bpf: replace big switch statement with a dispatch table
* bpf.c (DECL_BPF_CMD_DECODER, DEF_BPF_CMD_DECODER, BPF_CMD_ENTRY): New macros. (bpf_cmd_decoder_t): New typedef. Rename static parser functions using DEF_BPF_CMD_DECODER. (decode_BPF_MAP_LOOKUP_ELEM, decode_BPF_MAP_GET_NEXT_KEY): New proxy functions. (SYS_FUNC(bpf)): Replace big switch statement with a dispatch table.
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bpf.c
127
bpf.c
@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2015 Dmitry V. Levin <ldv@altlinux.org>
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* Copyright (c) 2015-2017 Dmitry V. Levin <ldv@altlinux.org>
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* Copyright (c) 2017 Quentin Monnet <quentin.monnet@6wind.com>
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* All rights reserved.
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*
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@ -40,9 +40,22 @@
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#include "xlat/bpf_attach_type.h"
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#include "xlat/bpf_attach_flags.h"
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static int
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bpf_map_create(struct tcb *const tcp, const kernel_ulong_t addr,
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unsigned int size)
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#define DECL_BPF_CMD_DECODER(bpf_cmd_decoder) \
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int \
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bpf_cmd_decoder(struct tcb *const tcp, \
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const kernel_ulong_t addr, \
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unsigned int size) \
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/* End of DECL_BPF_CMD_DECODER definition. */
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#define DEF_BPF_CMD_DECODER(bpf_cmd) \
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static DECL_BPF_CMD_DECODER(decode_ ## bpf_cmd)
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#define BPF_CMD_ENTRY(bpf_cmd) \
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[bpf_cmd] = decode_ ## bpf_cmd
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typedef DECL_BPF_CMD_DECODER((*bpf_cmd_decoder_t));
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DEF_BPF_CMD_DECODER(BPF_MAP_CREATE)
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{
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struct {
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uint32_t map_type, key_size, value_size, max_entries;
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@ -66,9 +79,7 @@ bpf_map_create(struct tcb *const tcp, const kernel_ulong_t addr,
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return RVAL_DECODED | RVAL_FD;
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}
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static void
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bpf_map_update_elem(struct tcb *const tcp, const kernel_ulong_t addr,
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unsigned int size)
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DEF_BPF_CMD_DECODER(BPF_MAP_UPDATE_ELEM)
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{
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struct {
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uint32_t map_fd;
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@ -79,12 +90,12 @@ bpf_map_update_elem(struct tcb *const tcp, const kernel_ulong_t addr,
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if (!size) {
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printaddr(addr);
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return;
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return RVAL_DECODED;
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}
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if (size > sizeof(attr))
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size = sizeof(attr);
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if (umoven_or_printaddr(tcp, addr, size, &attr))
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return;
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return RVAL_DECODED;
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PRINT_FIELD_FD("{", attr, map_fd, tcp);
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PRINT_FIELD_X(", ", attr, key);
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@ -92,11 +103,10 @@ bpf_map_update_elem(struct tcb *const tcp, const kernel_ulong_t addr,
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PRINT_FIELD_XVAL(", ", attr, flags, bpf_map_update_elem_flags,
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"BPF_???");
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tprints("}");
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return RVAL_DECODED;
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}
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static void
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bpf_map_delete_elem(struct tcb *const tcp, const kernel_ulong_t addr,
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unsigned int size)
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DEF_BPF_CMD_DECODER(BPF_MAP_DELETE_ELEM)
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{
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struct {
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uint32_t map_fd;
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@ -105,16 +115,17 @@ bpf_map_delete_elem(struct tcb *const tcp, const kernel_ulong_t addr,
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if (!size) {
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printaddr(addr);
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return;
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return RVAL_DECODED;
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}
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if (size > sizeof(attr))
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size = sizeof(attr);
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if (umoven_or_printaddr(tcp, addr, size, &attr))
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return;
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return RVAL_DECODED;
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PRINT_FIELD_FD("{", attr, map_fd, tcp);
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PRINT_FIELD_X(", ", attr, key);
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tprints("}");
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return RVAL_DECODED;
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}
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static int
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@ -149,9 +160,17 @@ bpf_map_io(struct tcb *const tcp, const kernel_ulong_t addr, unsigned int size,
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return 0;
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}
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static int
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bpf_prog_load(struct tcb *const tcp, const kernel_ulong_t addr,
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unsigned int size)
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DEF_BPF_CMD_DECODER(BPF_MAP_LOOKUP_ELEM)
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{
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return bpf_map_io(tcp, addr, size, "value");
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}
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DEF_BPF_CMD_DECODER(BPF_MAP_GET_NEXT_KEY)
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{
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return bpf_map_io(tcp, addr, size, "next_key");
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}
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DEF_BPF_CMD_DECODER(BPF_PROG_LOAD)
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{
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struct {
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uint32_t prog_type, insn_cnt;
