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99c55f7d47
BPF syscall is a multiplexor for a range of different operations on eBPF.
This patch introduces syscall with single command to create a map.
Next patch adds commands to access maps.
'maps' is a generic storage of different types for sharing data between kernel
and userspace.
Userspace example:
/* this syscall wrapper creates a map with given type and attributes
* and returns map_fd on success.
* use close(map_fd) to delete the map
*/
int bpf_create_map(enum bpf_map_type map_type, int key_size,
int value_size, int max_entries)
{
union bpf_attr attr = {
.map_type = map_type,
.key_size = key_size,
.value_size = value_size,
.max_entries = max_entries
};
return bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
}
'union bpf_attr' is backwards compatible with future extensions.
More details in Documentation/networking/filter.txt and in manpage
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
88 lines
2.3 KiB
C
88 lines
2.3 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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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 version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#ifndef _UAPI__LINUX_BPF_H__
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#define _UAPI__LINUX_BPF_H__
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#include <linux/types.h>
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/* Extended instruction set based on top of classic BPF */
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/* instruction classes */
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#define BPF_ALU64 0x07 /* alu mode in double word width */
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/* ld/ldx fields */
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#define BPF_DW 0x18 /* double word */
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#define BPF_XADD 0xc0 /* exclusive add */
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/* alu/jmp fields */
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#define BPF_MOV 0xb0 /* mov reg to reg */
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#define BPF_ARSH 0xc0 /* sign extending arithmetic shift right */
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/* change endianness of a register */
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#define BPF_END 0xd0 /* flags for endianness conversion: */
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#define BPF_TO_LE 0x00 /* convert to little-endian */
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#define BPF_TO_BE 0x08 /* convert to big-endian */
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#define BPF_FROM_LE BPF_TO_LE
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#define BPF_FROM_BE BPF_TO_BE
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#define BPF_JNE 0x50 /* jump != */
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#define BPF_JSGT 0x60 /* SGT is signed '>', GT in x86 */
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#define BPF_JSGE 0x70 /* SGE is signed '>=', GE in x86 */
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#define BPF_CALL 0x80 /* function call */
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#define BPF_EXIT 0x90 /* function return */
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/* Register numbers */
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enum {
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BPF_REG_0 = 0,
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BPF_REG_1,
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BPF_REG_2,
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BPF_REG_3,
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BPF_REG_4,
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BPF_REG_5,
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BPF_REG_6,
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BPF_REG_7,
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BPF_REG_8,
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BPF_REG_9,
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BPF_REG_10,
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__MAX_BPF_REG,
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};
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/* BPF has 10 general purpose 64-bit registers and stack frame. */
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#define MAX_BPF_REG __MAX_BPF_REG
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struct bpf_insn {
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__u8 code; /* opcode */
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__u8 dst_reg:4; /* dest register */
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__u8 src_reg:4; /* source register */
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__s16 off; /* signed offset */
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__s32 imm; /* signed immediate constant */
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};
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/* BPF syscall commands */
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enum bpf_cmd {
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/* create a map with given type and attributes
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* fd = bpf(BPF_MAP_CREATE, union bpf_attr *, u32 size)
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* returns fd or negative error
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* map is deleted when fd is closed
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*/
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BPF_MAP_CREATE,
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};
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enum bpf_map_type {
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BPF_MAP_TYPE_UNSPEC,
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};
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union bpf_attr {
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struct { /* anonymous struct used by BPF_MAP_CREATE command */
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__u32 map_type; /* one of enum bpf_map_type */
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__u32 key_size; /* size of key in bytes */
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__u32 value_size; /* size of value in bytes */
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__u32 max_entries; /* max number of entries in a map */
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};
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} __attribute__((aligned(8)));
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#endif /* _UAPI__LINUX_BPF_H__ */
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