1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * unwind_vdso.c - tests unwind info for AT_SYSINFO in the vDSO 4 * Copyright (c) 2014-2015 Andrew Lutomirski 5 * 6 * This tests __kernel_vsyscall's unwind info. 7 */ 8 9 #define _GNU_SOURCE 10 11 #include <features.h> 12 #include <stdio.h> 13 14 #include "helpers.h" 15 16 #if defined(__GLIBC__) && __GLIBC__ == 2 && __GLIBC_MINOR__ < 16 17 18 int main() 19 { 20 /* We need getauxval(). */ 21 printf("[SKIP]\tGLIBC before 2.16 cannot compile this test\n"); 22 return 0; 23 } 24 25 #else 26 27 #include <sys/time.h> 28 #include <stdlib.h> 29 #include <syscall.h> 30 #include <unistd.h> 31 #include <string.h> 32 #include <inttypes.h> 33 #include <sys/mman.h> 34 #include <signal.h> 35 #include <sys/ucontext.h> 36 #include <err.h> 37 #include <stddef.h> 38 #include <stdbool.h> 39 #include <sys/ptrace.h> 40 #include <sys/user.h> 41 #include <link.h> 42 #include <sys/auxv.h> 43 #include <dlfcn.h> 44 #include <unwind.h> 45 46 static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), 47 int flags) 48 { 49 struct sigaction sa; 50 memset(&sa, 0, sizeof(sa)); 51 sa.sa_sigaction = handler; 52 sa.sa_flags = SA_SIGINFO | flags; 53 sigemptyset(&sa.sa_mask); 54 if (sigaction(sig, &sa, 0)) 55 err(1, "sigaction"); 56 } 57 58 static volatile sig_atomic_t nerrs; 59 static unsigned long sysinfo; 60 static bool got_sysinfo = false; 61 static unsigned long return_address; 62 63 struct unwind_state { 64 unsigned long ip; /* trap source */ 65 int depth; /* -1 until we hit the trap source */ 66 }; 67 68 _Unwind_Reason_Code trace_fn(struct _Unwind_Context * ctx, void *opaque) 69 { 70 struct unwind_state *state = opaque; 71 unsigned long ip = _Unwind_GetIP(ctx); 72 73 if (state->depth == -1) { 74 if (ip == state->ip) 75 state->depth = 0; 76 else 77 return _URC_NO_REASON; /* Not there yet */ 78 } 79 printf("\t 0x%lx\n", ip); 80 81 if (ip == return_address) { 82 /* Here we are. */ 83 unsigned long eax = _Unwind_GetGR(ctx, 0); 84 unsigned long ecx = _Unwind_GetGR(ctx, 1); 85 unsigned long edx = _Unwind_GetGR(ctx, 2); 86 unsigned long ebx = _Unwind_GetGR(ctx, 3); 87 unsigned long ebp = _Unwind_GetGR(ctx, 5); 88 unsigned long esi = _Unwind_GetGR(ctx, 6); 89 unsigned long edi = _Unwind_GetGR(ctx, 7); 90 bool ok = (eax == SYS_getpid || eax == getpid()) && 91 ebx == 1 && ecx == 2 && edx == 3 && 92 esi == 4 && edi == 5 && ebp == 6; 93 94 if (!ok) 95 nerrs++; 96 printf("[%s]\t NR = %ld, args = %ld, %ld, %ld, %ld, %ld, %ld\n", 97 (ok ? "OK" : "FAIL"), 98 eax, ebx, ecx, edx, esi, edi, ebp); 99 100 return _URC_NORMAL_STOP; 101 } else { 102 state->depth++; 103 return _URC_NO_REASON; 104 } 105 } 106 107 static void sigtrap(int sig, siginfo_t *info, void *ctx_void) 108 { 109 ucontext_t *ctx = (ucontext_t *)ctx_void; 110 struct unwind_state state; 111 unsigned long ip = ctx->uc_mcontext.gregs[REG_EIP]; 112 113 if (!got_sysinfo && ip == sysinfo) { 114 got_sysinfo = true; 115 116 /* Find the return address. */ 117 return_address = *(unsigned long *)(unsigned long)ctx->uc_mcontext.gregs[REG_ESP]; 118 119 printf("\tIn vsyscall at 0x%lx, returning to 0x%lx\n", 120 ip, return_address); 121 } 122 123 if (!got_sysinfo) 124 return; /* Not there yet */ 125 126 if (ip == return_address) { 127 ctx->uc_mcontext.gregs[REG_EFL] &= ~X86_EFLAGS_TF; 128 printf("\tVsyscall is done\n"); 129 return; 130 } 131 132 printf("\tSIGTRAP at 0x%lx\n", ip); 133 134 state.ip = ip; 135 state.depth = -1; 136 _Unwind_Backtrace(trace_fn, &state); 137 } 138 139 int main() 140 { 141 sysinfo = getauxval(AT_SYSINFO); 142 printf("\tAT_SYSINFO is 0x%lx\n", sysinfo); 143 144 Dl_info info; 145 if (!dladdr((void *)sysinfo, &info)) { 146 printf("[WARN]\tdladdr failed on AT_SYSINFO\n"); 147 } else { 148 printf("[OK]\tAT_SYSINFO maps to %s, loaded at 0x%p\n", 149 info.dli_fname, info.dli_fbase); 150 } 151 152 sethandler(SIGTRAP, sigtrap, 0); 153 154 syscall(SYS_getpid); /* Force symbol binding without TF set. */ 155 printf("[RUN]\tSet TF and check a fast syscall\n"); 156 set_eflags(get_eflags() | X86_EFLAGS_TF); 157 syscall(SYS_getpid, 1, 2, 3, 4, 5, 6); 158 if (!got_sysinfo) { 159 set_eflags(get_eflags() & ~X86_EFLAGS_TF); 160 161 /* 162 * The most likely cause of this is that you're on Debian or 163 * a Debian-based distro, you're missing libc6-i686, and you're 164 * affected by libc/19006 (https://sourceware.org/PR19006). 165 */ 166 printf("[WARN]\tsyscall(2) didn't enter AT_SYSINFO\n"); 167 } 168 169 if (get_eflags() & X86_EFLAGS_TF) { 170 printf("[FAIL]\tTF is still set\n"); 171 nerrs++; 172 } 173 174 if (nerrs) { 175 printf("[FAIL]\tThere were errors\n"); 176 return 1; 177 } else { 178 printf("[OK]\tAll is well\n"); 179 return 0; 180 } 181 } 182 183 #endif /* New enough libc */ 184