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@ -183,9 +202,7 @@ bpf_prog_load(struct tcb *const tcp, const kernel_ulong_t addr,
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return RVAL_DECODED | RVAL_FD;
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}
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static int
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bpf_obj_manage(struct tcb *const tcp, const kernel_ulong_t addr,
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unsigned int size)
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static DECL_BPF_CMD_DECODER(bpf_obj_manage)
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{
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struct {
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uint64_t ATTRIBUTE_ALIGNED(8) pathname;
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@ -208,6 +225,16 @@ bpf_obj_manage(struct tcb *const tcp, const kernel_ulong_t addr,
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return RVAL_DECODED | RVAL_FD;
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}
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DEF_BPF_CMD_DECODER(BPF_OBJ_PIN)
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{
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return bpf_obj_manage(tcp, addr, size);
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}
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DEF_BPF_CMD_DECODER(BPF_OBJ_GET)
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{
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return bpf_obj_manage(tcp, addr, size);
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}
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static int
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bpf_prog_attach_detach(struct tcb *const tcp, const kernel_ulong_t addr,
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unsigned int size, bool print_attach)
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@ -237,66 +264,46 @@ bpf_prog_attach_detach(struct tcb *const tcp, const kernel_ulong_t addr,
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return RVAL_DECODED;
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}
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static int
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bpf_prog_attach(struct tcb *const tcp, const kernel_ulong_t addr,
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unsigned int size)
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DEF_BPF_CMD_DECODER(BPF_PROG_ATTACH)
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{
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return bpf_prog_attach_detach(tcp, addr, size, true);
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}
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static int
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bpf_prog_detach(struct tcb *const tcp, const kernel_ulong_t addr,
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unsigned int size)
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DEF_BPF_CMD_DECODER(BPF_PROG_DETACH)
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{
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return bpf_prog_attach_detach(tcp, addr, size, false);
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}
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SYS_FUNC(bpf)
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{
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static const bpf_cmd_decoder_t bpf_cmd_decoders[] = {
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BPF_CMD_ENTRY(BPF_MAP_CREATE),
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BPF_CMD_ENTRY(BPF_MAP_LOOKUP_ELEM),
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BPF_CMD_ENTRY(BPF_MAP_UPDATE_ELEM),
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BPF_CMD_ENTRY(BPF_MAP_DELETE_ELEM),
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BPF_CMD_ENTRY(BPF_MAP_GET_NEXT_KEY),
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BPF_CMD_ENTRY(BPF_PROG_LOAD),
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BPF_CMD_ENTRY(BPF_OBJ_PIN),
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BPF_CMD_ENTRY(BPF_OBJ_GET),
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BPF_CMD_ENTRY(BPF_PROG_ATTACH),
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BPF_CMD_ENTRY(BPF_PROG_DETACH),
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};
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const unsigned int cmd = tcp->u_arg[0];
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const kernel_ulong_t addr = tcp->u_arg[1];
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const unsigned int size = tcp->u_arg[2];
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int rc = RVAL_DECODED;
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int rc;
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if (entering(tcp)) {
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printxval(bpf_commands, cmd, "BPF_???");
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tprints(", ");
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}
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switch (cmd) {
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case BPF_MAP_CREATE:
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rc = bpf_map_create(tcp, addr, size);
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break;
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case BPF_MAP_LOOKUP_ELEM:
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rc = bpf_map_io(tcp, addr, size, "value");
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break;
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case BPF_MAP_UPDATE_ELEM:
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bpf_map_update_elem(tcp, addr, size);
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break;
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case BPF_MAP_DELETE_ELEM:
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bpf_map_delete_elem(tcp, addr, size);
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break;
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case BPF_MAP_GET_NEXT_KEY:
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rc = bpf_map_io(tcp, addr, size, "next_key");
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break;
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case BPF_PROG_LOAD:
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rc = bpf_prog_load(tcp, addr, size);
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break;
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case BPF_OBJ_PIN:
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rc = bpf_obj_manage(tcp, addr, size);
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break;
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case BPF_OBJ_GET:
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rc = bpf_obj_manage(tcp, addr, size);
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break;
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case BPF_PROG_ATTACH:
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rc = bpf_prog_attach(tcp, addr, size);
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break;
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case BPF_PROG_DETACH:
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rc = bpf_prog_detach(tcp, addr, size);
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break;
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default:
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if (cmd < ARRAY_SIZE(bpf_cmd_decoders) && bpf_cmd_decoders[cmd]) {
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rc = bpf_cmd_decoders[cmd](tcp, addr, size);
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} else {
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printaddr(addr);
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break;
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rc = RVAL_DECODED;
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}
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if (rc & RVAL_DECODED)
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