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d510296d33
Add -L flag to bpftool to use libbpf gen_trace facility and syscall/loader program
for skeleton generation and program loading.
"bpftool gen skeleton -L" command will generate a "light skeleton" or "loader skeleton"
that is similar to existing skeleton, but has one major difference:
$ bpftool gen skeleton lsm.o > lsm.skel.h
$ bpftool gen skeleton -L lsm.o > lsm.lskel.h
$ diff lsm.skel.h lsm.lskel.h
@@ -5,34 +4,34 @@
#define __LSM_SKEL_H__
#include <stdlib.h>
-#include <bpf/libbpf.h>
+#include <bpf/bpf.h>
The light skeleton does not use majority of libbpf infrastructure.
It doesn't need libelf. It doesn't parse .o file.
It only needs few sys_bpf wrappers. All of them are in bpf/bpf.h file.
In future libbpf/bpf.c can be inlined into bpf.h, so not even libbpf.a would be
needed to work with light skeleton.
"bpftool prog load -L file.o" command is introduced for debugging of syscall/loader
program generation. Just like the same command without -L it will try to load
the programs from file.o into the kernel. It won't even try to pin them.
"bpftool prog load -L -d file.o" command will provide additional debug messages
on how syscall/loader program was generated.
Also the execution of syscall/loader program will use bpf_trace_printk() for
each step of loading BTF, creating maps, and loading programs.
The user can do "cat /.../trace_pipe" for further debug.
An example of fexit_sleep.lskel.h generated from progs/fexit_sleep.c:
struct fexit_sleep {
struct bpf_loader_ctx ctx;
struct {
struct bpf_map_desc bss;
} maps;
struct {
struct bpf_prog_desc nanosleep_fentry;
struct bpf_prog_desc nanosleep_fexit;
} progs;
struct {
int nanosleep_fentry_fd;
int nanosleep_fexit_fd;
} links;
struct fexit_sleep__bss {
int pid;
int fentry_cnt;
int fexit_cnt;
} *bss;
};
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-18-alexei.starovoitov@gmail.com
380 lines
9.1 KiB
C
380 lines
9.1 KiB
C
// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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/* Copyright (C) 2018 Netronome Systems, Inc. */
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#define _GNU_SOURCE
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <bpf/libbpf.h>
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#include "disasm.h"
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#include "json_writer.h"
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#include "main.h"
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#include "xlated_dumper.h"
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static int kernel_syms_cmp(const void *sym_a, const void *sym_b)
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{
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return ((struct kernel_sym *)sym_a)->address -
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((struct kernel_sym *)sym_b)->address;
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}
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void kernel_syms_load(struct dump_data *dd)
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{
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struct kernel_sym *sym;
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char buff[256];
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void *tmp, *address;
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FILE *fp;
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fp = fopen("/proc/kallsyms", "r");
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if (!fp)
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return;
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while (fgets(buff, sizeof(buff), fp)) {
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tmp = reallocarray(dd->sym_mapping, dd->sym_count + 1,
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sizeof(*dd->sym_mapping));
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if (!tmp) {
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out:
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free(dd->sym_mapping);
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dd->sym_mapping = NULL;
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fclose(fp);
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return;
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}
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dd->sym_mapping = tmp;
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sym = &dd->sym_mapping[dd->sym_count];
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if (sscanf(buff, "%p %*c %s", &address, sym->name) != 2)
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continue;
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sym->address = (unsigned long)address;
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if (!strcmp(sym->name, "__bpf_call_base")) {
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dd->address_call_base = sym->address;
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/* sysctl kernel.kptr_restrict was set */
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if (!sym->address)
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goto out;
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}
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if (sym->address)
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dd->sym_count++;
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}
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fclose(fp);
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qsort(dd->sym_mapping, dd->sym_count,
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sizeof(*dd->sym_mapping), kernel_syms_cmp);
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}
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void kernel_syms_destroy(struct dump_data *dd)
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{
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free(dd->sym_mapping);
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}
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struct kernel_sym *kernel_syms_search(struct dump_data *dd,
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unsigned long key)
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{
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struct kernel_sym sym = {
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.address = key,
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};
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return dd->sym_mapping ?
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bsearch(&sym, dd->sym_mapping, dd->sym_count,
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sizeof(*dd->sym_mapping), kernel_syms_cmp) : NULL;
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}
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static void __printf(2, 3) print_insn(void *private_data, const char *fmt, ...)
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{
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va_list args;
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va_start(args, fmt);
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vprintf(fmt, args);
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va_end(args);
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}
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static void __printf(2, 3)
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print_insn_for_graph(void *private_data, const char *fmt, ...)
