMIT2(0x07fe);
 }
 
-/* Helper to find the offset of pkt_type in sk_buff
- * Make sure its still a 3bit field starting at the MSBs within a byte.
- */
-#define PKT_TYPE_MAX 0xe0
-static int pkt_type_offset;
-
-static int __init bpf_pkt_type_offset_init(void)
-{
-	struct sk_buff skb_probe = {
-		.pkt_type = ~0,
-	};
-	char *ct = (char *)&skb_probe;
-	int off;
-
-	pkt_type_offset = -1;
-	for (off = 0; off < sizeof(struct sk_buff); off++) {
-		if (!ct[off])
-			continue;
-		if (ct[off] == PKT_TYPE_MAX)
-			pkt_type_offset = off;
-		else {
-			/* Found non matching bit pattern, fix needed. */
-			WARN_ON_ONCE(1);
-			pkt_type_offset = -1;
-			return -1;
-		}
-	}
-	return 0;
-}
-device_initcall(bpf_pkt_type_offset_init);
-
 /*
  * make sure we dont leak kernel information to user
  */
@@ -753,12 +722,13 @@ call_fn:	/* lg %r1,<d(function)>(%r13) */
 		}
 		break;
 	case BPF_ANC | SKF_AD_PKTTYPE:
-		if (pkt_type_offset < 0)
+		offset = pkt_type_offset();
+		if (offset < 0)
 			goto out;
 		/* lhi %r5,0 */
 		EMIT4(0xa7580000);
-		/* ic %r5,<d(pkt_type_offset)>(%r2) */
-		EMIT4_DISP(0x43502000, pkt_type_offset);
+		/* ic %r5,<d(offset)>(%r2) */
+		EMIT4_DISP(0x43502000, offset);
 		/* srl %r5,5 */
 		EMIT4_DISP(0x88500000, 5);
 		break;
diff --git a/include/linux/filter.h b/include/linux/filter.h
index a5227ab..97e0549 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -424,6 +424,13 @@ static inline void *bpf_load_pointer(const struct sk_buff *skb, int k,
 	return bpf_internal_load_pointer_neg_helper(skb, k, size);
 }
 
+#ifdef __BIG_ENDIAN_BITFIELD
+#define PKT_TYPE_MAX	(7 << 5)
+#else
+#define PKT_TYPE_MAX    7
+#endif
+unsigned int pkt_type_offset(void);
+
 #ifdef CONFIG_BPF_JIT
 #include <stdarg.h>
 #include <linux/linkage.h>
diff --git a/net/core/filter.c b/net/core/filter.c
index d814b8a..b4a2e00 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -91,12 +91,7 @@ EXPORT_SYMBOL(sk_filter);
  * to make sure its still a 3bit field starting at a byte boundary;
  * taken from arch/x86/net/bpf_jit_comp.c.
  */
-#ifdef __BIG_ENDIAN_BITFIELD
-#define PKT_TYPE_MAX	(7 << 5)
-#else
-#define PKT_TYPE_MAX	7
-#endif
-static unsigned int pkt_type_offset(void)
+unsigned int pkt_type_offset(void)
 {
 	struct sk_buff skb_probe = { .pkt_type = ~0, };
 	u8 *ct = (u8 *) &skb_probe;
-- 
2.0.0

Re: [PATCH] net: export pkt_type_offset() helper

[Alexei Starovoitov]

On Wed, Sep 03, 2014 at 12:03:58AM +0400, Denis Kirjanov wrote:
> Currently we have 2 pkt_type_offset functions doing
> the same thing and spread across the architecture files.
> Let's use the generic helper routine.

that would be good cleanup.
Please tag your subject as '[PATCH net-next]...'

> Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
> Cc: Markos Chandras <markos.chandras@imgtec.com>
> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> Cc: Daniel Borkmann <dborkman@redhat.com>
> ---
>  arch/mips/net/bpf_jit.c      | 21 ---------------------
>  arch/s390/net/bpf_jit_comp.c | 38 ++++----------------------------------
>  include/linux/filter.h       |  7 +++++++
>  net/core/filter.c            |  7 +------
>  4 files changed, 12 insertions(+), 61 deletions(-)
> 
> diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
> -#define PKT_TYPE_MAX 0xe0
> -static int pkt_type_offset;
...
> -}
> -device_initcall(bpf_pkt_type_offset_init);

may be make sense to optimize common case via initcall() as well
instead of dropping it for s390?

