> On 24 Sep 2018, at 18:40, Eric Christopher <echri...@gmail.com> wrote: > > Dwarf 5, 7.3.1 > > "A DWARF expression may contain a DW_OP_addr (see Section 2.5.1.1 on 31 page > 26) which contains a location within the virtual address space of the 32 > program, and require relocation."
I think I've confused the issue by using the word relocation instead of the phrase "interpreted relative to the base address of the load object". I'm interested in the final state of an executable or shared object and I don't expect to find any remaining ELF-style (e.g. R_AMD64_64 and the like) run time (ld.so) relocations in non-loadable .debug_* sections. My question instead concerns things like initial_location in an FDE, which is interpreted relative to the base address of the enclosing load object. I can see that DW_CFA_set_loc's operand would also need to be interpreted as relative to the same base address. However, I'm trying to establish if there's anything else within .debug_frame that would be expressed relative to the same base address. For example, DW_CFA_expression assumes that the CFA is already on the stack and it would be perverse to expect the result to be anything other than an absolute address. But is the same true of DW_CFA_def_cfa_expressions? What about instructions within the expressions themselves... The DW_OP_addr case is confusing. As it's an object address its operand is highly likely to require an ELF-style (ld-style) relocation to produce an appropriate address in the linked object. However, I can see that in a shared object it would be plausible that the final, ELF-style relocated argument should additionally need to be interpreted as relative to the load object's base address. I assumed Greg was asserting the latter with: > On 24 Sep 2018, at 15:33, Greg Clayton <clayb...@gmail.com> wrote: > > Any DWARF expression can contain a DW_OP_addr, which has an address argument, > and would need to be relocated. and, not remembering any mention to the contrary in DWARF 2/3/4 wondered if this was really the case --- it would certainly have helped answer my actual concern about .debug_frame. However, the follow-up references to DWARF 5 7.3.1 and 2.5.1.1 are discussing ELF-style relocations, and are, unfortunately, red herrings. Robert _______________________________________________ Dwarf-Discuss mailing list Dwarf-Discuss@lists.dwarfstd.org http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org
