[Dwarf-Discuss] .debug_frame and the base address

Greg Clayton clayborg at gmail.com
Mon Sep 24 07:33:11 PDT 2018



> On Sep 24, 2018, at 7:15 AM, Robert Harris via Dwarf-Discuss <dwarf-discuss at lists.dwarfstd.org> wrote:
> 
> I'd like some clarification regarding what precisely needs to be relocated relative to
> the object load address when interpreting .debug_frame.  I'm interested in versions
> 2, 3 and 4.
> 
> I think the only explicit mention of relocation in DWARF 4 is § 6.4.1:
> 
> 	Abstractly, this mechanism describes a very large table...
> 	...
> 	The first column indicates an address for every location that contains
> 	code in a program. (In shared objects, this is an object-relative offset.)
> 
> Thus adjustments need to be made to only
> 
> 	An FDE's initial_location field
> 	DW_CFA_set_loc's operand
> 
> Have I missed anything?  I see some ambiguity in the definition of
> DW_CFA_def_cfa_expression and it's making me wonder if there are any
> other occasions when a result would require relocation.

Any DWARF expression can contain a DW_OP_addr, which has an address argument, and would need to be relocated. 

> 
> Robert Harris
> 	
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