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{
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char buf[64], *p;
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va_list args;
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va_start(args, fmt);
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vsnprintf(buf, sizeof(buf), fmt, args);
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va_end(args);
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p = buf;
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while (*p != '\0') {
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if (*p == '\n') {
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memmove(p + 3, p, strlen(buf) + 1 - (p - buf));
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/* Align each instruction dump row left. */
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*p++ = '\\';
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*p++ = 'l';
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/* Output multiline concatenation. */
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*p++ = '\\';
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} else if (*p == '<' || *p == '>' || *p == '|' || *p == '&') {
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memmove(p + 1, p, strlen(buf) + 1 - (p - buf));
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/* Escape special character. */
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*p++ = '\\';
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}
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p++;
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}
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printf("%s", buf);
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}
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static void __printf(2, 3)
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print_insn_json(void *private_data, const char *fmt, ...)
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{
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unsigned int l = strlen(fmt);
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char chomped_fmt[l];
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va_list args;
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va_start(args, fmt);
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if (l > 0) {
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strncpy(chomped_fmt, fmt, l - 1);
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chomped_fmt[l - 1] = '\0';
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}
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jsonw_vprintf_enquote(json_wtr, chomped_fmt, args);
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va_end(args);
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}
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static const char *print_call_pcrel(struct dump_data *dd,
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struct kernel_sym *sym,
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unsigned long address,
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const struct bpf_insn *insn)
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{
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if (!dd->nr_jited_ksyms)
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/* Do not show address for interpreted programs */
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snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
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"%+d", insn->off);
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else if (sym)
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snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
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"%+d#%s", insn->off, sym->name);
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else
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snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
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"%+d#0x%lx", insn->off, address);
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return dd->scratch_buff;
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}
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static const char *print_call_helper(struct dump_data *dd,
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struct kernel_sym *sym,
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unsigned long address)
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{
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if (sym)
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snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
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"%s", sym->name);
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else
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snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
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"0x%lx", address);
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return dd->scratch_buff;
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}
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static const char *print_call(void *private_data,
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const struct bpf_insn *insn)
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{
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struct dump_data *dd = private_data;
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unsigned long address = dd->address_call_base + insn->imm;
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struct kernel_sym *sym;
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if (insn->src_reg == BPF_PSEUDO_CALL &&
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(__u32) insn->imm < dd->nr_jited_ksyms && dd->jited_ksyms)
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address = dd->jited_ksyms[insn->imm];
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sym = kernel_syms_search(dd, address);
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if (insn->src_reg == BPF_PSEUDO_CALL)
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return print_call_pcrel(dd, sym, address, insn);
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else
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return print_call_helper(dd, sym, address);
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}
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static const char *print_imm(void *private_data,
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const struct bpf_insn *insn,
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__u64 full_imm)
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{
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struct dump_data *dd = private_data;
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if (insn->src_reg == BPF_PSEUDO_MAP_FD)
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snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
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"map[id:%u]", insn->imm);
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else if (insn->src_reg == BPF_PSEUDO_MAP_VALUE)
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snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
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"map[id:%u][0]+%u", insn->imm, (insn + 1)->imm);
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else if (insn->src_reg == BPF_PSEUDO_MAP_IDX_VALUE)
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snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
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"map[idx:%u]+%u", insn->imm, (insn + 1)->imm);
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else if (insn->src_reg == BPF_PSEUDO_FUNC)
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snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
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"subprog[%+d]", insn->imm);
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else
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snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
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"0x%llx", (unsigned long long)full_imm);
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return dd->scratch_buff;
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}
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void dump_xlated_json(struct dump_data *dd, void *buf, unsigned int len,
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bool opcodes, bool linum)
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{
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const struct bpf_prog_linfo *prog_linfo = dd->prog_linfo;
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const struct bpf_insn_cbs cbs = {
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.cb_print = print_insn_json,
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.cb_call = print_call,
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.cb_imm = print_imm,
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.private_data = dd,
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};
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struct bpf_func_info *record;
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struct bpf_insn *insn = buf;
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struct btf *btf = dd->btf;
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bool double_insn = false;
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unsigned int nr_skip = 0;
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char func_sig[1024];
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unsigned int i;
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jsonw_start_array(json_wtr);
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record = dd->func_info;
