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S. P. Prasanna wrote: >> >> Yes, that's simple. but slower, as you have a double jump. Probably >> a damned sight faster than int3 though. >> >> M. >> > > The advantage of using int3 over jmp to launch the instrumented > module is that int3 (or breakpoint in most architectures) is an > atomic operation to insert. > Yes, 5 bytes is not an atomic write except on 64-bit. So a race is possible. How about this workaround: 1. Overwrite the start of the function with a hlt, which is atomic. 2. Write that 5-byte jump after the hlt. 3. Overwrite the hlt with nop so things will work 4. interrupt any cpus that got stuck on the hlt - or just wait for the timer. Helge Hafting - 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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