A userspace process can call modify_ldt(2) to alter entries of its LDT. A debugger, to make correct analysis of what the process reads and where, as well as what code it executes currently, needs to know what descriptor a value of e.g. CS=0x7 selects.
Currently the only way I think could possibly work is injecting some code into debuggee to retrieve the LDT, executing it and then returning back to original state. But this is quite error-prone and is likely to break the debugger user's workflow e.g. when signals arrive.
So is there a better way? I've googled something like PTRACE_LDT, but the pages are from 2005, and grepping modern linux source doesn't find anything relevant to x86 other than comments.
