mirror of
https://github.com/xdp-project/BNG-router.git
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74 lines
2.0 KiB
C
74 lines
2.0 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (C) 2020 Authors of Cilium */
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/* For now, only import the xdp_load_bytes() and xdp_store_bytes() helpers
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* from Cilium.
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*/
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#ifndef __XDP_CONTEXT_HELPERS_H
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#define __XDP_CONTEXT_HELPERS_H
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#include <linux/types.h>
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#include <linux/bpf.h>
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#include "../bpf/builtins.h"
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#include "../bpf/errno.h"
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/* This must be a mask and all offsets guaranteed to be less than that. */
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#define __CTX_OFF_MAX 0x3fff
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static __always_inline __maybe_unused int
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xdp_load_bytes(const struct xdp_md *ctx, __u64 off, void *to, const __u64 len)
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{
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void *from;
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int ret;
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/* LLVM tends to generate code that verifier doesn't understand,
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* so force it the way we want it in order to open up a range
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* on the reg.
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*/
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asm volatile("r1 = *(u32 *)(%[ctx] +0)\n\t"
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"r2 = *(u32 *)(%[ctx] +4)\n\t"
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"%[off] &= %[offmax]\n\t"
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"r1 += %[off]\n\t"
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"%[from] = r1\n\t"
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"r1 += %[len]\n\t"
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"if r1 > r2 goto +2\n\t"
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"%[ret] = 0\n\t"
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"goto +1\n\t"
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"%[ret] = %[errno]\n\t"
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: [ret]"=r"(ret), [from]"=r"(from)
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: [ctx]"r"(ctx), [off]"r"(off), [len]"ri"(len),
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[offmax]"i"(__CTX_OFF_MAX), [errno]"i"(-EINVAL)
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: "r1", "r2");
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if (!ret)
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memcpy(to, from, len);
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return ret;
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}
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static __always_inline __maybe_unused int
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xdp_store_bytes(const struct xdp_md *ctx, __u64 off, const void *from,
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const __u64 len, __u64 flags __maybe_unused)
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{
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void *to;
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int ret;
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/* See xdp_load_bytes(). */
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asm volatile("r1 = *(u32 *)(%[ctx] +0)\n\t"
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"r2 = *(u32 *)(%[ctx] +4)\n\t"
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"%[off] &= %[offmax]\n\t"
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"r1 += %[off]\n\t"
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"%[to] = r1\n\t"
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"r1 += %[len]\n\t"
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"if r1 > r2 goto +2\n\t"
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"%[ret] = 0\n\t"
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"goto +1\n\t"
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"%[ret] = %[errno]\n\t"
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: [ret]"=r"(ret), [to]"=r"(to)
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: [ctx]"r"(ctx), [off]"r"(off), [len]"ri"(len),
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[offmax]"i"(__CTX_OFF_MAX), [errno]"i"(-EINVAL)
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: "r1", "r2");
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if (!ret)
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memcpy(to, from, len);
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return ret;
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}
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#endif
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