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| -rw-r--r-- | explore-elf.txt | 51 | ||||
| -rw-r--r-- | runtime-ld.txt | 62 |
2 files changed, 113 insertions, 0 deletions
diff --git a/explore-elf.txt b/explore-elf.txt new file mode 100644 index 0000000..d5bde46 --- /dev/null +++ b/explore-elf.txt @@ -0,0 +1,51 @@ +.:: Explore Elf ::. +-------------------------------------------------------------------------------- + +# toc +------ + |readelf| + |objdump| + |nm| + |c++filt| + +# readelf(1) *readelf* +============= + args: + --wide dont break output at 80 chars + -h print ELF header + -S print sections headers + -l print program headers + -d print dynamic section + -s print symbol table + +# objdump(1) *objdump* +============= + args: + -M intel use intil syntax + -d disassemble text section + -D disassemble all sections + -S mix disassembly with source code + -C demangle + -j <section> display info for section + --[no-]show-raw-insn [dont] show object code next to disassembly + + ## disassemble .plt section + objdump -j .plt -d <elf_file> + +# nm(1) *nm* +======== + args: + -C demangle + -u undefined only + +# c++filt(1) *c++filt* +============= + ## demangle symbol + c++-filt <symbol_str> + + ## demangle stream + nm <elf_file> | c++filt + +-------------------------------------------------------------------------------- +vim:sts=2:et:tw=80:cc=80:fo+=t:ft=help + diff --git a/runtime-ld.txt b/runtime-ld.txt new file mode 100644 index 0000000..86fe9ad --- /dev/null +++ b/runtime-ld.txt @@ -0,0 +1,62 @@ +.:: Runtime ld ::. +-------------------------------------------------------------------------------- + +# toc +------ + |ld_so| + |load_init_order| + +# ld.so(8) *ld_so* +=========== + env: + LD_PRELOAD=<l_so> colon separated list of libso's to be pre loaded + LD_DEBUG=<opts> comman separated list of debug options + =help list available options + =libs show library search path + =files processing of input files + =symbols show search path for symbol lookup + =bindings show against which definition a symbol is bound + + + ## LD_PRELOAD load & init order *load_init_order* + > ldd ./main + >> libc.so.6 => /usr/lib/libc.so.6 + + > LD_PRELOAD=liba.so:libb.so ./main + --> + preloaded in this order + <-- + initialized in this order + + - preload order determines the order libs are inserted into the link map + + - resulting link map: + +------+ +------+ +------+ +------+ + | main | -> | liba | -> | libb | -> | libc | + +------+ +------+ +------+ +------+ + + - see preload and init order in action + > LD_DEBUG=files LD_PRELOAD=liba.so:libb.so ./main + # load order (-> determines link map) + >> file=liba.so [0]; generating link map + >> file=libb.so [0]; generating link map + >> file=libc.so.6 [0]; generating link map + + # init order + >> calling init: /usr/lib/libc.so.6 + >> calling init: <path>/libb.so + >> calling init: <path>/liba.so + >> initialize program: ./main + + - see the symbol lookup in action and therefore the link map order + > LD_DEBUG=symbols,bindings LD_PRELOAD=liba.so:libb.so ./main + >> symbol=memcpy; lookup in file=./main [0] + >> symbol=memcpy; lookup in file=<path>/liba.so [0] + >> symbol=memcpy; lookup in file=<path>/libb.so [0] + >> symbol=memcpy; lookup in file=/usr/lib/libc.so.6 [0] + >> binding file ./main [0] to /usr/lib/libc.so.6 [0]: normal symbol + `memcpy' [GLIBC_2.14] + +-------------------------------------------------------------------------------- +vim:sts=2:et:tw=80:cc=80:fo+=t:ft=help + |