On Fri, 28 Jul 2006 11:32:23 -0700, David Daney <ddaney@xxxxxxxxxx> wrote: > >> This was always the tricky part for me. How do you know if the > >> function is a leaf? > > > > I think that if you cannot find a store instruction which saves RA to > > the stack -- either because it's a real leaf and there is no such store, > > or because the PC hasn't yet reached the store instruction -- then in > > both cases it can be treated as a leaf. Right. > Presumably you are walking the code back from the PC until you find the > prolog. How would you tell if you had gone past the beginning of a leaf > function? If you find a j $31 you might assume that it was the end of > the previous function. I think you are misunderstanding here. What the get_frame_info() doing is just searching "sw $ra, ofs($sp)" and "addiu sp,sp,-imm" instructions from beginning of the function. We can obtain the start address and size of the function by kallsyms_lookup(). This is why those stuff depend on CONFIG_KALLSYMS. > I may be missing something here, if you know of a failure-proof manner > to detect leaf functions I would appreciate hearing what it is. I have no good idea to do it without CONFIG_KALL_SYMS. I suppose there is no silver bullet here... --- Atsushi Nemoto
