Re: [PATCH] Add a text_poke syscall

[H. Peter Anvin]

Why? Live patching works fine and keys the other threads run along just fine.  We do this for ftrace already...

Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>"H. Peter Anvin" <hpa@xxxxxxxxx> writes:
>>
>> We're talking user space here, which has different requirement (COW,
>> memory protection, ...) which means it is not really the same code. 
>You
>> can't take a page fault while patching the kernel.
>
>The syscall pins the page, then it calls the kernel code.
>There are no page faults during patching.
>
>> I'm referring to if some thread actually stumbles over INT 3, which
>is
>> indeed not very long for one patch site (as long as you don't end up
>> with page faults.)  However, for tracing, you may want to do tens of
>> thousands of patches, and you really want to batch them.
>
>For tens of thousand of patches you very likely don't want 
>live patching, but a stop everything approach.
>
>-Andi

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