(2013/11/23 6:21), Andi Kleen wrote: > On Wed, Nov 20, 2013 at 04:22:21AM +0000, Masami Hiramatsu wrote: >> Use NOKPROBE_SYMBOL macro to protect functions from kprobes >> instead of __kprobes annotation in trap.c. >> This also applies __always_inline annotation for some cases, >> because NOKPROBE_SYMBOL() will inhibit inlining by referring >> the symbol address. > > NOKPROBE_SYMBOL seems to add a reference from some variable to the function? > > With LTO we can optimize away unused functions, but not > when there are references to the symbol. So this would likely > prevent optimizations with LTO. After considering this problem deeper, I decide to say NO against to your opinion. IMHO, the LTO is just an optimization, on the other hand, NOKPROBE_SYMBOL is more important because it is for avoiding kernel crash. I mean, the safety and stability should be prior to the performance. Anyway, such side-effect of NOKPROBE_SYMBOL looks very limited. Perhaps, less than 1% of functions will be marked. How much does it affect for the optimization? Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@xxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
