Commit 203e6aba authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Andrii Nakryiko
Browse files

selftests/bpf: print correct offset for pseudo calls in disasm_insn() 



Adjust disasm_helpers.c:disasm_insn() to account for the following
part of the verifier.c:jit_subprogs:

  for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
        /* ... */
        if (!bpf_pseudo_call(insn))
                continue;
        insn->off = env->insn_aux_data[i].call_imm;
        subprog = find_subprog(env, i + insn->off + 1);
        insn->imm = subprog;
  }

Where verifier moves offset of the subprogram to the insn->off field.

Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240722233844.1406874-6-eddyz87@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
parent 424ebaa3

tools/testing/selftests/bpf/disasm_helpers.c

+18 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include "disasm.h"



struct print_insn_context {

	char scratch[16];

	char *buf;

	size_t sz;

};
@@ -18,6 +19,22 @@ static void print_insn_cb(void *private_data, const char *fmt, ...) 
	va_end(args);

}



static const char *print_call_cb(void *private_data, const struct bpf_insn *insn)

{

	struct print_insn_context *ctx = private_data;



	/* For pseudo calls verifier.c:jit_subprogs() hides original

	 * imm to insn->off and changes insn->imm to be an index of

	 * the subprog instead.

	 */

	if (insn->src_reg == BPF_PSEUDO_CALL) {

		snprintf(ctx->scratch, sizeof(ctx->scratch), "%+d", insn->off);

		return ctx->scratch;

	}



	return NULL;

}



struct bpf_insn *disasm_insn(struct bpf_insn *insn, char *buf, size_t buf_sz)

{

	struct print_insn_context ctx = {
@@ -26,6 +43,7 @@ struct bpf_insn *disasm_insn(struct bpf_insn *insn, char *buf, size_t buf_sz) 
	};

	struct bpf_insn_cbs cbs = {

		.cb_print	= print_insn_cb,

		.cb_call	= print_call_cb,

		.private_data	= &ctx,

	};

	char *tmp, *pfx_end, *sfx_start;