Quelle  check_initial_reg_state.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * check_initial_reg_state.c - check that execve sets the correct state
 * Copyright (c) 2014-2016 Andrew Lutomirski
 */

#define _GNU_SOURCE

#include <stdio.h>

unsigned long ax, bx, cx, dx, si, di, bp, sp, flags;
unsigned long r8, r9, r10, r11, r12, r13, r14, r15;

asm (
 ".pushsection .text\n\t"
 ".type real_start, @function\n\t"
 ".global real_start\n\t"
 "real_start:\n\t"
#ifdef __x86_64__
 "mov %rax, ax\n\t"
 "mov %rbx, bx\n\t"
 "mov %rcx, cx\n\t"
 "mov %rdx, dx\n\t"
 "mov %rsi, si\n\t"
 "mov %rdi, di\n\t"
 "mov %rbp, bp\n\t"
 "mov %rsp, sp\n\t"
 "mov %r8, r8\n\t"
 "mov %r9, r9\n\t"
 "mov %r10, r10\n\t"
 "mov %r11, r11\n\t"
 "mov %r12, r12\n\t"
 "mov %r13, r13\n\t"
 "mov %r14, r14\n\t"
 "mov %r15, r15\n\t"
 "pushfq\n\t"
 "popq flags\n\t"
#else
 "mov %eax, ax\n\t"
 "mov %ebx, bx\n\t"
 "mov %ecx, cx\n\t"
 "mov %edx, dx\n\t"
 "mov %esi, si\n\t"
 "mov %edi, di\n\t"
 "mov %ebp, bp\n\t"
 "mov %esp, sp\n\t"
 "pushfl\n\t"
 "popl flags\n\t"
#endif
 "jmp _start\n\t"
 ".size real_start, . - real_start\n\t"
 ".popsection");

int main()
{
 int nerrs = 0;

 if (sp == 0) {
  printf("[FAIL]\tTest was built incorrectly\n");
  return 1;
 }

 if (ax || bx || cx || dx || si || di || bp
#ifdef __x86_64__
     || r8 || r9 || r10 || r11 || r12 || r13 || r14 || r15
#endif
  ) {
  printf("[FAIL]\tAll GPRs except SP should be 0\n");
#define SHOW(x) printf("\t" #x " = 0x%lx\n", x);
  SHOW(ax);
  SHOW(bx);
  SHOW(cx);
  SHOW(dx);
  SHOW(si);
  SHOW(di);
  SHOW(bp);
  SHOW(sp);
#ifdef __x86_64__
  SHOW(r8);
  SHOW(r9);
  SHOW(r10);
  SHOW(r11);
  SHOW(r12);
  SHOW(r13);
  SHOW(r14);
  SHOW(r15);
#endif
  nerrs++;
 } else {
  printf("[OK]\tAll GPRs except SP are 0\n");
 }

 if (flags != 0x202) {
  printf("[FAIL]\tFLAGS is 0x%lx, but it should be 0x202\n", flags);
  nerrs++;
 } else {
  printf("[OK]\tFLAGS is 0x202\n");
 }

 return nerrs ? 1 : 0;
}