| Andy Lutomirski | c2affbf | 2015-05-29 14:58:24 -0700 | [diff] [blame] | 1 | /* |
| 2 | * entry_from_vm86.c - tests kernel entries from vm86 mode |
| 3 | * Copyright (c) 2014-2015 Andrew Lutomirski |
| 4 | * |
| 5 | * This exercises a few paths that need to special-case vm86 mode. |
| 6 | * |
| 7 | * GPL v2. |
| 8 | */ |
| 9 | |
| 10 | #define _GNU_SOURCE |
| 11 | |
| 12 | #include <assert.h> |
| 13 | #include <stdlib.h> |
| 14 | #include <sys/syscall.h> |
| 15 | #include <sys/signal.h> |
| 16 | #include <sys/ucontext.h> |
| 17 | #include <unistd.h> |
| 18 | #include <stdio.h> |
| 19 | #include <string.h> |
| 20 | #include <inttypes.h> |
| 21 | #include <sys/mman.h> |
| 22 | #include <err.h> |
| 23 | #include <stddef.h> |
| 24 | #include <stdbool.h> |
| 25 | #include <errno.h> |
| 26 | #include <sys/vm86.h> |
| 27 | |
| 28 | static unsigned long load_addr = 0x10000; |
| 29 | static int nerrs = 0; |
| 30 | |
| 31 | asm ( |
| 32 | ".pushsection .rodata\n\t" |
| 33 | ".type vmcode_bound, @object\n\t" |
| 34 | "vmcode:\n\t" |
| 35 | "vmcode_bound:\n\t" |
| 36 | ".code16\n\t" |
| 37 | "bound %ax, (2048)\n\t" |
| 38 | "int3\n\t" |
| 39 | "vmcode_sysenter:\n\t" |
| 40 | "sysenter\n\t" |
| 41 | ".size vmcode, . - vmcode\n\t" |
| 42 | "end_vmcode:\n\t" |
| 43 | ".code32\n\t" |
| 44 | ".popsection" |
| 45 | ); |
| 46 | |
| 47 | extern unsigned char vmcode[], end_vmcode[]; |
| 48 | extern unsigned char vmcode_bound[], vmcode_sysenter[]; |
| 49 | |
| 50 | static void do_test(struct vm86plus_struct *v86, unsigned long eip, |
| 51 | const char *text) |
| 52 | { |
| 53 | long ret; |
| 54 | |
| 55 | printf("[RUN]\t%s from vm86 mode\n", text); |
| 56 | v86->regs.eip = eip; |
| 57 | ret = vm86(VM86_ENTER, v86); |
| 58 | |
| 59 | if (ret == -1 && errno == ENOSYS) { |
| 60 | printf("[SKIP]\tvm86 not supported\n"); |
| 61 | return; |
| 62 | } |
| 63 | |
| 64 | if (VM86_TYPE(ret) == VM86_INTx) { |
| 65 | char trapname[32]; |
| 66 | int trapno = VM86_ARG(ret); |
| 67 | if (trapno == 13) |
| 68 | strcpy(trapname, "GP"); |
| 69 | else if (trapno == 5) |
| 70 | strcpy(trapname, "BR"); |
| 71 | else if (trapno == 14) |
| 72 | strcpy(trapname, "PF"); |
| 73 | else |
| 74 | sprintf(trapname, "%d", trapno); |
| 75 | |
| 76 | printf("[OK]\tExited vm86 mode due to #%s\n", trapname); |
| 77 | } else if (VM86_TYPE(ret) == VM86_UNKNOWN) { |
| 78 | printf("[OK]\tExited vm86 mode due to unhandled GP fault\n"); |
| 79 | } else { |
| 80 | printf("[OK]\tExited vm86 mode due to type %ld, arg %ld\n", |
| 81 | VM86_TYPE(ret), VM86_ARG(ret)); |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | int main(void) |
| 86 | { |
| 87 | struct vm86plus_struct v86; |
| 88 | unsigned char *addr = mmap((void *)load_addr, 4096, |
| 89 | PROT_READ | PROT_WRITE | PROT_EXEC, |
| 90 | MAP_ANONYMOUS | MAP_PRIVATE, -1,0); |
| 91 | if (addr != (unsigned char *)load_addr) |
| 92 | err(1, "mmap"); |
| 93 | |
| 94 | memcpy(addr, vmcode, end_vmcode - vmcode); |
| 95 | addr[2048] = 2; |
| 96 | addr[2050] = 3; |
| 97 | |
| 98 | memset(&v86, 0, sizeof(v86)); |
| 99 | |
| 100 | v86.regs.cs = load_addr / 16; |
| 101 | v86.regs.ss = load_addr / 16; |
| 102 | v86.regs.ds = load_addr / 16; |
| 103 | v86.regs.es = load_addr / 16; |
| 104 | |
| 105 | assert((v86.regs.cs & 3) == 0); /* Looks like RPL = 0 */ |
| 106 | |
| 107 | /* #BR -- should deliver SIG??? */ |
| 108 | do_test(&v86, vmcode_bound - vmcode, "#BR"); |
| 109 | |
| 110 | /* SYSENTER -- should cause #GP or #UD depending on CPU */ |
| 111 | do_test(&v86, vmcode_sysenter - vmcode, "SYSENTER"); |
| 112 | |
| 113 | return (nerrs == 0 ? 0 : 1); |
| 114 | } |