On Mon, 2007-12-17 at 16:28 -0500, Masami Hiramatsu wrote: > Hi Harvey, > If you mention about a relative jump which is inserted by > resume_execution(), I think you might misunderstand that relative jump. > > The size of that relative jump, which will be embedded by kprobe-booster, is > 5-bytes(not 1 byte). So it needs 5 bytes space. > And we decided not to expand MAX_INSN_SIZE when we developed the booster. > The reasons are: > - it is supplemental feature(just accelerating kprobes), if we have no space, > we can disable it. > - 5 bytes are big enough compared with 15(=MAX_INSN_SIZE) > - the lengths of most of instructions are less than 10 bytes. > > Additionally, MAX_INSN_SIZE is used in kernel/kprobes.c to allocate an > instruction buffer which will be assigned to p->ainsn.insn. Since the > instruction buffer size is MAX_INSN_SIZE, you can not copy instructions > more than MAX_INSN_SIZE. > > BTW, in my patch, I unified MAX_INSN_SIZE to bigger one(16). > I think it is enough for us. >
I went with 15 in mine, I thought it made the code a little more readable, but I will defer if you think 16 is better. If you want me to send the whole series to you, let me know. I just sent out a series of 4 patches equivalent to your patches 1-4/6 but based on my already unified kprobes.c/h, You may want to check your handling of restored registers in trampoline_probe_handler which I found when rebasing yours on top of my cleanups. Not sure if this is important, but it was a difference I found. X86_32: regs->cs = __KERNEL_CS | get_kernel_rpl(); yours: regs->cs = __KERNEL_CS; Harvey -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
