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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /tools/bpf/bpftool/cfg.c | |
parent | Initial commit. (diff) | |
download | linux-upstream.tar.xz linux-upstream.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | tools/bpf/bpftool/cfg.c | 485 |
1 files changed, 485 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/cfg.c b/tools/bpf/bpftool/cfg.c new file mode 100644 index 000000000..1951219a9 --- /dev/null +++ b/tools/bpf/bpftool/cfg.c @@ -0,0 +1,485 @@ +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +/* Copyright (C) 2018 Netronome Systems, Inc. */ + +#include <linux/list.h> +#include <stdlib.h> +#include <string.h> + +#include "cfg.h" +#include "main.h" +#include "xlated_dumper.h" + +struct cfg { + struct list_head funcs; + int func_num; +}; + +struct func_node { + struct list_head l; + struct list_head bbs; + struct bpf_insn *start; + struct bpf_insn *end; + int idx; + int bb_num; +}; + +struct bb_node { + struct list_head l; + struct list_head e_prevs; + struct list_head e_succs; + struct bpf_insn *head; + struct bpf_insn *tail; + int idx; +}; + +#define EDGE_FLAG_EMPTY 0x0 +#define EDGE_FLAG_FALLTHROUGH 0x1 +#define EDGE_FLAG_JUMP 0x2 +struct edge_node { + struct list_head l; + struct bb_node *src; + struct bb_node *dst; + int flags; +}; + +#define ENTRY_BLOCK_INDEX 0 +#define EXIT_BLOCK_INDEX 1 +#define NUM_FIXED_BLOCKS 2 +#define func_prev(func) list_prev_entry(func, l) +#define func_next(func) list_next_entry(func, l) +#define bb_prev(bb) list_prev_entry(bb, l) +#define bb_next(bb) list_next_entry(bb, l) +#define entry_bb(func) func_first_bb(func) +#define exit_bb(func) func_last_bb(func) +#define cfg_first_func(cfg) \ + list_first_entry(&cfg->funcs, struct func_node, l) +#define cfg_last_func(cfg) \ + list_last_entry(&cfg->funcs, struct func_node, l) +#define func_first_bb(func) \ + list_first_entry(&func->bbs, struct bb_node, l) +#define func_last_bb(func) \ + list_last_entry(&func->bbs, struct bb_node, l) + +static struct func_node *cfg_append_func(struct cfg *cfg, struct bpf_insn *insn) +{ + struct func_node *new_func, *func; + + list_for_each_entry(func, &cfg->funcs, l) { + if (func->start == insn) + return func; + else if (func->start > insn) + break; + } + + func = func_prev(func); + new_func = calloc(1, sizeof(*new_func)); + if (!new_func) { + p_err("OOM when allocating FUNC node"); + return NULL; + } + new_func->start = insn; + new_func->idx = cfg->func_num; + list_add(&new_func->l, &func->l); + cfg->func_num++; + + return new_func; +} + +static struct bb_node *func_append_bb(struct func_node *func, + struct bpf_insn *insn) +{ + struct bb_node *new_bb, *bb; + + list_for_each_entry(bb, &func->bbs, l) { + if (bb->head == insn) + return bb; + else if (bb->head > insn) + break; + } + + bb = bb_prev(bb); + new_bb = calloc(1, sizeof(*new_bb)); + if (!new_bb) { + p_err("OOM when allocating BB node"); + return NULL; + } + new_bb->head = insn; + INIT_LIST_HEAD(&new_bb->e_prevs); + INIT_LIST_HEAD(&new_bb->e_succs); + list_add(&new_bb->l, &bb->l); + + return new_bb; +} + +static struct bb_node *func_insert_dummy_bb(struct list_head *after) +{ + struct bb_node *bb; + + bb = calloc(1, sizeof(*bb)); + if (!bb) { + p_err("OOM when allocating BB node"); + return NULL; + } + + INIT_LIST_HEAD(&bb->e_prevs); + INIT_LIST_HEAD(&bb->e_succs); + list_add(&bb->l, after); + + return bb; +} + +static bool cfg_partition_funcs(struct cfg *cfg, struct bpf_insn *cur, + struct bpf_insn *end) +{ + struct func_node *func, *last_func; + + func = cfg_append_func(cfg, cur); + if (!func) + return true; + + for (; cur < end; cur++) { + if (cur->code != (BPF_JMP | BPF_CALL)) + continue; + if (cur->src_reg != BPF_PSEUDO_CALL) + continue; + func = cfg_append_func(cfg, cur + cur->off + 1); + if (!func) + return true; + } + + last_func = cfg_last_func(cfg); + last_func->end = end - 1; + func = cfg_first_func(cfg); + list_for_each_entry_from(func, &last_func->l, l) { + func->end = func_next(func)->start - 1; + } + + return false; +} + +static bool is_jmp_insn(__u8 code) +{ + return BPF_CLASS(code) == BPF_JMP || BPF_CLASS(code) == BPF_JMP32; +} + +static bool func_partition_bb_head(struct func_node *func) +{ + struct bpf_insn *cur, *end; + struct bb_node *bb; + + cur = func->start; + end = func->end; + INIT_LIST_HEAD(&func->bbs); + bb = func_append_bb(func, cur); + if (!bb) + return true; + + for (; cur <= end; cur++) { + if (is_jmp_insn(cur->code)) { + __u8 opcode = BPF_OP(cur->code); + + if (opcode == BPF_EXIT || opcode == BPF_CALL) + continue; + + bb = func_append_bb(func, cur + cur->off + 1); + if (!bb) + return true; + + if (opcode != BPF_JA) { + bb = func_append_bb(func, cur + 1); + if (!bb) + return true; + } + } + } + + return false; +} + +static void func_partition_bb_tail(struct func_node *func) +{ + unsigned int bb_idx = NUM_FIXED_BLOCKS; + struct bb_node *bb, *last; + + last = func_last_bb(func); + last->tail = func->end; + bb = func_first_bb(func); + list_for_each_entry_from(bb, &last->l, l) { + bb->tail = bb_next(bb)->head - 1; + bb->idx = bb_idx++; + } + + last->idx = bb_idx++; + func->bb_num = bb_idx; +} + +static bool func_add_special_bb(struct func_node *func) +{ + struct bb_node *bb; + + bb = func_insert_dummy_bb(&func->bbs); + if (!bb) + return true; + bb->idx = ENTRY_BLOCK_INDEX; + + bb = func_insert_dummy_bb(&func_last_bb(func)->l); + if (!bb) + return true; + bb->idx = EXIT_BLOCK_INDEX; + + return false; +} + +static bool func_partition_bb(struct func_node *func) +{ + if (func_partition_bb_head(func)) + return true; + + func_partition_bb_tail(func); + + return false; +} + +static struct bb_node *func_search_bb_with_head(struct func_node *func, + struct bpf_insn *insn) +{ + struct bb_node *bb; + + list_for_each_entry(bb, &func->bbs, l) { + if (bb->head == insn) + return bb; + } + + return NULL; +} + +static struct edge_node *new_edge(struct bb_node *src, struct bb_node *dst, + int flags) +{ + struct edge_node *e; + + e = calloc(1, sizeof(*e)); + if (!e) { + p_err("OOM when allocating edge node"); + return NULL; + } + + if (src) + e->src = src; + if (dst) + e->dst = dst; + + e->flags |= flags; + + return e; +} + +static bool func_add_bb_edges(struct func_node *func) +{ + struct bpf_insn *insn; + struct edge_node *e; + struct bb_node *bb; + + bb = entry_bb(func); + e = new_edge(bb, bb_next(bb), EDGE_FLAG_FALLTHROUGH); + if (!e) + return true; + list_add_tail(&e->l, &bb->e_succs); + + bb = exit_bb(func); + e = new_edge(bb_prev(bb), bb, EDGE_FLAG_FALLTHROUGH); + if (!e) + return true; + list_add_tail(&e->l, &bb->e_prevs); + + bb = entry_bb(func); + bb = bb_next(bb); + list_for_each_entry_from(bb, &exit_bb(func)->l, l) { + e = new_edge(bb, NULL, EDGE_FLAG_EMPTY); + if (!e) + return true; + e->src = bb; + + insn = bb->tail; + if (!is_jmp_insn(insn->code) || + BPF_OP(insn->code) == BPF_EXIT) { + e->dst = bb_next(bb); + e->flags |= EDGE_FLAG_FALLTHROUGH; + list_add_tail(&e->l, &bb->e_succs); + continue; + } else if (BPF_OP(insn->code) == BPF_JA) { + e->dst = func_search_bb_with_head(func, + insn + insn->off + 1); + e->flags |= EDGE_FLAG_JUMP; + list_add_tail(&e->l, &bb->e_succs); + continue; + } + + e->dst = bb_next(bb); + e->flags |= EDGE_FLAG_FALLTHROUGH; + list_add_tail(&e->l, &bb->e_succs); + + e = new_edge(bb, NULL, EDGE_FLAG_JUMP); + if (!e) + return true; + e->src = bb; + e->dst = func_search_bb_with_head(func, insn + insn->off + 1); + list_add_tail(&e->l, &bb->e_succs); + } + + return false; +} + +static bool cfg_build(struct cfg *cfg, struct bpf_insn *insn, unsigned int len) +{ + int cnt = len / sizeof(*insn); + struct func_node *func; + + INIT_LIST_HEAD(&cfg->funcs); + + if (cfg_partition_funcs(cfg, insn, insn + cnt)) + return true; + + list_for_each_entry(func, &cfg->funcs, l) { + if (func_partition_bb(func) || func_add_special_bb(func)) + return true; + + if (func_add_bb_edges(func)) + return true; + } + + return false; +} + +static void cfg_destroy(struct cfg *cfg) +{ + struct func_node *func, *func2; + + list_for_each_entry_safe(func, func2, &cfg->funcs, l) { + struct bb_node *bb, *bb2; + + list_for_each_entry_safe(bb, bb2, &func->bbs, l) { + struct edge_node *e, *e2; + + list_for_each_entry_safe(e, e2, &bb->e_prevs, l) { + list_del(&e->l); + free(e); + } + + list_for_each_entry_safe(e, e2, &bb->e_succs, l) { + list_del(&e->l); + free(e); + } + + list_del(&bb->l); + free(bb); + } + + list_del(&func->l); + free(func); + } +} + +static void draw_bb_node(struct func_node *func, struct bb_node *bb) +{ + const char *shape; + + if (bb->idx == ENTRY_BLOCK_INDEX || bb->idx == EXIT_BLOCK_INDEX) + shape = "Mdiamond"; + else + shape = "record"; + + printf("\tfn_%d_bb_%d [shape=%s,style=filled,label=\"", + func->idx, bb->idx, shape); + + if (bb->idx == ENTRY_BLOCK_INDEX) { + printf("ENTRY"); + } else if (bb->idx == EXIT_BLOCK_INDEX) { + printf("EXIT"); + } else { + unsigned int start_idx; + struct dump_data dd = {}; + + printf("{"); + kernel_syms_load(&dd); + start_idx = bb->head - func->start; + dump_xlated_for_graph(&dd, bb->head, bb->tail, start_idx); + kernel_syms_destroy(&dd); + printf("}"); + } + + printf("\"];\n\n"); +} + +static void draw_bb_succ_edges(struct func_node *func, struct bb_node *bb) +{ + const char *style = "\"solid,bold\""; + const char *color = "black"; + int func_idx = func->idx; + struct edge_node *e; + int weight = 10; + + if (list_empty(&bb->e_succs)) + return; + + list_for_each_entry(e, &bb->e_succs, l) { + printf("\tfn_%d_bb_%d:s -> fn_%d_bb_%d:n [style=%s, color=%s, weight=%d, constraint=true", + func_idx, e->src->idx, func_idx, e->dst->idx, + style, color, weight); + printf("];\n"); + } +} + +static void func_output_bb_def(struct func_node *func) +{ + struct bb_node *bb; + + list_for_each_entry(bb, &func->bbs, l) { + draw_bb_node(func, bb); + } +} + +static void func_output_edges(struct func_node *func) +{ + int func_idx = func->idx; + struct bb_node *bb; + + list_for_each_entry(bb, &func->bbs, l) { + draw_bb_succ_edges(func, bb); + } + + /* Add an invisible edge from ENTRY to EXIT, this is to + * improve the graph layout. + */ + printf("\tfn_%d_bb_%d:s -> fn_%d_bb_%d:n [style=\"invis\", constraint=true];\n", + func_idx, ENTRY_BLOCK_INDEX, func_idx, EXIT_BLOCK_INDEX); +} + +static void cfg_dump(struct cfg *cfg) +{ + struct func_node *func; + + printf("digraph \"DOT graph for eBPF program\" {\n"); + list_for_each_entry(func, &cfg->funcs, l) { + printf("subgraph \"cluster_%d\" {\n\tstyle=\"dashed\";\n\tcolor=\"black\";\n\tlabel=\"func_%d ()\";\n", + func->idx, func->idx); + func_output_bb_def(func); + func_output_edges(func); + printf("}\n"); + } + printf("}\n"); +} + +void dump_xlated_cfg(void *buf, unsigned int len) +{ + struct bpf_insn *insn = buf; + struct cfg cfg; + + memset(&cfg, 0, sizeof(cfg)); + if (cfg_build(&cfg, insn, len)) + return; + + cfg_dump(&cfg); + + cfg_destroy(&cfg); +} |