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for (i = 0; i < len / sizeof(*insn); i++) {
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if (double_insn) {
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double_insn = false;
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continue;
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}
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double_insn = insn[i].code == (BPF_LD | BPF_IMM | BPF_DW);
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jsonw_start_object(json_wtr);
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if (btf && record) {
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if (record->insn_off == i) {
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btf_dumper_type_only(btf, record->type_id,
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func_sig,
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sizeof(func_sig));
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if (func_sig[0] != '\0') {
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jsonw_name(json_wtr, "proto");
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jsonw_string(json_wtr, func_sig);
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}
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record = (void *)record + dd->finfo_rec_size;
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}
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}
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if (prog_linfo) {
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const struct bpf_line_info *linfo;
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linfo = bpf_prog_linfo__lfind(prog_linfo, i, nr_skip);
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if (linfo) {
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btf_dump_linfo_json(btf, linfo, linum);
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nr_skip++;
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}
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}
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jsonw_name(json_wtr, "disasm");
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print_bpf_insn(&cbs, insn + i, true);
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if (opcodes) {
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jsonw_name(json_wtr, "opcodes");
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jsonw_start_object(json_wtr);
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jsonw_name(json_wtr, "code");
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jsonw_printf(json_wtr, "\"0x%02hhx\"", insn[i].code);
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jsonw_name(json_wtr, "src_reg");
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jsonw_printf(json_wtr, "\"0x%hhx\"", insn[i].src_reg);
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jsonw_name(json_wtr, "dst_reg");
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jsonw_printf(json_wtr, "\"0x%hhx\"", insn[i].dst_reg);
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jsonw_name(json_wtr, "off");
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print_hex_data_json((uint8_t *)(&insn[i].off), 2);
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jsonw_name(json_wtr, "imm");
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if (double_insn && i < len - 1)
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print_hex_data_json((uint8_t *)(&insn[i].imm),
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12);
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else
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print_hex_data_json((uint8_t *)(&insn[i].imm),
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4);
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jsonw_end_object(json_wtr);
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}
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jsonw_end_object(json_wtr);
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}
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jsonw_end_array(json_wtr);
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}
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void dump_xlated_plain(struct dump_data *dd, void *buf, unsigned int len,
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bool opcodes, bool linum)
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{
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const struct bpf_prog_linfo *prog_linfo = dd->prog_linfo;
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const struct bpf_insn_cbs cbs = {
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.cb_print = print_insn,
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.cb_call = print_call,
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.cb_imm = print_imm,
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.private_data = dd,
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};
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struct bpf_func_info *record;
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struct bpf_insn *insn = buf;
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struct btf *btf = dd->btf;
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unsigned int nr_skip = 0;
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bool double_insn = false;
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char func_sig[1024];
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unsigned int i;
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record = dd->func_info;
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for (i = 0; i < len / sizeof(*insn); i++) {
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if (double_insn) {
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double_insn = false;
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continue;
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}
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if (btf && record) {
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if (record->insn_off == i) {
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btf_dumper_type_only(btf, record->type_id,
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func_sig,
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sizeof(func_sig));
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if (func_sig[0] != '\0')
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printf("%s:\n", func_sig);
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record = (void *)record + dd->finfo_rec_size;
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}
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}
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if (prog_linfo) {
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const struct bpf_line_info *linfo;
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linfo = bpf_prog_linfo__lfind(prog_linfo, i, nr_skip);
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if (linfo) {
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btf_dump_linfo_plain(btf, linfo, "; ",
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linum);
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nr_skip++;
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}
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}
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double_insn = insn[i].code == (BPF_LD | BPF_IMM | BPF_DW);
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printf("% 4d: ", i);
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print_bpf_insn(&cbs, insn + i, true);
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if (opcodes) {
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printf(" ");
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fprint_hex(stdout, insn + i, 8, " ");
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if (double_insn && i < len - 1) {
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printf(" ");
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fprint_hex(stdout, insn + i + 1, 8, " ");
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}
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printf("\n");
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}
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}
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}
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void dump_xlated_for_graph(struct dump_data *dd, void *buf_start, void *buf_end,
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unsigned int start_idx)
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{
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const struct bpf_insn_cbs cbs = {
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.cb_print = print_insn_for_graph,
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.cb_call = print_call,
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.cb_imm = print_imm,
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.private_data = dd,
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};
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struct bpf_insn *insn_start = buf_start;
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struct bpf_insn *insn_end = buf_end;
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struct bpf_insn *cur = insn_start;
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for (; cur <= insn_end; cur++) {
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printf("% 4d: ", (int)(cur - insn_start + start_idx));
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print_bpf_insn(&cbs, cur, true);
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if (cur != insn_end)
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printf(" | ");
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}
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}
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