yunfeng zhang wrote: > The idea I got is about removing .got section in ELF format totally. > > Before we go, let's see the limitation on the idea > 1) It must be deployed on aligned segment model, such as Linux, which cs.start > = ds.start. > 2) Currently, I only know how to do on x86 ELF. > > Here is a typical sample in PIC model (shared library) when library want to > access its global data > ... > // Later code snippet template is used by gcc in almost all shared > function > // to imitate `mov %ip, %ebx'. > call next: > next: > pop %ebx // << A. > ... > movl new_offset(%ebx), %eax // << B. load global variable foo to eax. > ... > .global foo // << C. > OK!, to ld, offsetof(C - A) is const, and to gcc offsetof(B - A) is also > const, so to aligned segment model, new_offset = offset(C - A) - offset(B - > A), > right?
Surely not, because in a shared library the address of the data varies. There are in theory many copies of the library, each one with its r/w data in a different place. Andrew.
