1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * check_initial_reg_state.c - check that execve sets the correct state
4 * Copyright (c) 2014-2016 Andrew Lutomirski
5 */
6
7#define _GNU_SOURCE
8
9#include <stdio.h>
10
11unsigned long ax, bx, cx, dx, si, di, bp, sp, flags;
12unsigned long r8, r9, r10, r11, r12, r13, r14, r15;
13
14asm (
15	".pushsection .text\n\t"
16	".type real_start, @function\n\t"
17	".global real_start\n\t"
18	"real_start:\n\t"
19#ifdef __x86_64__
20	"mov %rax, ax\n\t"
21	"mov %rbx, bx\n\t"
22	"mov %rcx, cx\n\t"
23	"mov %rdx, dx\n\t"
24	"mov %rsi, si\n\t"
25	"mov %rdi, di\n\t"
26	"mov %rbp, bp\n\t"
27	"mov %rsp, sp\n\t"
28	"mov %r8, r8\n\t"
29	"mov %r9, r9\n\t"
30	"mov %r10, r10\n\t"
31	"mov %r11, r11\n\t"
32	"mov %r12, r12\n\t"
33	"mov %r13, r13\n\t"
34	"mov %r14, r14\n\t"
35	"mov %r15, r15\n\t"
36	"pushfq\n\t"
37	"popq flags\n\t"
38#else
39	"mov %eax, ax\n\t"
40	"mov %ebx, bx\n\t"
41	"mov %ecx, cx\n\t"
42	"mov %edx, dx\n\t"
43	"mov %esi, si\n\t"
44	"mov %edi, di\n\t"
45	"mov %ebp, bp\n\t"
46	"mov %esp, sp\n\t"
47	"pushfl\n\t"
48	"popl flags\n\t"
49#endif
50	"jmp _start\n\t"
51	".size real_start, . - real_start\n\t"
52	".popsection");
53
54int main()
55{
56	int nerrs = 0;
57
58	if (sp == 0) {
59		printf("[FAIL]\tTest was built incorrectly\n");
60		return 1;
61	}
62
63	if (ax || bx || cx || dx || si || di || bp
64#ifdef __x86_64__
65	    || r8 || r9 || r10 || r11 || r12 || r13 || r14 || r15
66#endif
67		) {
68		printf("[FAIL]\tAll GPRs except SP should be 0\n");
69#define SHOW(x) printf("\t" #x " = 0x%lx\n", x);
70		SHOW(ax);
71		SHOW(bx);
72		SHOW(cx);
73		SHOW(dx);
74		SHOW(si);
75		SHOW(di);
76		SHOW(bp);
77		SHOW(sp);
78#ifdef __x86_64__
79		SHOW(r8);
80		SHOW(r9);
81		SHOW(r10);
82		SHOW(r11);
83		SHOW(r12);
84		SHOW(r13);
85		SHOW(r14);
86		SHOW(r15);
87#endif
88		nerrs++;
89	} else {
90		printf("[OK]\tAll GPRs except SP are 0\n");
91	}
92
93	if (flags != 0x202) {
94		printf("[FAIL]\tFLAGS is 0x%lx, but it should be 0x202\n", flags);
95		nerrs++;
96	} else {
97		printf("[OK]\tFLAGS is 0x202\n");
98	}
99
100	return nerrs ? 1 : 0;
101}
102