(2013/11/27 2:23), Oleg Nesterov wrote: > On 11/26, Masami Hiramatsu wrote: >> >> (2013/11/26 4:29), Oleg Nesterov wrote: >>> +#define PSEUDO_REG_OFFSET 4096 /* arbitrary value > MAX_REG_OFFSET */ >>> + >>> +static unsigned long probe_get_register(struct pt_regs *regs, unsigned >>> long offset) >>> +{ >>> + if (offset < PSEUDO_REG_OFFSET) >>> + return regs_get_register(regs, offset); >>> + >>> + return pseudo_reg_table[offset - PSEUDO_REG_OFFSET].fetch(); >>> +} >> >> >> Hmm, I don't like this, since fetch_reg is the most frequently >> used fetch method, and it actually uses the offset in different >> way. > > Sure, this overloads the usage of FETCH_MTD_reg/offset. > > And btw, yes, the naming is ugly (I mean pseudo_*). But why this > is bad? This is cheap and simple.
I think it's not simple. The code looks short, but not well self-described. It is "hidden" in the structure, and double-meaning. > And, > >> Why don't you make another fetch function for vars? > > This is what I tried to avoid ;) I do not want to add another > FETCH_MTD_. To me, this looks like unnecessary complication and > bloat (but see below). I see, perhaps, it is a time to introduce independent fetch method implementation. Current one is not sophisticated nor generic. We need a kind of "bytecode" implementation for more complex expression, especially for the combination of several registers/variables on stacks. This feature will also be useful for some other scriptable tracers like ktap, systemtap etc. Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu...@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/