1 /* This test program is part of GDB, the GNU debugger. 2 3 Copyright 2015-2019 Free Software Foundation, Inc. 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 17 18 /* This is the test program loaded into GDB by the py-unwind test. */ 19 20 #include <stdint.h> 21 #include <stdio.h> 22 #include <stdlib.h> 23 24 static void * 25 swap_value (void **location, void *new_value) 26 { 27 void *old_value = *location; 28 *location = new_value; 29 return old_value; 30 } 31 32 static void 33 bad_layout(void **variable_ptr, void *fp) 34 { 35 fprintf (stderr, "First variable should be allocated one word below " 36 "the frame. Got variable's address %p, frame at %p instead.\n", 37 variable_ptr, fp); 38 abort(); 39 } 40 41 #define MY_FRAME (__builtin_frame_address (0)) 42 43 static void 44 corrupt_frame_inner (void) 45 { 46 /* Save outer frame address, then corrupt the unwind chain by 47 setting the outer frame address in it to self. This is 48 ABI-specific: the first word of the frame contains previous frame 49 address in amd64. */ 50 void *previous_fp = swap_value ((void **) MY_FRAME, MY_FRAME); 51 52 /* Verify the compiler allocates the first local variable one word 53 below frame. This is where the test unwinder expects to find the 54 correct outer frame address. */ 55 if (&previous_fp + 1 != (void **) MY_FRAME) 56 bad_layout (&previous_fp + 1, MY_FRAME); 57 58 /* Now restore it so that we can return. The test sets the 59 breakpoint just before this happens, and GDB will not be able to 60 show the backtrace without JIT reader. */ 61 swap_value ((void **) MY_FRAME, previous_fp); /* break backtrace-broken */ 62 } 63 64 static void 65 corrupt_frame_outer (void) 66 { 67 /* See above for the explanation of the code here. This function 68 corrupts its frame, too, and then calls the inner one. */ 69 void *previous_fp = swap_value ((void **) MY_FRAME, MY_FRAME); 70 if (&previous_fp + 1 != (void **) MY_FRAME) 71 bad_layout (&previous_fp, MY_FRAME); 72 corrupt_frame_inner (); 73 swap_value ((void **) MY_FRAME, previous_fp); 74 } 75 76 int 77 main () 78 { 79 corrupt_frame_outer (); 80 return 0; 81 } 82