* Ingo Molnar (mingo@xxxxxxx) wrote: > > * Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx> wrote: > > > Woooow, just a sec here. I removed the atomicity test _because_ there > > happen to be a case where it's safe to do non-atomic instruction > > modification. If we do : > > > > 1) replace the instruction first byte by a breakpoint, execute an > > instruction bypass (see the immediate values patches for detail) > > 2) modify the instruction non-atomically > > 3) put back the original instruction first byte. > > > > That's why I removed the BUG_ONs at the beginning of the function. > > That's also why it's required to deal with page crossing. > > but the code as-is is nonsensical. It checks for: > > BUG_ON(len > sizeof(long)); > > but then deals with page crossing... > That was in the initial version, before my patch, yes. I dealt with page crossing at first, then added a more restrictive test to "play safe" (I should have removed the page-crossing code at that point), but later on noticed that there was a single case where it's valid to do non-atomic updates, and it's when the execution flow is bypassed by a breakpoint (as the immediate values are doing), so the last patch you have removes the restrictive test and lets the page-crossing code in place. > it should also rename text_poke_early() to text_poke_core(), and call > _that_ from text_poke() if core_kernel_text(). From that alone the whole > poke_text() function would look a whole lot cleaner. > hrm, I am not convinced it's safe to call vmap() very early at boot time. In the immediate values implementation, I do call text_poke very very early at boot to populate the initial values. Or maybe are you proposing something different from what I currently understand ? Mathieu > Ingo -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
