On Fri, Nov 9, 2012 at 12:43 PM, Jonathan Wakely <jwakely.gcc@xxxxxxxxx> wrote: > On 9 November 2012 11:18, phi gcc wrote: >> >> Just wanted to precise that I was asking for x32 (x86 32 bits) not > > If you want to be precise then don't call it x32, that's something > completely different: http://en.wikipedia.org/wiki/X32_ABI > > If you mean x86 then just say x86, or IA-32 in Intel-speak. Well the suject is 'x86...' yet I got comment on x64 :) no blame, it is confusing :) To reply to Ian, yes I do unwind binary for wich I "don't want" to recompile, these are linux crashdump from all different kind of sources, often pretty old version, because production customers do keep old versions. Basically I triage them, before digging more in them. "Don't want" because no time for this, got the crashdump, run my kernel crashdump debugger, and that's it. This is even worst than that because linux world keep stripping the debug infos, and then they are non reliable when eventually retrieved back. So far I saw those calling conv non-static static non-static-fastcall old-gcc a4 16(%esp) 4(%esp) 8(%esp) 8(%esp) a3 12(%esp) 0(%esp) 4(%esp) 4(%esp) a2 8(%esp) ecx 0(%esp) 0(%esp) a1 4(%esp) edx edx edx a0 0(%esp) eax ecx eax The idea is to figure out in the call site what arg location has been loaded (if lucky) na=0 if ax is loaded it is a0 na=1 if dx is loaded it is a1 na=2 if cx is loaded if ax not loaded it is a0 if(!na)na=1 if ax loaded it is a3 na=3 0(sp) is a$na na++ 4(sp) is a$na na++ 8(sp) is a$na na++ I guess that for x86 (32 bits) gcc could do more tricks on static leaf (terminal) functions, but I never got a panic in such functions, probably because they simply got inlined then :) the old-gcc path could be hosed if a cx is loaded as temporary during the call site, it would make my heuristics think we are in hte cx as a2 case... All this is just for naming the args (regs or stack loc) this is not for fetching their values, this is another story that goes with callee save propagation from save state, frame tracking, and stack access. When asking I was hoping that I could find out quicker than just probing dumps to find out how many calling conv was use with gcc. I am gcc internals ignorant, I can download each gcc source code used for a given kernel build (got the gcc version there), then try to see if there is a config file for x86 (32bits) that would describe the calling conv for this version of gcc, but could not find this so far for old gcc. What would be a common place to look? I did loolk at libffi but it doesn't help. Thanx to all. Cheers, Phi
