1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2 1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2 2
3 #include <bpf/bpf.h> 3 #include <bpf/bpf.h>
4 #include "disasm.h" 4 #include "disasm.h"
5 5
6 struct print_insn_context { 6 struct print_insn_context {
7 char scratch[16]; 7 char scratch[16];
8 char *buf; 8 char *buf;
9 size_t sz; 9 size_t sz;
10 }; 10 };
11 11
12 static void print_insn_cb(void *private_data, 12 static void print_insn_cb(void *private_data, const char *fmt, ...)
13 { 13 {
14 struct print_insn_context *ctx = priva 14 struct print_insn_context *ctx = private_data;
15 va_list args; 15 va_list args;
16 16
17 va_start(args, fmt); 17 va_start(args, fmt);
18 vsnprintf(ctx->buf, ctx->sz, fmt, args 18 vsnprintf(ctx->buf, ctx->sz, fmt, args);
19 va_end(args); 19 va_end(args);
20 } 20 }
21 21
22 static const char *print_call_cb(void *private 22 static const char *print_call_cb(void *private_data, const struct bpf_insn *insn)
23 { 23 {
24 struct print_insn_context *ctx = priva 24 struct print_insn_context *ctx = private_data;
25 25
26 /* For pseudo calls verifier.c:jit_sub 26 /* For pseudo calls verifier.c:jit_subprogs() hides original
27 * imm to insn->off and changes insn-> 27 * imm to insn->off and changes insn->imm to be an index of
28 * the subprog instead. 28 * the subprog instead.
29 */ 29 */
30 if (insn->src_reg == BPF_PSEUDO_CALL) 30 if (insn->src_reg == BPF_PSEUDO_CALL) {
31 snprintf(ctx->scratch, sizeof( 31 snprintf(ctx->scratch, sizeof(ctx->scratch), "%+d", insn->off);
32 return ctx->scratch; 32 return ctx->scratch;
33 } 33 }
34 34
35 return NULL; 35 return NULL;
36 } 36 }
37 37
38 struct bpf_insn *disasm_insn(struct bpf_insn * 38 struct bpf_insn *disasm_insn(struct bpf_insn *insn, char *buf, size_t buf_sz)
39 { 39 {
40 struct print_insn_context ctx = { 40 struct print_insn_context ctx = {
41 .buf = buf, 41 .buf = buf,
42 .sz = buf_sz, 42 .sz = buf_sz,
43 }; 43 };
44 struct bpf_insn_cbs cbs = { 44 struct bpf_insn_cbs cbs = {
45 .cb_print = print_insn_c 45 .cb_print = print_insn_cb,
46 .cb_call = print_call_c 46 .cb_call = print_call_cb,
47 .private_data = &ctx, 47 .private_data = &ctx,
48 }; 48 };
49 char *tmp, *pfx_end, *sfx_start; 49 char *tmp, *pfx_end, *sfx_start;
50 bool double_insn; 50 bool double_insn;
51 int len; 51 int len;
52 52
53 print_bpf_insn(&cbs, insn, true); 53 print_bpf_insn(&cbs, insn, true);
54 /* We share code with kernel BPF disas 54 /* We share code with kernel BPF disassembler, it adds '(FF) ' prefix
55 * for each instruction (FF stands for 55 * for each instruction (FF stands for instruction `code` byte).
56 * Remove the prefix inplace, and also 56 * Remove the prefix inplace, and also simplify call instructions.
57 * E.g.: "(85) call foo#10" -> "call f 57 * E.g.: "(85) call foo#10" -> "call foo".
58 * Also remove newline in the end (the 58 * Also remove newline in the end (the 'max(strlen(buf) - 1, 0)' thing).
59 */ 59 */
60 pfx_end = buf + 5; 60 pfx_end = buf + 5;
61 sfx_start = buf + max((int)strlen(buf) 61 sfx_start = buf + max((int)strlen(buf) - 1, 0);
62 if (strncmp(pfx_end, "call ", 5) == 0 62 if (strncmp(pfx_end, "call ", 5) == 0 && (tmp = strrchr(buf, '#')))
63 sfx_start = tmp; 63 sfx_start = tmp;
64 len = sfx_start - pfx_end; 64 len = sfx_start - pfx_end;
65 memmove(buf, pfx_end, len); 65 memmove(buf, pfx_end, len);
66 buf[len] = 0; 66 buf[len] = 0;
67 double_insn = insn->code == (BPF_LD | 67 double_insn = insn->code == (BPF_LD | BPF_IMM | BPF_DW);
68 return insn + (double_insn ? 2 : 1); 68 return insn + (double_insn ? 2 : 1);
69 } 69 }
70 70
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