Re: [PATCH v5 21/27] x86/ftrace: Adapt function tracing for PIE support

[Steven Rostedt]

On Mon, 25 Jun 2018 15:39:09 -0700
Thomas Garnier <thgarnie@xxxxxxxxxx> wrote:

> When using PIE with function tracing, the compiler generates a
> call through the GOT (call *__fentry__@GOTPCREL). This instruction
> takes 6-bytes instead of 5-bytes with a relative call.
> 
> If PIE is enabled, replace the 6th byte of the GOT call by a 1-byte nop
> so ftrace can handle the previous 5-bytes as before.
> 
> Position Independent Executable (PIE) support will allow to extend the
> KASLR randomization range 0xffffffff80000000.
> 
> Signed-off-by: Thomas Garnier <thgarnie@xxxxxxxxxx>

Thanks for doing it this way.

Reviewed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>

-- Steve