Messages in this thread | | | Date | Fri, 22 Sep 2006 13:03:21 -0400 | From | Karim Yaghmour <> | Subject | Re: [PATCH] Linux Kernel Markers 0.5 for Linux 2.6.17 (with probe management) |
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Mathieu Desnoyers wrote: > First of all, I think that specific architecture-specific optimisations can and > should be integrated in a more generic portable framework.
No disagreement there. If Ingo would care to comment, I think it might be an acceptable compromise to have x86 fully use kprobes/djprobes immediately, and the other archs could walk there at their rate. Practically, some stuff in include/asm-i386/markers.h and include/asm-x86_64/markers.h would contain the binary modifiable stuff and include/asm-generic/markers.h could contain a platform-independent fallback.
> Hrm, your comment makes me think of an interesting idea : > > .align > jump_address: > near jump to end > setup_stack_address: > setup stack > call empty function > end: > > So, instead of putting nops in the target area, we fill it with a useful > function call. Near jump being 2 bytes, it might be much easier to modify. > If necessary, making sure the instruction is aligned would help to change it > atomically. If we mark the jump address, the setup stack address and the end > tag address with symbols, we can easily calculate (portably) the offset of the > near jump to activate either the setup_stack_address or end tags.
That's another possibility. It seems more C friendly than the simple short-jump+3bytes.
Ingo?
Karim -- President / Opersys Inc. Embedded Linux Training and Expertise www.opersys.com / 1.866.677.4546 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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