> diff --git a/include/linux/filter.h b/include/linux/filter.h
> index a5227ab..97e0549 100644
> --- a/include/linux/filter.h
> +++ b/include/linux/filter.h
> @@ -424,6 +424,13 @@ static inline void *bpf_load_pointer(const struct sk_buff *skb, int k,
>  	return bpf_internal_load_pointer_neg_helper(skb, k, size);
>  }
>  
> +#ifdef __BIG_ENDIAN_BITFIELD
> +#define PKT_TYPE_MAX	(7 << 5)
> +#else
> +#define PKT_TYPE_MAX    7
> +#endif

these defines don't need to move. keep them in filter.c

Re: [PATCH] net: export pkt_type_offset() helper

[Daniel Borkmann]

On 09/03/2014 12:59 AM, Alexei Starovoitov wrote:
> On Wed, Sep 03, 2014 at 12:03:58AM +0400, Denis Kirjanov wrote:
>> Currently we have 2 pkt_type_offset functions doing
>> the same thing and spread across the architecture files.
>> Let's use the generic helper routine.
>
> that would be good cleanup.
> Please tag your subject as '[PATCH net-next]...'
>
>> Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
>> Cc: Markos Chandras <markos.chandras@imgtec.com>
>> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
>> Cc: Daniel Borkmann <dborkman@redhat.com>
>> ---
>>   arch/mips/net/bpf_jit.c      | 21 ---------------------
>>   arch/s390/net/bpf_jit_comp.c | 38 ++++----------------------------------
>>   include/linux/filter.h       |  7 +++++++
>>   net/core/filter.c            |  7 +------
>>   4 files changed, 12 insertions(+), 61 deletions(-)
>>
>> diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
>> -#define PKT_TYPE_MAX 0xe0
>> -static int pkt_type_offset;
> ...
>> -}
>> -device_initcall(bpf_pkt_type_offset_init);
>
> may be make sense to optimize common case via initcall() as well
> instead of dropping it for s390?

I think that probably might not be a bad idea. pkt_type_offset
should be a __read_mostly candidate then. As we have things like
PTP classifier that is being loaded in core_initcall(), we might
need to initialize pkt_type_offset then via pure_initcall(),
for example. I think that should be doable, as it doesn't have
any dependencies elsewhere.

>> diff --git a/include/linux/filter.h b/include/linux/filter.h
>> index a5227ab..97e0549 100644
>> --- a/include/linux/filter.h
>> +++ b/include/linux/filter.h
>> @@ -424,6 +424,13 @@ static inline void *bpf_load_pointer(const struct sk_buff *skb, int k,
>>   	return bpf_internal_load_pointer_neg_helper(skb, k, size);
>>   }
>>
>> +#ifdef __BIG_ENDIAN_BITFIELD
>> +#define PKT_TYPE_MAX	(7 << 5)
>> +#else
>> +#define PKT_TYPE_MAX    7
>> +#endif
>
> these defines don't need to move. keep them in filter.c
>

Re: [PATCH] net: export pkt_type_offset() helper

[Denis Kirjanov]

On 9/3/14, Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:
> On Wed, Sep 03, 2014 at 12:03:58AM +0400, Denis Kirjanov wrote:
>> Currently we have 2 pkt_type_offset functions doing
>> the same thing and spread across the architecture files.
>> Let's use the generic helper routine.
>
> that would be good cleanup.
> Please tag your subject as '[PATCH net-next]...'
>
>> Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
>> Cc: Markos Chandras <markos.chandras@imgtec.com>
>> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
>> Cc: Daniel Borkmann <dborkman@redhat.com>
>> ---
>>  arch/mips/net/bpf_jit.c      | 21 ---------------------
>>  arch/s390/net/bpf_jit_comp.c | 38 ++++----------------------------------
>>  include/linux/filter.h       |  7 +++++++
>>  net/core/filter.c            |  7 +------
>>  4 files changed, 12 insertions(+), 61 deletions(-)
>>
>> diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
>> -#define PKT_TYPE_MAX 0xe0
>> -static int pkt_type_offset;
> ...
>> -}
>> -device_initcall(bpf_pkt_type_offset_init);
>
> may be make sense to optimize common case via initcall() as well
> instead of dropping it for s390?

Yeah, it's a better option.
>
>> diff --git a/include/linux/filter.h b/include/linux/filter.h
>> index a5227ab..97e0549 100644
>> --- a/include/linux/filter.h
>> +++ b/include/linux/filter.h
>> @@ -424,6 +424,13 @@ static inline void *bpf_load_pointer(const struct
>> sk_buff *skb, int k,
>>  	return bpf_internal_load_pointer_neg_helper(skb, k, size);
>>  }
>>
>> +#ifdef __BIG_ENDIAN_BITFIELD
>> +#define PKT_TYPE_MAX	(7 << 5)
>> +#else
>> +#define PKT_TYPE_MAX    7
>> +#endif
>
> these defines don't need to move. keep them in filter.c

I'll respin. Thanks!
>
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-- 
Regards,
Denis