Messages in this thread | | | Date | Tue, 04 Feb 2014 19:05:20 +0900 | From | Masami Hiramatsu <> | Subject | Re: Re: Re: [PATCH -tip v2 4/8] perf-probe: Use _stext based address instead of the symbol name |
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(2014/02/04 18:49), Masami Hiramatsu wrote: >>> Couldn't we just use kmap->ref_reloc_sym instead of the hard-coded >>> "_stext"? You might want to check the Adrian's recent kaslr fixes (now >>> in tip/perf/urgent). >> >> Yeah, I just found Adrian's work and this series must be updated for that, >> because symbol's address is now based on the real (relocated) address. >> OK, I'll try to use a symbol in ref_reloc_sym. ;) Thank you for pointed it out! > > Hmm, I've tested using ref_reloc_sym for new version, setting probes was OK, > but getting the address of "_text" always failed. It seems that the kmaps > doesn't make a symbol for "_text", on the other hand, "_stext" seems always > available. So I think there are two ways to fix this, use "_stext" as this > version, or use "_text" and fix dso__load_sym to load "_text" as a function > symbol if exist. > I'm not sure why the "_text" is not loaded, is that a policy?
Ah, I see. "_text" is not a function, just a label. That is why it is not found in function map. Hmm, in that case, maybe I should use a special case for checking reference symbol is a ref_reloc_sym and if so, use ref_reloc_sym->unrelocated_addr.
Thank you,
-- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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