Libunwind for (FreeBSD) kernel

About

This is project was started in order to bring libunwind to the FreeBSD kernel. Why would you want libunwind in the kernel? To support no-cost exception handling in Objective-C (see https://github.com/charlieMonroe/libobjc-kern).

Source code

Simply modifying the libunwind code is almost impossible. Hence only relevant parts have been taken and put together in this project - most of the remote-related code has been removed (though some might have been left there) and generally only the x86-64-related code has been left.

Obstacles

Unfortunately, this project isn't finished - it compiles and runs as a separate kernel module, can create backtraces, but cannot unwind stack. This is because it fails to find sufficient data in the .eh_frame section and ends up guessing the stack pointer based on rsb, which results in a very wrong value most of the time.

If you want to go have a whack at it, the relevant code is in the Gfind_proc_info-lsb.c, where the linear_search function fails finding the needed info.

Name		Name	Last commit message	Last commit date
Latest commit History 227 Commits
include		include
setjmp		setjmp
.gitignore		.gitignore
Gcreate_addr_space.c		Gcreate_addr_space.c
Gdestroy_addr_space.c		Gdestroy_addr_space.c
Gdyn-extract.c		Gdyn-extract.c
Gexpr.c		Gexpr.c
Gfde.c		Gfde.c
Gfind_dynamic_proc_info.c		Gfind_dynamic_proc_info.c
Gfind_proc_info-lsb.c		Gfind_proc_info-lsb.c
Gfind_unwind_table.c		Gfind_unwind_table.c
Gget_accessors.c		Gget_accessors.c
Gget_fpreg.c		Gget_fpreg.c
Gget_proc_info.c		Gget_proc_info.c
Gget_proc_info_by_ip.c		Gget_proc_info_by_ip.c
Gget_proc_name.c		Gget_proc_name.c
Gget_reg.c		Gget_reg.c
Gget_save_loc.c		Gget_save_loc.c
Gglobal.c		Gglobal.c
Ginit.c		Ginit.c
Ginit_local.c		Ginit_local.c
Gos-freebsd.c		Gos-freebsd.c
Gparser.c		Gparser.c
Gpe.c		Gpe.c
Gput_dynamic_unwind_info.c		Gput_dynamic_unwind_info.c
Gregs.c		Gregs.c
Gresume.c		Gresume.c
Gset_caching_policy.c		Gset_caching_policy.c
Gset_fpreg.c		Gset_fpreg.c
Gset_reg.c		Gset_reg.c
Gstash_frame.c		Gstash_frame.c
Gstep.c		Gstep.c
Gtrace.c		Gtrace.c
Lcreate_addr_space.c		Lcreate_addr_space.c
Ldestroy_addr_space.c		Ldestroy_addr_space.c
Ldyn-extract.c		Ldyn-extract.c
Ldyn-remote.c		Ldyn-remote.c
Lexpr.c		Lexpr.c
Lfde.c		Lfde.c
Lfind_dynamic_proc_info.c		Lfind_dynamic_proc_info.c
Lfind_proc_info-lsb.c		Lfind_proc_info-lsb.c
Lfind_unwind_table.c		Lfind_unwind_table.c
Lget_accessors.c		Lget_accessors.c
Lget_fpreg.c		Lget_fpreg.c
Lget_proc_info.c		Lget_proc_info.c
Lget_proc_info_by_ip.c		Lget_proc_info_by_ip.c
Lget_proc_name.c		Lget_proc_name.c
Lget_reg.c		Lget_reg.c
Lget_save_loc.c		Lget_save_loc.c
Lglobal.c		Lglobal.c
Linit.c		Linit.c
Linit_local.c		Linit_local.c
Los-freebsd.c		Los-freebsd.c
Lparser.c		Lparser.c
Lpe.c		Lpe.c
Lput_dynamic_unwind_info.c		Lput_dynamic_unwind_info.c
Lregs.c		Lregs.c
Lresume.c		Lresume.c
Lset_caching_policy.c		Lset_caching_policy.c
Lset_fpreg.c		Lset_fpreg.c
Lset_reg.c		Lset_reg.c
Lstash_frame.c		Lstash_frame.c
Lstep.c		Lstep.c
Ltrace.c		Ltrace.c
Makefile		Makefile
Readme.md		Readme.md
Unwind.c		Unwind.c
_ReadSLEB.c		_ReadSLEB.c
_ReadULEB.c		_ReadULEB.c
backtrace.c		backtrace.c
dwarf_Gstep.c		dwarf_Gstep.c
dwarf_Lstep.c		dwarf_Lstep.c
dyn-cancel.c		dyn-cancel.c
dyn-register.c		dyn-register.c
elf64.c		elf64.c
elf64.h		elf64.h
elfxx.c		elfxx.c
elfxx.h		elfxx.h
flush_cache.c		flush_cache.c
getcontext.S		getcontext.S
global.c		global.c
init.c		init.c
init.h		init.h
is_fpreg.c		is_fpreg.c
libunwind.c		libunwind.c
longjmp.S		longjmp.S
malloc_types.c		malloc_types.c
mempool.c		mempool.c
offsets.h		offsets.h
os-freebsd-kern.c		os-freebsd-kern.c
regname.c		regname.c
remote.h		remote.h
setcontext.S		setcontext.S
siglongjmp.S		siglongjmp.S
strerror.c		strerror.c
ucontext_i.h		ucontext_i.h
unwind-internal.h		unwind-internal.h
unwind_i.h		unwind_i.h

charlieMonroe/libunwind-kern

Folders and files

Latest commit

History