Quuxplusone
commented
3 years ago I don't think that's quite what is going on. "thread return" doesn't change the stop reason for the thread (because it doesn't actually cause the thread to run it just changes the pc & sp). So until you run again the stop reason is going to be the same.
When you do run again, the process crashes with an EXC_BAD_ACCESS on a different address. The first one was "address=0x7b", the last one was "address=0x27e80d". In this case it looks like we did proceed correctly from the "thread return" but your attempt to repair the session was unsuccessful, and lead to us crashing somewhere else.
This seems correct behavior to me.
Repro:
Using the following test code:
// bad_access.cc 1 // bad_access.cc 2 #include
3 #include
4
5 int bad_acc(void){ 6 printf("in bad_acc()\n"); 7
8 // cause bad mem access here 9 return (int)(123); 10 } 11
12 int main () { 13 printf( "hello world\n"); 14 // bad access here 15 bad_acc(); 16 printf("bye world\n"); 17 return 0; 18 } vyng-macbookpro2% // Compile and run with lldb:
% clang -g -o bad_acc bad_access.cc % lldb (lldb) target create "bad_acc" Current executable set to '/bad_acc' (x86_64).
(lldb)
Current executable set to '/bad_acc' (x86_64).
(lldb) run
Process 97548 launched: '/bad_acc' (x86_64)
hello world
in bad_acc()
Process 97548 stopped
8 // cause bad mem access here -> 9 return (int)(123); 10 } 11
12 int main () { Target 1: (bad_acc) stopped. (lldb) thread return
main at bad_access.cc:16:3 13 printf( "hello world\n"); 14 // bad access here 15 bad_acc(); -> 16 printf("bye world\n"); 17 return 0; 18 } (lldb) register write pc$pc-8(lldb) register write pc$pc-8` (lldb) btmain at bad_access.cc:13:3 frame #1: 0x00007fff204e8f5d libdyld.dylibstart + 1 frame #2: 0x00007fff204e8f5d libdyld.dylib`start + 1 (lldb) n Process 97548 stopped12 int main () { -> 13 printf( "hello world\n"); 14 // bad access here 15 bad_acc(); 16 printf("bye world\n"); Target 1: (bad_acc) stopped.
Details:
After the processed stopped on bad_access.cc:9, I used
thread returnand tworegister write pc$pc-8`` hoping to get back to bad_access.cc:13 to restart the exececution.btshowed that we were now back to line 13).