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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/net/sched/em_cmp.c
15109 views
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/*

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 * net/sched/em_cmp.c	Simple packet data comparison ematch

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 *

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 *		This program is free software; you can redistribute it and/or

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 *		modify it under the terms of the GNU General Public License

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 *		as published by the Free Software Foundation; either version

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 *		2 of the License, or (at your option) any later version.

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 *

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 * Authors:	Thomas Graf <[email protected]>

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 */

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#include <linux/module.h>

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#include <linux/types.h>

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#include <linux/kernel.h>

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#include <linux/skbuff.h>

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#include <linux/tc_ematch/tc_em_cmp.h>

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#include <asm/unaligned.h>

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#include <net/pkt_cls.h>

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static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp)

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{

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	return unlikely(cmp->flags & TCF_EM_CMP_TRANS);

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}

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static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em,

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			struct tcf_pkt_info *info)

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{

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	struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data;

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	unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off;

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	u32 val = 0;

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	if (!tcf_valid_offset(skb, ptr, cmp->align))

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		return 0;

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	switch (cmp->align) {

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	case TCF_EM_ALIGN_U8:

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		val = *ptr;

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		break;

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	case TCF_EM_ALIGN_U16:

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		val = get_unaligned_be16(ptr);

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		if (cmp_needs_transformation(cmp))

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			val = be16_to_cpu(val);

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		break;

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	case TCF_EM_ALIGN_U32:

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		/* Worth checking boundries? The branching seems

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		 * to get worse. Visit again.

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		 */

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		val = get_unaligned_be32(ptr);

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		if (cmp_needs_transformation(cmp))

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			val = be32_to_cpu(val);

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		break;

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	default:

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		return 0;

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	}

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	if (cmp->mask)

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		val &= cmp->mask;

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	switch (cmp->opnd) {

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	case TCF_EM_OPND_EQ:

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		return val == cmp->val;

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	case TCF_EM_OPND_LT:

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		return val < cmp->val;

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	case TCF_EM_OPND_GT:

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		return val > cmp->val;

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	}

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	return 0;

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}

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static struct tcf_ematch_ops em_cmp_ops = {

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	.kind	  = TCF_EM_CMP,

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	.datalen  = sizeof(struct tcf_em_cmp),

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	.match	  = em_cmp_match,

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	.owner	  = THIS_MODULE,

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	.link	  = LIST_HEAD_INIT(em_cmp_ops.link)

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};

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static int __init init_em_cmp(void)

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{

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	return tcf_em_register(&em_cmp_ops);

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}

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static void __exit exit_em_cmp(void)

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{

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	tcf_em_unregister(&em_cmp_ops);

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}

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MODULE_LICENSE("GPL");

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module_init(init_em_cmp);

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module_exit(exit_em_cmp);

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MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP);

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