Thread specific data from linux core dump
coredump, gdb, linux
Solution
If you're debugging a live program, you can:
print pthread_getspecific(i)
If you have access to the pthread_t of the thread, you can:
print ((struct pthread*)pth)->specific[i/32][i%32]
where i in the index you want and pth is the pthread_t. See nptl/pthread_getspecific.c in the glibc sources.
To do this without calling a function, you need to find the struct pthread. On x86-64, it's stored in the fs base, which is set using arch_prctl(ARCH_SET_FS_BASE, ...). I don't know how to access this from gdb, but you can get it with eu-readelf. Run `eu-readelf --notes core_file` and look through the records for `fs.base`. That number is the pthread_t value. (To figure out which one it is, you can match up the `pid` field in the same record with the LWP shown in gdb's `info threads` command.)
Good luck!
Problem
How do I get pointer to thread's local storage or thread specific data while analyzing core dump for Linux ? I use `pthread_setspecific` to store some data in the `pthread`'s local storage. my multi threaded program on Linux crashed, and I want to see what is stored in current running thread's local storage. If I get pointer to thread's local storage I can use key to get the data that is stored. Is there a command in gdb to get the pointer to thread's local storage?